United States Department of Agriculture

Forest 

Service

General Technical 

Report NRS-143

Northern 

Research Station January 2015

ROMI 4.0: Rough Mill Simulator 

4.0 Users Manual

R. Edward Thomas, Timo Grueneberg, 

and Urs Buehlmann
Abstract

The Rough MIll simulator (ROMI Version 4.0) is a computer software package for 

personal computers (PCs) that simulates current industrial practices for rip-first, chopfirst, and rip and chop-first lumber processing. This guide shows how to set up the 

software; design, implement, and execute simulations; and examine the results. ROMI 

4.0 accepts cutting bills with as many as 600 solid and/or panel part sizes. Plots of 

boards processed are easily viewed or printed as are detailed summaries of processing 

data (number of rips and crosscuts) and yields for each grade. ROMI 4.0 optimization 

algorithms are based on a red oak database containing 3,500 boards of all common 

National Hardwood Lumber Association grades. Even though ROMI is based on red oak, 

the digitized board information can be adapted and modified to several other common 

hardwood species. 

Note: This report is updated from ROMI 3: Rough Mill Simulator Version 3.0: User’s 

Guide, General Technical Report NE-328, by J. Weiss and R.E. Thomas, published 

in 2005.

The Authors

R. EDWARD THOMAS is a research computer scientist with the U.S. Forest Service, 

Northern Research Station at Princeton, West Virginia. 

TIMO GRUENEBERG is a research scientist at Virginia Polytechnic Institute and State 

University (Virginia Tech). 

URS BUEHLMANN is an associate professor at Virginia Tech’s Department of 

Sustainable Biomaterials. 

The use of trade, firm, or corporation names in this publication is for the 

information and convenience of the reader. Such use does not constitute an 

official endorsement or approval by the U.S. Department of Agriculture or the 

Forest Service of any product or service to the exclusion of others that may 

be suitable.

For additional copies:

U.S. Forest Service

Publications Distribution

359 Main Road

Delaware, OH 43015-8640

Fax: 740-368-0152

Published by:

U.S. FOREST SERVICE

NORTHERN RESEARCH STATION

11 CAMPUS BLVD, STE 200 

NEWTOWN SQUARE, PA 19073-3294

January 2015
The computer program ROMI 4.0, described in this publication, is available upon 

request with the understanding that the U.S. Department of Agriculture cannot assure its 

accuracy, completeness, reliability, or suitability for any other purpose than that reported. 

The recipient may not assert any proprietary rights thereto nor represent it to anyone as 

other than a Government-produced computer program.

For an executable copy of the program, write to:

U.S. FOREST SERVICE 

NORTHERN RESEACH STATION 

ATTN: EDWARD THOMAS

241 MERCER SPRINGS ROAD 

PRINCETON, WV 24740

VIRGINIA TECH

DEPT. OF SUSTAINABLE BIOMATERIALS 

ATTN: URS BUEHLMANN 

BROOKS CENTER 0503 

BLACKSBURG, VA 24061

or email: ethomas@fs.fed.us

or download from: www.nrs.fs.fed.us/tools/ROMI
Contents

1 Introduction .............................................................................................................. 1

2 Installation of ROMI 4.0 under Windows 7 ............................................................... 3

 2.1 Windows Virtual PC (XP mode system) ............................................................. 4

 2.2 In the Users Directory of Windows 7 .................................................................. 4

 2.3 On the Desktop under Windows 7 (default installation) ..................................... 4

3 Installation ................................................................................................................ 5

 3.1 Running the Install Program ............................................................................... 5

 3.2 Starting ROMI 4.0 ............................................................................................ 10

4 Using ROMI 4.0 ......................................................................................................11

 4.1 Defining and Selecting Part Grades .................................................................11

 4.1.1. Clear-Two-Face (C2F) Part Grades ........................................................... 13

 4.1.2 Clear-One-Face Part Grades (C1F) ........................................................... 14

 4.1.3 Sound-Two-Face Part Grades (C2F) ......................................................... 15

 4.1.4 Re-Rip/Salvage Part Grades ..................................................................... 16

 4.1.5 Part Grades: An Additional Feature............................................................ 16

 4.1.6 Predefined Part Grades based on Wood Component 

 Manufacturer Association specifications ................................................... 17

 4.2 Cutting Bill Setup ............................................................................................. 19

 4.2.1 Opening and Importing Cutting Bills .......................................................... 19

 4.2.2 Cutting Bill Editing ..................................................................................... 20

 4.2.3 Cutting Modes ........................................................................................... 21

 4.2.4 ChopSaw Setup ........................................................................................ 22

 4.2.5 RipSaw Setup ........................................................................................... 24

 4.2.6 Mill Control Setup ...................................................................................... 28

 4.2.7 Salvage Parts Setup .................................................................................. 29

 4.2.8 Prioritization Setup .................................................................................... 30

 4.2.9 Part Scheduling and Replacement ............................................................ 31

 4.2.10 Predefined Cutting Bill Examples ............................................................ 31

5 Datafile Selection ................................................................................................... 33

 5.1 Customize BoardData for Datafile Selection .................................................... 33

 5.2 Creating Custom Grade Mix and Specified Files ............................................. 33

 5.2.1 Custom Grade Mix .................................................................................... 34

 5.2.2. Choose Boards ......................................................................................... 38

 5.2.3. File Control ............................................................................................... 42

6 Output Options ....................................................................................................... 43

 6.1 Selecting an Output File .................................................................................. 43

6.2 Thickness Option ............................................................................................. 43
7 Starting the Analysis .............................................................................................. 45

 7.1 Pre-Run Checking for Errors ............................................................................. 45

 7.2 Interactive Mode ............................................................................................... 46

 7.3 Batch Mode ...................................................................................................... 46

8 Simulation Results ................................................................................................. 48

 8.1 View Simulation Results................................................................................... 48

 8.2 Yield Summary Results .................................................................................... 49

 8.3 Summary Table Results ................................................................................... 49

 8.4 Cutting Bill Results ........................................................................................... 50

 8.5 Board Plots ...................................................................................................... 51

9 Least Cost Grade Mix ............................................................................................ 54

 9.1 Setup ............................................................................................................... 54

 9.2 Results ............................................................................................................. 55

10 The Mechanics of ROMI 4.0 .................................................................................. 56

 10.1 Gang-Ripsaws ............................................................................................... 56

 10.1.1 Fixed Blade Arbors ................................................................................... 56

 10.1.2 Best-Spacing-Sequence Arbors ............................................................... 58

 10.1.3 All-Blades-Movable Arbor ......................................................................... 58

 10.1.4 Optimizing Arbor Comparison .................................................................. 59

 10.1.5 Optimizing Fixed-Blade Saw Spacing Sequences ................................... 61

 10.2 Part Prioritization ............................................................................................ 61

 10.2.1 Value-based Part Prioritizing ................................................................... 62

 10.2.2 Area-Based Part Prioritizing .................................................................... 62

 10.2.3 Dynamic Part Prioritizing ......................................................................... 63

 10.2.4 Selecting a Part-Prioritizing Strategy ....................................................... 64

 10.2.5 Processing Salvage Parts ........................................................................ 64

 10.2.6 Smart Salvage ......................................................................................... 65

11 User Information Features ..................................................................................... 66

 11.1 Cutting Bill Information .................................................................................... 66

 11.2 Help ................................................................................................................ 67

 11.2.1 Help Menu ................................................................................................ 69

Acknowledgments ...................................................................................................... 78

Literature Cited ........................................................................................................... 78

Appendix I .................................................................................................................. 80

Appendix II ................................................................................................................ 81
Page intentionally left blank
1

1 INTRODUCTION

Version 4.0 of the ROMI (Rough Mill Simulator) is the latest in a series of rough mill 

simulation programs developed by the U.S. Forest Service in cooperation with the 

Department of Sustainable Biomaterials at Virginia Polytechnic Institute and State 

University (Virginia Tech). The ROMI 4.0 installation CD contains sample runs, all 

required programs, and the publication 1998 Data Bank for Kiln-Dried Red Oak 

Lumber (Gatchell et al. 1998), which includes nearly 3,500 digitized boards. A digitized 

board is a board with dimensions and defects expressed in x/y coordinates, e.g., a 

digital representation of the actual board. A custom data file creation utility included 

in the software package allows users to create board samples that correspond to 

their specific lumber supply. ROMI 4.0 processes the board data according to users’ 

processing specifications. Outputs, including part counts and yields, graphical plots of 

boards processed, and processing requirements are available for each simulation run. 

This manual shows users how to install and run ROMI 4.0, as well as how to design 

simulations to answer questions related to rough mill processing.

The ROMI 4.0 simulator incorporates the simulation modes rip-first, chop-first, and 

rip and chop-first into a single program. Thus, ROMI 4.0 officially replaces all previous 

versions of the ROMI 3.0 Rough-Mill Simulator (Thomas and Weiss 2006), the ROMIRIP 2.0 (Thomas 1999), and ROMI-CROSS (Thomas 1997) computer programs. ROMI 

4.0 can import all settings and cutting bills from these earlier simulators. Like earlier 

versions, ROMI 4.0 can produce parts of different quality specifications to simulate the 

production of clear-two-face (C2F), clear-one-face (C1F), and sound-two-face (S2F) 

parts. ROMI 4.0 also can handle different predefined part grades and includes the LeastCost-Grade Mix feature (Buehlmann et al. 2011, Zou et al. 2004).

The ROMI 4.0 simulator incorporates several new tools that improve user capabilities to 

accurately simulate and improve rough mill operations while simplifying the simulation 

process. The core functions and routines remain similar to the previous version for 

practiced users. Versions up to ROMI 3.0 were optimized for computer operating 

systems up to Windows® XP. ROMI 4.0 received a new installation routine that is now 

compatible with Windows 7. The improvements will allow an easier setup, improved 

performance, and better analysis of the simulation’s output data.

ROMI 4.0 also includes several additional new features, such as a thickness option, 

a combined rip and chop option, and predefined grades for part qualities rules. These 

features give users more options to simulate specific rough mill operation settings and 

optimize output. Also, implementation and update of the National Hardwood Lumber 

Association’s 2011 grading rules (NHLA 2011) was part of this updated version of 

ROMI 4.0 as were improvements and verifications of the optimization algorithms.

Limitations to ROMI 4.0 are listed in Appendix I.
2

The minimum computer system requirements to run ROMI 4.0 are:

• An IBM Compatible PC with a 1.0 GHz Pentium IV processor or newer

• 512 MB of RAM

• 200 MB hard drive space available

• Microsoft Windows® 2000/XP/Windows71

• CD-ROM drive (for installation from a ROMI 4.0 CD-ROM)

• Internet connection (for installation via download)

• Printer (optional but recommended)

To avoid confusion and make this users guide easier to understand, several conventions 

have been adopted for displaying operating system and ROMI 4.0 prompts and inputs. 

For all prompts and buttons, text is in italics. For choices on the user interface, bold

is used.

1

Microsoft Windows® 2000/XP/Windows7 are registered trademarks of Microsoft Corporation, Inc.
3

2 INSTALLATION OF ROMI 4.0 UNDER WINDOWS 7

The installation of ROMI 4.0 under the Windows 7 environment requires some additional 

actions compared to earlier versions of Windows. To install and run ROMI 4.0 under 

Windows 7, two options are shown in this manual. You can decide which will be best 

for your personal needs. Also, local requirements, such as user privileges, have to be 

determined with the computer’s administrator.

With the release of Windows 7, Microsoft Corporation changed the default folder and file 

attributes. Per default, all folders and files are selected as read only (Fig. 2.1.1). Even 

though Windows 7 might let users change the attributes from read only to full access, 

the change is not transferred, which means that the option chosen will not be saved and 

Windows 7 will overrule the users’ specifications based on the system’s security settings 

(Fig. 2.1.2)

Figure 2.1.1—Properties of a folder with 

its attributes; read-only option is the 

default setting that cannot be removed.

Figure 2.1.2.—Read-only option setting 

change is not transferred by Windows 7 and 

is “overruled” by the system.

The installation and operation of ROMI 4.0 requires that full attributes (reading and 

writing rights) of folders and subfolders are granted (Fig. 2.1.3). With the original attribute 

settings of Windows 7, ROMI 4.0 cannot be used. Therefore, this manual explains two 

ways to solve the issue of installing and operating ROMI 4.0 under Windows 7.
4

Figure 2.1.3—Advanced attributes of Windows 7 

folders.

2.1 Windows Virtual PC (XP mode system)

The first option to run ROMI 4.0 is the installation of a Windows Virtual PC using a XP 

Mode System, which needs to be downloaded for free from Microsoft. This setup allows 

you to install ROMI 4.0 in any directory or folder. Due to the setup of the XP system, the 

“read and write”-attributes can be modified and will not be overruled by the XP system. 

To download and install the Windows Virtual PC, visit the Web address below:

http://www.microsoft.com/en-us/download/details.aspx?id=19889

Once you have successfully installed Windows Virtual PC XP mode, you can proceed 

with the installation of ROMI 4.0 in the installed Virtual PC XP mode.

2.2 In the Users Directory of Windows 7

Another way to install ROMI 4.0 in Windows 7 is to install ROMI 4.0 in the 

Users Directory. Note, if you are using Windows 7, it is recommended that you change 

the install directory to your user directory. Figure 3.1.2 shows the Users Directory folders 

for the installation of ROMI 4.0.

You can browse the directories by double clicking the file names or by manually entering 

a path in the box at the top of the window. To change the drive you are browsing, click 

the drop down arrow at the top left of the screen. For example, under Windows 7, if 

your user name is “Johnson,” then you would install ROMI 4.0 to the directory “c:\users\

johnson\ROMI-4.” Click OK when you are satisfied with the install directory.

2.3 On the Desktop under Windows 7 (default installation)

The default option for installing ROMI 4.0 is on the user’s desktop. Using this installation 

procedure, you can follow the instruction given in the following chapters. If you are 

operating in a network environment and an installation on your desktop is not possible, 

the authors recommend the installation described in 2.2. 
5

3 INSTALLATION

3.1 Running the Install Program

To install ROMI 4.0 on your computer, place the ROMI 4.0 CD into the CD-ROM drive of 

your computer. Alternatively, you can download ROMI 4.0 from the following URL: 

www.nrs.fs.fed.us/tools/ROMI/ 

You can start the install by navigating to the CD ROM drive using the “My Computer” 

icon and then clicking on the file named “ROMI40.” You can also start the install by 

clicking start and then run. In the run window, type “d:\ROMI40” (if installing from a CD) 

without the quotes substituting the letter ‘d’ for the appropriate letter of your CD-ROM 

drive and click OK. Now you should see the window shown in Figure 3.1.1.

Figure 3.1.1.—ROMI 4.0 Setup Wizard window.

If you want to keep the default install directory, click next. If you want to change the 

default, click on Change and you will see the screen shown in Figure 3.1.2. 

Figure 3.1.2.—Depending on the user’s installation routine, the 

destination folder may need to be changed (e.g., Users Directory).
6

If you want the install procedure to place a shortcut icon on your desktop, leave the 

checkmark in the box (Fig. 3.1.1 last line) and click next. If you do not want an icon, then 

remove the checkmark in the box and click next. You are now ready to install ROMI 4.0. 

The window shown in Figure 3.1.2 now shows the setup options and folder destination 

you have selected. The installation starts and may take some time depending on the 

speed of your computer.

Click next and you will see the default installation screen of ROMI 4.0. To install 

ROMI 4.0, you have to read and agree to the ROMI 4.0 guidelines (Fig. 3.1.3). Once you 

agree to the ROMI 4.0 guidelines, the Next button will become active (Fig. 3.1.4). After 

you hit the Next button, ROMI 4.0 will start the installation (Fig. 3.1.5).

Figure 3.1.3.—ROMI 4.0 installation guidelines, Next button is not 

active because the user did not yet agree with the software agreement.

Figure 3.1.4.—Once the user agrees with the ROMI 4.0 software 

usage agreements, the Next button becomes active.
7

Figure 3.1.5.—ROMI 4.0 installation in progress window.

After about 90 percent of the installation process is done, a second installation window 

will open. This window will guide you through the installation process of the Oracle’s 

JavaTM, a free program that is necessary to run ROMI 4.0 on your computer. Figure 3.1.6 

shows the Java Setup window. You must accept the license agreement to proceed with 

the installation.

Because an Internet connection is optional for the use of ROMI 4.0, when installing 

the Java Program you might choose whether the Ask-Browser should be set as 

Default Search Provider or not. The setting does not have an influence on ROMI 4.0’s 

performance (see Fig. 3.1.7 and Fig. 3.1.8). Click on Next and Java will be installed 

(Fig. 3.1.9). After the successful installation of Java®, click Close (Fig. 3.1.10). 

Figure 3.1.6.—Java setup window.
8

Figure 3.1.7.—Java Setup - Ask Toolbar window (Ask chosen as 

default search provider based on user preferences).

Figure 3.1.8. —Java Setup - Ask Toolbar window (Ask not 

chosen as default search provider based on user preferences).

Figure 3.1.9.—Java Setup progress window (Installation progress).
9

Figure 3.1.10.—Java installation nished window.

After Java has been installed, ROMI 4.0 finishes its installation procedures and you will 

see the following screen (Fig. 3.1.11) at the end of the installation.

Figure 3.1.11.—Install nished window.

If you want ROMI 4.0 to start immediately, leave the check in the box and click finish. 

If you want to wait before starting ROMI 4.0, make sure the check box is clear and 

click finish.
10

3.2 Starting ROMI 4.0

There are two ways to start ROMI 4.0. If you chose to create a desktop icon (by leaving 

the desktop icon in Fig. 3.1.1 activated), you can simply double click the desktop icon 

ROMI 4.0 and you will see the main interface (Fig. 3.2.1) after startup. Or, click start in 

Windows, then click programs (“All Programs” in Windows 7 or Virtual XP Mode) and you 

will see the name you chose to install the ROMI 4.0 program (users name in the Users 

Directory of your chosen system). Let’s assume the user’s name is Jim Brown; the setup 

will look as follows: Computer/Local Disk (C:)/Users/Jim Brown/ROMI 4.0. If you kept the 

default name, it will be ROMI 4.0. You should see an arrow out scroll down menu from 

the name indicating that there is a submenu. Move the mouse over the name and the 

menu will show four items. The first item is ROMI 4.0. Clicking this will start ROMI 4.0, 

and ROMI 4.0’s main window will appear (Fig. 3.2.1).

Figure 3.2.1.—ROMI 4.0 main interface window.
11

4 USING ROMI 4.0

4.1 Defining and Selecting Part Grades

You can specify a range of defect types, sizes, acceptable distances (from the part 

edge[s]), and whether each defect is acceptable on the face, back, or on both faces. 

There is no limitation on the number of part grades you may define. A part grade is 

composed of one or more rules defining the grade. Each rule specifies that a defect 

or category of defects is acceptable on a part face. To open the Part Grades Editor, 

click the Part Grades button in the main ROMI 4.0 interface (Fig. 3.2.1). You will 

then see a window displaying the current part grade’s information (Fig. 4.1.1). The 

setup and customization options for the ROMI 4.0 part grades are explained in the 

following sections. 

Figure 4.1.1. —Part Grades Editor window showing default part grade’s le.

By default, the file named Grade.def, which is installed with ROMI 4.0 and is the 

standard grade definition file, is loaded into the Part Grades Editor. However, after 

opening the Part Grades Editor, you can save your own part grades definitions under 

new file names. Part grades definition files from ROMI versions 3.0 and 3.1 can be used 

with ROMI 4.0. To use a saved definition file, click File and then Open. You will now see 

the file open window displayed in Figure 4.1.2.
12

Figure 4.1.2. —Part Grades Denition le selection window.

Navigate to the file you want and double click on the file name to open it. Your chosen 

definition file will now show in the Part Grades Editor.

To define a set of custom part grades, you may start a blank file or edit an existing file. 

To start a new part grades file, click File and then New. You will have a clear grade 

definition window except for the first two rows. The first two rows, scrap and clear-twoface (C2F), are mandatory and may not be changed. ROMI 4.0 uses scrap internally 

to identify all board areas that do not meet any part grade definition and, therefore, 

no parts may be cut from scrap. A part grades specification file is composed of one or 

more part grades, where, in turn, part grades are composed of one or more rules. The 

rules that make up a single grade all have the same grade code (Fig. 4.1.1). The grade 

codes are sorted so that all the rules of a single grade are listed together. Several types 

of information must be specified for a part grades specification file. This information is 

covered in detail in this section. Starting at the third row, when you double click in the 

Grade Code, min Proximity, or the max Proximity columns, you will see a window like 

the one in Figure 4.1.3. Simply enter the desired value into the text box and click OK.

Figure 4.1.3.—Input dialog box.

The second column indicates the Side of the board on which to allow the defect to be 

on. The values may be toggled from Face to Back by double clicking in the cell that you 

want to change. The third column is Defect Codes and the fourth column is Description. 

Each defect code has a description so if you change the value in one it will place the 

corresponding code or description in the other. To change these, double click in the cell

and you will see a window like the one in Figure 4.1.4. 
13

Figure 4.1.4.—Defect selection window.

Use the scroll bar to view all of the defects available and click on the one you want. 

Column five is Proximity and column eight is Re-Rip. Both Proximity and Re-Rip contain 

check boxes where a check means yes and the absence of a check means no. You can 

either click the box with the mouse or move to the cell and hit the space bar to toggle 

them on or off. To delete a grade, click on the grade that you want to delete and the 

whole row will be highlighted. Click Edit and then Delete and the table will be updated.

4.1.1. Clear-Two-Face (C2F) Part Grades

Before we start, let’s clear the table by clicking File and then New. This will clear the 

table except for the first two rows as described above and shown in Figure 4.1.5. 

These two rows are mandatory predefined grades in the grade definition file that we 

cannot modify. These rows are all that is needed to define a clear-two-face (C2F) part 

grade. Note: You are able to run all your simulations with this part grade. It is the most 

“conservative” approach of determining yield. 

Figure 4.1.5.—Part Grades Editor window showing a Clear-Two-Face part.
14

4.1.2 Clear-One-Face Part Grades (C1F)

To create a clear-one-face (C1F) part grade, we need to define it as two separate 

grades: one with defects located on the face and one with defects located on the back 

of the parts. Let’s say you want a C1F with sound knots containing a surface area of 

less than 1⁄2 inch. To add this grade, you double click in the first blank cell in the Grade 

Code column. The next available grade code will be added. Looking at Figure 4.1.1, if 

you click the blank cell below the Grade Code 1, a 2 will be added as the next Grade 

Code. To change this code, simply double click on it and change it to the number (with 

this number representing your chosen lumber grade) you want and update your part 

grades specification table. The lumber grade can be chosen in a popup window when 

you double click on the code cell. Next, you double click in the Side column and the 

value will become Face. Now, double click in the Defect Code column. You will see the 

window shown in Figure 4.1.4. Scroll down the list until you find the sound knot defects 

and select the one that says sound knots ≤0.50-inch area. The Defect Code and 

corresponding Description will now be added to the table. We do not want Proximity 

enabled, so we will leave the Proximity columns alone. We do not want to Re-Rip, so we 

leave it as is. The table should now look like Figure 4.1.6.

Figure 4.1.6.—Part Grades Editor window showing a Clear-One-Face part dened on the face of a board.

Because this is a C1F grade, we need to make two grades with the second one having 

defects located on the back face. You can repeat the previous steps for adding a rule 

and change the side or use the shortcut for adding rules. First, you click the rule you 

want to duplicate and it will be highlighted. Now, you click Edit and then click Copy 

Rule. You will now see an exact copy of the rule in the next row. Double click in the cell 

containing the side and it will change to the back of the part. We also must change the 

Grade Code so double click in the Grade Code cell and enter 3. The Part Grades Editor 

should look like the example in Figure 4.1.7. We now have two grades that define the 

C1F part quality for that specific part. The conjunction between a defined part grade and 

the part itself is done in the cutting bill. The specification is done for all parts with that 

particular specification.
15

Figure 4.1.7.—Part Grades Editor window showing a Clear-One-Face (C1F) part dened on the back of 

a board.

Remember that we have to define the Defect Codes for the Face and Back side of each 

board, because ROMI handles each side as an independent surface. If you do not 

specify the defect for a given side, it is handled as an acceptable defect for that side. 

4.1.3 Sound-Two-Face Part Grades (C2F)

In most cases, Sound-Two-Face (S2F) part qualities are easier to define than C1F part 

qualities, because you need to define one grade and then copy it to make it applicable 

to the opposite part side. Let’s say you want a S2F grade that defines three defects 

on each side. First, you double click in the next blank Grade Code cell and the next 

available code will be added. Next, double click on the side and Face will be added. 

Now double click in the defect code cell and choose Defect Code 111 Shot worm hole 

(1/16 -1⁄4) area from the list. Because we want this rule for both sides, we click the row to 

highlight it and click Edit, then click Copy Rule. Double click in the side to change it from 

Face to Back. Now, copy the rule and change the side to Face and change the Defect 

Code to a 211 Pin worm hole (< 1/16) area. Next, copy this rule and change the side to 

Back. Last, we want Defect Code 1504 Sound knots ≤1.0-inch area on both the Face 

and Back. When you are finished, your editor should look like Figure 4.1.8.

Figure 4.1.8.—Part Grades Editor window showing a Sound-Two-Face (C2F) part.
16

4.1.4 Re-Rip/Salvage Part Grades

The last grade we have to define is a re-rip or salvage part grade, independently, if we 

use the salvage option or not. Let’s say we want our salvage parts to be C2F. Double 

click in the next empty Grade Code cell and the value “5” will appear as the next 

available code. Because this is a S2F, we need to define our defects on only the Face 

or Back, but not both. Double click in the cell in the Side column that makes it Face. 

Next, double click the defect code cell and choose defect code 999 Clear, No Defect. 

Because we want this to be a re-rip, double click on the box in the last column under the 

heading Re-Rip and a check mark will now be in the box. The completed part grades 

definition for all our grades should look like Figure 4.1.9. Remember, ROMI allows you to 

define only one salvage grade, 

Figure 4.1.9.—Part Grades Editor window showing a salvage part grade.

Now, all we need to do is save the file. Click File and then Save, choose a name for the 

file, and click the OK button.

4.1.5 Part Grades: An Additional Feature

A feature not used in the previous examples allows you to define defect types that are 

acceptable when they occur a specific distance from the edge. This feature is useful 

for moulding and millwork parts where defects are acceptable as long as they are not 

in an area that will be machined. To enable this feature in part grades, double click on 

the proximity check box in the row of the desired rule. Next, double click on the min 

Proximity cell and enter the minimum acceptable distance from the edge. Do the same 

for max Proximity and the result should look like Figure 4.1.10. If there is no maximum 

acceptable distance, enter the maximum strip width on which it will be used. The 

Proximity needs to be defined for each side of the board. 
17

Figure 4.1.10.—Part Grades Editor window showing the use of min and max proximity.

4.1.6 Predefined Part Grades based on Wood Component 

Manufacturer Association specifications

In ROMI 4.0, a set of predefined part grades based on Rules and Specifications 

for Dimension and Woodwork by the Wood Component Manufacturers Association 

(WCMA 2007) has been implemented as part of the standard software package and 

will help users operate and simulate their tests more efficiently. Following the WCMA 

part grades, these part grades are predefined in three different quality grades: slight, 

medium, and heavy defects. Thus, sound knots would be allowed in different sizes in the 

different classes: slight ≤ 1⁄4 inch, medium ≤ 1⁄2 inch, and heavy ≤1 inch. Each predefined 

part grade can be modified by the user and be adapted to the specific needs and 

circumstances of a given supplier-customer relationship. A detailed overview about the 

specification for each Face is given in Section 11.2.1 (Table 3). Figure 4.1.11 shows the 

predefined Part Grades for C1F Face A parts.

Figure 4.1.11.—Predened Part Grades based on WCMA specication; for example, Face A Grade Code 2 

(Clear-One-Face [C1F]).
18

Figure 4.1.12.—Predened Part Grades based on WCMA specication; for example, Face C Grade Code 4 

(Sound-Two-Face [S2F]).

Note: Birdseye and color parameters are not part of Gatchell’s 1998 Red Oak Database 

and therefore cannot be included in the predefined part grades. Also, the size of strips 

and the board width need to be defined in the arbor setup settings (Section 4.2.5).
19

4.2 Cutting Bill Setup

Once part grades have been defined and saved or a part grade file has been selected, 

you are ready to begin working with the cutting bill. The cutting bill is the central part 

of a simulation run because it defines the part sizes in respect to quantities and 

qualities that are required. As such, it ties together the part grade definitions with the 

individual part requirements and dictates the arbor setup as well as other processing 

options. Figure 4.2.1 shows the main interface of ROMI 4.0 in which the cutting bill is 

always displayed.

Figure 4.2.1.—Sample window showing table where the cutting bill information is entered and displayed.

4.2.1 Opening and Importing Cutting Bills

If you have been using ROMI-RIP 2 or ROMI-CROSS, you can import your old cutting 

bills into ROMI 4.0. To do this, click File, then move the mouse down to Import, and 

under the submenu click ROMI-Rip File (.rip) or ROMI-Cross File (.rmx .cut). You will 

see a File Open window as shown in Figure 4.2.2.
20

Figure 4.2.2.—ROMI 4.0 le selection window.

Navigate to where your files are saved and double click on the file name. Once you have 

imported your cutting bill, you will have to save it in the ROMI 4.0 format that has the 

.rr3 extension. The rr3. file extension, which was originally introduced for ROMI 3.0, was 

retained for use in ROMI 4.0 to maintain compatibility with files from the earlier version. 

To open a ROMI 4.0 file, use the same process as importing, except click File, and 

then click Open. You will once again see the File Open window shown in Figure 4.2.1. 

Navigate to where your files are saved and double click on the file name or click the file 

name and click Open. Your settings will be loaded and the cutting bill will be displayed in 

the table.

4.2.2 Cutting Bill Editing

Data are entered into the cutting bill editing window just like data are entered into an 

MS Excel spreadsheet. Hitting the tab key will move the cursor to the cell to the right 

of the current position. If you are in the last column, then the cursor will advance to the 

first column of the next row. Hitting the enter key will move the cursor to the next row 

but in the same column that you are currently editing. You also can use the arrow keys 

to move between cells. To enter data into the table, simply move to the desired cell and 

start typing. There are two methods of editing the data contained in a cell. One method 

is moving the cursor to the cell and pressing the backspace key, which erases data 

from right to left. Or, you can double click in the cell, which will cause a blinking cursor 

to appear where you will start editing. Two columns must be handled differently: the 

Random Y/N and the Panel Y/N. These columns contain check boxes where a check 

means yes and the absence of a check means no. You can either click the box with the 

mouse or move to the cell and hit the space bar to toggle them on or off.
21

More editing features include cut, copy, paste, and insert row. The cut and copy features 

are similar except cut removes the data from the table whereas copy does not. To use 

the cut feature, select the items in the table by holding the mouse button down and 

dragging the cursor along the rows, which highlights these rows. Next click Edit and click 

Cut, or to use Copy click Edit and then click Copy. The items that were highlighted are 

now on the system clipboard. This means that you can paste them to another position 

in the table. You can also copy the information to an external application, such as a 

spreadsheet, using this procedure. To paste, click the cell where you want the data to 

appear and click Edit then click Paste. If you cut or copy a cell that has a checkbox and 

then paste it into an external Excel spreadsheet, the checkbox data will be displayed 

as either 0, meaning no check, or 1, meaning it is checked. Therefore, if you edit your 

cutting bill in Excel, you will put a 0 if you do not want a check and a 1 if you do. The last 

editing feature is insert row. To insert a row, click in the table where you want the blank 

row to be placed and click Edit and then click Insert Row. One blank line will appear and 

the data below will be moved down one position. If you want to insert more than one 

blank row, click and drag the mouse downward, highlighting the same number of rows 

that you want to insert.

A new feature in ROMI 4.0 is the ability to process random length and fixed length 

parts for the same strip width. Earlier versions could process either fixed length parts 

or random length parts for a specific width, but not both at the same time. Due to the 

requirements of modern rough mills and cutting bills, a feature to process random length 

and random width parts simultaneously was implemented in ROMI 4.0.

4.2.3 Cutting Modes

At the top of the main interface window on the left side, there is a drop-down box 

besides Mode that contains three items (rip first mode, chop first mode, and a combined 

rip and chop-option mode, Fig. 4.2.3). Choosing Rip-First will allow you to define all the 

system parameters to perform a rip-first simulation. Similarly, choosing Chop-First allows 

you to setup a chop-first simulation. The third option, Rip and Chop, allows you to define 

a simulation capable of performing either rip-first or chop-first processing. In Rip and 

Chop, the potential prioritized part value, based on the resulting yield, is determined for 

each processing mode and evaluated. The prioritized part values used for determining 

the best processing methods are calculated using the part-prioritization method selected 

for a given cutting bill. For more information about part prioritization, see Section 10.2. 

The method that has the highest prioritized part value is used to process the board. With 

Rip and Chop, ROMI 4.0 reports the volume and number of boards processed using ripfirst and chop-first processing, as well as overall.

As you change the cutting modes, the setup items displayed on ROMI 4.0’s main user 

interface changes to reflect the selected cutting mode. For example, chop-first has fewer 

setup options resulting in simpler configuration windows and menus.
22

Figure 4.2.3.—ROMI 4.0 cutting modes.

4.2.4 ChopSaw Setup

The Chopsaw setup is a rather simple setup compared to the rip-first setup. If you click 

on the ChopSaw button while you are in Chop First mode, you will see the ChopSaw 

window (shown in Fig. 4.2.4).The ChopSaw window allows you to set the parameters for 

a Chop-first simulation.

Figure 4.2.4.—Chopsaw setup in Chop-rst cutting mode.

If you click the ChopSaw button while you are in Rip-First mode, you will see a different 

setup window (shown in Fig. 4.2.5). The Chopsaw setup, when in rip-first mode, allows 

you only to define end trim solutions and parameters. 
23

Figure 4.2.5.—Chopsaw setup window in Rip-rst cutting mode.

There are two settings you can modify in this window. By using the plus (+) and minus 

(-) buttons, you can increase or decrease the values. The top setting indicates the 

amount of end trim that you want to allow in sixteenths of an inch. A zero indicates that 

there will be no endtrimming. The bottom shows the amount of kerf and the saw blade 

thickness that will be used in your simulations. Figure 4.2.5 shows no endtrim and an 

eighth inch kerf. When you are satisfied with the settings, click OK and the window will 

be closed. Note that you must save your cutting bill file before the settings will take 

effect, a rule that applies to all changes made throughout the ROMI 4.0 software.
24

4.2.5 RipSaw Setup

Clicking RipSaw button causes the window shown in Figure 4.2.6. to appear.

Figure 4.2.6.—Ripsaw setup window.

The box on the left side of the window shows the distance between the blades on the 

arbor. Adding these widths together including ripsaw kerfs between spacings gives 

you the total arbor width. As an example, six saw spacings require seven blades; if 

each outside blade kerf is 4/16 and each interior blade kerf is 2/16, the arbor width should 

be 2(4/16) + 5(2/16) = 17.125. However, the outer edging blades or “hogging blades” are 

applied to the board before it enters the arbor in separate operations of the simulation. 

These edging blades were included to simulate the removal of crook from boards, to 

simulate strip flooring production, and similar operations. The boards were edged and 

afterwards processed through the arbor. Thus, the true arbor width is 16.625 inches 

as reported in the ripsaw setup window as shown in Figure 4.2.6. This is displayed in 

the box next to the label Current Arbor Width. The plus and minus buttons beside Saw 

Spacing Cnt control the number of blades on the arbor. Increasing the number adds 

blades to the arbor and decreasing removes them. If you add a blade, it will appear in 

the list of arbors with a value of zero. You must then click on that number and a popup 

window will appear allowing you to select a width for the spacing (Fig. 4.2.7).
25

Figure 4.2.7.— 

Popup window 

for choosing arbor 

spacings.

Click on a width to select or click Custom to enter your 

own width (in quarter-inch increments). Custom width entry 

allows you to enter spacing widths that are not represented 

as a part size requirement in the cutting bill. This can be 

especially useful if the cutting bill is composed primarily of 

panel parts, where the addition of extra widths will improve 

strip and resulting part yield. The next three settings control 

the kerf and edgings and are represented in sixteenth inch 

increments. Eight different types of arbors may be used in the 

ripsaw setup. They are selected from the drop-down box at 

the top of the window (Fig. 4.2.8).

Figure 4.2.8.—Drop-down box showing types of arbors that 

may be used.

If you choose Selective Rip from the arbor drop-down box, two fields in the ripsaw 

settings window (Fig. 4.2.9) are enabled. One field allows each blade on the arbor to be 

specified as either fixed or movable. Clicking on the fixed or movable setting alternates 

between the two settings. Note that the selective rip arbor does not allow adjacent 

blades to be specified as movable. If you require this feature, use the All-BladesMovable arbor. The second field enabled for the movable-blade arbors (Saw Blade 

Proximity) allows you to specify how close (1/16 inch) the moving blades on the arbor can 

come to adjacent blades. This setting is usually set to 12/16 (3⁄4) inch or 14/16 (7/8) inch and 

corresponds to the collar thicknesses and mechanical limits of gang-ripsaws.
26

Figure 4.2.9.—Ripsaw setup using Selective-Rip arbor.

Clicking the Optimize Arbor button will bring up the window shown in Figure 4.2.10. The 

arbor optimizer will examine your current cutting bill and determine the best possible 

arbor for you. The arbor optimizer takes a modified approach to the arbor design 

algorithm created by Gatchell (1996). The arbor optimizer was developed at North 

Carolina State University in cooperation with the U.S. Forest Service (Mitchell and 

Zou 2001).

Figure 4.2.10.—Optimizer Arbor setup window.
27

Enter your arbor width in inches, the kerf (saw blade thickness in 1/16 inch), and whether 

you want to optimize for just the solid widths or widths including panels. When you are 

ready, click Continue. It may take a few minutes to get the results depending on your 

computer’s speed. When the optimizer is finished, you will see the arbor results window 

(Fig. 4.2.11).

Figure 4.2.11.—Arbor optimizer results window.

Depending on your options and your cutting bill part widths, you may have two different 

arbors to choose from. If the optimizer gets a good yield while not including all of the 

widths in your cutting bill, the arbor setup will be displayed followed by the arbor that 

include all widths. ROMI 4.0 gives users two arbors to choose from when a higher yield 

can be realized from omitting a specified width (or two) and if the width omitted is not 

associated with a large part requirement. Remember that ROMI can mix in randomwidth parts to improve yield when producing panels. In some cases, users may not want 

to include these random-width parts in the arbor. You can examine the yield results and 

choose the arbor you want by clicking the Use button.
28

4.2.6 Mill Control Setup

Clicking the Mill Control button in the main interface window will bring up the Mill Control 

window (Fig. 4.2.12). 

Figure 4.2.12.—Mill Control setup window.

The top two buttons in the Mill Control setup window allow you to toggle between using 

inches or millimeters throughout your setup. Note that this button does not do any 

conversions. For example, 4/16 inch simply becomes 4 mm. The part counts settings 

control how often part counts and priorities, when using a dynamic prioritization method, 

are updated. Use the plus (+) and minus (-) buttons to change how often the count is 

updated or set it to zero to update constantly. The Primary operations avoid orphan 

parts and Salvage cuts to cutting bill requirements settings instruct the simulator not to 

cut excess primary parts without determining whether the area can be salvage ripped 

to obtain a narrower cutting bill part. Use the Random width strip parts okay in panels

setting if you are not concerned with what width parts are used to make up panels. If 

you are using a moving-blade arbor, then you should enable this setting to take full 

advantage of the arbor. You also may use the option (as shown in Fig. 4.2.12) to set the 

minimum and maximum widths to use to make up a panel. For fixed-blade-best-feed and 

selective-rip arbors, this setting controls how many feed positions are examined per inch 

of arbor width. For example, a cut-up optimization step of 4 would examine one feeding 
29

position every 4/16 inch. For a 24-inch-wide arbor, ROMI 4.0 would examine 96 ((24 * 

16) ÷ 4) feed positions. For the all-blades-movable arbor, the setting controls how many 

random widths are examined by the arbor. A cut-up optimization step of 4/16 inch would 

examine widths to the nearest quarter inch, while a setting of 2/16 inch would examine 

widths to the nearest eighth inch. Note that the smaller the optimization step becomes, 

the longer the simulation run time will be as the software’s calculations increase.

4.2.7 Salvage Parts Setup

Clicking the Salvage Parts button from the main window will bring up the window shown 

in Figure 4.2.13.

Figure 4.2.13.—Salvage Parts setup window.

There are three possible settings each for the salvage widths and lengths. Random 

Salvage allows the program to randomly pick the parts it tries to obtain from salvage. 

Picking Salvage Specific Widths or Lengths will enable a box that lets you pick the 

widths or lengths for salvage parts manually (Fig. 4.2.14).

Figure 4.2.14.—Salvage settings using specic widths 

and lengths.
30

To edit a width or length, click on it and you will see the window shown in Figure 4.2.15.

Figure 4.2.15.—Window used to enter specic 

widths and lengths.

Enter the value that you want and click OK. To delete a width, click on it and enter zero 

in the window. The last option is Salvage Uses Primary Widths or Lengths. This will 

make ROMI 4.0 try to obtain salvage parts with the same widths and/or lengths found in 

the cutting bill.

4.2.8 Prioritization Setup

When processing to meet a cutting bill’s requirements, the goal is to cut all the required 

part sizes from a minimal amount of lumber while generating a minimal number of 

excess parts. This problem is made more difficult by variations in lumber grades and 

dimensions. To solve these problems in simulation, seven part-prioritization strategies 

are available that range from simple to complex (Thomas 1996). The simple methods 

prioritize parts based on their area. Complex methods generate part priorities based 

on each part’s size and current required quantity. The complex methods are dynamic in 

that a part priority can be updated continually as parts are cut and the current quantity 

decreases. As the quantity requirements for a part size are met, emphasis shifts to other 

part sizes. The decision on which combination of parts to cut from a board is based on 

maximizing the total weighted area of parts for each board resulting in maximum yield. 

More information on individual part-prioritization strategies can be found in Section 10.2.

The Prioritization button is located at the top of the main interface window. Clicking it will 

bring up the Prioritization window (Fig. 4.2.16). In this window, you can select the type of 

prioritization strategy that you want to use.
31

Figure 4.2.16.—Prioritization setup window.

4.2.9 Part Scheduling and Replacement

A scheduling problem exists when the number of different part sizes in a cutting bill 

exceeds a rough mill’s sorting capacity. Decisions have to be made about that parts will 

be processed first and the order in which the remaining part will be processed as initial 

part requirements are met. ROMI 4.0 allows this scheduling with the Scheduling Level

variable (Fig.4.2.1) associated with each part. Parts with a level of 1 are cut first. Parts 

with a level of 2 are used to replace Level 1 parts as Level 1 parts requirements are met. 

Parts with larger level values are entered in sequence. The total number of parts with a 

Level 1 is the total number of different sorts that are available in a given rough mill.

4.2.10 Predefined Cutting Bill Examples

To give the novice user an easier start with creating a cutting bill, ROMI contains several 

simple examples of common operations, such as millwork or cabinet doors. These 

examples show a simplified cutting bill of a given operation and can be customized to 

your needs. 

Figure 4.2.17 shows an example from a standard millwork operation. The cutting bill 

contains parts of rather narrow width and random length. This feature allows you to use 

the raw material in an optimal way, because no fixed length is needed to satisfy the 

requirements of the cutting bill. When the random length feature is enabled, the Quantity

measure automatically adjusts from piece count to linear board feet (a common measure 

in the millwork industry). For this operation, a Scheduling level is not recommended 

because it will influence the yield, i.e., ROMI is unable to provide the ideal solution. 
32

Figure 4.2.17.—ROMI 4.0 simplied millwork example. 

Figure 4.2.18 shows an example from a cabinet door operation. Unlike the mill work 

example, the cabinet door example contains fixed length parts and a panel part. As 

shown in the example, the cutting mode is rip-first; when the Panel feature is enabled 

and a significant portion of panel stock is produced, ROMI will offer you two options after 

the arbor optimization run. While the first arbor would be satisfactory for processing the 

cutting bill, the second would result in higher yield due to its efficient generation of panel 

stock. These two arbor choices reflect two common ways of designing rip-first arbors.

Figure 4.2.18.—ROMI 4.0 cabinet door example.
33

5 DATAFILE SELECTION

5.1 Customize BoardData for Datafile Selection

Clicking the Board Data button at the top of the main ROMI 4.0 window brings up the 

Datafile selection window (Fig. 5.1.1). This window is where you choose files containing 

digitized boards from the databank (Gatchell et al. 1998). The top box shows the 

available board files (see Gatchell et al. 1998 for more information about the content of 

each board file) and the bottom box shows the selected board files to use. To choose a 

board file, double click on the name of the file and it will be shown in the bottom box. You 

can use multiple files and the same file multiple times. To remove a file, double click on 

the name in the bottom box. When you have activated all the board data files you need, 

click the OK button. 

Figure 5.1.1.—Datale selection window.

5.2 Creating Custom Grade Mix and Specified Files

You can create custom board data files by clicking the Customize Data button. This will 

start the MakeFile program (Fig. 5.2.1) that allows you to specify a grade mix or choose 

individual boards for your simulations. By using the MakeFile program, you can create 

board data sets that closely resemble the characteristics (width and length distribution, 

grades) of the actual lumber being processed in your rough mill. The board data 

included with ROMI 4.0 are from the 1988 Data Bank for Kiln-Dried Red Oak Lumber 

(Gatchell et al. 1998) and are graded to 1998 NHLA rules (NHLA 1998). For more 

information about the lumber data, see Appendix II and the Help menu.
34

Figure 5.2.1.—MakeFile program.

5.2.1 Custom Grade Mix

Custom Grade Mix is the default tab that is selected when MakeFile is started. This 

tab allows you to specify percentages of desired lumber grades from the lumber 

databank. The percentage column is where you specify the percentage of each grade. 

If you want 50 percent No. 1 Common, select the cell next to 1 Common and enter 

50; if you want 20 percent 2A Common, select the cell next to 2A Common and enter 

20. The total percentage for all grades is displayed on the Totals line and must be 100 

before generating the file. As you change the percentages, you will see the Totals field 

change. If you go over 100 percent, the total number will change to red indicating that 

total percentage is too high. Under the Total Board Feet column, you will notice that the 

default sample size is 1,000 board feet. To change the sample size, select the cell and 

enter the amount of board feet you want. When the sample size is changed, MakeFile

automatically recalculates the total board feet needed for each grade based on the 

percentage entered. It also is possible to specify board minimum and maximum width 

and lengths. Both length and width are measured in inches to the nearest 1⁄4 inch. In 

the example shown in Figure 5.2.2, we specified a 2,500 board foot (BDFT) sample 

consisting of a 30 percent No. 1 Common and 70 percent No. 2A Common grade mix 

with no minimum or maximum length or width.
35

Figure 5.2.2—MakeFile showing a sample grade mix.

For those who wish to match a specific width and/or length distribution, a distribution 

editor is available. For each grade, a distribution of as many as 20 size ranges can be 

specified. There is a button for each grade under the Distribution column that is labeled 

No by default. Clicking any of the Distribution buttons will bring up the window shown in 

Figure 5.2.3.
36

Figure 5.2.3.—Distribution editor window.

Click on the percent or length and width cells to edit them. As you add percentages, 

you will notice that they will be added and displayed in the Total Pct: box (Fig. 5.2.4). 

The total must add up to 100 percent. Note that these distributions are a percent of a 

percentage. Thus, if 30 percent of the sample is No. 1 Common and 20 percent of the 

No. 1 Common distribution is to be 6 to 7 inches wide, we are referring to 6 percent of 

the total sample size. Once a distribution has been defined, it must be activated before 

it can be used. To do this, click the Activate check box that will place a check in the box 

(Fig. 5.2.4).
37

Figure 5.2.4.—Sample data in MakeFile Distribution editor.

If you choose not to use the distribution, simply remove the check from the box. When 

you are satisfied with your distribution, click Close and you will be taken back to the 

main screen; if you enabled the distribution, the button will now say Yes in red. All grades 

that have a distribution defined will say Yes on the button.

You must now enter a name for the data file in the box that says Data File Name (Fig. 

5.2.2). If you want the boards in the resulting file to be randomly mixed, then put a check 

in the box next to the Randomly Mix Board Data Destination File label. To create the 

data file, click on the Generate button. Depending on the speed of your computer and 

the size of the file created, you will see a box that says Generation Successful. Click OK

and your file will appear in the list of available data files (Fig. 5.2.1). You are now finished 

creating a data file and can exit the MakeFile program or save your grade mix settings. 

Click the Save button to bring up the file selection. Navigate to where you want to save 

your current settings and click Save. You may return to MakeFile at any time and open 

your grade mix by clicking the Open button and navigating to the location of your file and 

opening it. Click Exit to close the MakeFile program.
38

5.2.2. Choose Boards

ROMI 4.0 and MakeFile give users the ability to create a data file that contains boards 

from several different data files. If you click the tab at the top of the main window that 

says Choose Boards, you will see the window shown in Figure 5.2.5. You will notice that 

the left list shows all of the available board data files. A single click on any of the data 

files will open it and display all of the boards in that file (Fig. 5.2.6). 

Figure 5.2.5.—Choose boards window.
39

As you can see in Figure 5.2.6, the source file name is 1C-1.dat. The left list shows the 

individual boards and grade in the 1C-1.dat file. To choose a board, you can double 

click on it or click once and then click the arrow button. You also may choose more than 

one board at a time by clicking a board to highlight it and then hold down shift and click 

another board in the list that will highlight everything in between the two click-selected 

boards. Now, click the arrow button to move them to the board list on the right. To choose 

multiple boards that are not next to each other in the list, hold down ctrl and click each 

board you want. When you are ready, click the arrow button and all selected boards will 

be placed in the list on the right. You also may use boards from other board data files by 

clicking the up arrow beside the source file box. This arrow will take you back to the 

list of data files. Repeat the process to choose individual boards and the result should be 

similar to that shown in Figure 5.2.7.

Figure 5.2.6.—Contents of a board data le in Choose 

Boards window.
40

Figure 5.2.7.—Selected boards in Choose Boards window.

Notice that the list on the right also contains the data file name that the boards came 

from as well as the board number and grade. When you have all of the boards that you 

want, type a file name in the Destination File box and click Generate. Depending on 

the speed of your computer and the size of the file created, you will see a box that says 

Generation Successful. Click OK and your file will now show up in the list of available 

data files (Fig. 5.1.1). You have now finished creating your data file and can click the 

button at the top of the window that says Exit.
41

You also have the ability to see the width class (e.g., the class-wise distribution of 

widths, rounded to the next inch, Gatchell et al. 1998) over standard length distribution 

of a chosen board data set by clicking on the Data Graph button. Figure 5.2.8 shows the 

width class of a standard length distribution of a 1 Common board data set based on the 

1998 Gatchell database (Gatchell et al. 1998).

Figure 5.2.8.—Width class of a standard length distribution of a board data set (here 1 Common).
42

5.2.3. File Control

Clicking the File Control tab will show the window in 5.2.9. To delete a file, click the file 

name to highlight it and click the button that says Delete.

Figure 5.2.9.—File Control window.
43

6 OUTPUT OPTIONS

6.1 Selecting an Output File

The name of the file in which your output will be stored is listed at the bottom of the 

screen in the Output File entry box. Figure 6.1.1 indicates that an output file has not yet 

been selected (no File Name insert). Selecting an output file will bring up a window like 

the one in Figure 4.1.2. You may select where you want to put the file and either enter a 

name or write over an existing file. When you have the file name that you want, click the 

Save As button.

Figure 6.1.1.—Congure Output Options window.

6.2 Thickness Option

Beginning with ROMI 4.0, you can choose between different thicknesses based on 

the National Hardwood Lumber Association (NHLA 2011) lumber grading guidelines. 

You have the option to choose among standard thicknesses from 3⁄8 inch to 24/4 inch 

(Fig. 6.2.1). 
44

Figure 6.2.1.—Pull down menu of ROMI 4.0 for the thickness 

option based on NHLA Rules.

The selected board thickness measurement is used by ROMI to adjust the volume of 

lumber processed. The board data are based on 4/4 boards from Gatchell et al.’s (1998) 

red oak database. Thus, any adjustment other than 4/4 thickness is an estimate based on 

the original 4/4 board data contained in Gatchell et al. (1998).
45

7 STARTING THE ANALYSIS

All the preceding work you have done has been in preparation for this step – producing 

rough dimension parts from your lumber grade mix using the cutting bill and processing 

options. The Simulation Checklist (at the right hand side of the main user interface) 

helps you to see directly and easily which setup parameters have been completed for 

the simulation. The actual simulation of your input can take from a few minutes to hours 

to complete depending on the size of your cutting bill, processing options, and computer. 

In most cases, the simulation analysis is done rather speedily. If a simulation started 

successfully, the saw blades in the simulation window are moving. If the saw blades are 

not moving, the simulation did not start and the chosen parameters (sections before) 

need to be double checked. 

7.1 Pre-Run Checking for Errors

Your cutting bill and processing settings are automatically checked for errors before each 

run. If any errors are found, you will see the error report window shown in Figure 7.1.1. 

Errors, if any, should be corrected before continuing. If you suspect that something might 

be wrong with your cutting bill or process settings while you are setting up a simulation, 

you can manually run error checking at any time. To do this, select File from the 

ROMI 4.0 main window (Fig. 3.2.1) and then press Check for Errors.

Figure 7.1.1.—Example Error Report window.

There are two ways to run the analysis: interactive or batch. Running the analysis 

interactively is the easiest way but may tie the computer up for long periods of time. 

Running the analysis in batch mode is slightly more difficult but allows you to run more 

than one analysis at a time. Batch mode also allows you to run the analysis at night or 

when you will be away from your computer.
46

7.2 Interactive Mode

To start the analysis, click the button labeled Run in the main interface window 

(Fig. 3.2.1). If you failed to select any board data files for processing or have any other 

errors, ROMI 4.0 will inform you. A processing window will open and list board numbers 

and dimensions as they are processed. ROMI 4.0 will automatically stop processing 

when all cutting bill requirements have been met or all boards in the selected data files 

have been processed (Fig. 7. 2.1.).

Figure 7. 2.1.—Simulation Run window (Example run).

7.3 Batch Mode

ROMI 4.0. has extensive batch-run capabilities. This feature is useful if you have several 

large simulations you would like to run overnight. Remember that you should run each 

cutting bill in interactive mode before running in batch mode to ensure that all settings 

are adjusted correctly. To start the batch mode editor, click Setup from the ROMI 4.0 

main interface window (Fig. 3.2.1), then click Batch Job, and the window shown in 

Figure 7. 3.1 will open.
47

Figure 7.3.1.—Example Batch Job Editor window.

To set up a batch run, click the button labeled Add. This will bring up a file selection 

as shown in Figure 4.1.2. Here you will select your cutting bill files. Next a window will 

open showing all possible board data files. This window is comparable to the data file 

selection window in the main ROMI 4.0 users interface. The last window to open will 

allow you to choose where you want to store the output of the run. You may turn on 

summary tables, but they must be set up in the main interface first (see Section 8.3).

Click the Add button again and repeat the previous steps for additional runs. You need to 

ensure that the output file names do not get duplicated because this will overwrite your 

results with the last run. If at any time you need to change the setup, click the desired 

cell and click the Edit button. This will open a new window for that cell that will allow 

you to change the contents. The Delete button is used to remove an entire row from the 

list. To do this, click the first cell of the row containing the cutting bill name and click the 

Delete button. All of the settings will be adjusted. 

Another feature of the batch editor is the ability to copy and paste the cells that already 

contain data. To use this feature, click on a single cell or highlight a group of cells and 

click Edit on the menu bar and then click Copy. Now, click the cell where you want to 

start pasting and click the Edit menu again and click Paste. You will now see an exact 

copy of your data.

The last feature of the batch editor is the ability to save your batch file setup and reopen 

it at any time. If you want to save your current setup, click File then click Save. You will 

now see a file selection window and can navigate to where you want to save your file. 

The batch files are saved with a .btc extension. When you want to open this file or any 

other, click File and then click Open. Your settings will now be displayed in the editor. 
48

To start the batch run, click the Run button. You will notice that each cell in the status 

column (Fig. 7.3.1.) will now contain one of three values: Waiting, Running, or Finished. 

When all of the runs are done, a window will open telling you that the simulation is 

complete. Click the OK button and you will be back in the editor. Close the editor window 

and you will be back in the ROMI 4.0 main interface window.

8 SIMULATION RESULTS

8.1 View Simulation Results

ROMI 4.0 provides users with numerous ways to see and analyze results for each 

simulation. These include summary tables, yields and processing requirements, cutting 

bill reports, and board plots. The report types are intended to be printed out or examined 

using the Viewer in ROMI 4.0. To run the Viewer, click the button labeled View Results in 

the main ROMI 4.0 interface (Fig. 3.2.1). Figure 8.1.1 shows the Viewer window.

Figure 8.1.1.—Results Viewer main window.

When the viewer is first opened, the screen will be gray until you open a file and select a 

result type using the buttons at the top of the window (Fig. 8.1.1). To select a results type, 

click File and then click Open. You will see a file selection just like the one in Figure 4.1.2. 

Select the file that contains the ROMI 4.0 output that you wish to view. To view results, 

select one of the result buttons at the top of the window. When you have finished viewing 

and printing summaries and board plots, click the Exit button to leave the viewer.
49

8.2 Yield Summary Results

To view yield summary results, click the Yield Summary button at the top of the window 

(Fig. 8.1.1). The first part of the yield report summarizes the processing options used 

in the analysis. Items such as arbor type, kerf sizes, and prioritization settings are 

listed. Yield summary tables (Fig. 8.2.1) are displayed after this summary of processing 

options used.

Figure 8.2.1.—Example Yield summary results.

For each grade processed and all grades combined, these tables list the yield and 

processing requirements (numbers of strips, parts, rips, and crosscuts) for primary, 

salvage, excess primary, and excess salvage yield categories.

8.3 Summary Table Results

Summary tables provide detailed information on parts and yield. They list the number of 

parts generated, surface area, and percentage of parts by user-defined width and length 

groupings. Select Summary Tables from the top of the viewer window (Fig. 8.1.1). The 

first part of the summary table report lists the processing options and yield summaries 

discussed in Section 8.1. Because summary tables can be large, you may want to print 
50

them for easier examination. Select File and then click Print to print summary table 

results (Fig. 8.1.1). All summary tables for an input file are placed in a single output file 

with the .sum extension. Six summary tables describe yield distributions. The first three 

tables give the distributions based on surface area, and the other summary tables give 

the distribution based on lumber grades used. A sample summary table is shown in 

Figure 8.3.1.

Figure 8.3.1.—Example Summary Table results.

In each length-width cell, the upper number is the board feet of surface area and the 

lower number is the yield percentage. The percentages in all columns sum to 100. 

The first table is the distribution of total yield. The second and third tables contain the 

surface-area distributions for the primary and salvage cuttings. The last three tables 

are based on the number of parts produced. These tables are organized in the same 

manner as the first three tables. In each length-width cell, the upper number is the part 

quantity and the lower number is the percentage of total part quantity.

8.4 Cutting Bill Results

The information generated by ROMI 4.0 when processing lumber to meet a cutting 

bill allows you to analyze the lumber volume, grade mix, and processing required to 

satisfy cutting bill requirements. Select Cutting Bill Results to view or print this type 
51

of information. Like summary tables, the first part of the cutting bill results contains 

processing and yield information. See Section 8.1 for a complete description of 

this output. Figure 8.4.1 shows a portion of the Cutting Bill Overall Part Quantity 

Obtained report.

Figure 8.4.1.—Example Cutting Bill results.

The width and length of each part is shown at left of the part listing in Figure 8.4.1. 

For random-length parts, the minimum and maximum lengths are displayed to the 

right of the part’s width on two lines. The Level column indicates the scheduling and 

replacement level number for that part. In the simulation performed to create Figure 

8.4.1, no scheduling and replacement of parts was chosen, e.g., there are only Level 1 

parts. The comment ***UNMET*** in the last column appears when the part quantity 

requirements of a given cutting bill were not met with the quantity of lumber allocated 

to this simulation run. In particular, either grade mix or board data input (number of 

selected board data files) was not large enough to meet all the cutting bill requirements.

8.5 Board Plots

ROMI 4.0 allows you to view or print plots of individual boards along with their parts, 

defects, and kerfs. The information used to generate board plots is maintained in output 

files with the extension .PLT. You can view board plots for an entire run or for a selected 

board. To do this, select Board Plots from the top of the viewer program. This brings up 

the board plot viewer window (Fig. 8.5.1).
52

Figure 8.5.1.—Example Board Plots results.

By default, it shows the first board in the file, e.g., the first board processed. Click the 

Search button to choose a board for plotting boards by board number (Fig. 8.5.2).
53

Figure 8.5.2.—Example Board search.

Boards are displayed as if they are transparent with color-coded defects from both sides 

visible at once. The toggle buttons at the bottom of the screen are to turn the defects for 

each side and the primary and salvage parts shown on and off. Click the Legend button 

at the bottom of the screen for an explanation of the different defect colors (Fig. 8.5.3).

Figure 8.5.3.—Board Plot legend.

Use the plus (+) and minus (-) zoom buttons to reduce or increase the size of the 

board in the viewer (Fig. 8.5.1). Click the Next and Previous buttons to see the next or 

previously viewed board. You may print the current board by clicking File and then Print. 

Note that the viewer prints only what is shown in the window. To print an entire board, 

you must zoom out to make the whole board visible in the viewer. When you are finished, 

click the Exit button to close the viewer.
54

9 LEAST COST GRADE MIX

The least cost solution determined by ROMI uses the methodology developed by 

Zou et al. (2004) and Buehlmann et al. (2011). This method is a significant departure 

from previous methods (Lawson et al. 1996, Schumann 1971, Wodzinski et al. 1966) 

that assumed a linear relationship between cutting bill yields and lumber grades. As 

shown by Zou et al., the existence of a linear relationship cannot always be guaranteed. 

Thus, Zou et al. (2004) created a least cost grade mix calculator that does not rely on a 

linear relationship between cutting bill yields and lumber grades. The method used by 

ROMI 4.0 develops a series of yields that are based on the user’s equipment settings, 

optimization settings, cutting bill demands, part grades, lumber costs, and processing 

costs. In this way, the least cost solution calculated by ROMI 4.0 is tailored to the 

user’s situation.

Previous versions of ROMI’s least cost grade mix solver were written using the SAS 

statistical package (SAS Institute 2002). The current least cost grade mix solution uses 

R statistical software, and all calculations are performed locally on the user’s computer 

(Buck et al. 2010). With the installation of ROMI 4.0 on your computer, the R software 

is installed automatically. R does not require an Internet connection to perform 

the calculations.

9.1 Setup

Clicking the Least Cost Grade Mix button in the main ROMI 4.0 interface (Fig. 3.2.1) will 

open the window shown in Figure 9.1.1.

Figure 9.1.1.—Least Cost Grade Mix Setup.
55

In the Least Cost Grade Mix Setup menu, you may enter the cost of each board grade 

per 1,000 board feet and the cost to process 1,000 board feet of each grade. Clicking 

the Save button will store the information for later use. Clicking the Run button will cause 

ROMI 4.0 to run the Least Cost Grade Mix simulation. When the simulation is finished, 

the Least Cost Grade Mix Results window will appear.

9.2 Results

The Least Cost Grade Mix Results window (Fig. 9.2.1) shows the lowest cost grade mix 

based on the input data by the user.

Figure 9.2.1.—Least Cost Grade Mix Results.

If a specific lumber grade is not desired in the results, then click the check box next to 

the grade and the window will update with the next higher quality grade mix. Save the 

results of a least cost grade mix for future reference by either clicking the Save Results

button or clicking File and then Save Results (Fig. 9.2.2).

Figure 9.2.2.—Least Cost Grade Mix Results menu options.

The saved results file will be saved with the .lcr file extension. If results are saved, 

you may open the results viewer at any time and click the Open button and use the 

file selection to locate and open the results file. Clicking the Print All Results button 

or choosing it from the File menu will open a printer dialog and allow you to print the 

results. Note, the results files may be large and require several pages to print. Close the 

Least Cost Grade Mix Results window by clicking the Close Window button.
56

10 THE MECHANICS OF ROMI 4.0

This section describes in greater detail how ROMI 4.0 processes lumber to match the 

demands of a cutting bill. Understanding the elements discussed in this section will 

allow users to better configure ROMI 4.0, resulting in better simulations of rough mill and 

processing conditions. The elements of ROMI 4.0 covered in this section include gangripsaws, part prioritization, and salvage part processing.

10.1 Gang-Ripsaws

ROMI 4.0 simulates eight types of gang-ripsaws: (1) fixed arbor, (2) fixed arbor with 

movable outer blade, (3) fixed-blade-best-feed arbor, (4) simple fixed-blade-best-feed, 

(5) best-spacing-sequence, (6) best-spacing-sequence with movable-outer blade, 

(7) selective-rip arbor, and (8) all-blades-movable arbor. Unless otherwise specified, all 

arbors process the board from the right edge to the left edge, with the right edge against 

the fence (Fig. 10.1.1). When simulating a fixed-arbor saw, the spacings are specified so 

that the first spacing is closest to the rip fence. The ripsaw kerf is adjustable to 1/16 of an 

inch and the width to 3⁄8 of an inch.

Figure 10.1.1—Rip-fence, board, and arbor relationship.

10.1.1 Fixed Blade Arbors

ROMI 4.0 has five different fixed-blade arbor types: fixed, fixed with movable-outer blade, 

simple fixed-blade-best-feed, fixed-blade-best-feed, and selective rip. The fixed-bladebest feed arbors simulate currently available optimizing lumber feeding systems. For all 

five fixed arbor configurations, users specify the saw spacing sequence by specifying 

as many as 15 spacings. Earlier versions of ROMI-RIP were limited with respect to the 

number of widths that could be placed on the arbor. ROMI 4.0 allows you to include 

additional widths not included in the cutting bill that allow optimizing for the productions 

of widths for panels. 

The fixed blade and fixed blade with movable outer blades are the simplest arbors 

available in ROMI 4.0. These arbors perform no optimization and rip every board with 

its right edge against the fixed fence. This generates primary width strips and, normally, 
57

in the case of the fixed-blade arbor, an edging strip. The movable outer blade variant 

avoids generating narrow unusable edging strips. When using this arbor, ROMI 4.0 uses 

the minimum primary part width for making panels and uses that width in deciding when 

to move the outer saw blade. If the current spacings would generate an edging strip with 

less than the minimum acceptable primary width, the last blade is moved to the edge of 

the board and a single, wider, random-width strip is generated. 

Figure 10.1.2.—Fixed-blade-best-feed arbor layout.

The fixed-blade-best-feed arbors use a movable fence to optimize the placement of the 

board with respect to the saw blades on the arbor. Figure 10.1.2 shows the layout of 

the fixed-blade-best-feed arbors. The simple fixed-blade-best-feed arbor optimizes for 

the fitting of strip widths within each board to maximize the accumulated width of the 

strips and minimize the production of edgings. The regular fixed-blade-best-feed arbor 

optimizes for the production of strips that will generate the highest prioritized value of 

parts as required by the cutting bill. In general, the simple fixed-blade-best-feed arbor 

obtains lower yields and requires more board footage to satisfy cutting bill requirements 

than does the regular fixed-blade-best-feed arbor.

The selective-rip arbor models industrial selective-rip gang-ripsaws that are currently 

available. As with the other fixed-blade ripsaws, users specify the sequence of widths 

on the arbor. In addition, you select which saw blades are allowed to move on the arbor. 

There are two restrictions to the movement of saw blades: (1) movable saw blades 

cannot be adjacent, and (2) a movable saw blade can move no closer than 0.75 inch to 

another saw blade. The restriction in movement is due to the collars on the arbor that 

hold the saw blades. In general, the selective rip arbor achieves the highest yield of any 

of the fixed-blade arbor variants. However, the higher yield comes at the cost of greater 

optimization and increased simulation processing time.
58

10.1.2 Best-Spacing-Sequence Arbors

The best-spacing-sequence arbors optimize the sequence of the saw spacings. The 

spacings are selected so that widths with the greatest prioritized value of needed 

primary cuttings are generated. See Section 10.2 for information on how part priorities 

are determined and how they impact the parts selected to be cut from each board.

The optimal placement of the saw spacings along an arbor is determined by an 

exhaustive search. Every possible combination of spacings is examined for each board. 

The actual number of spacings used is determined by an interaction between the board 

width and the specified cutting widths.

The best-spacing-sequence arbor with movable-outer blade operates much like the 

best-spacing-sequence arbor discussed above. A movable-outer blade is added 

to minimize edging strips. This arbor assumes that random pieces are acceptable. 

An additional strip width, narrower than all the primary widths, is specified (see 

Section 4.2.6) and represents the minimum width acceptable for gluing into panels. 

After ROMI 4.0 determines the best-spacing sequence, the remainder of the board 

is examined. If the remainder meets or exceeds the additional narrow strip width, the 

processing continues. If it is narrower, the last specified width is not taken. Then the 

last saw blade is moved to the outer edge of the board and a wider random width strip 

is sawn.

10.1.3 All-Blades-Movable Arbor

The all-blades-movable arbor is uniquely different from all other arbors that have at least 

one fixed-saw spacing. Because there is no preset width, the saw spacings are usually 

set by the amount of the highest priority cuttings that can be obtained. These will usually 

be the widest and longest cuttings. In addition, a new “null” saw spacing is added to 

enable the saw to box in defects into narrow waste strips anywhere on the board face. 

For example, a board containing a large amount of pith and associated small knots 

along the middle of the board could use a null strip to box in the defects. The inclusion 

of null strips usually will result in wider strips that contain fewer defects. Null widths from 

0.75 inch to 2.5 inches can be generated depending on the maximum yield of primary 

cuttings and board characteristics.

Simulating the all-blades-movable arbor is similar to the best-spacing-sequence arbors 

discussed in Section 10.1.2. The only difference is that spacer widths are added to the 

primary widths to allow for the creation of null spacings. Spacer widths determine the 

possible random width distances between the fixed width primary strips. Three space 

widths—0.75, 1, and 1.25 inch—are used to simulate all possible random width null 

spacings greater than 0.75 inch. To limit the number of combinations that have to be 

examined, the maximum null spacing is 2.5 inches and the minimum spacing between 

saws is 0.75 inch. The 0.75 inch minimum spacing is based on the fact that most 

currently available selective-rip gang-rip saws with movable-blade arbors can move 

saws no closer than 0.75 inch.
59

10.1.4 Optimizing Arbor Comparison

Each of the five optimizing arbors (best-spacing-sequence, fixed-blade-best-feed, 

simple fixed-blade-best-feed, selective-rip, and all-blades-movable) have different 

optimizing characteristics and give different yields. For the comparison, a 2A Common 

board (#3159 measuring 9 inches x 96.5 inches with 6 board feet) was sawn using 

the different arbors. Figure 10.1.3 shows the different gang-rip solutions for board 3159 

given the different arbor types. Table 1 shows the cutting bill used for these examples. 

The CDE prioritization strategy was used to prioritize parts during processing. Table 2 

summarizes the volumes of parts and percent yields obtained from the sample board 

for each optimizing arbor. Figure 10.1.3 shows the rip and chop solution for each of the 

optimizing arbors.

Table 1.—Cutting bill used to 

process sample board 3159 

shown in Figure 10.1.3

Width Length Quantity

Inches Inches Number

4 58 200

4 18 400

4 14 100

4 8 50

2.75 52 200

2.75 41.5 150

2.75 34 100

2.75 22 125

2.75 20 150

2.75 18 50

2.75 14 150

2.75 8 100

12 (panel) 24 50

10 (panel) 20 50

 Table 2.—Optimizing arbor part volume and yield comparison for 2AC board 3159

Primary Salvage Total

Arbor Type

Part 

volume Yield

Part 

volume Yield

Part 

volume Yield

Board

feet Percent

Board

feet Percent

Board

feet Percent

Best-Spacing-Sequence 3.65 60.83 0.23 3.83 3.88 64.67

Fixed-Blade-Best-Feed 4.11 68.50 0.00 0.00 4.11 68.50

SimpleFixed-Blade-Best-Feed 4.22 70.33 0.00 0.00 4.22 70.33

Selective-Rip 3.97 66.17 0.23 3.83 4.20 70.00

All-Blades-Movable 3.97 66.17 0.23 3.83 4.20 70.00
60

Figure 10.1.3.—Sample board sawn using, from top to bottom, the best-spacing-sequence,xedblade-best-feed, simple xed-blade-best-feed, selective-rip, and all-blades-movable-arbors.

Overall, the best-spacing-sequence arbor obtained the lowest yield of all the optimizing 

arbors examined. However, like the movable blade arbors, the best-spacing-sequence 

arbor was able to obtain the wider 4.0-inch-wide parts. Because these wide parts can be 

difficult to obtain using 2A Common, this solution is desirable. 

The fixed-blade-best-feed (FBBF) arbor obtained the second highest yield with the 

simple fixed-blade-best-feed (SFBBF) arbor achieving the highest yield. The simulated 

hardware of these two arbors are identical; the only difference is how the cutting solution 

is optimized. While the SFBBF arbor achieved higher yield, it does not consider cutting 

bill requirements when it makes its optimization decision it considers only optimizing the 

accumulated width of cuttings within the board. Therefore, toward the end of processing, 

when some widths are no longer required, the SFBBF arbor may have difficulties 

obtaining strip widths that are still needed. The FBBF arbor does not have this problem 

because it cuts according to remaining priorities.
61

The selective-rip arbor starts with the optimal spacing arrangement used by the 

FBBF and SFBBF arbors, but is allowed to move user-specified spacings to obtain 

difficult to obtain part sizes and to maximize yield and cutting opportunities. The allblades-movable (ABM) arbor simply moves all blades and has the advantages of the 

selective-rip arbor but with greater flexibility. The selective-rip and ABM arbors are tied 

in achieving the third highest yield of all the optimizing arbors. The solutions from the 

two arbors are identical for this board due to similarities in the simulated hardware and 

optimizing methods. The solutions from both arbors returned wider, more valuable, and 

more difficult to obtain parts than did the FBBF and SFBBF arbors. 

10.1.5 Optimizing Fixed-Blade Saw Spacing Sequences

One industry expert is quoted as saying that, “There are thousands of ways to arrange 

a few different saw spacings. Most are poor and unrealistic...” (Gatchell 1996, p.37). 

Successfully optimizing the sequence of fixed-blade saw spacings requires that you 

know the width distribution of the lumber to be processed and the volume of finished 

parts required in each part width. In addition, you need to recognize that an arbor is not 

just a sequence of spacings, but a sequence of combinations that overlap and interact 

(Gatchell 1996). The publication Designing a Fixed-Blade Gang Ripsaw Arbor with a 

Pencil (Gatchell 1996) explains how to easily design arbors that are near optimal, if 

not optimal.

The fixed-blade arbor optimization tool included with ROMI 4.0 automates the method 

designed by Gatchell (1996). ROMI 4.0 makes a single optimization run with the userspecified cutting bill and lumber data using the best-spacing-sequence arbor. Recall 

that this arbor generates for each board the optimal fixed-blade saw spacing sequence. 

As ROMI 4.0 processes boards, it remembers the set of saw spacing sequences. The 

sequences not only show the optimal solution for each board, but also represent the 

interaction between board widths and cutting bill width requirements. For example, part 

widths that have higher requirements are used more often and appear in the set of 

sequences more frequently.

ROMI 4.0 sorts and summarizes the set of saw spacing sequences and begins building 

the arbor with the saw spacing sequence that is used most often. The optimizer adds 

sequences to the arbor such that the interaction between the spacings provides the 

most optimal combination and does not repeat any existing combination. For more 

information on how to run the ROMI 4.0 arbor optimizer, see Section 4.2.5.

10.2 Part Prioritization

Interactions among length, width, and quality of boards and parts are critical to efficient 

processing. The goal is to cut only needed parts from as little lumber as possible, while 

minimizing the production of “orphan” parts. Longer and wider parts are more difficult to 

obtain from the lower grades. Also, lumber quality varies from board to board within a 

lumber grade. To solve these problems, a method is needed to prioritize the parts so that 

the simulator can make a decision on which part size to cut.
62

ROMI 4.0 allows you to select one of several part-prioritizing strategies based on area, 

dollar value, or automatically assigned parts values using one of ROMI 4.0’s dynamic 

strategies. The goal of these strategies is to meet all of a cutting bill’s required cuttings 

while using the least amount of lumber. Value-based and area-based strategies are 

included because they are widely used and might still simulate some rough mills. 

Although these methods are static in nature (the first and last pieces cut for a part 

size have the same priority), we have included a simple modifier for each that will 

make them somewhat dynamic. However, the recommended strategy is the dynamic 

exponent method.

10.2.1 Value-based Part Prioritizing

ROMI 4.0 contains two value-based part-prioritization strategies: Part Value and 

Dynamic Part Value. Part Value is similar to strategies used in earlier rough mill 

simulations such as CORY (Brunner et al. 1987). With part valuing, each part size 

is assigned a value. The decision, which parts get a higher dynamic part value, is 

determined by the user. Normally, parts that are needed more are given a higher value. 

Smaller part sizes are given a lower value. Obviously, very different results can be 

obtained by using different part values. In reality, the values assigned to the different part 

sizes may or may not reflect the actual value of the part. The simulation is dependent on 

your assumptions about parts’ values.

Most dollar valuation systems cannot consider the part quantities needed. If a part is 

valued high at the beginning of processing, it will have the same high value at the end 

of processing even if the required number of cuttings is met shortly after processing 

begins. A better solution is to decrease the value of the part as its requirements are met 

(DYNAMIC PART VALUE). This shifts emphasis from quantity requirements for parts 

that are nearly satisfied to those that are not being met. If the required quantity for a part 

size is N, the value of the part is reduced 1/N each time a part is cut. For example, if you 

value a part size at $1.00 and require 50 of them, cutting one part of this size will reduce 

the value of the next part to $0.98.

10.2.2 Area-Based Part Prioritizing

ROMI 4.0 contains three part-prioritization strategies based on part area: AREA, L2W, 

and L2W x NEED. AREA part prioritization equally prioritizes the width and length of 

parts and is the true yield optimization prioritization mode. Thus, the highest overall yield 

can be expected when using this method. However, because it places no emphasis 

on wider or longer parts, it is likely to prioritize parts inconsistent with the demands of 

the cutting bill. The L2W strategy is the same formula found in Thomas’ YIELD program 

(Thomas 1962), Brunner’s CORY (Brunner et al. 1987), and the Forest Products Lab’s 

YIELD program (Wodzinski and Hahm 1966). L2W builds in a preference for longer 

cuttings and is more likely to correspond to cutting bill requirements. It does not, 

however, consider part quantity.
63

Cutting bills where the numbers of different parts vary greatly are difficult to analyze. A 

simple improvement to the L2W formula is L2W x NEED (Thomas 1996). L2W multiplied 

by NEED, the current number of parts required for a particular part size, results in a L2W 

strategy that is sensitive to quantity demands. Overall performance is improved. As a 

part is cut, the need for that part size is decreased by one. The L2W x NEED strategy 

can be regarded as a simple dynamic strategy.

10.2.3 Dynamic Part Prioritizing

Dynamic part-prioritizing strategies seek to overcome many of the problems associated 

with dollar-based or area-based strategies. Dynamic strategies are distinguished from 

others by the ability to reduce priorities as part requirements are met. Rather than 

depend on part size alone or on an operator’s judgment about which values to assign to 

different part sizes, dynamic strategies assign each part size a priority based on its size 

and quantity needed. This allows cutting preference to shift from parts with low quantities 

to those that require a higher quantity.

ROMI 4.0’s dynamic strategies calculate exponential weighing factors that are based 

on the needed quantity of a part size. These exponential factors typically range in value 

from 1.0 to 3.2, depending on the needed quantity of the part size. ROMI 4.0 allows 

you to pick from one of two exponential part-prioritizing strategies: Simple Dynamic 

Exponent (SDE) or Complex Dynamic Exponent (CDE). As the name implies, CDE 

considers more information about the cutting bill’s current requirements than SDE when 

assigning part priorities. For example, CDE is sensitive not only to how many parts are 

currently needed for each size, but also to how many have been cut. This sensitivity is 

useful when a cutting bill contains large parts with relatively small quantities needed. 

Because large parts will be harder to obtain, using only a quantity-based exponential 

weighting factor, these parts may not be given high enough priority to be obtained 

opportunistically. CDE increases the priority of such parts so that they can be obtained 

at earlier, more opportune times in processing. 

CDE and SDE should not be confused with dynamic variants of the value-based and 

area-based strategies. The simplistic dynamic value and area strategies mentioned 

earlier reduce their priorities linearly; CDE and SDE reductions are exponential. A major 

drawback to linear reductions is that the priority of a part is reduced much more rapidly 

than with the exponential method (Fig. 10.2.1). The key advantage of the CDE and SDE 

strategies is that they maintain priority levels until most of the required cuttings for the 

part have been obtained. Figure 10.2.1 shows a comparison between the linear dynamic 

area strategy and the exponential CDE strategy. A full discussion of the evolution of the 

dynamic prioritizing strategies is found in Prioritizing Parts from Cutting Bills when Gang 

Ripping First (Thomas 1996).
64

Figure 10.2.1.—L2W x Need and CDE prioritizing 

comparison for a 2 x 48-inch part.

10.2.4 Selecting a Part-Prioritizing Strategy

ROMI 4.0’s default part-prioritizing strategy is CDE. CDE prioritizes parts so they can 

be obtained from the least amount of lumber most of the time. However, this level of 

efficiency may be too high for some users. If chop saws are being run on a longestlength-first basis, the L2W or L2W x Need strategies might predict yield better. 

10.2.5 Processing Salvage Parts

Clear areas of a strip section that do not contain primary parts but that can contain 

salvage parts are called salvage areas. When the available clear area for a salvage part 

is identified, several options can be used to determine which part size to cut from the 

clear area. The simplest option takes the full width of the area to generate a random 

width part. For this method, you need to specify the minimum acceptable salvage width. 

A second method rips the area to the widest possible specified primary-part width. The 

third method rips the area to the widest possible salvage-part width. Salvage-part widths 

are specified by the user separately from the primary widths and used only for salvage.

Three different methods can be used to determine which salvage-part length to cut. The 

simplest method takes the longest random length possible with respect to the minimum 

and maximum primary-part lengths. The second method takes the longest primarypart length that will fit. The third method takes the longest salvage-part length. Salvage 

specific part lengths are specified separately from the primary lengths. After the first 

salvage part has been cut, the remaining area is examined. Cuttings are removed until 

there is no area large enough for the smallest salvage cutting.
65

10.2.6 Smart Salvage

If specified, ROMI 4.0 will attempt to cut a part from salvage that is needed by the 

cutting bill (see Section 4.2.7 for more information about configuring ROMI 4.0 to do 

this). ROMI 4.0 first determines the widest possible primary part that will fit in the clear 

salvage area. Next, a check is made to see that there is a need for a part length that 

will fit in the clear area. If any are needed, the most desirable (depending on partprioritization strategy) primary-size part is cut. If there is no need for that size, the largest 

primary part that fits the clear area is cut.

The benefits of salvaging according to the cutting bill are maximized when primary 

operations are prevented from cutting orphan or excess parts. This allows the salvage 

operations to look at larger areas and potentially cut larger parts that are needed by the 

cutting bill. This approximates the re-saw or re-rip operations found in rough mills. Resaw involves re-ripping a strip to a width that will yield a part needed by the cutting bill. 

This operation will be referred to as “smart salvage.”

Figure 10.2.2 shows a strip where all possible primary parts have been cut from the 

full-width clear area and one salvage part from the right end. In this example, only the 

leftmost parts are actually needed by the cutting bill. The remaining primary part is an 

excess or orphan part. Figure 10.2.3 shows the same strip processed when the primary 

operations cut only needed parts. This yielded two needed parts and one needed 

primary-size salvage part.

Figure 10.2.2.—Conventional primary operation.

Figure 10.2.3.—Smart salvage operation.

Although smart salvage reduces salvage yield, it has the potential to reduce the amount 

of lumber required to meet a cutting bill. ROMI 4.0 simulations, comparing yields 

between smart salvage and standard operations across several cutting bills and lumber 

grades, show a reduction of 0.4 to 2.2 percent in the total amount of lumber required to 

meet a given cutting bill. Several factors can influence this reduction. Obviously, if the 

cutting bill is well matched to the lumber, few orphans, and acceptable yield, the benefits 

from using smart salvage will be lower. Sawing wider strips increases smart salvage 

chances of finding required cuttings.
66

11 USER INFORMATION FEATURES

11.1 Cutting Bill Information

One of the big changes in ROMI 4.0 is improved usability for the novice user. The core 

functions and routines remain similar to the previous version for practiced users. To 

improve the usability and auditability of the run simulation, ROMI 4.0 tracks information 

about the cutting bill in a file menu creating a file property sheet. A file property is a set 

of information that helps to identify your file (cutting bill and simulation) either now or 

later. For example, the title of your document is a property, as are the author and date 

of creation or the date the file was modified. Monitoring of file properties is important to 

track changes and to know the latest version of a file or when a modification or update 

took place.

In ROMI 4.0 the Cutting Bill information is displayed on the main user interface and 

includes the most important information such as User name, Simulation date, Grade Mix 

used, Order comments, and the modification parameter check boxes Enable Cutting Bill

and Display on Output. Figure 11.1.1 shows the Cutting Bill Information window at the 

bottom right field within the main user interface.

Figure 11.1.1.—Cutting Bill Information feature on the main user interface of ROMI 4.0.

Clicking the button labeled Edit Cutting Bill Info will cause ROMI 4.0 to open the Cutting 

Bill Information window and collect information (such as user name, simulation date, 

grade mix used, and other comments regarding the cutting bill file) from the current 

cutting bill and send it to the main user interface and, after a simulation, to the output 
67

file. Figure 11.1.2 shows the Cutting Bill Information window. Within the Cutting Bill 

Information window the user can specify details about the simulation and the cutting bill 

used. Also, the configuration of the output file properties for the cutting bill information is 

possible here. To close the window, click on the Okay button. 

Figure 11.1.2.—Cutting Bill Information feature information window; stores the most important information 

about the processed cutting bill.

11.2 Help

ROMI 4.0 offers the user help, if necessary. In the task line of ROMI 4.0 (Fig. 3.2.1) the 

user can click on Help and a window will open (Fig. 11.2.1). The Help function includes 

a Help Menu (see Section 11.2.1), the Users Manual, and About (including contact 

information and the link to the ROMI 4.0 homepage for updates and news). 

In addition to the Help function on ROMI 4.0, there are 27 related publications on the 

installation CD. These are included to give the user a more detailed understanding of the 

ROMI program and the simulation of rough mill processes. 
68

Figure 11.2.1.—ROMI 4.0 Help function.
69

11.2.1 Help Menu

For terms used in ROMI 4.0 (The number in brackets behind some terms refers to 

digitized defect code used in ROMI 4.0).

1998 Data Bank for KilnDried Red Oak LumberThe representation of red oak boards used for simulations in ROMI. Gatchell et al.’s 

(1998) database contains 3,487 boards with a total of 20,021 board feet 4/4 kiln-dried 

red oak boards graded using NHLA Grading Rules FAS, F1F, Select, No.1 Common, 

No.2 Common, and No.3A Common.

Adventitious buds Adventitious buds are subnormal buds and can be found at any points along the stem. 

They arise from latent or dormant buds in the leaf axils (angle between the branch 

and the stem) of the young stem and persist for an indefinite number of years within 

the cortical-cambial zone. They retain connection back to the pith by means of a stele, 

e.g., a bundle of water-conducting tissues also known as a bud trace.

Arbor Arbors are the axis on which the saw blades that rip the boards into smaller strips are 

fixed on.

Arbor, All-bladesMovableAn arbor on which all blades are allowed to move to generate specified or randomwidth strips that best match the characteristics of the board and the demands of a 

given cutting bill.

Arbor, Best-SpacingSequenceThe best fixed blade saw spacing arrangement is generated for each board by moving 

the rip fence onto which the board’s edge is pressed into the most preferred position 

relative to the saw blades.

Arbor, Fixed The saw spacing arrangement specified by the user and used for all boards. Each 

board is ripped with one edge against the edge of the fixed fence.

Arbor, Fixed-BladeBest-FeedThe saw spacing arrangement specified by the user and used for all boards. Each 

board is positioned automatically with respect to the saw spacings such that the 

strips generated best match the characteristics of the board and the demands of the 

cutting bill.

Arbor, MovableOuter-BladeAn arbor on which the last blade can be moved out to the edge of the board. The 

blade is moved out if an edging strip less than the minimum primary width would be 

generated. This produces a single, wider random-width strip, or a strip of the widest 

width possible.

Arbor, Selective-Rip This arbor consists of fixed and movable blades. The user specifies the distance 

between the blades (the strip widths) and indicates which blades are allowed to move. 

In addition, the user specifies the distance the movable blades are allowed to move, 

thus allowing the simulator to position the board and move blades such that the strips 

generated best match board characteristics and cutting bill demands.

Bark Bark is the outermost layer of a living tree. It serves to protect the tree from insect, 

bacterial, and animal attack.

Bark pocket [10] A space between annual growth rings that contains bark. Bark pockets appear 

different in the anatomical directions of the cut: as dark streaks on radial surfaces and 

as rounded areas on tangential surfaces.

Bird peck [23] A small hole or patch of distorted grain resulting from birds pecking through the 

growing cells in the tree. The shape of bird peck usually resembles a carpet tack 

with the point toward the bark. Bird peck is usually accompanied with discoloration

extending for considerable distance along the grain and to a much lesser extent 

across the grain.

Board Lumber that is less than 38 mm standard (2 foot nominal) thickness and greater than 

38 mm standard (2 inch nominal) width. Boards less than 140 mm standard (6 inch 

nominal) width are sometimes called strips.
70

Board foot (BF) A board foot (BF) is the unit of measurement used for hardwood lumber in the United 

States. A board foot is a volume of lumber 1 foot long x 1 foot wide x 1 inch thick (1 

foot = 0.305m, 1 inch = 25.4 mm). The formula for determining board feet in a board is:

(BF) = (Width in inch x Length in feet x Thickness in inch)

12

The percentage of clear wood required for each grade, based on NHLA Grading 

Rules, are based on this 12 foot unit of measure.

Board Segment Used in cross-cut first operations. A full-width section of a board produced by 

crosscutting the board to a specified part length. Board segments are ripped to 

produce one or more primary parts.

Bud Trace with Bark / 

Check [20]

See Adventitious buds.

Burl [13] Bulges and irregular growth that form on the trunks and roots of trees. Burls are 

highly sought after for the aesthetically appealing veneer they yield, but have to 

be considered as defects in regular rough mill operations when occurring as small 

artifacts in boards. 

Callus wood [21] Callus wood grows around a correct pruning cut and seals the cut. This callus 

wood later becomes woundwood and can be up to 40 percent stronger than the 

original wood. Also, callus wood has a slightly altered chemical makeup because its 

composition is designed to fight any kind of pathogens.

Check A lengthwise separation of the wood that usually extends across the rings of 

annual growth and commonly results from stresses building up in wood during 

seasoning (drying).

Check, Surface [14] Checks are small splits on the surfaces of lumber that are no longer than 2 inches and 

do not completely penetrate the board. Checks can either be caused by mechanical 

means or occur naturally. Checks occur on board surfaces after or during drying 

and processing.

Chip [16] (Machine) chip or torn grain results from mechanical forces, caused by machines, 

through the wood structure. Chip refers to a smaller area (normally only fiber bundles 

or local spots) of torn-out wooden material. (See also Snipe / Tear out).

Crook A lumber defect where an edgewise warp affects the straightness of the board, 

thereby affecting board quality and yield. 

Cutting bill A specified list of part sizes and quantities. (See also Dynamic Prioritization 

Methods and Static Prioritization Methods).

Cutting stage A single ripping or crosscut operation. For example, crosscutting a board into primary 

part length board sections is a cutting stage. The production of primary parts requires 

two stages: crosscutting and ripping or vice versa.

Decay [4] Refers to the decomposition of wood substance by fungi (basidiomycetes, such as 

white or brown rot).

Decay, Advanced or 

common

The more advanced stages of decay in which the destruction of the wood substance 

is readily recognized as the wood has become punky, soft and spongy, stringy, 

ringshaked, pitted, or crumbled. Also, advanced discoloration or bleaching of the 

wood occurs at this stage.

Decay, Incipient [18] The early stage of decay that has not yet softened or otherwise perceptibly impaired 

the hardness of the wood. Incipient decay is usually accompanied by a slight 

discoloration of the wood.

Dimension component As defined by the Wood Components Manufacturers Association (WCMA), 

dimension components are hardwood and softwood parts, normally kiln-dried, which 

have been processed to a point where the maximum waste is left at the dimension 

mill, and the maximum utility is delivered to the user. The components are categorized 

in quantity and quality, such as dimensions, surface quality, raw material, and 

part grades.
71

Dimension component, 

Part grade

See Part grade, Dimension component and Table 3.

Dimensional lumber See Lumber

Discoloration The act of (wood) changing its original color (of a material or substance) to a different 

color or shade. Also, discoloration due to an external action or act, e.g., attack by 

micro-organism, chemical reactions.

Excess Part See Part, Orphan

Excess Primary Part Part produced using only the two original cutting stages (e.g., no salvage operation) 

for which there is no requirement in the cutting bill, but whose size (width and length)

are found in the cutting bill.

Excess Salvage Part Parts produced in three or more cutting stages (e.g., the two primary cutting stages 

plus additional salvage cutting stages) for which there is no requirement in the 

cutting bill. 

FAS A quality classification of hardwood lumber according to NHLA Grading Rules. (See 

Hardwood grades and Table 4).

F1F A quality classification of hardwood lumber according to NHLA Grading Rules. (See 

Hardwood grades and Table 4).

Grain The direction, size, arrangement, appearance, or quality of the fibers in wood or 

lumber. To have a specific meaning, the term must be specified, such as close-grained 

(fine-grained), cross-grained, or edge-grained wood.

Grading rules A set of criteria by which to judge various pieces of lumber or panels in terms of 

appearance, strength, and suitability for various uses. Regional grading agencies 

draw up rules for grading based on the voluntary product standards issued by the U.S. 

Bureau of Standards. ROMI uses the most widely followed standards issued by NHLA. 

(See NHLA Grading Rules.)

Grub hole [11] Grub holes resulting as pre-stage result of wood destroying beetles. Typically grub 

holes are 0.25 inch in diameter or larger (depending on the species).

Hardwood grades Hardwood lumber is usually graded (according to the NHLA Grading Rules, see 

National Hardwood Lumber Association) on the basis of the size and number of 

cuttings (pieces) that can be obtained from a board when cut up. Hardwood grades 

are used in the manufacture of a hardwood product. The upper grades, including 

FAS, FAS-One-Face (F1F) and Selects, are most suitable for long clear cuttings (such 

as mouldings and joinery products). The common grades, primarily No.1 Common 

(No.1C) and No.2A Common (No.2AC), are likely to be the most suitable for smaller 

cuttings (such as kitchen cabinet and furniture parts). Worth noting is the fact that 

once resawn, the cuttings obtained from the Common grades will be of the same clear 

wood as the upper grades, but smaller (shorter and/or narrower) cuttings will have 

been obtained. Table 4 gives an overview of the characteristics of each hardwood 

grade class.

Kerf The amount of wood removed by a saw blade. Common kerf thicknesses simulated by 

ROMI 4.0 are 0.125 and 0.1875 of an inch. (See saw kerf.)

Knot The portion of a branch or limb that has been surrounded by subsequent growth of the 

stem. The shape of the knot as it appears on a cut surface depends on the anatomical 

direction and on the angle of the cut relative to the axis of the knot. For determining the 

quality of the wood, further determination of the knot’s size and health are necessary. 

It is necessary to evaluate if knots are sound knots or unsound / loose knots.

Knot, pin A knot that does not exceed 0.25 inch in average diameter in its sound portion or 1⁄8

inch in average diameter in its unsound portion.

Knot, sound [15] A knot that is solid across its face, at least as hard as the surrounding wood, and 

shows no indication of decay.

Knot, unsound (loose) 

[12]

A knot that is not held firmly in place by growth or position and that cannot be relied 

upon to remain in place. Refers also to a knot that is decayed or that shows decay. 
72

Length (of a board) The length of a board is defined as the length of the piece in axial (grain) direction, 

expressed in feet.

Lumber The product of the saw and planing mill for which manufacturing is limited to sawing, 

resawing, passing lengthwise through a standard planing machine, crosscutting to 

length, and matching. Lumber may be from either softwood or hardwood.

Mechanical damage [1] Refers to artificial damage to lumber or dimension components that occurs along the 

product’s value chain, e.g. holes from moisture meters, hooks, nicks, grooves, or other 

damages from a foreign object.

Mineral streak [25] Normally an olive to greenish-black or brown discoloration caused in hardwoods due 

to the storage and incorporation of minerals in the wood structure during tree growth.

National Lumber 

Hardwood Association 

(NHLA)

The purpose of the NHLA is to establish, maintain, and apply a uniform system 

for the inspection, measurement, and grading of hardwood lumber; to establish 

and maintain training schools and instructional courses and to publish books and 

literature applicable to the study of the NHLA grading standards and their applications; 

to conduct conferences, seminars, and other educational activities on subjects 

of importance to the hardwood trade; to encourage research in hardwood timber 

management and utilization, and to disseminate information to the industry; to promote 

the welfare and protect the interests of the hardwood trade.

(NHLA) Grading Rules NHLA Grading Rules provide both the buyer and seller with a consistent language 

to use in specifying hardwood lumber transactions. Knowledge of the NHLA Grading 

Rules is essential for buyers on a global scale to understand the terms of the trade.

No. 1 Common A quality classification of hardwood lumber according to NHLA Grading Rules. (See 

Hardwood grades and Table 4).

No. 2 Common A quality classification of hardwood lumber according to NHLA Grading Rules. (See 

Hardwood grades and Table 4).

No. 3A Common A quality classification of hardwood lumber according to NHLA Grading Rules. (See 

Hardwood grades and Table 4).

Panel A panel is made up of two or more edge-glued wood pieces of specified length 

and width. Typically, panels are produced to approximate sizes and later cut to 

specific parts.

Part grade, Dimension 

component

Classification dimension components based on quality according to rules established 

by the Wood Component Manufacturers Association (WCMA). In rough or semimachined dimension parts, for any grade, those blemishes that will be removed in 

planing or machining to finished sizes are permitted. Three face grades for hardwood 

dimension components are specified:

“A” Face – Material that is acceptable for prominent surfaces such as tops, doors, 

and drawers.

“B” Face – Material that is acceptable for surface of intermediate visibility such as 

exteriors of most end panels; the interior of end panels on an open case, shelves, and 

the inside of drawer fronts. 

“C” Face – Material that is acceptable for low visibility parts where strength and 

smoothness is the deciding factor – such as back edges of rails, or the underside 

portion of any table that is susceptible to touch and feel. (See Table 3.)

Part, Orphan A primary part that is cut but is not needed; that is, the required numbers of parts of 

this particular size have been met already. An “extra” piece.

Part, Primary Parts produced by ripping board sections to primary part widths.

Pith [3] The small, soft inner core of a tree trunk, branch, twig, or log.

Pith fleck(s) A narrow streak, resembling pith on the surface of a piece, resulting from burrowing of 

larvae in the growing tissues of the tree. (See Callus cells).

Pith related tear or 

split [6]

Tear or split induced by inner tension related to dimensional change and/or shrinkage 

beginning at the pith of a tree trunk, branch, twig, or log.

Primary Part Length Any length specified in a cutting bill is a primary part length. Primary part lengths are 

the lengths that are crosscut from the board (cross-cutting first) or the strip (rip-first).
73

Primary Part Width The part widths used when ripping board segments to specified part sizes. Any part 

width listed in a cutting bill is a primary part width. 

Primary Part Width 

Minimum

The minimum primary width that is specified when processing random width 

part sizes. 

Prioritization Methods With a proper part prioritization and scheduling strategy, cutting bill requirements can 

be met using less board footage compared to no or sub-optimal prioritizing strategies. 

Essentially makes some part sizes more preferred than others at any given point in 

the cut-up cycle. Optimized lumber cut-up (e.g., lumber cut-up using prioritization 

methods) results in lower lumber requirements, less lumber handling and processing, 

higher production capacity, and lower numbers of unneeded parts (orphan and excess 

salvage parts). 

Prioritization, Dynamic 

Method

A method of prioritizing parts required in a cutting bill so that the part priorities 

change as parts are produced. Dynamic methods generally require less board 

footage than static methods to meet a given cutting bill. (See Cutting Bill and Static 

Prioritization Methods.)

Prioritization, Static 

Method

A method of prioritizing cutting bill parts. The priority assigned to a cutting bill part at 

the start of a lumber processing cycle is the same priority that is used at the end of the 

processing cycle. Numbers or dollar values are good examples of a static prioritization 

strategy. Static prioritization generally is less efficient than dynamic strategies. (See 

Cutting Bill and Dynamic Prioritization Methods.)

Proximity rule The Proximity rule is useful for moulding and millwork parts where defects are 

acceptable in areas where no machining takes place. The rule has to be defined from 

both edges, respectively, the minimum and maximum distance from the machined 

edge. The definition of proximity rules will help to improve yield when defects are 

acceptable in certain areas.

Rough (sawn) lumber Lumber that has not been dressed (surfaced) but has been sawn, edged, and trimmed.

Salvage Parts that are obtained involving at least one additional cutting operation beyond the 

two original cuts (rip-first and cross-cut first or vice versa). The additional cut makes 

these parts more expensive to produce and, therefore, less desirable. Unlike excess 

salvage, salvage parts are required by the cutting bill.

Saw kerf (1) Grooves or notches made in cutting with a saw. (2) That portion of a log, timber, or 

other piece of wood removed by the saw in parting the material into two pieces.

Saw line [9] Special case of mechanical damage, e.g., a partial cut through the board either axial 

or across the board from an earlier processing stage (logging, sawmill, etc.).

Saw Space Sequence The sequence or arrangement of widths on the arbor. It is important that this sequence 

be developed in consideration of the width distribution of the lumber and the surface 

area required for each part width as described by the cutting bill.

Selects A quality classification of hardwood lumber according to NHLA grading rules. (See 

Hardwood grades and Table 4.)

Shake A separation of the wood structure along the grain, the greater part of which occurs 

between the rings of a tree’s annual growth. Usually considered to have occurred on 

the standing tree or during felling.

Snipe [17] (Machine) Snipe or Tear out as result of a medium to exert major mechanical force 

through the wood structure, refers to a bigger area being affected compared to 

(Machine) Chip or Torn grain.
74

Split [24] An axis-wise separation of the wood. Induced by internal or external forces to 

irreversibly tear apart the wood cells.

Split, Machine made [7] Major splitting that may happen during the machining process of wood, also called 

tear out or torn grain depending on the size of the damage. Machine made split 

usually occurs in planning or molding operations, but may also happen with other 

machines featuring rotating knives.

Stain A discoloration in wood that may be caused by such diverse agencies as microorganisms, environmental influences, chemicals, metals, 

and /or combinations of the above. The term is also used for materials that are used to 

impart die onto wood. (See Stain, sap.)

Stain, sap [22] A discoloration of a tree’s sapwood caused by the growth of certain fungi mainly 

on the surface but also in the interior of the wood. Stain discolors the wood but does 

not lead to a reduction of the material’s mechanical properties. However, conditions 

allowing stains to grow also favor the growth of other (wood destroying) fungi.

Stain, sticker [19] A brown or blue stain that develops when seasoning lumber where the lumber surface 

has been in contact with the stickers.

Sticker(s) A .75 to 1 inch wood strip that is inserted between stacks of green lumber and spaced 

between 16 to 24 inches to allow air to flow through the stack to ensure proper drying.

Strip A narrow, board-length piece of wood produced by the gang-ripsaw using ripfirst processing.

(Standard) Thickness Standard thickness (based on NHLA grading rules) for rough sawn lumber is 

expressed in quarters of an inch, e.g., 1 inch= 4/4. The majority of U.S. hardwood 

lumber production is sawn between 1 inch and 2 inch, although other thicknesses are 

available in more limited quantities. The NHLA Grading Rules include a list of standard 

thicknesses for rough (sawn) lumber.

Standard thicknesses (according to NHLA grading rules) for rough lumber are: 3⁄8, 1⁄2, 

5⁄8, 3⁄4, 1, 1-1⁄4, 1-1⁄2, 1-3⁄4, 2, 2-1⁄2, 3, 3-1⁄2, 4, 4-1⁄2, 5, 5-1⁄2, and 6 inch. One inch and thicker 

may also be expressed in quarter inches as follows: 4/4, 5/4, 6/4, 7/4, 8/4, 10/4, 12/4, 14/4, 16/4, 

18/4, 20/4, 22/4, and 24/4.

(Standard) Length Standard lengths (according to NHLA Grading rules) are 4, 5, 6, 7, 8, 9, 10, 11, 12, 

13, 14, 15, and 16 feet.

Surface measure (SM) Surface measure (SM) is the surface area of a board in square feet. To determine 

surface measure, multiply the width of the board in inches by the length of the board 

in feet and divide the sum by 12 (rounding up or down to the nearest number). The 

percentage of clear wood for each grade is based on the surface measure, not the 

board feet measure. Thus, all boards, no matter what their (standard) thickness, are 

graded in the same way.

Surfaced lumber Lumber that is dressed by running it through a planer.

Tear out See Snipe.

Torn Grain See Chip.

Void [2] Unfilled or unoccupied space within the wood structure. Due to the lack of material 

and the associated lower mechanical properties of a piece this needs to be 

considered a defect. This lack of material poses problems in material handling in 

advanced processing. Also, void has an undesirable impact on the appearance of the 

wood (product). 

Wane [8] Bark or lack of wood from any cause on the edge or corner of lumber or a component 

except for eased edges.

Warp Warp is any variation from a plane surface. Warp generally includes bow, crook, cup, 

and twist, or any combination thereof.

Wood Components 

Manufacturers 

Association (WCMA)

The basic goals of the Wood Components Manufacturers Association (WCMA) are 

to establish and maintain specifications and commercial standards for the hardwood 

dimension manufacturing industry.

Worm hole(s) Holes and channels cut in wood by insects.
75

Worm hole(s), Pin [211] One spot worm hole not over 1/16 inch in diameter.

Worm hole(s), Spot [111] One spot worm hole over 1/16 inch but not more than 1⁄8 inch in diameter.

Worm hole(s), Shot One spot worm hole over 1⁄8 inch but less than 1⁄4 inch in diameter.

Yield Yield is defined as the ratio of aggregate part surface area output to aggregate lumber

surface area input.
76

Table 3.—Summary of dimension component part specifications per Face Grade according to the 

Wood Component Manufacturers Association (WCMA 2007, adapted) 

“A” Face – Material that is acceptable for prominent surfaces such as tops, doors and drawer fronts. 

Will admit:

Small sound knot specks

Small dark mineral streaks or pitch pockets not over 1/16 inch x 1 inch (1.6 mm x 25.4 mm)

Light discoloration

Size of strips (staves): 1 inch (25.4 mm) min., 5 inch (127 mm) max., narrow strips (staves) to 

be well scattered

Will not admit: 

Birds eye

Any knots other than small specks

Splits, checks, or shake

Holes, gouges, or other open areas deeper than 1/32 inch (0.8 mm)

Bark or wane

Mineral streaks larger than 1/16 inch x 1 inch (1.6 mm x 25.4 mm)

Large dark discolored areas

Punky or unsound wood

“B” Face – Material that is acceptable for surface of intermediate visibility such as the exterior of most end 

panels, the interior of end panels on an open case, shelves, and the inside of drawer fronts. 

Will admit: 

Occasional pin knots and small sound knots not over 1⁄8 inch (3.2 mm)

Occasional mineral streak not over 1⁄4 inch x 2 1⁄4 inch (6.4 mm x 63.5 mm)

Moderate discoloration

Occasional birdseye

Size of strips (staves): 3⁄4 inch (19.1 mm) min., 5 inch (127 mm) max., narrow strips (staves) to 

be well scattered.

Will not admit: Any knots over 1⁄8 inch (3.2 mm)

Splits, checks or shake

Holes, gouges or other open areas deeper than 1/32 inch (0.8 mm)

Bark or wane

Punky or unsound wood

Mineral streaks over 1⁄4 inch x 2 1⁄2 inch (6.4 mm x 63.5 mm)

Large dark discolored areas

“C” Face – Material which is acceptable for low visibility parts where strength and smoothness is the 

deciding factor – such as back edges of rails, underside portion of any table that is susceptible to touch 

and feel.

Will admit:

Unlimited discoloration or mineral streaks

Solid knots up to 1⁄2 inch (12.7 mm) diameter

Surface checks

Open defects up to 1⁄8 inch x 1 inch (3.2 mm x 25.4 mm) or 1⁄4 inch (6.4 mm) diameter

Unlimited birdseye

Small areas of punky or unsound wood

Boards of any width up to 5 inch (63.5 mm)

Will not admit:

Large open knots

Wane

Large areas of punky or unsound wood
77

Table 4.—Summary of grade classes and particular requirements per class 

according to the National Hardwood Lumber Association (NHLA 2011, adapted)

Grade

Board length Board 

width Minimum Clear area Allowable cuts to obtain Part dimensions

Minimum Minimum Part size Part length Cuts

Feet Inches Percent Feet

FAS 8 6 4 in x5 ft or 

3 in x 7 ft 83 1⁄3

4-7

8-11

12-15

≥16

1

2

3

4

SEL 6 4 4 inch x 5 ft 

or 3 in x7 ft 66 2⁄3

better side same as FAS 

reverse side better than 

1 Com.

1 Com. 4 3 4 in x2 ft or 

3 in x7 ft 66 2⁄3

3-4

5-7

8-10

11-13

≥14

1

2

3

4

5

2A Com. 4 3 3 in x 2 ft 50

2-3

4-5

6-7

8-9

10-11

12-13

≥14

1

2

3

4

5

6

7

3A Com. 4 3 3 in x 2 ft 33 1⁄3 no limit to number of cuts

3B Com. 4 3 1 1⁄2 in x2 ft 25 no limit to number of cuts
78

ACKNOWLEDGMENTS

The work upon which this publication is based was funded in part through a grant 

awarded by the Wood Education and Resource Center, Northeastern Area State and 

Private Forestry, U.S. Forest Service, the U.S. Forest Service Northern Station, Virginia 

Tech, Virginia Cooperative Extension Service, the Wood Component Manufacturers 

Association (WCMA), and Super Thin Saws.

LITERATURE CITED

Brunner, C.C.; White, M.S.; Lamb, F.M.; Schroeder, J.G. 1987. CORY. A computer 

program for determining dimension stock yields. Forest Products Journal. 

39(2): 23-24.

Buck, R.; Buehlmann,U.; Thomas.R.E. 2010. ROMI’s integrated least-cost grade-mix 

solver for local computer use. Forest Products Journal. 60(5): 432-439.

Buehlmann, U.; Thomas, R.E.; Zou. X. 2011. Cost minimization through optimized 

raw material composition. Robotics and Computer-Integrated Manufacturing. 

27(2011): 746-754.

Gatchell, C.J. 1996. Designing a fixed-blade gang ripsaw arbor with a pencil. Forest 

Products Journal. 46(6): 37-40.

Gatchell, C.J.; Thomas, R.E.; Walker, E.S. 1998. 1998 data bank for kiln-dried red oak 

lumber. Gen. Tech. Rep. NE-245. Radnor, PA: U.S Department of Agriculture, Forest 

Service, Northeastern Research Station. 47 p.

Lawson, P.; Thomas, R.E.; Walker, E.S. 1996.OPTIGRAMI: Optimum V2 user’s guide.

Gen. Tech. Rep. NE-190. Radnor. PA: U.S. Department of Agriculture, Forest Service, 

Northeastern Research Station. 46 p.

Mitchell, P.; Zou. X. 2001. Optimizing gang ripsaw fixed-blade arbor spacings to 

improve rough mill conversion efficiency. Final Project Report. U.S. Forest Service. 

Cooperative Grant: 23-99-0058. Raleigh, NC: North Carolina State Univ.

Moody, J.; Gatchell, C.J.; Walker, E.S.; Klinkhachorn, P. 1998. User’s guide to UGRS: 

the Ultimate Grading and Remanufacturing System (version 5.0). Gen. Tech. Rep. 

NE-254. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern 

Research Station. 40 p.

National Hardwood Lumber Association (NHLA). 1998. Rules for the measurement 

and inspection of hardwood and cypress lumber. Memphis, TN: National 

Hardwood Lumber Association.
79

National Hardwood Lumber Association (NHLA). 2011. Rules for the measurement 

and inspection of hardwood and cypress plus NHLA sales code & inspection 

regulations. Memphis, TN: National Hardwood Lumber Association.

SAS. 2002. SAS System for Windows® 8.2. Cary, NC: SAS Institute, Inc.

Schumann, D.R. 1971. Dimension yields from black walnut lumber. Res. Pap. FPL162. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products 

Laboratory. 16 p.

Stiess, T.S. 1995. Simulation in the wood products industry. Wood & Wood Products. 

September: 133-135.

Thomas, R.E. 1996. Prioritizing parts from cutting bills when gang-ripping first. 

Forest Products Journal. 46(10): 61-66.

Thomas, R.E. 1997. ROMI-CROSS: ROugh MILL CROSScut-first simulator. Gen. 

Tech. Rep. NE-229. Radnor, PA: U.S. Department of Agriculture, Forest Service, 

Northeastern Forest Experiment Station. 56 p.

Thomas, R.E. 1999. User’s guide to ROMI-RIP 2.0: A ROugh MILL RIP-first 

simulator. Gen. Tech. Rep. NE-259. Radnor, PA: U.S. Department of Agriculture, 

Forest Service, Northeastern Research Station. 64 p.

Thomas, R.E.; Weiss. J. 2006. Rough mill simulator version 3.0: an analysis tool for 

refining rough mill operations. Forest Products Journal. 56(5): 53-56.

Thomas, R.J. 1962. The rough end yield research program. Forest Products Journal. 

12(11): 536-537.

U.S. Department of Agriculture, Forest Service. 1956. Wood – colors and kinds. Agric. 

Handb. 101. First issued October 1956, approved for reprinting August 1981.

Wodzinski, C.; Hahm, E.; 1966. A Computer program to determine yields of lumber. 

Gen. Tech. Rep. FPJ-66-009. Madison, WI: U.S. Department of Agriculture, Forest 

Service, Forest Products Laboratory. 34 p.

Wood Component Manufacturers Association (WCMA). 2007. Rules and specifications 

for dimension and woodwork. 8th ed. Lindstrom, MN: Wood Component 

Manufacturers Association. 

Zou, X.; Buehlmann, U.; Thomas, R.E. 2004. Investigating the linearity assumption 

between lumber grade mix and yield using design of experiments (DOE). Wood 

and Fiber Science. 36(4): 547-559. 
80

APPENDIX I

System Limitations

Current specifications and limitations of the ROMI 4.0 simulator: 

Board width: 48 inches (1.219 meters) 

Board length: Unlimited 

Cutting bill 

Maximum individual part quantity: 32,000 

Maximum individual part value: 32,000 

Maximum number of part sizes: 400 

Board data files processed at once: 10

Length ranges: 10 

Width ranges: 15

Lengths 

Primary: 30 or random

Salvage: 15 or random 

Widths 

Primary: 20 or random 

Salvage: 15 or random

Gang-ripsaw arbor

Width 48

Number of spacings 15
81

APPENDIX II 

Board Data Bank Description

This appendix describes the contents of the board data files (Gatchell et al. 1998) 

included with ROMI 4.0. All data files have an eight letter primary file name followed by 

a .DAT extension. All of the boards in each data file are one of six grades. The grade of 

lumber in a particular data file is determined by looking at the file name. 

If the file name 

begins with The grade is

FAS FAS

F1F FAS one Face

SEL Select

1C No. 1 Common

2AC No. 2A Common

3AC No. 3A Common

The boards supplied with ROMI 4.0 are from the 1998 Data Bank for Red Oak Lumber 

by Gatchell et al. (1998). The following tables show the total number of boards in each 

of the six grades. The boards in each grade are randomly sorted into subsets containing 

approximately the same number of boards. Data files ending with a letter contain boards 

that are mirror images of their corresponding files with number endings. For example, 

1C-A contains boards that are mirror images of the boards in 1C-1, 2AC-3 mirrors 

boards in 2AC-3, and so on. MIX files contain all boards, both normal and mirrored, for 

the grade. 

Lumber 

grade

Total 

boards

Board 

footage

Number 

of subsets

FAS 659 5,134 10

FAS one Face 348 2,552 5

Selects 279 1,052 2

No. 1 Common 1,039 5,887 11

No. 2A Common 922 4,737 9

No. 3A Common 240 1,012 2
82

In addition, a small cherry lumber database is available. These data file names all begin 

with “Cherry-“ and are stored with the red oak lumber data. The small number of boards 

available in the cherry databank prevents ROMI from being able to create random 

datasets from the cherry data. The cherry databank consists of the following:

Lumber 

grade

Total 

boards

Board 

footage

FAS one Face 3 28

Selects 1 5

No. 1 Common 34 242

No. 2A Common 72 556

No. 3A Common 148 965

Total 258 1,796
Printed on Recycled Paper

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on 

the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial 

status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because 

all or part of an individual’s income is derived from any public assistance program. (Not all prohibited 

bases apply to all programs.) Persons with disabilities who require alternate means for communication 

of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at 

(202)720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of 

Civil Rights, 1400 Independence Avenue, S.W., Washington, DC 20250-9410, or call (800)795-3272 

(voice) or (202)720-6382 (TDD). USDA is an equal opportunity provider and employer. 

Thomas, R. Edward; Grueneberg, Timo; Buehlmann, Urs. 2015. ROMI 4.0: Rough mill 

simulator 4.0 users manual. Gen. Tech. Rep. NRS-143. Newtown Square, PA: 

U.S. Department of Agriculture, Forest Service, Northern Research Station. 82 p.

The Rough MIll simulator (ROMI Version 4.0) is a computer software package for 

personal computers (PCs) that simulates current industrial practices for rip-first, 

chop-first, and rip and chop-first lumber processing. This guide shows how to set up 

the software; design, implement, and execute simulations; and examine the results. 

ROMI 4.0 accepts cutting bills with as many as 600 solid and/or panel part sizes. 

Plots of boards processed are easily viewed or printed as are detailed summaries of 

processing data (number of rips and crosscuts) and yields for each grade. ROMI 4.0 

optimization algorithms are based on a red oak database containing 3,500 boards 

of all common National Hardwood Lumber Association grades. Even though ROMI 

is based on red oak, the digitized board information can be adapted and modified to 

several other common hardwood species. It is an updated version of ROMI 3: Rough 

Mill Simulator Version 3.0: User’s Guide, General Technical Report NE-328.

KEY WORDS: rough mill, cutting bill, simulation, hardware lumber
Northern Research Station

www.nrs.fs.fed.us