Reference number  
DRS 156: 201 8 
© RSB 2018 
 
 
   
RWANDA 
STANDARD   
DRS  
156 
 
2nd  edition  
Publish by RSB2018 -mm-dd 
(Reaffirmed yyyy)  
Comb foundation mill -specification   
 DRS 156: 201 8 
©RSB 2018- All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2018 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 156: 201 8 
iii                ©RSB 2018- All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope (mandatory)  ................................ ................................ ................................ ................................  1 
2 Normativ e references (mandatory)  ................................ ................................ ................................ ...... 1 
3 Terms and definitions (mandatory)  ................................ ......................... Error! Bookmark not defined.  
4 Symbols (and abbreviated terms)  ................................ ............................ Error! Bookmark not defined.  
5 Clause  ................................ ................................ ................................ ......... Error! Bookmark not defined.  
5.1 Subclause (level  1) ................................ ................................ .................... Error! Bookmark not defined.  
5.1.1  Subclause (level  2) ................................ ................................ .................... Error! Bookmark not defined.  
5.1.2  Subclause (level  2) ................................ ................................ .................... Error! Bookmark not defined.  
5.2 Subclause (level  1) ................................ ................................ .................... Error! Bookmark not defined.  
6 Clause  ................................ ................................ ................................ ......... Error! Bookmark not defined.  
7 Special  ................................ ................................ ................................ ........ Error! Bookmark not defined.  
Annex  A (normative)  Annex title  ................................ ................................ .......... Error! Bookmark not defined.  
A.1 General  ................................ ................................ ................................ .......Error! Bookmark not defined.  
A.2 Clause  ................................ ................................ ................................ ......... Error! Bookmark not defined.  
A.2.1  Subclause (level  1) ................................ ................................ .................... Error! Bookmark not defined.  
A.2.2  Subclause (level  1) ................................ ................................ .................... Error! Bookmark not defined.  
A.3 Clause  ................................ ................................ ................................ ......... Error! Bookmark not defined.  
Annex  B (informative)  Which styles correspond to which element — Quick reference guide Error! Bookmark not defined.  
 DRS 156: 201 8 
©RSB 2018- All rights reserved                  iv 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratifie d by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 156 was prepared by Technical Committee RBS/TC 27, Beekeeping and beekeeping products.  
In the preparation of this standard, reference was made to the following standard: KS 658:20120, 
Specification for comb foundation mill  
The assistance derived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following orga nizations were represented on the Technical Committee on beekeeping and beekeeping 
products  (RSB/TC 027) in the preparation of this standard.  DRS 156: 201 8 
v                ©RSB 2018- All rights reserved  
 Introduction  
The comb foundation mill is used for embossing plain and pure beeswax sheets with the exact cell outline of 
the honeycomb for fixing into the frames of a beehive. Such embossed comb foundation sheets form a base 
for the bees to build up new combs. This helps to conserve the energies of bees to secure drawn -out combs 
of adequate cell -size duly related to natural body -size of local races of bees.  
The main  structure  of the comb  foundation  mill consists  of two rollers  fixed  horizontally  close  together  in a cast 
iron frame. The surface of these rollers has a honeycomb cell design which embosses the comb fou ndation 
sheets  
 DRS 156: 201 8 
1                ©RSB 2018- All rights reserved  
 Comb foundation mill -specification  
1 Scope  
This Rwanda Standard specifies the requirements for the comb foundation mill used for embossing plain and 
pure beeswax sheets with the honeycomb cell outline.  
2 Normative references  
The following documents are referred to in the text in such a way that some or all of their content constitutes 
requirements of this  document.  For dated references, only the edition  cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies.  
RS 157 , Comb foundation sheets — Specification  
ISO 185, Grey cast irons — Classificat ion 
ISO 3755, Cast carbon steels for general engineering purposes  
ISO 21988, Abrasion -resistant cast irons — Classification  
3 Description  
The comb foundation mill shall have the following main parts (see also Figure 1):  
a) frame;  
b) rollers;  
1) roller body ; 
2) roller shaft; and  
3) Roller  surface . 
c) roller adjusting device ; 
d) roller springs (to keep the rollers in position ); 
e) handle;  
f) gears;   
©RSB 2018- All rights reserved                  2 
 g) bearings;  
h) oil tubes (with spring  cap);  
i) water  tub; 
j) screws  ;and 
k) alignment  synchronizer  
 
 
DRS 156: 201 8 
3                ©RSB 2018- All rights reserved  
 Figure 1 — Comb foundation mill  
4 Materials  
The materials for the manufacture of rollers, gears and bearings shall be as given in Table 1. For other parts, 
materials indicated in Table 2 may be used.  
Table 1 — Requirements for materials for rollers, gears and bearings of the comb foundation mill  
 
S/No.  Name of the part  Material  Conforming to  Grade  
(1) (2) (3) (4) (5) 
i) Rollers:  
 Roller  body  
Roller  shaft)  
Roller  surface   
Fringed steel White metal   
ISO 3755  
ISO 185   
C 40  
— 
ii) Gears  Fringed steel  ISO 3755  C 40  
iii) Bearings  Cast iron  ISO 21988  3 B 
Table 2 — Requirements of materials for other parts of the comb foundation mill  
 
S/No.  Name of part  Material  
(1) (2) (3) 
i) Frame  Grey cast iron  
ii) Roller adjusting device  Cast iron or any other suitable material  
iii) Handle  Cast iron, fringed steel or any other suitable material  
iv) Water tub  Galvanized steel sheet or any other suitable material  
5 Shape and  dimensions  
5.1 Shape  
The shape of the comb foundation mill may be as given in Figure 1.  
5.2 Dimensions  
The dimensions of the various components of the comb foundation mill (see Figure 1) as given in 6.2 to 6.7 
pertain to a particular type and are for guidance only.   
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 6 Assembly  
6.1 Frame  
The cast iron frame shall be suitably designed to hold the rollers (see 6.2) horizontally and to hold the water 
tub having a s emi-circular bottom. The frame shall have suitable arrangement to fix the mill during operation. 
The construction of the frame shall be such that it remains stable during operation  
6.2 Rollers  
There shall be two rollers, namely, the top roller and the bottom r oller. The surface of the rollers shall be 
engraved to have the hexagonal honeycomb cell outlines matching with the cell -sizes specified in RS 157,  so 
astogetthesize ofthecell embossed onplainbeeswaxsheetsandalsothecellwallsshall veryclearlystand out as 
prescribed in RS 157 . The minimum diameter of the rollers shall be 75 mm and the minimum length 100mm. 
The rollers  shall have  suitable  opening  in the centre  to allow  the passage  of the roller  shaft  (see6.3).  
6.3 Roller shaft  
The roller shaft shall be of fringe d steel bar of at least 22 mm in diameter. The ends of the rollers shall fit into 
the bearings (see 6.6) provided on either sides. The groove shall be connected to the oil tube.  
6.4 Roller adjusting  device  
A suitable device shall be provided in the mill to adj ust the clearance in steps of the top roller with the bottom 
roller as desired to get proper alignment. The steps may preferably be in 1, 1.5 and 2 mm. A suitable locking 
arrangement at the lowest recommended position shall be provided to avoid damage to t he surface of the 
rollers. The gear shall remain loose on the top roller shaft.  
6.5 Alignment synchronizer  
A suitable device shall be provided so as to have synchronized alignment of the two rollers.  
6.6 Bearings  
There shall be four bearings at the ends of the two rollers to support the roller shafts. The bearings shall have 
openings in the centre to allow the passage of the roller shafts. The bearings shall be so assembled as to be 
easily lubricated and replaced, when desired.  
6.7 Gears  
There shall be four frin ged steel spur gears. The width of the teeth of the gears shall be about 20 mm, module 
2 (12 DP) and number of teeth 30. These may be cast integrally with roller shafts.  DRS 156: 201 8 
5                ©RSB 2018- All rights reserved  
 6.8 Handle  
The handle shall be suitably fixed into the shaft of the bottom roller. A suita ble grip shall be provided. The handle shall be 
operated sideways.  
7 Workmanship and  finish  
7.1 Frame  
The frame shall be free from blow holes and cracks and the surface of the frame shall be made smooth. The 
frame may also be enamel -sprayed.  
7.2 Water tub  
The water tub of the mill shall be properly brazed to avoid leakage.  
7.3 Gears  
The gears shall be finely machined all over.  
7.4 Handle  
The handle may be spray -enamelled.  
7.5 Screws  
All removable screws shall be made rust proof independently before assembly.  
7.6 Mechanical  parts  
All mechanical parts should be suitably galvanized to prevent rusting.  
8 Marking and packing  
8.1 Marking  
8.1.1.  The comb foundation mill shall be marked with the following  particulars:  
l) manufacturer's name or recognized  trade -mark;  
m) year of manufacture;  and 
n) Batch  or code  number.  
8.1.2 . Subject  to an agreement  between  the purchaser  and the vendor, the  marking  may bed on eon brass  
plate soundly soldered to the frame of the comb foundation  mill.  
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 8.2 Packing  
The comb foundation mill shall be packed as agreed to between the bu yer and the supplier.  
  DRS 156: 201 8 
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 Bibliography  
1. Codex Alimentarius website: http://www.codexalimentarius.net/mrls/pestdes/jsp/pest_q -e.jsp  
2. European Union: http://ec.europa.eu/sanco_pesticides/public  
3. IS 3894:1978(R2004), Specification for Comb FoundationMill  
4. USDA Foreign Agricultural Service website: http://www.mrldatabase.com  
5. USDA Agricultural Marketing Service website: http://www.ams.usda.gov/AMSv1.0/Standards  
6. USDA Plant Inspectorate Service website: http://www.aphis.usda.gov/import_export/plants  
 DRS 156: 2018  
ICS 67.020 
 
©RSB 2018  - All right s reserved