Thickness Control Technique for Printing Tactile Sheetswith Fused Deposition Modeling
Haruki Takahashi
Meiji University
Nakano, Tokyo, Japan
haruki@meiji.ac.jp

Homei Miyashita
Meiji UniversityNakano, Tokyo, Japanhomei@homei.com

ABSTRACT

We present a printing technique that controls the thicknessof objects by increasing and decreasing the amount ofmaterial extruded during printing. Using this technique,printers can dynamically control thickness and output thicker
objects without a staircase effect. This technique allows
users to print aesthetic pattern sheets and objects that aretactile without requiring any new hardware. This extends thecapabilities of fused deposition modeling (FDM) 3D printersin a simple way. We describe a method of generating andcalculating a movement path for printing tactile sheets, anddemonstrate the usage and processing of example objects.
Author Keywords

3D printing; digital fabrication; thickness control; haptics;
texture
ACM Classification Keywords

H.5.m. Information interfaces and presentation (e.g., HCI):
Miscellaneous.
INTRODUCTION

Advances in digital fabrication techniques such as 3D
printers have made it possible to create 3D objects accuratelyand cheaply. Fused deposition modeling (FDM) printers, inparticular, have become famous and available on the market
owing to several advantages: ease of use, choice of materials,and low running cost. In association with this advance, newand interesting printing techniques utilizing thecharacteristics of FDM have been proposed (e.g., printing
hair-like structures [3] and spiral printing for generative art[2]). On the other hand, many researchers focus on printing
quality because the aesthetics of look and feel is one of themost important features for printed objects [1, 5]. However,to print high-quality objects, most techniques require anexpensive printer or long printing time. Objects printed by
FDM have a rough and uneven surface, which is called thestaircase effect [4].

Figure 1. (a) Thickness control technique and close-up.
(b) Tactile sheet that combines flexible material.

In this paper, we present a technique that controls thethickness of objects by increasing and decreasing the amountof material and by moving the position of the printer head in
the height direction (Figure 1a). Using this technique,printers can dynamically control thickness and output thicker
objects without a staircase effect. Our technique consists
only of software that can generate corresponding Gcode; thisdoes not require any new hardware or improvements to theprinter. We utilize this technique to print a tactile sheet(Figure 1b). This sheet has a smooth tactile sense because it
is not printed layer by layer. We demonstrate the usage andpost-processing technique of this sheet.
CONTROLLING THICKNESSThe basic idea of controlling thickness is to increase theamount of material extruded during printing. To control theamount of material, we edit Gcode that contains thecommands used to control CNC machines including 3Dprinters. In Gcode, G1 controls the movement of the printerhead and uses an E parameter that controls the amount ofmaterial extruded between the starting and ending points. We
can increase the amount of material used by increasing the Evalue. However, as the thickness of an object increases, theamount of material extruded in one second is increased. Thiscondition of printers is essential for printing at high speed.
Thus, the limit on the speed of the stepper motor built into
the extruder become problematic. To decide the ideal Fparameter (i.e., extrusion speed) for every thickness, we mustclarify the features of the extruder.
In order to find the limits of the extruder, we define theextrusion rate [mm3/s], which is the volume extruded in one
second. We weigh the extruded object to calculate theextrusion rate using digital scales. We determine themaximum extrusion rate, which is utilized to decide on theideal extrusion speed, by comparing the requested extrusion
with the actual extrusion.
Our technique uses two equations to set parameters. In theequations, let Height, Width, and Length be the scale of anobject being printed. The E and F parameters are calculated
as follows:
𝐻𝑒𝑖𝑔ℎ𝑡 × 𝑊𝑖𝑑𝑡ℎ × 𝐿𝑒𝑛𝑔𝑡ℎ
𝐶𝑟𝑜𝑠𝑠‐ 𝑆𝑒𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝐴𝑟𝑒𝑎 𝑜𝑓 𝐹𝑖𝑙𝑎𝑚𝑒𝑛𝑡(1)

𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐸𝑥𝑡𝑟𝑢𝑠𝑖𝑜𝑛 𝑅𝑎𝑡𝑒F ≤× 60
𝐻𝑒𝑖𝑔ℎ𝑡 × 𝑊𝑖𝑑𝑡ℎ(2)E=Figure 3. Application using various materials (top). We
created a tactile sheet using PLA and flexible material(bottom).

The maximum extrusion rate is obtained by conducting anexperiment. We conducted the experiment using NinjaBot
NJB-200 3D printer (http://ninjabot.jp/), and the maximum
extrusion rate was approximately 11 mm3/s. This means thatthe printer can extrude with the requested rate up to 11 mm3/s.
Using these equations, we implemented a system thatgenerates Gcode using several parameters: size of sheet,number of bumps, and height of a bump. Gcode generated byour system is divided into micromovements for changing thethickness dynamically (Figure 2). Three-dimensional
printers allow their heads to move obliquely, but they cannot
control the amount of material corresponding to the height.

Figure 2. Mechanism of dynamic thickness control.
EXAMPLES

We show the example objects created while applying ourtechnique. To print example objects, we used NJB-200 andset the temperature of the printer head and build platform tothe recommended value for each material.
Various Materials
We used eight available materials:
MakerBot ABS, PolyPlus PLA, flexible, polywood, copper,
magnetic iron PLA, carbon, and graphene (Figure 3, top).
We confirmed that our basic idea, which changes thethickness of an object dynamically, can be applied to all ofthe materials. In particular, PLA and flexible filaments wereprinted cleanly without staircase effects or damage to theaesthetic appearance. As shown in Figure 1b, the flexible one
can be bent by hand, and all linear objects in the structure
adhere to each other. These materials are suitable for printing

Figure 4. Laser-cutting (left). Cutting out a sheet for acoaster (center) and watch strap (right).

a tactile sheet (Figure 3, bottom). The size of the sheet isfreely adjustable according to the parameters used. NJB-200
has a 200 × 200-mm build platform, and we confirmed that
our technique can be applied to every size. Note that thelargest sheet (200 × 200 mm) takes two hours to print.
Application
These printed sheets can be easily cut using
scissors or a laser cutter (Figure 4, left). By cutting as
required, we can utilize these sheets to assist with daily needs.
For example, a sheet printed with flexible filament can beused as a coaster (Figure 4, center). This printed coaster is
not only cut into a round shape to fit glasses, but also
provides an antiskid function. This sheet can be also attached
to existing objects. We attached it to a watch strap to change
the feeling when touched into something resembling
alligator hide (Figure 4, right).
CONCLUSION

We presented a technique that controls the thickness ofobjects being printed, and showed example objects and theirusage. Like all printing techniques, our idea has limitations.
The thickness in our technique depends on the performanceof the 3D printer and the characteristics of the material.
Although we showed that several materials can be used, it isnecessary to analyze each factor in further detail. We will
also investigate the features of objects printed using thistechnique (e.g., printing tactile cues).
ACKNOWLEDGMENTS

This work was supported by COI, JST.

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