8. Open source hardware: from fibers to fabric#

This week I worked on hacking my vinyl cutter (KNK Zing) to be able to cut stretchy/knit fabrics without the use of stabilizer.

Research, motivation and proof of concept test#

Vinyl cutters typically use a drag blade which is problematic for cutting textiles because it will pull on the textile. Furthermore, in order to cut textiles, a stabilizer must be added which affects the final feel of the fabric. Handheld rotary blade cutters are usually used to cut textiles for quilting and do not pull on the fabric. The motivation for this week's assignment was to create an automated textile rotary cutter that could be used with a vinyl cutter. I prototyped with cardboard, bamboo skewers and a rotary blade to see if this concept was feasible. Turns out it was, at least for cutting straight lines initially:

The blade holder for my KNK zing cutter is shown below:

Figure 1. From left to right: (1) tension adjuster which has ball bearings to allow for free rotation, (2) shaft, (3) drag blade*, (4) spring, (5) cap.
*the drag blade was used to model and make the holder for the rotary blade hack in this assignment.

Current status#

I designed: (1) a rotary blade holder, and (2) an adapter to hold the blade using the KNK Zing's cylindrical blade holder. To design the blade holder, I recorded the dimensions of the KNK Zing blade holder and the smallest handheld rotary cutter I could find (18mm). Handheld sketches of my thought process are below:

I used the open source 3D design program, blender, to design the rotary blade holder. The following picture is the resultant 3D model. On the left, is a model of a modified drag blade without the blade (#3 in Figure 1) and with a hole that allows for a paperclip-like stick (not picture) to fix the model on the left to the model on the right.

You can download the stl file here.

I made many attempts to 3D print the model. My most successful print involved printing on a Markforged printer using their Onyx filament, which is a mix of carbon fiber and nylon. It had pretty good material structural integrity. Pictures of the resultant prints are below: top are prints of the modified drag blade without the blade, and bottom two pictures are of the rotary blade holder. The blade is held to the printed rotary blade holder using an adapter that came with the Olfa handheld rotary cutter

From a test using the 3D printed parts, I found that the modified drag blade (the 'stick') didn't have enough structural integrity to withstand the forces needed to cut. In other words, it started bending, and so creating this part out of metal would be ideal. Further work can be done here.