Elastic Buttonhole Laser Rig

thingiverse

I've been working closely with my local makerspace to create and print Personal Protection Equipment for healthcare workers in our area. One of the items that has become hard to find is the buttonhole elastic used with the Prusa Face Shield. As such, I quickly developed this rig to feed and laser cut buttonholes in regular elastic banding. I pulled this design and build together in under 24 hours, so it's not perfect, but it works... This design requires standard 3D printer/CNC hardware, a 5 – 15 watt laser, CNC shield, and an Arduino board. Specifically, you'll need; - 132mm 8mm Smooth Rod - Xmm 8mm Smooth Rod (Note: X value is not specified) - 8mm Linear Bearing - Minimum 140mm T8 lead screw and corresponding nut (can be longer, it will just stick out the end) - 8mm pillow block - 2 Nema 17 stepper motors - 5mm to 8mm Coupler - Some elastic bands to fit the 20mm radius drive drum. I used elastics from broccoli bunches; they are nice and wide. - Some 12 – 16 3mm screws that work with plastic, (through holes are 1.75mm radius, screw holes are 1.25mm radius) - 8 – 12mm(ish) M3 screws to attach the Nemas - A bit of super glue - A laser (I used an 8.5w blue laser) - Some metal tape or aluminum foil (to keep the laser from burning the bed underneath) - Something to screw all the parts into (plywood) - CNC Shield and Arduino board (with stepper drivers) I've included the .stl files, Sketchup design file, drilled hole svg, and laser gcode for 7mm holes that are 15mm on center. Please share any updates so others can use. The gcode is relatively simple; I just reset the x and y to 0 after the hole is cut and then repeat the hole cutting gcode. It would be a small job to write the gcode to cut a handful of holes at each end of a target length band, and then cut off the band. If I have the chance, I'll add a base file for this. I normally print with 3 shells at 25% infill, but for this project, I dropped the shells down to 2 and the infill to 15%, with the exception of the drive drum, which I printed with 3 shells and 50% infill. Using a standard CNC shield with all the jumpers set (1/32 steps), the steps/mm for the drum is around 52. The T8 Lead screw steps/mm is set to 800 steps/mm. I found that hanging a couple of bag clips on the hanging elastic helped a lot, as did a fan to keep the cutting area cool. The fumes from this are very nasty; recommend doing this outside, garage, or other well-ventilated space. I hope that this design helps! Good luck, be safe, and stay healthy.