Elastic Buttonhole Laser Rig

I’ve been working with my local makerspace to build/print Personal Protection Equipment for healthcare workers in our area. One of the items that has become scarce is the buttonhole elastic used with the Prusa Face Shield. As such, I quickly pulled together this rig to feed and laser cut buttonholes in regular elastic banding.

I pulled this design and build together in less than 24 hours, so it’s not pretty, but it is functional…

This design requires standard 3D printer/CNC hardware, 5 – 15 watt laser, CNC shield and an UNO.

Specifically, you’ll need;

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    132mm 8mm Smooth Rod
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    Xmm 8mm Smooth Rod
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    8mm Linear Bearing
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    Minimum 140mm T8 lead screw and corresponding nut (can be longer, it&#039;ll just stick out the end).

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    8mm pillow block
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    2 Nema 17s
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    5mm to 8mm Coupler
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    Some elastic bands to fit the 20mm radius drive drum. I used elastics from broccoli bunches, they are nice and wide. Hoarders unite!

    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.

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    A bit of super glue
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    A laser (I used 8.5w blue laser)
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    Some metal tape or tinfoil (to keep the laser from burning the bed underneath)

    Something to screw all the parts into (plywood)

    CNC Shield and Uno (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 for others to use.

The gcode is pretty simple, I just reset the x and y to 0 after the hole is cut and then repeat the hole cutting gcode. 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 a 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 well did a fan to keep the cutting area cool.

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!

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