Sewing machine belts

I struggle to buy sewing machine belts locally, and my various machines take different size belts. I have been servicing and calibrating my 3D printer to use PETG  and TPU 95 correctly, and have been having great success printing items hade from TPU95, which is a flexible, stretchy material. I made a couple of belt pouches for my Swiss army knife and my ‘Octopus’ tool for my bike which works really well.

I had read somewhere that TPU also works for sewing machine belts, so I gave it a try. My first attempts were circular section belts, which failed miserably, TPU95 is much too stiff to work in a circular cross section. Maybe TPU 85 or a similar Shore number would work, but that is a bit hard to find here. So I looked at flat, tapered cross section belts, but these would have the same issues. Eventually I worked out that a toothed belt would provide the flexibility. I knocked up a design and printed my prototype. It fitted onto my development machine(my 319k) and worked perfectly. It was a little too big being at the limit of it’s adjustment, so I created a parametric version of the design, so that I can print at any size, and it automatically changes the number of teeth to match the circumference. A new version (355mm instead of 375mm circumference fitted well and allows full adjustment as required.

Some serious stress and longevity testing will be done over the next few months.