I had need for a replacement drive belt. A good excuse to try out printing with flexible TPU.
I managed to pick the wettest day in months although luckily the humidity where my printers are only got up to 57%. I was not expecting great results. I have not attempted to dry the filament. It's new, straight out of the vacuum sealed bag. I have an AMS HT on pre-order specifically for this purpose but that is not here yet and I still wanted to have a go.
I've used Bambu Lab TPU 90A filament through a 0.8mm nozzle, which I will dedicate to only use TPU. I've created the model of the belt in FreeCAD and deliberately put a flat base with 45 degree tangential slopes leading into the otherwise 4mm diameter cross section belt. I've sliced this with 99 wall loops so the result is solid and random seam locations for added strength.
There are contradicting instructions on Bambu's site. The filament purchase page in the store saying use glue stick for TPU and the wiki saying don't use glue stick on a textured PEI plate because it might stick too much.
https://wiki.bambulab.com/en/h2/h2d-tpu-printing-guide
I opted not to use glue stick and I was easily able to remove the printed belt using an old plastic membership card, sharpened at one end.
Even with a simplified filament path, approximately as instructed by Bambu but without a suitable container, the pull on the new heavy filament spool was greater than I thought suitable. I made a make shift bush out of a pipe but that barely helped. I thought about pulling out the length of filament needed and cutting, so there would be no spool to pull, but my solution for today was that I kept returning to the print while it was in progress to pull lengths of filament off of the spool by hand, so the extruder had minimal resistance.
The results, although not pretty, are very serviceable for the purpose.
This can only get better when more suitable kit arrives.
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