Adapter for Inexpensive 19T Plastic Pulleys
by CodeCreations, published
About a year ago I discovered a very inexpensive source for 18T plastic pulleys that appeared to be nearly perfect for 3D printer and other robotics projects. (Then I came into some metal pulleys, so I abandoned this research, but in sourcing pulleys for a 3D printer project at a local school, I decided to take it up again.)
The pulleys I found are for hobby cars. They're 5mm bore, 18T pulleys with a 3mm tooth pitch that appears to be a standard curvilinear profile, like HTD. In fact, one of the mating belts appears to be Bando Synchro-Link HT. IMPORTANT: I have not verified that a standard 3mm HTD belt will fit them -- so if anyone has one, please chime in with some good news!
These are US$9 for four and widely available. They're called "Duratrax Timing Pulley 18T Street Force GP", often listed under item number DTXC9698. They have a groove in one side that's meant to receive a metal pin that holds the pulley in place.
This adapter is fully parametric so it can be used for other pulleys, but it's set up to fit this pulley in particular. You can glue this adapter against the pulley, and then fasten it to the motor shaft with the captive nut and a 3mm screw.
1) Print adapter.
2) Dry fit, and then glue adapter to plastic pulley.
3) For added strength, use a couple of tiny screws in the pulley holes to fasten it to the adapter.
4) Glue the cap onto the pulley.
5) Mount to 5mm motor shaft and start pulley-ing.
6) Let me know if you discover that it works well with a standard 3mm HTD belt.
Note: Obviously the "peg" that mates with the pulley start at a layer transition, so be sure your layers are sticking well to each other. I ordered some tiny M1x5.5 self tapping screws that have 1.9mm diameter heads -- the same size as the holes in the pulley. I'll try to use these to strengthen the bond.