What does everyone use for the tooth profile offset for HTD and GT2 pulleys when 3D printing on the Markforged Printers with Onyx?
Historically we have used no profile shift or profile offset, but I’m questioning if that is correct due to some assembly difficulty. I have yet to conduct the test where we print the same profile as used in an OTS pulley and tune it in.
The HTD pulley generator in the MKCad library does not make functional HTD pulleys, especially when printed on a Markforged. I recommend making your own variation of this generator which has the correct profile: Onshape
Here’s a quick comparison of the HTD profile generated by the MKCad one (Blue) and the Vexpro profile (Red):
I’m guessing you’re finding that your belts are much too tight/have too much friction because the belt does not properly wrap around the pulley.
You can see here that when the belt is wrapped tightly around the pulley, the alignment of the belt teeth and pulley teeth get farther and farther apart:
Can I add this to MKCAD?
This isn’t my own file, but I’m sure whoever the original creator is wouldn’t mind. It was the first result that appeared for “Onshape HTD Pulley Generator”.
The GT2 profile generator in the MKCad library works perfectly.
Thanks, This is likely the solution to my problem
Ok. this is in MKCad - Pulleys (Configurable) now and is called Printable HTD Pulley. It may take a little bit to get it into the MKCAD App.
Thanks Ty! I’ll test it out soon
I’ve also just pushed a new version of my FRC Belt Calculator FeatureScript implementing the new HTD profile. The existing 3mm GT2 profile is unchanged (although I’m open to also switching it over if people find the MKCad 3mm version works better for GT2 belts, too).
You can find my belt calculator FeatureScript here:
https://cad.onshape.com/documents/9cffa92db8b62219498f89af/w/06b332ccabc9d2e0aa0abf88/e/29b8ab37be03b929639dfcd5
You can find documentation for it here:
https://alexkempen.github.io/alex-featurescript-docs/robotics/frc-belt-calculator.html
So with this configurable pulley u see it can do 3mm pitch but this file is for HTD pulleys. Has anyone tried this with the 3mm GT2 belts from vex?
HTD and GT2 are close enough in profile that you shouldn’t really notice a difference in FRC applications.
That being said, MKCAD does have a 3mm GT2 pulley generator.
which document is this? Printable HTD Pulley?
yes
I just pushed a new version that should fix your issue
I used the geometry to update the original configurable 5mm pulley in MKCAD. it now has the better profile and a 3mm pitch option.
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