Creating HTD Timing Belt in Inventor 2019

Hello, I am trying to 3D print a 12 in Pulley that would be compatible with the Vex HTD timing belts, when I go to the Synchronous belt creator there is no option for an HTD type belt and most of the other options are unlike the HTD in that they use trapezoids rather than semicircles for their belt grooves. Does anyone know how I can create an HTD belt in Inventor?

Take a look at this post. I also use inventor, but when I want to make a custom pulley profile, I just use this generator and export a step. Then you have the profile and can do with it as you please. Just make an onshape account and copy the generator so you can make your own pulleys.

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Appreciate the shoutout - I personally had some problems at given tooth counts and would recommend using this:

Instead. Very easy to generate a pulley for the profile then modify for your desired bore or other features.

What kind of errors?

A few years back I did some prints for pulleys on later rev prototypes. A few worked, a few didn’t. I think the profile must have been messed up slightly- maybe due to print error or anything else I did wrong. I don’t have any formal documentation or anything, but I started using that thingiverse customizer later that season and didn’t go back.

Happy you’ve had success with it

I’ve designed a lot with it, but I’ve only actually printed one set of pulleys that hasn’t been assembled to final product yet.

I’d urge you to test the tooth profile by running against any belt you might have around. You should be able to tell pretty easily if it works or if it doesn’t. Feel free to pm me for further discussion here.

HTD-5-Master.ipt (603 KB)

This is our HTD-5 Master ipt file to quickly make a different pulley you go “Save as” to a different name (to not mess up the original) and then go into Manage then parameters and change the Variable for the “teeth” There are other variables in there too as we are also using it for different pulleys like “Pitch” “Offset” (which is .7 mm for a HTD 5 and Overprint which adjusts for over/underprint on your printer. Print a pulley that is about 50 tooth big and put a belt around it if it has a tough time filling the gaps lower the Overprint value (you can go negative) or if its too loose increase it. Most printers with PLA have a slight overprint of .050 to .1mm depending on nozzle size and extrusion rate that means if you print a wall 2mm thick you will get one 2.1 mm hence .1mm overprint so the overprint will be added/subtracted to/from the offset to adjust for that. It has those .050mm rectangles cut through to make internal spokes (fool the slicer) otherwise you get a weak pulley that can have the teeth circle twist off the hub. Depending on nozzle size you should print it with enough walls to get at least 3 - preferably 4mm wall thickness if you use them in a drive train or to pick up heavy stuff. We use mostly HIPS or ABS for pulleys and also sometimes PLA and sometimes NYLON. PETG gets a little sticky with the belts. We usually print them with a .8 nozzle with .96mm wall thickness .4mm layer height 7 floors and ceilings (2.8mm) 6 perimeters (5.72mm) and 10% infill (just enough so the ceiling does not collapse. We have posted that and some of the resulting pulleys in our reveal and multiple times on request. (We also printed some for local area teams) Inspect the slice and if your slicer does not make the internal “spokes” then increase the size of the slots with some you have to go up all the way to .2mm

HTH

One more thing - its possible that the IPT is inventor 2020 as we are in the process of converting everything to 2020 as the school upgraded to 2020

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