[Chris is me]

Originally Posted by yarden.saa

Hi CD,
For the first time I am trying to design a drivetrain with belts. I would like to keep everything in the minimum size.
**I will attach a photo of the drivetrain I want to convet to belts.
We are using a direct drive with hex shaft. the problem is that Vex doesn't offer pulleys it the same diameter as the hex pulleys. adding a hex hub over the pulleys will make the thickness of the wheel+pulley+hexhub+bolts+nuts too thick. I looked at andymark solution in their AM14U, they made holes in their pulley so the hub will fit in the pulley. I am looking for a solution that will work with vex wheels because andymark pulleys doesn't have the versa key pattern. Andymark variety of pulleys and belts is pretty small so I can allow my self using it.

If you are using VersaWheels with Vex pulleys, you may not need to add a hex hub to both the wheel AND the pulley. Just use a hex hub on the wheel and maybe put a hex bearing in the pulley itself just to support the pulley on the shaft. You can rely on the screws and the VersaKey pattern to transmit torque between the pulley and the wheel. Just like the sprocket your old design has doesn't have a hex bore but works just fine, the same is likely true for pulleys.