VersaChassis CAD

Here is my first CAD attempt.

31x24" Long chassis
8 x 4" Wheels
3 Cim WCP shifter
HTD 5mm 9mm wide belts
30T pulleys
Distance between center wheels: 9.8435" (130T belt)
Distance between outer wheels: 7.2844" (104T belt)
calculated with

How much does belt stretch? If I round those center to center distances to an easily measurable number will the belts fit? (9+13/16" and 7.25")

If I use the center to center distances do I still need to use the WCP cams to tension the belts?

Bumper mounts.
Make additional holes for Ball shifter
Cut down T brackets.
Belly pan.
Battery holder.
Choose wheels.
Add all hardware and spacers to wheel assemblies.


Looks pretty solid. Honestly, I would definitely suggest putting the cams on there. Not because belt stretches, but because it acts as great insurance to keep the VersaBlocks in their place, and it’s really easy to do.

I’d also size down to 24 tooth pulleys, because then you can fit a 1/4" plywood bellypan underneath your bot and not have to worry about the belt touching the wood.

Also, I noticed you used some other website to calculate center to center distances. That’s cool and all, but WCP has a calculator on their website which is also extremely useful.

Other than that, it’s really solid as long as you make the changes you said you’re planning. I’d personally do the math on your 3 CIM transmission using JVN’s Mechanical Design Calculator and the attached Acceleration Calculator (sorry, forgot who made it) to see if you really need the extra CIMs on each side. I love 6 CIM drivetrains, but you can see in the math they’re only marginably better than what you’d get from a 4 CIM shifter in most scenarios unless you’re running PTO. I plan on running WCP 2 CIM DS this season even though we ran 3 CIM in the offseason because it’s pretty much the same (unless you really care about .16 seconds of travel time).

Acceleration Spreadsheet.xlsx (110 KB)

Acceleration Spreadsheet.xlsx (110 KB)

Have you guys put together your own personal library of what you needed from vexpro or what?

Do you happen to have a download link you could post? I would very much appreciate it if you do. Thank you for creating this model nevertheless.:]