Team 4904 Swerve Drive Prototype CAD (Looking for reviewers)

This is my first iteration of a swerve drive module for Team 4904 Bot-Provoking.
Both steering and drive are handled by 775’s and geared down through VersaPlanetary gearboxes (current gearing ratios TBD) and position will be judged using the VP’s integrated encoder stage. All plates are 1/2" thick, with the exception of the top one which could probably be made thinner if need be (although there’s probably no reason to decrease thickness there). The module consists of two main subassemblies: the joint, or the part that’s attatched to the drivetrain, and the fork, or the part that spins. The fork slips into bearing hole in the joint, where radial loads are dealt with by two needle roller bearings and vertical loads are dealt with by a thrust bearing.

The two main issues that I’ve found are that

a) the VP’s output shaft isn’t long enough for the drive sprocket to reach its desired location,

and,

b) the only thing preventing the fork from slipping out of the joint is a 0.375" retaining ring.

The VP issue is very minor, but I’m looking for feedback on how to secure the module vertically. Thanks everyone for your help!

Also, I’m a freshman and this is my first year in FRC so pls don’t judge my CAD skills T-T

Let me know if you need any more pictures!

http://s1249.photobucket.com/user/Kaorin/media/Full_zpsnpepsk33.jpg.html?sort=3&o=5

http://s1249.photobucket.com/user/Kaorin/media/full2_zpsjslpm112.jpg.html?sort=3&o=4

http://s1249.photobucket.com/user/Kaorin/media/full3_zps2zh7cklr.jpg.html?sort=3&o=3

http://s1249.photobucket.com/user/Kaorin/media/full4_zpssqiwtq4n.jpg.html?sort=3&o=2

http://s1249.photobucket.com/user/Kaorin/media/full5_zpsd53mwlbp.jpg.html?sort=3&o=1

It looks good! A few issues that I could see (they may just be because your CAD isn’t entirely done:

  • How do you plan on attaching the module to your robot’s frame?
  • The wheel being sllightly off-center of the fork might cause a few issues, but I’m not particularly sure about that
  • It’s generally useful to be able to access the control motor, so you might want to flip that over. This could also fix the issue with the VP shaft not being long enough
  • I’ve found that using sprockets on the fork module makes it a bit easier to modify than gears.
  • The backs of the motors are close enough to the ground that I’m concerned wires could drag

Take these with a grain of salt, these ideas are just from a quick glance at the module. Great work!

Hey ClayTown, thanks for your feedback! (also, what would be a better thread to use… this post doesn’t seem to get much traffic)

The plan is to make little bolt holes sticking off of the sides of the top plates that would attatch to the tubing that makes up the robot’s frame.

I also noticed that the wheel in the fork was off-center, and I’m working to try to fix that. I’ve been prototyping with 3D printed parts recently though, and when I finish a mock-up model I guess we’ll see whether or not it works as-is.

I made sure there was a good amount of clearance under the motors (±0.75") so the wires (ideally) won’t drag on the ground. Ideally.

But isn’t it more safe to make sure you electrical wires are grounded?:stuck_out_tongue:

Technical discussion is visited far more than CAD. CAD subforum is usually deserted.

Thanks a ton man!

I tried submitting the post again to technical discussion, but my account is new and it takes like 2 days to upload stuff, (The mods have to check it before it can go up) so I have no clue when it’ll post.