Basic Drive Base


Although our team is not new, we’ve basically missed two complete seasons due to Covid restrictions in our province of Quebec. This means that for this year, we only have 3 students in our team who have any FRC experience at all (and that was only a half season!). So we are basically training an almost all-rookie crew this year.

To this end, I have been developing a design for a basic drive base to teach Solidworks as well as manufacturing concepts and techniques. I have posted these files on GrabCAD and would appreciate any feedback on the design. I am an aerospace engineer, but not a designer, so cadding is not my top skill.

At this point, there are no fasteners in the model, though we are planning on riveting the structural components, and screws/bolts for equipment. Also, the wheel design needs some refining, but we hope to be able to 3D print our own wheels this year.

If anyone finds these models useful, please feel free to download and use them. Note that motors, gearboxes and related components are from Vex Robotics. Thanks!

Overall, the design looks good. I do have some suggestions:

  1. Usually when teams go for the aluminum tube construction like this, they place the chain on the other side of the shaft to the wheel (“inside” the tube frame). This allows to place the wheel closer to the bearings which greatly reduces the load on the shafts. This does mean that the sprockets have to be inside the gearbox, but vexpro sells a version of the same gearbox with a WCD variant(217-3422).
  2. It seems that the bearing block for the gearbox has nothing to screw into on the other side, I would swap that out for the gearbox bearing block sold on vexpro (217-3634) that interfaces with said gearbox.
  3. On the subject of bearing blocks, the clamping blocks you used interface with the “WCP cam” (217-3431) that helps prevent everything from sliding around and greatly reduces the load against the clamping force(plus it makes it that much easier to tension the chain).
  4. I would advise against using shaft collars on the drivertrain, since there are pretty large side loads on the wheels while turning/getting pushed. From our experience they tend to slip and it makes for a maintenance nightmare. Retaining rings are a good solution but require a lathe, or you could tap the end of the shaft and use a screw+washer (thunderhex shafts make it very easy to do)
  5. The long standoffs that cross the frame aren’t really necessary, the tube+gusset assembly is plenty strong by itself.

That said, if I were in your position I would personally go for the KOP drive and devote my resources to making better subsystems
Hope it helps and good luck!


Agreed with this statement. Make some minor modifications to the Kitbot if you want but channel that effort into other subsystems. Also, if you go with the Kitbot, you can have people start working on it from day 1, and get it driving around in no time! It’s a very robust drivetrain that’s been proven for years to work. That being said, I think for your teaching goals drivetrains are a perfect subsystem to design - similar in concept year to year, and plenty of examples to go off of. Take a look at some other teams’ CADs as well that follow the tube and gusset style. From the top of my head, 1678 and 254 have a lot of documentation you could go through.

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