8X 775 SS WCD

FIRST General Forum
1

Okay, last one for a while I promise. This one is actually useful, unlike the 1.625" wheel one. This is a good setup to test some different things with a 775 drive, as it allows us to test anywhere from 4-8x 775s and see how the drive performs.

22.34lbs, with everything in picture. Only missing rivets.

12:60 32DP gear reduction off the motors.
16:70 20DP gear reduction to the wheel.

Theoretical free speed of 14.94fps; adjusted of 12.1fps.

The second gear reduction can also be switched to either of the following:

20:66; theoretical free 19.81fps; adjusted 16.05fps
14:72; theoretical free 12.71fps; adjusted 10.3fps

4"x1.5" VEX Colson wheels, 18T #25 sprockets with 12.768" spacing between wheels.

Tubing for testing will probably not actually be lightened, and a custom belly pan will probably not be manufactured (plywood or polycarb instead).

Custom parts include the gearbox plate for each side, 5 shafts cut to length per side (middle wheel shaft turned down on end to couple encoder), and side drive tubes. In this version I turned down the standoffs mounting the gearbox to be able to clamp around drive tube, but could just be a normal standoff to mount if desired.

Imgur Album

Questions/comments welcome. Let me know if you’re interested in the CAD model, or would just like the print for the single gearbox plate.

2

That is a pretty interesting setup! I love the low profile motor arrangement.

Did you calculate the torque at the wheels for eight 775 pros, that should be impressive?

Let us know how it goes.

3

Hm I like your gearing arrangement. Why 1.5" wide wheels over the 7/8" wide?
Overall, it looks like your main saving is in space inside the chassis, would have been very useful this year. What is your opinion on 775pro drives in general?

4

I’ve noticed that you lighten all the rectangular tubing on your drivetrains. Is that something you would do in a typical FRC game? How about for something like Stronghold?

5

As a repeated user of 6cim drive, I am very curious of the results that are possible from the proposed testing. I am most interested in the results from the 6 775pro 14:72; theoretical free 12.71fps; adjusted 10.3fps setup.

Please keep us updated if you do happen to do this in the “offseason”. Thanks.

6