Banebots 36mm gearbox: Recommendations for use

[Joe Johnson]

UPDATE:
I have finally had a spare minute from the 56mm DD issue to get some time to actually evaluate my prediction with respect to the 36mm gearbox.

As you know from above, I recommended that teams that use the Banebot motor, keep the ratio below 55:1, much lower with impact loads.

I am in the middle of my test but I have enough to give a prelimary update.

Used the 64:1 kit transmission for theses test.

Preliminarily, used 6V and ran 50 +stall -stall cycles with the roto "locked" Actually I could not get a good lock on the output shaft so it rotated 5 deg or so.

The backlash in the joint opened up to about 10deg after these 50 cycle.

I repeated the test with 12V, again another 50 +stall -stall cycles (careful to stop when the motor gets hot and blow air on it for a bit).

The backlash in the joint opened up to about 15 deg after these 50 cycle.

I allowed the gearbox output shaft to now rotate about 20 deg or so and immediately stop -- a pretty rough test, because it is enough freeplay to let the motor reach full speed.

No noticeable increase in backlash.

I will continue the test tomorrow. But, I believe that the joint may be better than I had projected. There are lots of possible reasons. One may be that the materials are workharding with each impact.

This is encouraging results because I suppose even if I DO eventually get the gearbox to fail, it is not a 1 hit, boom and your done type failure but something that takes time. This will allow teams to do R&R after each match if needed.

There is a great quote from Raul-the-magnificent that I think about a lot, I don't have it exactly but the basic idea is this: "In FIRST, you can either have comfortable safety margins or you can have a competitive robot, you can't have both."

True dat.

Joe J.