How are <1.5 sec Minibots doing it ? Gearbox mods allowed ?

[Gary Dillard]

Originally Posted by Chris is me

This is blatantly incorrect. You are allowed to modify the gearboxes but not the motors. Anyone who said otherwise just doesn't know the rules.

And I'm pretty sure that the GDC knows the rules

http://forums.usfirst.org/showthread.php?t=16779

[Free Willy]

Can someone post a picture of a modified gearbox? Thanks!

[Mr V]

Here is a pic of un-modified transmission.


The way you modify it to become a 10.4 to 1 can be achieved in a couple of ways. All of them involve removing the 30:15 and 25:10 gears and mating the 26:10 to the 40t output gear.

The way we did it was to machine a spacer that fits around the output shaft and raises it to the proper position to engage the 10t on the 26:10 gear. Then we machined the end of the output shaft you can see in the pic the same amount so the end plate fits back on with the proper end play.

A team we gave our spare minibot pieces to in Seattle knurled the output shaft so the 40t gear could be pressed up the corresponding amount. In the picture you can barely see the knurling on the output shaft where the 40t gear is pressed on.

I have also read on here of 2 other ways. #1 removing the gear and staking it around it's ID to reduce that diameter, then pressing it back on with thread locker as a little extra insurance. #2 shorten the case, and swap the existing spacers around, use the one that is under the 25:10 under the 26:10 and the one that came off the top of the 26:10 on top. This method also requires shortening the output shaft so the case fit's back together. This method is the most complex.

So there are a number of ways to skin this cat depending on the tooling and skills your team has.