High Torque Gearboxes

[EricH]

Originally Posted by Aren_Hill

4 CIMs is overkill for every robot I've seen at that competition, the 2013 ISU bot was 2 Mini-CIMs, one per side.
Good luck, it's a fun competition (I was with the Iowa State team 2012 and 2013)

-Aren

SDSM&T, 2012, for me. Try 775-18s for a direct drive via BaneBots gearboxes, maybe--that's what we used that year, 4 of 'em. Just make sure your circuit protection--and speed controllers--can handle the current. I don't think we ever blew a fuse (yep, we used inline fuses) but we also had speed controllers that would shut off under high-current conditions (say, about 3-10 seconds into a run) and not reboot. So we got some without that safety and... well... It worked until we dug ourselves into a small hole and got stuck on our last run. We could smell the smoke when we opened the case.

[Ginger Power]

Originally Posted by EricH

SDSM&T, 2012, for me. Try 775-18s for a direct drive via BaneBots gearboxes, maybe--that's what we used that year, 4 of 'em. Just make sure your circuit protection--and speed controllers--can handle the current. I don't think we ever blew a fuse (yep, we used inline fuses) but we also had speed controllers that would shut off under high-current conditions (say, about 3-10 seconds into a run) and not reboot. So we got some without that safety and... well... It worked until we dug ourselves into a small hole and got stuck on our last run. We could smell the smoke when we opened the case.

In other words...avoid doing that. Gotcha. Thanks for the input everybody! The current plan is to go with a single cim Gem500 with 3 or 4 stages- still deciding. If anybody is interested in seeing the CAD (or just a picture) PM me!

Also, can anybody speak to how well the Gem500 (and mounting bracket) can handle side loads to the output shaft (30-50lbs)?

[marshall]

Originally Posted by Ginger Power

In other words...avoid doing that. Gotcha. Thanks for the input everybody! The current plan is to go with a single cim Gem500 with 3 or 4 stages- still deciding. If anybody is interested in seeing the CAD (or just a picture) PM me!

Also, can anybody speak to how well the Gem500 (and mounting bracket) can handle side loads to the output shaft (30-50lbs)?

One issue we ran into with the GEMs was that the pressed in pinions that the planet gears sit on can wobble out if there is a lot of side loading. It depends a great deal on the type of GEM used as AM has switched out the parts over the years. In theory, there are large washers inside the GEM to help with this. We went so far as to weld them at one point and even had the shop attempt to harden them... no luck, they snapped like twigs.

Also, with 4 stages, it is possible to corkscrew the output shaft so run your calculations carefully before running it on a robot.

[Monochron]

Originally Posted by Ginger Power

Is anybody aware of a gearbox with a ratio on the order of 70:1 that is compatible with 2 cim motors and has a hex output shaft? I can't seem to find something that fits all three characteristics anywhere.

I believe the BaneBots P80's used to be able to give the kind of reduction and motor input that you want, but sadly the dual input has been discontinued.
http://www.chiefdelphi.com/media/papers/2990

Edit: Doh, I don't think they offer a hex shaft regardless.

[EricH]

Originally Posted by Ginger Power

In other words...avoid doing that. Gotcha.

Just the speed controllers--the 775s worked like a charm if the controllers weren't taking a siesta. They were also easy to dustproof...

[Gdeaver]

If 18 or 24 volt power is possible, look at some cordless power tools. Refurbed tool only prices can be good. I have an old 24 volt impact drill. 80 - 100 rpm. Can be put into rotation only. Unbelievable torque. It's green - Hitachi?

[CJ_Elliott]

... Now I must cad this...