pic: 2386 Drive Gearbox

This is one of the 2 gearboxes used on 2386’s machine for the 2017 game, FIRST SteamWorks. We realized early on in the build season that space would be at a premium this year (even more so than usual). Our solution was to use the space normally wasted in the sides of our chassis and flip our CIMs 90deg. They ended up working flawlessly. Never failed us during a match, easy to remove and work on should the need arise, and were simple enough for the students to manufacture in house on our CNC’s. We started the season with them geared for 9fps and swaped ratios at champs for a final speed of 13fps.

We did the same thing last year for stronghold except our gear box was identical but doubled version of the AM bevel box.100% 3d printed box and it had no issues at all. We did this so we could used the same gears. My question to you is what gears did you use for the 90 bevel? Where did you find them? I would like to utilize this design more but sourcing gears is a bit tricky. Perhaps I just don’t know where to look.

I, too, would like to learn about gear sourcing for this.

All the gears are sourced from vexpro. The bevels are these guys. We broached the ones for the CIMs to 1/2in hex and then used an 8mm to 1/2in hex adapter. I have seen some concern in the past about whether there is enough meat left over on bevels once you broach them out to 1/2in but we saw no issues. Part of this, however, is due to them being in the first stage of the gearbox (relatively low load).

All other gears are just your standard 3/8 and 1/2in hex gears from vexpro.

Nice job and some ingenious engineering. I like it.

Ok, so you did a 1:1 with the bevel gears, then transferred that over to the larger gear, over the wheel and to the final reduction. Nice job. :slight_smile:

When we did ours we used the bevel gears from AM which had a 2:1 ratio, and then reduced further from there. I thought maybe you found a larger bevel somewhere.

Is that 9fps and 13fps adjusted, or free speed?

Ya that’s the one thing I disliked about this gearbox, was the 3 stages instead of our regular 2. Originally we were going to use the andymark ones too. But unfortunately it isnt cost or time effective for us to order from them. Vexpro can get us products within 1-2 days tops for usually more than 15 dollars Canadian. From andymark it takes usually at least a week and costs an arm and a leg between shipping and the exchange rate.

That’s adjusted. 9fps was great at our earlier events (especially at McMaster, letting us play our defense on 2056), however come champs we wanted to play more offensively and the 13fps allowed us to do just that.

If someone was concerned about this, an alternative that we’ve used for right-angle drive are these from McMaster-Carr. They’re a bit larger 16 dp gear.

If you wanted the same-sized 12 dp gear, McMaster has this which also has a smooth 1/2" bore to broach. It looks like basically the same gear that Vex has (there is even a 3/8" bore version). I’m guessing that Vex just gets these in bulk from the supplier, broaches them, and doesn’t add the McMaster speed of delivery markup.

Personally, I prefer broaching a gear that is already bored to 1/2".