Impractical Single Stage Gearbox


Put simply, I’ve gotten quite bored during isolation and wanted to try and make something new. The output gear is 113T and the pinion gears can be 10T, 11T, and 12T. The hope with this gearbox is to potentially have a better efficiency and less backlash than traditional 2 stage gearboxes. Let me know if you have any questions or concerns.

CAD:

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Oh yes many

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Hence the impractical

bruh just use the gear as the wheel

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Gotta love quartine cd-more or less summer cd.

Obviously it is impractical, but if you were to build this, where would you source the 113t gear from or how would you make it?

Probably would contact a local gear cutter that could do it for us, or maybe get it water jet cut then use a cnc to machine out the middle section.

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Boston Gear makes a 112T 20DP gear (cast iron)

https://www.bostongear.com/-/media/Files/Literature/Brand/boston-gear/catalogs/p-1930-bg-sections/p-1930-bg_spur-gears.ashx

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If you are okay with being a little “zipper” on the field, the 9 tooth pinion paired with the 84 tooth gear worked as a pretty solid drive.

That said, not sure we got the efficiency or backlash reduction you were aiming for…it just ended up being really simple and elegent drive solution for us.

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If I had to guess, that gear is aluminum. Did you have any issues with stripping?

It is indeed aluminum. We had no issues after 1 event.

In that setup, it was very easy to inspect the gearbox between matches. Also fairly quick to change out the gears if needed.

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If you did that with a belt you wouldn’t have to worry about banging the gear on the field and you could print the pulleys.

I swear I saw something like that on CD in ye olden days…

I like it though, creative packaging. Are you worried about the cantilevered motor plate flexing and causing the gears to strip?

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I get the point behind a single stage gearbox, but why use a 10t pinion? One of the main reasons for using the spline shaft on the Falcon was to be able to get an 8t pinion. You can get all the way up to a 10.5:1 reduction with an 8t pinion and 84t gear, and you don’t need to make anything custom or worry about the gear OD being so close to the carpet. If you really need an 11.3:1 ratio you can find/make a 90t gear and still have 0.7" clearance with the ground on a 6" wheel.

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Yes that was one of my worries, I think the best way to counter act that is to either add a second plate on the back side then spacer it off from the other plate, or go out to .3125" thickness.

I wanted to use those to start but I wanted to use 3 falcons on this gearbox so I had to use a bigger gear to clear the tubing and the motors intersecting each other. The main decision driving it was just real estate on the gear. Currently the motors are already .01" away from each other and .03" away from the 2x1. If you wanted to move down to 2 falcons then using the 84t and 8t combo would be the move.

You could clock the falcons so their flats line up. It’s not much, but I’ve already seen a few designs that rely on that teeny bit of extra space. There’s probably a position where the mounting screws can still be accessed through the gear and wheel pocketing.

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Maybe this is a stupid question but what exactly is so impractical about this? I could see being concerned about the gear picking up debris from the carpet but that’s all that jumps to mind. I suppose 3 Falcons probably have enough torque to cause some deflection but I don’t think it would be enough to damage anything. Anyone care to enlighten me?

Besides the flaws I’m apparently missing I think this is a really neat design. I’d love to see it utilized on an actual robot.

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You’re absolutely right on that front- the gear gear would become very carpet flavored even after a little while. This might end up causing some jamming or damage to the gears.

The only other issue would be manufacturing the gear, which is rather difficult, though others above have mentioned it.

A possible solution to both these problems would be to use a pulley instead of a gear, which would be (my guess) resistant (but not immune) to the carpet gunk, and would be easier to make using the skip-tooth pulley trick.

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3 Falcons on one wheel seems like a bit much - you’d have (at minimum) a 6 Falcon 2 wheel drivetrain, which arguably is impractical.