12T Gear 1/4" Shaft

If you have a bit of money, machining skills, and access to a metal lathe and a hydraulic press you can modify the 12 tooth metal gear fit onto the 1/4" shaft.

I used the following parts:

  1. Center Drill
  2. 17/64 Drill Bit
  3. Square Broach, 1/4" Square. (McMaster Carr # 3156A15) $105.37

Attached is a picture of the tooling and a few finished gears. The 1/4" shafts have a chamfer so I only needed to press the broach about 1/2 way through. These have worked out beautifully.

Thanks for the info @MNVex. I’m curious, what use cases have you found for the 1/4" shafts?

1/4" shafts are sweet for any high torque or cantilevered (impractical to support on both sides) applications

Very cool!

Sample you tube video. Vex legal until the heat treating…

No heat treating involved…
link text

Does the pinion gear still remain strong? With such a big hole, it might make the pinion gear crack easier

I haven’t tested these in high torque applications. But they did work nicely in a nothing but net ball launcher. Zero failures so far.

That’s very cool. Thanks for sharing this. Just one question: is it possible to have the corners of the square hole end up “under” a gear tooth rather than under a “bottom land” ? I was wondering if that might help it be a little stronger.

Yes this should be possible. You have to drill out the center first anyways with a 17/64" bit, so it would just be a matter of turning the 12t gear the appropriate way before pressing the broach through.