Turning down the OD of a gear

[Rauhul Varma]

Originally Posted by EricH

If your center-center is exact distance, most FRC folks will add 2-3 thou to that to account for manufacturing tolerances; if you make it 10 thou instead, you've really only added 7-8 to what is normally done.

Personally, I wouldn't attempt turning down a gear once it was cut, for the reasons listed above--there's too many things that could go wrong, minor enough it would seem, but just too many items to tempt Murphy and his gremlins. That goes for both a mill and a lathe, BTW. If someone really knew what they were doing, then that could work, but in FRC, those types of folks are rarer then we'd like to think, unfortunately.

Is it really that common in FRC to add 2-3 thou? (I honestly don't know) For every gearbox I've designed I've only added half a thou and haven't had any problems with wear.

I do see the problems with the actually trimming the OD, depending on the team's machining expertise and capabilities it could be quite difficult to do. correctly