VEX pro bearings tolerances

[DampRobot]

Originally Posted by cxcad

I can't seem to find any information on the tolerances for the VEX-pro bearings. I want to be able to press fit some bearings into a plate; particularly 217-2733 and 217-2731. Any help would be greatly appreciated.

Basically the only way to be sure that you're getting the exact fit you want is to test the fit of the bearing as you machine. If you CAD the bearing hole at 1.124" for example, it doesn't really matter if that's the dimension the CNC (or machinist) is cutting. Surface finish of the cut or cutter deflection/kerf can make the fit deviate from what you want, even though the dimension cut might be what you specified. It's a lot more helpful for the machinist to know to get a press fit for a certain bearing than to tell them to hit some arbitrary dimension exactly. If you give us more info on what machine the hole is being cut on, we can give better advice on getting the fit you want.

On the other hand, it's usually possible to get a press fit on a CNC the first time around if you know the machine, material, and cutter your using fairly well, and do finish passes at the correct speeds/feeds. But again, that's more about the machinist and machining process than the specified dimension.

In some cases, it may be easier manufacturing or assembly wise to cut the bearing hole as a slip fit and have other things (rivets, screws, stuff on the shaft) retain the bearing. Sometimes, retaining the bearing in other ways just isn't possible, or doesn't do what you want, but it's usually a ton easier to machine a slip fit than a press fit.

Anecdotal evidence usually isn't very helpful, but in case it's what you're looking for, I've never measured a R6 or R8 bearing at anything other than the nominal dimension with digital calipers.