There have been a handful of threads on this subject before, and have proven that +.003 spacing is pretty much fool proof on most FRC applications.
Sometimes you'll encounter a situation where you're getting off the beaten path at which point, you'll need to deviate from the tried and true method of +.003 spacing. Usually, this is in higher reduction gearboxes where you're trying to minimize backlash. At this point you'll need to look at all of the part fits, including how well the gear fits on the shaft, how well the shaft fits into the bearings, etc. Depending on what exactly is going on in your mechanism, you could find something like .015" of backlash just in the fit of your gear bore - at which point you definitely don't want to add anything to the gear spacing.
Quote:
Originally Posted by DampRobot
Also, we've had mixed results using a .003" adder on worm gears. Proceed with caution, if you're not using spur gears and want to put in an adder.
|
We build a worm box mid-season to cut down on the backlash in our system and to have a passive braking mechanism and ran exact C-C on between the worm and worm wheel shafts. In our case, we were using a harden steel worm with a bronze worm gear (16DP if anyone cares) and the gear ended up 'cutting' the wheel as the box broke in. The fit between the worm and worm wheel was fantastic after the break in period* and there was no noticeable backlash in that stage of the transmission.
*I highly suggest running in any custom worm box on a bench - especially if it's a single start worm. IIRC, we ran ours via a drill for something like 10-15 minutes continuously before we started to notice gains in efficiency... Meaning that we'd have more than likely never actually broken it in during the season.