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Unread 04-08-2016, 00:10
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Re: Custom Gearboxes

Quote:
Originally Posted by Knufire View Post
Depending on your machining resources, don't forget about all the little stuff. The plates are the hard-to-machine part, but all the little bits (spacers, standoffs, shafts) can really add up time. With a bit of forethought, it's possible to do most of these COTS from AM/VEX/McM.
+1.

In all my gearboxes I generally keep the custom parts to only the gearbox plate(s), the drive tube (if WCD Style) or sheet metal chassis, and maybe an encoder mounting plate of some kind. Otherwise the only machining I'm looking at doing is cutting shafts to length and tapping them for retention.

You can just buy standoffs from McMaster, etc. if you want instead of making your own. If your economical and don't mind spending the time making your own can be worth it, but the ones from McMaster aren't too pricey and are well made if you only need 8 or so for two gearboxes.

One thing I do tend to do that is a little extra machining is a little trick for mounting a gearbox to a drive tube. Sometimes I'll take the standoffs that would be mounting the gearbox to the inside wall of the tube, and instead I turn part of the standoffs down on a lathe to .249" diameter. Then on my drive tube I put a .251" thru hole on both sides. What this does is allows the standoffs to slip fit through those holes in the tube, and you put your bolt into the end of the standoff on the outside face of the tube. What this does is mounts the gearbox to the tube by essentially trapping the standoff onto the tube. This is a stronger way to mount then traditional methods. You can bolt the standoffs directly to the inner face, but it technically isn't as strong and depending on the design it could be difficult to get the screws in the tube. You could run the bolt through both sides of the tube instead of inside the tube, but you then run the risk of crushing the tube some if over-tensioned.

That said, I wouldn't suggest doing this for most teams that have limited time or access for machining as its a relatively minor gain in strength and you have to spend some lathe time to do it.
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