Custom Gearboxes

[Chak]

Originally Posted by pwnageNick

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.

I'm not sure I understand what you mean. Do you have a picture of the setup?

[pwnageNick]

Originally Posted by Chak

I'm not sure I understand what you mean. Do you have a picture of the setup?

Sorry for the large image.

So in the picture you can see where the standoffs are round. The 2x1 tubing goes along where those standoffs are rounded. The tube is then trapped with the face of the hexagon portion of the standoff on one side and a washer and bolt on the other side.

This isn't the best example as I accidentally used 5/16" hex standoffs when I should have used 3/8" or larger. This would help create more surface contact to help spread the load over a bigger area.