pic: Modular Gearbox

[Ari423]

Originally Posted by Chris is me

While this is a cool design and all and I don't mean to discourage you, it certainly has been done before. One of AndyMark's early products was the StackerBox (now discontinued?), which did essentially the same thing as this. One could also argue that this is basically what a VersaPlanetary is, minus the planetary part of course.

I would switch the bearing holes to 1.125". You can get both 3/8 and 1/2" hex in that size, so you can pick what size shaft to use based on the stage of the gearbox.

I can't find the StackerBox on AndyMark's website, but from what I can tell they seem like similar ideas (great minds think alike!). Any idea why the Stackbox wasn't successful and was discontinued? My idea was to have something similar to a VersaPlanetary in its versatility except a spur gearbox not planetary, so it can be used in higher torque situations like a drivetrain or a heavy arm. Also spur gearboxes allow you to make smaller changes in gear reducation than planetaries, which can be useful to maximize the mechanism's efficiency.

The bearing holes, aka the two in the center where the axles go in the example, are 1.125" for exactly that reason (well 1.123" for a tight fit but yeah). All of the 3/4" holes are just lightening holes because the full aluminum tube was unnecessarily heavy IMO. I suppose you could put a bearing in them for some reason or other, but that's not their intended purpose. The only holes that are intended to have bearings in them are the two 1.125" holes in the center (or the four 1.125" holes in the double block).