[Chris is me]

Originally Posted by Chak

So this is a common problem? Thicker plates it is. 3/16'' maybe. What would you suggest?
If that's a real concern, we could also extend the 3/8'' shaft and put retaining rings on both sides, so the shaft becomes structural and helps the plate out.

It happens sometimes. It's one of the mechanical "gotchas" that makes swerve way harder than it looks; along with the coaxial shaft bearing support, path planning, etc.

My gut (note: my gut isn't a substitute for actual engineering) says 3/16" would be fine. I believe that is what the Robonauts Revolution module uses among others. It helps that you've added standoffs between your two reductions; you're clearly thinking about this sort of thing.

I don't think switching to retaining rings on both sides of the 3/8 shaft would make it much more rigid. You can't really use a live axle structurally without loading up your bearings. That said, it's probably more rigid than not doing it, but also probably not worth the effort.

The easiest way to add in rigidity for "free" is to make the output shaft a dead axle, but obviously with very small wheels a dead axle isn't really an option.

hmmmm...
I guess this would be a alternative trade-off we would make during competition season: less weight and simplicity versus more machining and less ease of gearbox repair.
Thanks for the idea! We didn't even realize that the spacers are almost exactly 2'' long, since we let them grow with the gearbox.

Yeah, this certainly isn't something you HAVE to do, and it would probably require a lot of rearrangement to make it work, but it would result in a very rigid, solid gearbox for even less weight than your current setup. You could use a few standoffs on the other two sides to hold the gearbox loosely together on the shelf, then clamp it down around (and bolt through) the tube when you're mounting it.

Another thing: if you tuck your steering gear totally underneath the 2x1 and have the VP output drop down from above, you can use a steering gear much larger than your module and it can overlap the 2x1 tube somewhat, maybe letting you push the module a smidge further out the frame. This is getting a bit ridiculous though, and isn't worth a whole redesign.