I don't trust our ability to make a reliable press fit onto the CIM shaft, so I've been looking at alternatives. It seems like there's enough space on the shaft to allow for the "top hat" piece to be extended back to the motor mounting plate and keyed. Has anyone tried this?
Because we cannot conveniently (or, really, inconveniently) key hubs, I instead was considering that we build up a keyed "top hat" from layers of delrin or some other plastic. We can laser cut 1/8" and 1/16" layers as necessary and extend the overall length of the finished piece into the gap that currently exists between the motor mounting plate and the carrier/pinion gear. This'll get us about 1/2" of key and I'm going by gut when I assume that we can find a plastic that'll hold up sufficiently well this far up the gearing. We could then loosen or eliminate completely the press fit.
We'd be looking at stacking up this assembly on the motor shaft, gluing the layers togethers, then tapping through all of the pieces of plastic at once. Conceivably, we could try plasma cutting these same pieces from aluminum, but we've had mixed results with the plasma cutter, particularly because of its relatively large kerf. It's difficult to get it to make small cuts and holes cleanly.
Also, I'd love it if someone was able to tell me what the distance is between the back of the "top hat" and the motor mounting plate if this is built according to spec. in the whitepaper. The drawing doesn't include that information, nor the face width of the gears in the transmission, from what I've been able to tell. Based on the drawing below, I know only that the overall dimension from the face of the carrier gear to the motor mounting plate is .647" and that the top hat is .188".
I love the idea of making these work for us, but the build out called for in the white paper seems to call for all of our weakest abilities -- press fits, welding, accuracy (
)... and the changes we're making to accomodate that seem significantly vast that we have some concerns. Still, for the weight and price, this arrangement can't be beat, it seems.
