I really like this sort of drive train. They can be made to be lightweight, sturdy and accept all types of gearboxes and transmissions.
It seems as though, as Jesse mentions, you’re tensioning your chain by sliding the wheels in a slot you will cut through the extrusion. I’m interested in learning more later about that works for you. We tensioned chain last season by sliding wheels in aluminum tubing – a similar idea – but had some trouble with the wheels toeing in or out if the two bearing plates became out of alignment. It looks like you’re using channel to bridge over the 1x2 extrusion, though, and won’t have that problem. Bumpers should protect the wheels from being pushed in their slots by other robots.
My concern was with how you’re apparently planning to mount the AM gearboxes, though I may be misinterpreting something from this picture. It seems like you’re planning to either replace or modify the outermost plate on the gearboxes to eliminate its mounting flanges and instead using the spacer hardware to go straight into a t-nut within the extrusion. Is that true?
If so, you might want to consider adding holes to the outermost plates above the existing holes and also tying them in to the upper slot on the extrusion. Those AM shifters with two motors are pretty substantial and I’d be uncomfortable supporting that weight on two t-nuts. It’s not unprecedented for t-nuts to tear themselves loose and you’ll have nearly 8 lbs. cantilevered on them.
What’s your source for replacement sprockets for the AM output? They’re furnished with sprockets that have a narrowed hub out of the box – are you just going to find 1/2" bore, keyed #25 chain sprockets somewhere and take down the hubs yourselves?