Quote:
Originally Posted by Chris is me
I take it these are your transmission axles, and the step hexing allows for round bearings everywhere while using COTS sprockets.
Impressive work - how was it made?
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We actually make our sprockets as well, from 7075 bar stock, but they're basically a copy of the AndyMark or VexPro ones. We do use all round bearings in the drive system. That's the benefit of going down to 7/16" hex at the wheels and front and back sprockets. Also, we have no keys anywhere in the robot other than the 2mm key on the CIM motors, but we do use hex bearings (unfortunately) on the choo-ch.....uhh, other gearbox for a few reasons we couldn't easily avoid.
Machining this was a bit of a pain, primarily due to the length of the shaft and number of setups required. The machine shop that did these for us tells me that it was two CNC lathe and two CNC mill setups, with a 4th axis in a vertical machining center. The chatter marks on the 7/16" hex are because they didn't have a tailstock for their 4th axis, so it was sticking way out there.
The right way to do this would be with a live tooled Y axis lathe, or even better, a swiss screw machine. But, we don't (yet) have a sponsor with these types of machines.