One thing to check is the height of the motors in the clips. If they press too far up, it'll allow more weight to be supported by the felt pads which reduces traction. You want enough room that the robot rocks front and back a bit. You can also make sure the pads are clean. We once ran it on a white board to trace a line, but the dry erase ink got on the pad which turned out to be fairly tacky, so that caused a breaking action as it went around a smooth surface.
One quick warning about press-fitting something to the end of the shaft.... when you press it onto the shaft, be sure to give equal pressure to the rear black cap on top of the motor where the wires come out. When you press inward axially on the shaft, all the pressure ends up on this back cap, which itself is press fit into the motor. It is possible to pop this off and re-seating it can mess up the commutator contacts and ruin the motor.
To really get better traction...
I would suggest adding some really thin heat shrink to the shafts. We were going to do this from the start, but what we realized is that over time, the heat shrink would always start to release from the shaft so the shaft would spin inside the shrink and you wouldn't get movement. We figured it was best to send them with bare shafts than to have lots of people running into this trouble.
If you go the shrink route, it's important to get the end perfectly round otherwise it'll "bump" as it rotates. A trick we used was to set the motor to run at high speed, then lightly touch the running end to a hot soldering iron - this tends to kind of "lathe" the end of the shrink to make it round.
We also tried putting a dab of rubber potting material, but this too always came loose.
Another possible solution the next time we need motors is to see if they can stamp some sort of grooves into the shaft. This may allow better placement of some sort of traction material.
-KevinStatistics: Posted by Kevin — Sat Nov 21, 2015 2:09 am
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