[magnets]

As an offseason project, our team is designing and making a telescoping arm, like 233. We've done one in the past, but maintenance was a big issue. Our goal is to make one that is really strong, so we don't have to keep taking the stupid thing apart.

After our first brainstorming session, we have a few questions about the best way to make this thing. Our first question deals with the belt/wire/chain that raises and lowers the arm. We really liked our chain system, which worked the same way that 254's belts from 2013 worked. We'd like to implement a very similar system, but use some type of cable instead. We'd have a drum with two separate cables wound in different directions so that as the drum rotated, one cable would get pulled in, while the other would get let out. Our question is, what type of cable can we use? We're looking at cable designed to be used on pulleys and drums, rated for 1,000 lbs with a .125 diameter. We're not sure what we will end up doing with our arm, but lets say we lifted our robot. Is this strong enough?

Our second question deals with the drum itself. Is winding up the cable in a nice way something to be concerned about, or will it be okay to just let it wind up any way it wants?

Our final question has to do with the bearing setup. We plan on having ball bearings roll along the inside wall of the tubes, but we're afraid that inconsistencies in the wall thickness could be an issue. Is it?