Quote:
Originally Posted by Chris is me
I think the friction he is talking about isn't just the simple contact friction between the carriage and the channel, but the friction caused by misalignment between the two channels. If your chassis / structure isn't rigid enough, load on the elevator will cause some degree of flex between the two channels, which leads to more friction force. It's not something to be written off, certainly. Good design can help keep a chassis rigid and elevator beams roughly coplanar.
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Our structure was quite rigid. Most of the friction came form the massive forces on the bearings due to a forklift-like design (so the lever arm on teh carriage was huge) and the motors themselves. 2 RS-775s going through a 21:1 reduction to a 1" diameter pully led to a lot of friction. With no motors it was okay, but once the motors went on it was very hard to lift.