What is the best place to mount CIM motors...?

[Richard Wallace]

I like driving the center wheels with relatively short #35 chains, and placing the motors fairly close to the center -- anywhere from directly above the center axle to offset as much as 5 inches fore or aft, depending on where we need the CG and what scoring mechanisms are required. #35 chain provides a little extra reliability, and re-tensioning is not a problem because it won't stretch much. The corner wheels can be driven with longer #25 chains, one for each wheel, two driven from each center wheel. So center wheels each get one #35 sprocket and two #25 sprockets.

This set-up requires some method of tensioning the corner wheel chains. Several good methods have been discussed in other threads.

We used the set-up described above on our 2007 robot with good results. Drivers reported easy handling. We only had one chain failure all season, and that one was easily repaired -- a few minutes work field-side between elimination matches at Boilermaker.