Update

We have decided to revisit the centrifugal force application concept. It was ruled out months ago because its need for fine tuning, but at this point we needed a way to harness the centrifugal forces instead of fighting it.

We have been very busy redesigning, haven't had time for detailed posts. We have a good design now, we think we can get it together in time and we're feeling good about it now. We have about a month to build and test. It is going to be very busy. Here are some Creo models.

Central stationary shaft, with 2 bearings (red) in a bearing housing attached to a timing belt pulley. A steel channel is attached to the bearing housing and hangs out on both sides. The holes are a pivot point for the force applicator.

Force applicator operates when the centrifugal forces on the bottom mass (nut on thread) out weight the centrifugal forces on the roller (top). They pivot about the steel pin held by black collars.

This is the full functional assembly. The cylindrical bearing housing rotates the steel channel and pivoting force applicator around the stationary composite disc.

Big Design problem

We have been working on getting our design together to start ordering and fabrication in the past few days. Unfortunately, we have run into a problem in our concept that, embarrassingly enough, we overlooked while designing this concept.

The problem is overcoming the centrifugal force that will act on the roller as it spins around the composite disc. Because of the small radius and extremely fast rotation, even 5000 rpm, and 1lb weight estimation will cause approx 3000 lbf of centrifugal force. With our design that would require the spring to overcome that 3000 lbf to apply any force to the disc. I attached a quick sketch for clarity. 

We need to make drastic design changes, this will set us back enormously because we are suppose to be fabricating in a few weeks.