Daniel,
The Chief mount is effectively two pices. It has the part which either mounts directly to the ceiling or is hung from a pole (call it part A) and it has the plate which is attached to the projector (part B).
The 1/2" thick piece of oak fits between part A and part B.
On the plate (part B) that is attached to the projector there are 6 bolts with thumb nuts which fit into Part A to hold the projector up. That is where the quick release comes from on the RPA mount. Those 6 bolts are replaced with ones slightly longer, they just unscrew from the part b and new bolts can be screwed in. The oak is cut such that its width fits between the outer four bolts in part B. With a tight fit there those four bolts keep the oak from moving horizontally.
You need to drill two holes in the oak for the inner two bolts of part B. If you left it like this when you install/remove the projector/part B from part A the oak/lens could flop around as nothing at that point is holding the oak from moving vertically. This is why I drilled a small recess into the top of the oak on one of the two inner holes to allow you to fit a nut down over either inner bolt to hold the oak in place without interfering with the fit of part a/oak/b together.. it needs to be flush.
After you have that you cut down the length of the oak board to whatever is appropriate for your lens/projector and then mount the lens to the oak itself. In my case I drilled a hole in the base plate of the ISCO II and drilled another hole in the oak and held the lens in place with bolt/rubber washers/washers/t-nut. By loosening that bolt the lens can be rotated as needed then tightened down to keep it from moving. The lenses vertical height and tilt is accomplished using the ISCO mount itself.
Because of the way the oak is sandwiched between part a and part b adjustments to the Chief mount (roll,yaw,pitch) are also applied to the lens as well.
Shawn
