Frank,
Okay, I'll confess. The spinner gave me some trouble to figure out how to measure and cut. In fact my wife and kids went out of town for a weekend and I took advantage to do this with no distractions. What seemed to be the magic that made the entire process fall into place was to use masking tape. A piece was wrapped around the spinner (where the bolts will hold it to the backing plate) until it overlapped itself. Then using a razor blade I cut the tape off just past the overlap making sure to cut thru both layers. The result will be a piece of tape that is exactly the circumference of your spinner. Then the tape was carefully removed and taped down to my kitchen table. (Remember, wife gone) All measurements and markings for the holes were now able to be layed out in a flat 2 dimensional format that my brain could wrap around. There was a second piece of tape set up the same way on the backing plate. This one had reference marks put on the tape and backing plate so that when removed it could be put back the same way. The prop info was put onto this piece of tape and then it was overlaid onto the the spinners tape on the kitchen table. it was so simple that it amazed me how quickly it finally went once the system was thought out. After marked the tape was put back onto the spinner and the cuts were made and the holes were drilled. It fit perfectly on the first try.
