For anyone who is interested, I am still working on my concept of a rotary jig. I have built a second prototype which has some improvements. I first one is that the measurement procedure is now simpler. The jig is in the rear position for the dowel measurement and is pulled forward after the natural pause to install the bit. This required a major change in the design of the axle slides to include a slot for the bit "bob". Also, a lever was added to release the pressure on the dowel so that initial setup adjustments (rotate dowel, slide driver board, adjust height) are easier to make before and after the jig is clamped down in the machine.