Not to long ago, I saw an interesting You Tube video on "Home built camsaft grinding machines". The little machine was built from common stock size and did not require a lot of complicated gadgetry to get the end result. The priciple that it worked on was a master cam profile that was also home built and a follower which was attached on a hinge and rail, this set up had a small high speed motor(similar to a sewing machine motor?)with a fine grit grinding wheel attached. You would set the profile of the cam by turning its gear to the starting point, then engage the rotational feed gear and start the grind. It looked to me like the 360 degree disc attached to the cam profile gear would be used to set up the grind on the following lobes, you could preset the overlap as needed, I am sure this as well as others are still on You Tube, I think Sherline builds a cam grinder that is pretty much the top of the line for model engine builders, dont have a clue as to the cost, hope this helps you!