It is a wonderful feeling in machining when you figure out how to transfer features mechanically without going through a numerical intermediate. You are essenti

It is a wonderful feeling in machining when you figure out how to transfer features mechanically without going through a numerical intermediate. You are essentially working with a compass and straightedge in your mind, comparing surfaces, lines and single points of contact directly. There is no accumulation of error from approximate measurements. Regardless of accuracy, your precision is infinite. Look up a 'sine bar' and gauge blocks for inspiration. :) It is also interesting to note that functional surfaces are very simple, being composed of flats, rounds and inclined planes. This is why you can make nearly anything with a lathe (and a mill to spare your sanity).