I’m assuming from the second drawing the #608 key needs to be machined by 0.1691”?There are two different collet drawings out there with slightly different versions of the keyway. This drawing summarizes them:
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Here's my design for the collet key, made by machining down a #608 Woodruff key:
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I have yet to make one and I don't have a real Van Norman "E-37½" key to check the finished depth. But people have used the above to make keys and so far have not indicated that it won't work. As far as the "tit" on the key goes, my plan is to make the key, insert it in the spindle with a collet, then use a transfer punch to mark the location of the dowel pin. The dowel pin hole is machined perpendicular to the flat, so it should be pretty straight forward.