If I am shooting a shaft that is 3/8" and the bowyer recommends to start tuning at 5/8" I am to put the bottom of the shaft at 5/8" over 90 degrees..? Or do I start at 1/2 or the shafts diameter and go up 5/8" from 3/16" over 90 degrees?
Use a T-square and measure from the shelf to the bottom of the nock. With the dimensions you mentioned the bottom of the shaft would be 2/8 (1/4) above 90 degrees.
or bow-square measure to top, if you nock under.
measurement will be a little different.
I shoot 3 under with the string nock above the arrow.
Go at leas 5/8ths above 90 degrees ecsp. with that large of a diameter shaft. For some reason I need real high nock point for all my bows. I like 7/8ths. to 1 inch. Shawn
Snag:
Nock point depends on a lot of factors. Tiller, 3under or split-finger, and how you grip the bow, a straight wrist grip will nock lower than bent wrist. If your bow is tillered for split-finger I would start at 3/16" to 1/4" above square, measure to the bottom of the arrow. This is only a starting point you will have to play with it.
Bob