If you look at the pic of the rotary indexing head in pic # 32 above, you'll notice little shims between the jaws and the M16 barrel stub I'm using as a mandrel. That's because the M16 barrel OD is not concentric with the bore. I have a small 3-jaw chuck that is centered on the indexing head, but that gets thrown all out of whack with an eccentric workpiece.
The stub was .012" off center. Trying to figure out how much shimming is needed at the two 'low' jaws to get it centered is a royal PITA. I spent an hour one night and another hour the next morning and finally got it within .002". I decided that was 'close enough'.
I just got in a small 4-jaw chuck for the indexing head (I have a 6" 4-jaw for the lathe) that will make this job much easier/quicker in the future. Lot easier when the other jaws aren't moving when you shim one of them.
