I have a part that needs to go into production to be machined and I have, to my thinking, a nightmare of a workholding situation. I attached a bit of a blueprint for reference, but I need to use a 0.310 diameter hole with flats that are only open to 0.205 to hold my parts. I tried using a 1/2" head diameter 5c collet turned and machined to size, but the head sides end up so thin that they just twist and break. Just to get the sample out, I made a mandrel to size and drilled and tapped the end so that the parts could be machine that way, but that isn't going to cut it when it comes time for production. Also, of the 7 turning centers that I have, only 2 of them have a tailstock, so I can't rely on that for workholding. My idea was that we shouldn't be doing these parts, but that fell on deaf ears. So, any thoughts on how to possibly hold this would be appreciated.