Chucking on Tapered Hex

[Tazzer]

I have a part I need to turn down but I am having a hard time figuring out a way to hold it. The part is hex shaped with a 2-3 degree taper. Now I have tired shimming it but after a few hours tring to shim it, i cannot get it to run true.

I am considering ordering some pie jaws or expandbable 5C collet and machine the the hex taper and thought I would check in here to see if anyone has any suggestions????

[One of Many]

Milling flat tapers into some soft jaws is probably the safest bet if a production run. This may take a trial cut angle to check where the jaws actually grip on the material.

You could turn a split tube with the taper inside it. Depends on size, quantity and all that needs to be done to the stock. Turning the tubes ID and OD at the same time is wise, but at least mark the jaw alignment so it gets oriented back "as turned" to minimize runout on the part you plan on turning with it.

I've had reasonable success with a shorter split ring at the back of the jaws while the front part of the jaws still grip on the stock itself. Use care with cut force direction, interupted cuts and chatter so it don't vibrate out of that taper grip.

Then as a last option, there is using lead and other soft low temp alloys for creating odd custom fit shaped nests to hold parts for machining.

Even Bondo works in a pinch. Just make sure to use parting compound so the part will release at some point.

DC