(12-21-2016, 10:20 PM)pepi Wrote: Mounted the 4 jaw chuck, and went to school indicating a work piece. Watched a couple of videos before attempting the dance. Using two chuck keys machinist make it look like a no brainier.
Made a few feeble attempts to copy the moves, going around the chuck (laughing @ myself) in circles. Started to understand the concept, and developed my own routine using a single chuck key.
Came together nicely, I'll go back a few times just to indicate some different size and shape of bar. I like the 4 jaw and the goal is to use it most of the time.
A question, other than the expense & holding power of a 6 jaw chuck are there other advantages to know about?
Greg
One aspect of a 4 jaw is that it holds a part/bar stock much more rigid than a 3 jaw.
Typically I'll start by aligning the 4 jaws equally by eye to one of the rings cut in the face of a 4 jaw. Scale the part/bar stock and adjust two adjacent jaws 1/2 the difference. Put the part/stock in then run in the other jaws so they are snug.
Set up a dial indicator and check 4 points corresponding to the jaws. Tighten high and loosen low. Make small adjustments until you've got it within .010" TRI or so. Then start tightening OR loosening opposing jaws watching your adjustment by the movement of the indicator. You'll be finished before you know it.
BTW, this is also a good technique if you have an out-of-round part or material. Get jaws 1 and 3 as close to each other as possible. The same for jaws 2 & 4. You may need to work back & forth between the two sets of jaws.
I have a 8" Buck 6 jaw and love it. It's the most accurate single adjustment point chuck I've ever used. If you're doing a short run it can be adjusted for the exact diameter/hex of your bar stock to run with minimal run out. It's stable mates are a 12" and 6" four jawed chucks, a 6" 3 jaw (also used on the RT and the indexer for the mill) and a collet chuck.