Holding fairly thin plates in CNC lathe

Hi guys, I'm sure this has been discussed before but I was curious what everyone's thoughts are on holding onto larger diameter somewhat thin round plates and turning them in the cnc lathe. Specifically when the material is not very round. Do you skim the od of the blanks before hand or use pies jaws etc....

Thanks,
Jerod

How thin? how big? What material?
ID or OD turning??

Peter

Seems something like this would do the trick:

Roto-Vac Gen II | Mitee-Bite Products LLC.

Steel blanks about 10 inch diameter but 3/4 inch thick needs to be turned and has some fairly heavy drilling, milling of slots etc. The issue is the material is not very round and I feel as though it’s not a very safe or effective set up that is being done now. It is being done on a dual spindle lathe utilizing a transfer to finish the part complete. They gave me some regular jaws that are mashed up from cranking up pressure to hold the uneven parts each jaw is only holding onto about .300 if that.

Jerod said:

Steel blanks about 10 inch diameter but 3/4 inch thick

Click to expand...

That's not skinny. That's a ton of holding ...

They gave me some regular jaws that are mashed up from cranking up pressure to hold the uneven parts each jaw is only holding onto about .300 if that.

Click to expand...

Are they hardened ? I'm guessing not if they are mashed up. So drop a plug in the chuck and face them back and rebore. Put an undercut in the corner. If you want to go crazed, sink in some of those little hardened jaw inserts with the grippy teeth then set this group of jaws aside for this job in future..

No big.

A3 jaw chuck will likely average out the "out-of-round" .

.300 in a 3 jaw on your part should be just fine, and it sounds like you could use serrated jaws to boot.

I don't see the problem here.



-------------------

Think Snow Eh!
Ox

Sounds like the blanks don't have any existing features that need to be centered. So even better than serrated jaws would be load-leveling jaws, which are old-school back to at least the era of large manual turret chuckers. These are used with castings or other irregularly prepared part blanks. For this job, you want the kind that equalize in the plane of rotation. (There were other deep jaws that equalized in the axis of rotation). Essentially, each jaw has a rocker. The rocker has two pads near the ends which make part contact, and the pads are usually serrated, and frequently replaceable bolt-on grippers.

Jaws like these let you hold some pretty bumpy "round" parts that would never hold in regular chuck jaws.