I bought a used 13 X 40 Jet lathe a few weeks ago. When I bought it
I knew the 3 jaw chuck didn’t run true but the price was right. The
chuck it self hold true to less the 1 mil TIR but anything chucked up
wobbles about 20 mill. This chuck has the replaceable jaws and is a
D4 mount. The annoyance level has reached critical values so I am
going to fix it.

Does anyone have some ideas on how to fix this?

I bought a new plain back chuck and a back plate. Any lesions
learned machining the back plate?

Thanks

Just the obvious, make certain the cam pins rotate the correct amount and
the new back plate and spindle are spotlessly clean. take a light test cut
on the backing plate, release and remount. Make certain that the backing
plate mounts true consistently. Then and only then machine to size.
Steve

wrote in message
...
I bought a used 13 X 40 Jet lathe a few weeks ago. When I bought it
I knew the 3 jaw chuck didn’t run true but the price was right. The
chuck it self hold true to less the 1 mil TIR but anything chucked up
wobbles about 20 mill. This chuck has the replaceable jaws and is a
D4 mount. The annoyance level has reached critical values so I am
going to fix it.

Does anyone have some ideas on how to fix this?

I bought a new plain back chuck and a back plate. Any lesions
learned machining the back plate?

Thanks

On Wed, 1 Apr 2009 16:48:17 +0200, "Steve Lusardi"
wrote:

Just the obvious, make certain the cam pins rotate the correct amount and
the new back plate and spindle are spotlessly clean. take a light test cut
on the backing plate, release and remount. Make certain that the backing
plate mounts true consistently. Then and only then machine to size.
Steve

wrote in message
...
I bought a used 13 X 40 Jet lathe a few weeks ago. When I bought it
I knew the 3 jaw chuck didn?t run true but the price was right. The
chuck it self hold true to less the 1 mil TIR but anything chucked up
wobbles about 20 mill. This chuck has the replaceable jaws and is a
D4 mount. The annoyance level has reached critical values so I am
going to fix it.

Does anyone have some ideas on how to fix this?

I bought a new plain back chuck and a back plate. Any lesions
learned machining the back plate?

Thanks



If the chuck body is running true, have you got the numbered
chuck jaws in their correct numbered slots?

Jim

On Apr 1, 12:56*pm, wrote:
On Wed, 1 Apr 2009 16:48:17 +0200, "Steve Lusardi"





wrote:
Just the obvious, make certain the cam pins rotate the correct amount and
the new back plate and spindle are spotlessly clean. take a light test cut
on the backing plate, release and remount. Make certain that the backing
plate mounts true consistently. Then and only then machine to size.
Steve

wrote in message Jim
...
I bought a used 13 X 40 Jet lathe a few weeks ago. * When I bought it
I knew the 3 jaw chuck didn?t run true but the price was right. * The
chuck it self hold true to less the 1 mil TIR but anything chucked up
wobbles about 20 mill. *This chuck has the replaceable jaws and is a
D4 mount. * The annoyance level has reached critical values so I am
going to fix it.

Does anyone have some ideas on how to fix this?

I bought a new plain back chuck and a back plate. * Any lesions
learned machining the back plate?

Thanks

*If the chuck body is running true, have you got the numbered
chuck jaws in their correct numbered slots?

* * * * * * * * * * * * * * Jim- Hide quoted text -

- Show quoted text -

hanks Steve and Jim.

I mounted the mounted the chuck to the back plate last night taking
Steve’s advice to make sure everything was clean. I had to adjust the
holding pins to the correct height but no big deal. Then I took 30
mills off the back plate face to square it up then cut 150 mill
shoulder that centered the chuck.

When I put everything together on the mill the chuck has a 2 mill TIR
at 2” extensor. I am thrilled :-)

Jim:

The type of chuck has no removable moving internal jaws and clam on
reversible jaws. In theory the removable jaws are the same.