xray wrote:

I have a lathe with a 2 1/4" threaded spindle with 6 tpi. It came with a
3-jaw but no 4-jaw chuck. I got an 8-inch 4-jaw off ebay that didn't fit
and then a cast iron backplate which had the proper thread. Saturday, I
cut down the backplate to fit the chuck and drilled and tapped it to
attach.

First time I used it, it got no heavy loading, but I though I was never
going to get the chuck back off. Eventually a bunch of hammering on a
lever bar broke it free. The 3-jaw has never needed more than a couple
hits with a dead-blow hammer, even after I jammed a tool into the work.

Is there anything obvious I should think about to keep it easier to
remove? The main interface between the backplate and the spindle seems
to be the flat surface on the backplate that is about 3 3/8" in
diameter. I never turned that part of the backplate, but I have since
polished it with some fine emory and greased it.

Anything obvious I should do beyond what I have already done?

Clean the threads meticulously, then put a drop of oil on them each time you
mount a chuck. The book "How To Run A Lathe" shows how to make a little tool to
clean out the internal threads on a chuck backplate. I haven't ever done that,
but I use an old toothbrush and occasionally I take my chucks apart and clean
everything with solvent, brushes, and compressed air.

If it goes on easily and jams coming off, it may be due to a chip stuck in there
is what I'm thinking. The flat area at the back of the backplate is called the
"register" and this by rights should be hand-scraped to closely fit. If it's a
bad fit and spun on tightly, this could have the effect of jamming the threads
and making removal difficult.

Normal chuck removal procedu chuck a 1' long piece of 2x4 so it sticks
sideways out the jaws. Put the lathe in backgear and strike the 2x4 once hard,
in the direction to unscrew the lathe. It should free it.

Grant

xray wrote:
I have a lathe with a 2 1/4" threaded spindle with 6 tpi. It came with a
3-jaw but no 4-jaw chuck. I got an 8-inch 4-jaw off ebay that didn't fit
and then a cast iron backplate which had the proper thread. Saturday, I
cut down the backplate to fit the chuck and drilled and tapped it to
attach.

First time I used it, it got no heavy loading, but I though I was never
going to get the chuck back off. Eventually a bunch of hammering on a
lever bar broke it free. The 3-jaw has never needed more than a couple
hits with a dead-blow hammer, even after I jammed a tool into the work.

Is there anything obvious I should think about to keep it easier to
remove? The main interface between the backplate and the spindle seems
to be the flat surface on the backplate that is about 3 3/8" in
diameter. I never turned that part of the backplate, but I have since
polished it with some fine emory and greased it.

Anything obvious I should do beyond what I have already done?

Clean the inside of the backing plate with solvent, and then mark
it with dy-kem, Hi-Spot blue, or even magic marker. Screw the chuck
on and back off, and the place where the dye is removed will show
where it is binding.

Jon

In article , Jon Elson says...

Clean the inside of the backing plate with solvent, and then mark
it with dy-kem, Hi-Spot blue, or even magic marker. Screw the chuck
on and back off, and the place where the dye is removed will show
where it is binding.

I keep one of the "extra-huge" blue sharpie pens in the workshop.
Almost as good as dye-chem and they don't spill.

He probably has the register diameter a bit short, or a bit small,
on the backplate.

Jim


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JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
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xray wrote:
I have a lathe with a 2 1/4" threaded spindle with 6 tpi. It came with a
3-jaw but no 4-jaw chuck. I got an 8-inch 4-jaw off ebay that didn't fit
and then a cast iron backplate which had the proper thread. Saturday, I
cut down the backplate to fit the chuck and drilled and tapped it to
attach.

First time I used it, it got no heavy loading, but I though I was never
going to get the chuck back off. Eventually a bunch of hammering on a
lever bar broke it free. The 3-jaw has never needed more than a couple
hits with a dead-blow hammer, even after I jammed a tool into the work.

Is there anything obvious I should think about to keep it easier to
remove? The main interface between the backplate and the spindle seems
to be the flat surface on the backplate that is about 3 3/8" in
diameter. I never turned that part of the backplate, but I have since
polished it with some fine emory and greased it.

Anything obvious I should do beyond what I have already done?


All of our hydraulic chucks at work have anti-seize put on the drawtube
threads, however they still bolt through to the nosepiece.

--
Steve Walker
(remove wallet to reply)

On Mon, 19 Sep 2005 15:28:38 -0700, Grant Erwin wrote:


Normal chuck removal procedu chuck a 1' long piece of 2x4 so it sticks
sideways out the jaws. Put the lathe in backgear and strike the 2x4 once hard,
in the direction to unscrew the lathe. It should free it.

Maybe I'm doing it wrong, but I always use the key inserted in one of
the sockets. I only need to give either of my chucks a gentle tug to
break them loose. I've never had a need to do it, but what if you
want to keep a workpiece mounted in the chuck (as in to move it
over to a dividing head on a milling machine)?

Artemia Salina wrote:

.. what if you
want to keep a workpiece mounted in the chuck (as in to move it
over to a dividing head on a milling machine)?

Ah. That's when you break out the Ridgid strap wrench! - GWE

On Wed, 21 Sep 2005 14:10:56 -0700, Grant Erwin wrote:
Artemia Salina wrote:

.. what if you
want to keep a workpiece mounted in the chuck (as in to move it
over to a dividing head on a milling machine)?

Ah. That's when you break out the Ridgid strap wrench! - GWE

OK, show of hands, who _else_ wants to make the obvious, off-color joke
here?