Hi all,
I am aware of the fact that parting is (usually/always?) not recommended if
the workpiece is held between centers.
What about parting off with the workpiece mounted between a regular 3-jaw
chuck and a live center? (1/4 hp lathe, Workpiece: brass, 5/8'' diameter).
Thanks,
Fred

In article , Fred Splittgerber says...

Hi all,
I am aware of the fact that parting is (usually/always?) not recommended if
the workpiece is held between centers.
What about parting off with the workpiece mounted between a regular 3-jaw
chuck and a live center? (1/4 hp lathe, Workpiece: brass, 5/8'' diameter).

You can try but what will most likely happen is that
when you part through (or get close to going through) the
bit at the tailstock end no longer has any support and will
try to pivot out of the center in the tailstock. This
causes it to jam the cutoff blade and typically will snap
it.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Loosen the tailstock when you get down to 1/8" dia in the cut.---You are
cutting
close to the 3-jaw aren't you??

Fred Splittgerber wrote:

Hi all,
I am aware of the fact that parting is (usually/always?) not recommended if
the workpiece is held between centers.
What about parting off with the workpiece mounted between a regular 3-jaw
chuck and a live center? (1/4 hp lathe, Workpiece: brass, 5/8'' diameter).
Thanks,
Fred

Fred Splittgerber wrote:

Hi all,
I am aware of the fact that parting is (usually/always?) not recommended if
the workpiece is held between centers.
What about parting off with the workpiece mounted between a regular 3-jaw
chuck and a live center? (1/4 hp lathe, Workpiece: brass, 5/8'' diameter).
Thanks,
Fred

Loosen off tailstock when the cut gets down to 1/8" dia.---I usually stop &
flex the piece till it breaks off.---You are cutting close to the 3-jaw aren't
you ??

"jerry Wass" wrote(
)

stop & flex the piece till it breaks off.---You are cutting close to
the 3-jaw aren't you ??
Thanks - I am. Your question brings another question to mind: Would it be
possible/sensible to use a parting tool to the right of a fixed steady?
(googling did not really help in this matter)

All the best,
Fred

"Fred Splittgerber" wrote in message
...
"jerry Wass" wrote(
)

stop & flex the piece till it breaks off.---You are cutting close to
the 3-jaw aren't you ??
Thanks - I am. Your question brings another question to mind: Would it be
possible/sensible to use a parting tool to the right of a fixed steady?
(googling did not really help in this matter)

Possible indeed. However, real care needed for

1. allignment -- when I have to do that, I routinely use a dial indicator
to set the work in the steady.
2. tool height adjustment -- depending on the diameter and how much you're
cutting, you may have to change this. For a solid piece, that is -- for
tubing, probably not.
3. go really slow. Use the back gear. But note that the feed has be
reasonably high -- as for any cut off operation. Too small a feed and the
tool skips over until it digs in.
4. A lot depends on the material also. I've done this routinely with
plastic, brass, aluminum. For steel I cut off with a band saw and finish
off in the steady -- it's faster and less risky.

Boris

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In article , Fred Splittgerber says...

....Would it be
possible/sensible to use a parting tool to the right of a fixed steady?
(googling did not really help in this matter)

Yes. This is indeed the best way.

In fact, using a center on work held in a chuck is
considered incorrect by most. The holding is over-defined
in principle. Better to either a) use a chuck alone, b)
turn between centers, or c) chuck and steady rest.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Fred Splittgerber wrote:

Hi all,
I am aware of the fact that parting is (usually/always?) not recommended if
the workpiece is held between centers.
What about parting off with the workpiece mounted between a regular 3-jaw
chuck and a live center? (1/4 hp lathe, Workpiece: brass, 5/8'' diameter).
Thanks,
Fred

Do a Google search in alt.machines.cnc and you will find good info.

michael

Thanks for everyone's input.
Fred

In article ,
Fred Splittgerber wrote:
Hi all,
I am aware of the fact that parting is (usually/always?) not recommended if
the workpiece is held between centers.

Always. Think of what happens when it gets down to the point
where the remaining section is easy to bend. It will bend (away from
the parting tool, or up), rotate up, and slam down on the parting tool,
likely leading to something breaking, and at least to marring of the
workpiece.

What about parting off with the workpiece mounted between a regular 3-jaw
chuck and a live center? (1/4 hp lathe, Workpiece: brass, 5/8'' diameter).

I do it when working with fairly large and long workpieces, with
one caveat. Before I get to the point where it will *really* part off,
I loosen the center a bit, so it won't pinch, but the center will still
catch the free end. (Usually, the parted end winds up resting against
the side of the parting tool.)

The center serves in the early stages to keep chatter under
control, but once you are down to perhaps 1/2" or less left (of a 3"
workpiece), it serves little purpose, and could generate problems when
the part is (nearly) completed, binding the parting tool between the
workpiece in the chuck and the part just parted off.

Always think about what could happen when you are trying
something, and take steps to prevent the bad ones. (E.g. removing the
center's pressure before you get too deep, but after the support is no
longer needed.)

Enjoy,
DoN.
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Don, thanks for your thoughtful comments.
Fred