Lathe parting operations

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 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( news: snipped-for-privacy@tds.net )

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

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

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 ==================================================

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

michael

Thanks for everyone's input. Fred

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.

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.

Don, thanks for your thoughtful comments. Fred