Using a cutoff tool
- When using a cutoff tool, do you put the top edge at center? or just
The other day when I was using the cutoff tool it caught and jumped
causing the piece I was cutting to break. I was using the back gears,
so lathe was turning slow.
- countrybj2006 wrote:
>When using a cutoff tool, do you put the top edge at center? or justCutoff work requires a very sturdy lathe and setup. The downward force
>The other day when I was using the cutoff tool it caught and jumped
>causing the piece I was cutting to break. I was using the back gears,
>so lathe was turning slow.
on the toolpost, and the reaction to the high infeed force can lift the
rear of the carriage or otherwise deflect the lathe such that the tool tip
goes below the workpiece center, or the workpiece climbs over the
tool. If you chuck jaws are worn at the tips (VERY common) then you
can't really grip the work right at the edge of the chuck jaws. You
want the compound slide backed up such that the cutting edge is
supported by the lower part of the compound and the cross slide.
It may be necessary to tighten the compound gibs, or even the cross
slide gibs, to keep things rigid.
Grinding a slight groove in the top of the cutoff tool so that the
chip folds inward on itself seems to help prevent the chip binding
up on the sides of the cut. This groove should be radial from the
workpiece, ie. running straight down the length of the cutoff tool.
Lots of lube is needed to keep the chips flowing out of the groove.
And, it may be that the backgear speed is too slow. Depending on
the material, a higher speed may cut better. And, my experience
is that parting-off large diameter pieces of aluminum may be a fool's
errand, even on the most rigid of lathes, due to the extension of
the tool bit required. It works great even for thick wall tubing, but
if you have to go all the way to the center, it gets messy. I do all
that work on the bandsaw, now.