Peter Fairbrother wrote:

I'm doing facing cuts and the tool is grabbing because the rake is too
positive (I think. There's a graunchy noise and the feed goes slack for a
bit. Worse near the center, I'm not sure why. Chinese minilathe, 0.5 mm cut,
brazed carbide tool on cast iron).

It's not really practical to change or regrind the tool. I'm dead on center
height, and wondered whether changing the height might make it better by
changing the effective rake somehow?

If so, which way? And why? I tried to work it out but got confused, and came
up with two different answers.

Is this a BIG facing job? (more than a couple of inches in diameter?)
If so, you may have to increase the spindle speed to keep the cutting
speed in the desirable range as you move from or toward center.

Pete


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Pete Snell
Royal Military College
Kingston Ontario


The reasonable man adapts himself to the world;
the unreasonable one persists in trying to adapt the world to himself.
Therefore all progress depends on the unreasonable man.
- George Bernard Shaw