Jerry Foster wrote:

What is the material?
[..]

"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).

Cast iron. Grey, fine-grained, not scrap.

[..]
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.

What I really wanted was a quick rundown on how changing tool height might
change the effective rake, and why. I'm sure I've read something about it,
but I can't remember where.


--
Peter Fairbrother