Quote Originally Posted by irving2008 View Post
Hmmm, checked tool height by expedient of trapping a thin steel rule between work and tool - it remains essentially vertical.
Yes, but carbide will cut with 90 degrees at the tip so you could be above centre and pass that test. Facing the end so it doesn't leave a pip, or snap a pip off, is more of a test. I'd say the tool is either too high or it's lost it's tip. Something rubbing is the usual way to that blistered appearance. :nope:

If the tool leading left hand edge is set perpendicular to the axis of rotation (12 o'clock) you could do well to rotate it clockwise a tadge (12:05). Any rotation counterclockwise (11:55) can be seriously bad news because it pulls on the work rather than pushing against it.

If I got a cut like that I'd start by sharpening the tool