Dave,
Thanks, I'll have a look at the paraboloid roughing code.
Bubba,
It's only a test at the moment, I will try to add a form today that allows some adjustment, thanks for the feedback.
Gary,
I think step over is going to be a function of the number of turns in the spiral, I'm hoping to get a form made today to allow adjustment.
Tau (et al)
I removed the line about about disappointing feedback this morning, I think I was at a brief low point last night, things seem brighter this morning.
Yes I understand what you mean about the asymptotic run out at the boundary.
Yves,
Yes that will be possible with the Windows Form I hope.