"Ed Huntress" wrote in message news
On Fri, 29 Mar 2013 16:13:03 -0700, "PrecisionmachinisT"
wrote:

--even with single point diamond tooling, surface finish becomes a big factor when it comes to accurately gaging workpiece diameter..

Keep in mind that master hard-drive disks and the production disks,
back when they were made this way, were single-point turned. No
grinding. We built lathes especially for turning them at Wasino -- and
they were all shipped to Singapore. sob


Still they were nowhere near to a mirror finish.

And those were flat.


Moore Special Tool built special turning machines for making
assymetrical lenses for the Defense Dept. They were all single-point
turned, although some of them (for shorter wavelengths of light) were
polished.

The point of those Wasino machines I mentioned is that they were made
for turning parts that could not be ground, either because of
microchecking or production volume requirements. They were fast and
left a polished surface.


As I said, surface finish becomes a big factor...

Pretty sure in this situation, the material basically liquefies--high-speed-micro-photographs would be an interesting study.