Re: [ARSCLIST] ET groove cutting ( was "More about ET preservation", was "Comparable collections anywhere?")

[Eric Jacobs <ericj@xxxxxxxxxxxxxxxxxxx>]

Graham Newton wrote:

> The BIGGEST problem was that most people trying to cut a disc NEVER read
the
> "how to " manual and didn't have the foggiest idea of how to do it right.
> They cut using chipped styli, worn styli and styli that had cut so deeply
that
> it hit the disc's base material, usually aluminum.  Worse, they often had
the
> cutting head and stylus mis-aligned to the surface of the disc.  The
resultant
> grooves bore the scars of the mistreatment and that consequently, is what
you
> often see when looking at a groove under a microscope.

Thanks so much for that bit of history.

Actually, all the variations that I see in the grooves that I was refering
to
are on professionally cut studio lacquers, or on lacquer dubs.  I just wish
I knew what aspect of the cutting process failed to create the groove
distortions I see.

I'd like to be able to name these distortions more accurately in my groove
condition descriptions that go into the technical metadata.

For example, sometimes the bottom of the groove is very rough - it almost
looks scaly.  It seems that either the cutter wasn't hot enough or the
angle was wrong, but I have no idea really what happened.

Other times, the groove bottom has a bumpy quality, almost like a smooth-ish
lava flow.  The walls will still look just fine, but these are suprisingly
noisy.

Other times, the bottom of the groove will be striated - I can't think of a
stylus that would create that sort of wear pattern on a flat groove bottom.
I have to assume that the cutter was perhaps worn, but maybe it's something
else?

Those are some of the things I'm curious about.