[ATM] Open Question Concerning Pitch Laps

[Bryan Stiles <bryan.stiles@gmail.com>]

I have experienced a phenomenon on two separate occasions that I would
appreciate some input on.

This question is a direct result of my prior posts about the inability
to remedy a central hole in my mirror. I tried all the suggestions
kindly provided but to no avail...I went back to fine grinding. In a
nutshell the question is why does my lap quit responding?

I am working on my second mirror and have come to a point where I seem
to be unable to get the lap to make any difference in the figure of my
glass. I have cold and warm pressed, faceted, trimmed, beveled,
channelled, more pressure, less pressure, thinned CeO mix and
thickened CeO mix. Unless I really try to do damage (i.e. don't rotate
the mirror at all) I can't seem to get the thing to respond in the
time frames mentioned in various replies and web sites.

Case in point: As mentioned above I used too long a figuring stroke
(for 10-12 minutes) and polished a decent hole in the center of my
mirror (8" f/6). I tried for approximately three weeks to get that
hole out. TOT 1/3-1/4 COC, smallish W stroke, etc. All told 10 hours
of time pushing the thing around trying to fix the hole.  The upside
was the glass was really, really clear.

Now I don't mean to paint too drastic a picture here. During the
course of the 10 hours I raised a few spots and was able to smooth
them out in fairly short order by concentrated effort, so I felt that
things were working properly albeit slowly.

I understand that it takes a while to clean up some mistakes (central
hole, turned edge, etc.) but the times I've read about were on the
order of an hour or two not 10.

If this helps, the pitch is soft burgundy from Will-Bell. Room temp
hovers between 68-70° F. I noticed after  channelling and beveling
etc., that my central square was a bit too close to the actual center
of the glass (what exactly does that cause?) so I scraped it down
lower that the surround squares.

Is this an issue with my patience or methods / materials? My resolve,
I fear, is also being tested. :)

Trying Hard to Learn, Bryan
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