Re: [ATM] Pit Stop (Pun) - Newbie needs advice.

["Bob May" <bobmay@nethere.com>]

Other than you probably have been using way too much grit, you may be ready
to go to the next grade.
When you apply the grit, an 8" mirror should be using maybe 1/10th of a
teaspoon of grit per wet.  Each wet should last until the sound is fairly
quiet from the grinding operation.  The initial grinding (first 20 strokes)
is quite loud compared to the later grinding.  I usually wait until the
grit/glass appears to be about the color of Haze Gray (Navy's color for the
top parts of their ships) in the coarser grades.
If you still have some grit left, mark off a few of the large pits and do a
wet.  If thoes large pits move about on the surface of the glass, you have
already finished up that grit size and it is time to go to the next grit.
If you don't have any more of the 120 grit, go to the next grit and do a few
wets.  I find that 5-8 wets done right usually prepare the surface for the
next grit size.  Do the mark and grind and see if any of the pits stay.  If
so, keep grinding until the pits go away.
Finally, don't forget to keep track of your ROC otherwise you may end up
making a F2 mirror by mistake.  Do remember that FL is 1/2 of the ROC!  I've
seen people forget this and react to the large difference in what they had
and what the wanted.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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