Re: [ATM] First mail to atm list

[Dave Smith <smithersscope@yahoo.com>]

Mahmooe,
Welcome to the world of ATM!
With regard to your issues with pits, I suspect the
glass is fine. Your problem is most likely in the
grit. You've probably got large grains mixed in with
your finer grit. There are ways to separate finer and
finer sizes of grits. Mixing the grit up in a large
bucket of water and letting it settle out by gravity
may be the easiest way and cleanest way to recover
different grit sizes--with the largest settling first
and the finer grains settling last. I'm sure there is
at least one thread on this subject in the archives.
Are you familiar with the ATM archives? They are
keyword searchable. A true wealth of information.
I hope this helps!
Don't give up, and as they say, grind more, worry
less!

Dave

p.s. the first surface mirrors from photocopy machines
will work fine as secondary mirrors. You should have
no problem recovering one of sufficient diameter (or
width--minor axis) for your 6" mirror!

--- Mahmood Hassan <emhl95@yahoo.com> wrote:
 
> After a hell lot of market research I was able to
> get a 6-inch mirror blank with 0.75-inch thickness,
> which is usually used in sugar industry as sight
> hole glass for evaporators. How I acquired grits is
> another long story. These grits were contaminated
> with uneven grains, but luckily I had access to
> vibrator sieve equipment in the facility where I
> work. So this solved the problem to some extent.
> 
> PROBLEM; The problem with this blank is this that
> when I moved on to fine grinding some of the larger
> pits are not going to disappear (I even went back to
> larger grits to remove these pits but with no
> positive results). The strangest thing is that as I
> applied more pressure during grinding some of the
> pits became even bigger. After so many hours of
> useless work and going back to larger grit numbers
> again and again, I think that it is the quality of
> glass, which is causing this problem. Any
> suggestions please!



		
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