Re: [ATM] mirror grinding

["Scott Ewart" <scott.e@quicksurfer.com>]

    As long as you're still grinding, there will always be pits.  That's how 
grinding works, by chipping out tiny pieces of glass.  Only when you polish 
do the pits disappear.  If you want to get an idea how big the pits should 
be, sprinkle a few grains of the dry grit you're working with at the time 
around the area you're using the magnifier on.  The pits should be about the 
same size as the grit.
    Don't worry about using too much magnification.  There's no such thing. 
If the scratches you see at high magnification are not visible at 5x, don't 
worry.  They'll polish out quickly.

Scott


----- Original Message ----- 
From: "Cec & Cris" <ccabar@bigpond.com>
To: <atm@atmlist.net>
Sent: Tuesday, June 21, 2005 6:03 AM
Subject: [ATM] mirror grinding


| I,m in the process of grinding out my 250 mm mirror and I'm up to the 12 
micron stage. My 5x Magnifying glass does not let me see more than a couple 
of pits. I've been on this grit for 20 minutes. I decided to use a 25mm lens 
upside down and I saw all manner of pits. The more I ground the more 
imperfections I saw. I even saw some scratches that are not visible with the 
magnifying glass. They don't look anywhere near as deep as some of the pits. 
I can also clearly count the fingerprint lines on my finger. Have I used 
too a large magnification or will the mirror always have some sort of 
scratch or pit under high magnification. I used a 10x magnifying glass to 
view the mirror on saturday and I still couldn,t see any pits or scratches. 
This was while I was on the 500 grit. I do not own a 10x Magnifying glass I 
borowed that one for a few minutes. Can someone let me know please.
|
| Regards Cristian
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