From: James P Crombie 
To: Atm List 
Reply-To: James P Crombie 


Hello all
  I finally got around to using my mirror grinding machine.  I got my
slop tray finished on the weekend and the blank mounted on the overarm
yesterday with little beeswax and duct tape(thank god for Red Green :-) I
did three sessions or about 1 hour each.  I am using a tile tool and MOT
with aprox 1/3 overhang.  The first series of wets took off the mold marks
from the 8" pyrex blank and left a sagita of about .001.   After
the final session I have a sagita of .004.  May have used 2oz of 60grit SiC
over the three sessions.
  Grinding machine specs are      Swing arm  6rpm
                                             Platter speed 23rpm
                                Aprox 15lb weight on mirror
I have some pictures and will get them up a little later. Does this sound
about right for a mirror grinder?

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James P Crombie

Summerside                   Machinist
Prince Edward Island         Amateur Astronomer
Canada                       3D Designer

E-mail                       jpcrombie{at}pei.eastlink.ca
Astronomy webpage            http://www.jamescrombie.com
Rhinoceros 3D webpage        http://www.jamescrombie.com/rhino/
Mirror Grinder page          http://www.jamescrombie.com/pics/
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