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Re: [ATM] ATM Digest, Vol 51, Issue 36

Bob Thanks for the advice
  One question 
  If I use pitch to hold the blank to the mould how will I remove it to rotate/test?Will a sharp tap with a wooden mallet separate them?
  Could I just duct tape aroung the edge with a thin rubber pad between the mould and blank? This will allow me to easily separate the glass by cutting the tape?
   
  Thanks
  Ulhas

  
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Message: 1
Date: Sat, 29 Mar 2008 13:56:26 -0800
From: "Bob May" 
Subject: Re: [ATM] Polishing /Figuring a Slumped Blank
To: 
Message-ID: <003001c891e7$bce8b7a0$ddadfea9@amd>
Content-Type: text/plain; charset="iso-8859-1"

Get the glass slumped by the glassworkers.
Mold a back to it with the dental stone or other good plaster or
cement and use pitch or waxc to hold it to the mold. Don't hold
the glass in the plaster or you will stress it and thus make for
problems. When you are ready to do the last grit, warm the glass
and mold to get the glass to take a nice set andd finish the
grinding. If desired, you can also just remove the glass from
the mold at this point and work without it as there are no longer
any real forces that you have to deal with. When teesting the
glass, remove it from the mold to insure that it doesn't affect
the figure of the glass. Astigmatism will be your biggest
problem with gluing the glass to the mold so be careful of that.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net





       
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