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  1. #11

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    Although they're burnished in, the burnished section can be straightened. A very fine blade is worked around the edge several times lifting very small sections at a time. On reassembly they are simply burnished down again.
    If you cut the burnished section off the group can be epoxied in place, simply running a small bead or a few drops around the edge.
    I've always used Acetone to separate elements but am going to try lacquer thinner for those more persistent jobs.
    To the OP don't separate the elements in place, You're going to need to remove them to recement them. I use an optical cement available at my local hardware store, I believe the brand is "Crystal Clear" it comes in a small red syringe & is a UV cured glue. Sunlight or florescent both work.
    Heavily sedated for your protection.

  2. #12
    Steve Smith's Avatar
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    Quote Originally Posted by Ian Grant View Post
    What's the optical cement you use called ?
    We have three types:

    Optimax, Dymax and one other which I can't remember the name of.

    Here is the Dymax website: http://www.dymax.com/

    I will post the details of the actual products we have when I get back to work on Wednesday.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  3. #13
    Ian Grant's Avatar
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    No rush Steve my wife's just postponed my Aegean/Mediterranean trip & visit to Venice

    Ian

  4. #14

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    John (and all),

    I decided to try straightening the burnished section. I was able to get a sharp knife point under but couldn't budge it (and was worried about scratching/damaging the glass). So, I took a small (eyeglass) screwdriver and tapped the back with a pair of pliers to try to work it under. The entire burnished ring just popped right off. So, as solid as the burnished section seemed, the bend point must have been pretty thin.

    The glass wouldn't come out though. I put a cutoff wheel into my drill press (300 rpm) and tried to remove more metal - although I cut some away, I was afraid of getting too close to the glass with it. That was a mistake because I think it pushed the remaining metal against the glass tighter (it moved even less freely when I was done with this operation).

    So, back to working a knife point under the edge a little at a time. This time, though, it worked and after another 15 minutes the glass came out nicely. There's a little chipping around the edges but nothing more than 1/2 mm or less so I don't think it'll matter.

    Total time, around an hour and a half.

    Next step, removing the balsam. Any thoughts - does it need to be acetone or will mineral spirits, turpentine, lighter fluid or any of the other hazardous materials I already have in my basement work?

    Thanks,
    Dan

  5. #15
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    I believe balsam is soluble in all the solvents you mentioned, but some act more rapidly than others. I think the more volatile solvents will work quicker. Let me know how the project goes, because I've got a 13" 1A Raptar with real bad internal separation. Both groups will need to be recemented.
    Happiness is a load of bulk chemicals, a handful of recipes, a brick of film and a box of paper. - desertrat

  6. #16

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    The Raptar is probably cemented using a synthetic material, not balsam. So, methods/materials will be different. But, I'll follow-up once I've let it soak for a while.

    Dan

  7. #17

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    You might check the link for the hot water technique above.
    A little dab of black paint goes a long way to solve small chips.
    Heavily sedated for your protection.

  8. #18

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    I suppose this should have occurred to me earlier, but this thing is a rapid retilinear type so it's actually three pieces of glass so I just doubled my work. I guess I should be happy its not a T-R triple (I have one of those with some edge separation but I"m not messing with it)

    Dan

  9. #19
    Steve Smith's Avatar
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    Quote Originally Posted by Ian Grant View Post
    What's the optical cement you use called ?
    Norland 121: http://www.norlandprod.com/adhesives/nea%20121.html

    Dymax 4-20688: http://www.dymax.com/products/optical/index.php

    Novachem Optimax 4008: http://novachem.ie/Brochures%20Downl...tems%20pdf.pdf

    The Norland 121 hasn't been used for a while so may be a bit old.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  10. #20

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    Quote Originally Posted by Fotoguy20d View Post
    I suppose this should have occurred to me earlier, but this thing is a rapid retilinear type so it's actually three pieces of glass so I just doubled my work. I guess I should be happy its not a T-R triple (I have one of those with some edge separation but I"m not messing with it)

    Dan
    Actually most RRs are just two pieces of glass in each element. Gundlach had a habit of adding another glass, which didn't do much, to their designs. I believe the Radar was like that for example, and like you say the T-R lenses were.

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