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  1. #11

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    Not sure if I can picture your problem, but I once jammed a enlarging lens and someone on APUG suggest I place a wide rubberband (like the ones on fresh brocoli in the supermarket) around the lens to provide a better grip. Make sure its tight--I was amazed at the amount of torque I could impart over such a small area. Good luck!

  2. #12
    Sanjay Sen's Avatar
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    Nope, no luck. Four hours in the fridge, and it still wouldn't budge, not even with gloves on.

  3. #13

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    How about rubber strap wrenches? I bought a set for about $5 at one of those import hardware stores. one on an element and one on the barrel would give you a a lot of torque!

  4. #14
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    I have a 5-7/8" mystery lens in an Melles Griot Synchro Electronic #3 shutter. MG denies it's their lens.

    I struggled with it forever trying to get the rear cell out, and one day instead of trying to unscrew it, I pulled (not terribly forcefully) while trying to unscrew it, it it just popped out.

    Just a guess, as far as liquids go, a tiny amount of alcohol, if the threads are aluminum. Machinists like alcohol when machining aluminum.

    If you have nothing to lose, a tiny tiny drop of Tap-Eaze or whatever it's called, a metal-working lubricant. Clean it off with cotton swabs ASAP afterward.

    Have you tried a pair of latex 'dishwashing' gloves? Turns puny weakling hands into Gorilla Grips.

    If saving the threads is not possible and it becomes evident you will never be able to convince a buyer the appearance doesn't affect it's function, and it's thus yours forever, and you get it apart improperly, I wouldn't be above sanding the threads on the offending lens cell (then cleaning them) and gluing it back, maybe contact cement, that would be solvent-releasable.
    Murray

  5. #15

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    Quote Originally Posted by John Kasaian View Post
    How about rubber strap wrenches? I bought a set for about $5 at one of those import hardware stores. one on an element and one on the barrel would give you a a lot of torque!
    Well John, in this case getting one wrench on the barrel without screwing up the iris mechanism is problematic. The outer part of the barrel is the iris adjustment mechanism and is, if not fragile, prone to being over torqued.
    San needs to be careful or send it to a repair person. Problem is,it's not a valuable lens ( I don't think).

    tim in san jose
    Where ever you are, there you be.

  6. #16

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    Quote Originally Posted by Sanjay Sen View Post
    Nope, no luck. Four hours in the fridge, and it still wouldn't budge, not even with gloves on.
    Hi Sanjay,

    I'd suggest finding a really cold deep freeze. If there is a commercial cold storage place near you, they may have a unit as low as -30. Bag the lens in plastic before putting it in the freezer. Leave it in overnight. Wear insulated gloves under rubber gloves when you try to get it apart. Getting it truly cold will maximize the contraction differences between the metals, and possibly give you a longer working time to get it apart. Good luck!

  7. #17
    resummerfield's Avatar
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    I've had similar problems where I was distorting the barrel by gripping it near the threaded portion. The more force I used the more I distorted the barrel, seizing the threads. My solution was to grip the barrel as far from the threads as possible.

    Use a rubber strap wrench, or a sheet of rubber or a rubber glove, gripping it around the barrel, near the glass. Grip the other end of the lens as far away from the threads as possible.

    Another possibility is to place the lens vertical on a rubber sheet, and apply downward pressure on the other end of the lens, in an attempt to screw the lens together.
    —Eric

  8. #18

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    If you want to try the thermal thing, after freezing the whole enchilada, you might try heat ing the component with female threads with a blow drier or hot air gun?

  9. #19
    Sanjay Sen's Avatar
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    Thanks, guys, for all the suggestions.

    One option I will probably try next is mounting the lens on a board to get a better grip, and then having another go at it - with latex dish-washing gloves, as Murray suggests. It's not an expensive lens, so sending it to SK Grimes does not make sense.

  10. #20

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    Sanjay:

    Be careful, if you use the rubber strap wrenches, as they will exert a lot of inward pressure on the lens where the handle touches the lens, just as a pipe wrench would.

    That said, I have successfully unscrewed lenses with a pipe wrench by wrapping the lens with many layers of electrical tape to absorb that oressure, and using my judgement as to when I was applying too much torque.

    The last-resort method, which has never failed me, is to drill a hole in a scrap piece of wood so that the lens fits inside tightly. I then dribble some water unto the wood, causing it to swell and grip the lens evenly. At that point, you can use a big ol' wrench and crank it 'til the threads rip.

    Charley

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