Can filter threads be straightened?

Discussion in 'Miscellaneous Equipment' started by David Brown, Jul 9, 2005.

  1. David Brown

    David Brown Subscriber

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    Opps. Dropped a lens. :mad:

    It seems fine as to focus, aperture amd glass; but, of course, the filter threads took the worst of it. I could live without a filter, but a screw-on lens hood would be nice. (So would a filter, actually ...)

    Can this be done successfully? Any recommendations for a tech?

    Thanks!

    David
     
  2. jjstafford

    jjstafford Inactive

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  3. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    It's worth a try, but an iffy proposition. They often just don't work well after being straightened.
     
  4. bobfowler

    bobfowler Subscriber

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    And sometime - even if you use the correct tools - the threads will just break off when you try to straighten them. That is especially true with older aluminum lens barrels.
     
  5. paul ron

    paul ron Member

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    It's a crap shoot.

    The only way to know if it can be done is to do it. First you have to get the lens round again. That is where the tool comes in handy although I like the wood plug and tap it gently with a leather hammer to get the shape back.

    Once that is done, you have to chase the threads out. Either you use a thread tap made for the size or an old filter ring with grooves cut in it to let out the scrap metal shavings as it goes around. A small amt of tapping fluid is used and cutting has to be done very slowly backing the tap out for every 1/8th turn you make or you'll clog the cutter. Sometimes the thread tear out if the aluminum is old and brittle but then again if the damage wasn't too bad it works like a charm.

    If it doesn't work, Corkin filters are your best friend.
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    If it kind of works but not well, and it's not a wide lens where vignetting would be a problem, one option is to put an empty filter ring on the lens, and then put any additional filters on the empty ring.
     
  7. paul ron

    paul ron Member

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    How about using a step up ring to avoid these problems? You'll just have to buy a new set of filters in your new size.
     
  8. colrehogan

    colrehogan Member

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    How bad is the dent?
     
  9. Earl Dunbar

    Earl Dunbar Member

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    My concern would be whether any of the internals of the lens were thrown out of alignment, or other invisible damage. That said, I have an Oly 35RC with dinged threads, and the lens seems super sharp. Same with a 100mm lens for OM, though I haven't critically evaluated that one.

    Earl
     
  10. jimgalli

    jimgalli Subscriber

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    Stepping ring is the ticket. I usually get a smaller ring that will fit loosely in the threads where the ding is then carefully apply outward pressure on the smaller ring which is protecting the important threads with a pliers. It'll never be perfect again but if it's good enough to force a stepping ring on, you're back in business.
     
  11. resummerfield

    resummerfield Subscriber

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    I've used the thread repair tools from micro-tool on two badly dented lenses. Using a small hammer and gently expanding and relocating the tool, I was able to "repair" both so that they accept filters nicely.

    paul ron-- where do you find the thread ring tap you mention? I've never seen one that large (49mm, 52mm, 67mm and 72mm).
     
  12. paul ron

    paul ron Member

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    The thread ring chaser is an old trick. You can make your own chaser from an old filter step down ring since they are nice and beefy. By cutting grooves in the ring, you allow waste to escape but be sure to go slow and back it in and out after every 1/8th turn.

    You can get real chasers from industrial tool companies. I have a set I got in Long Island City in Queens NY from a company called Carter Milchman Frank (CMF) on 31st street.

    Some sources I found on the interent that may be of interest...

    http://www1.mscdirect.com/CGI/N2DRVSH

    http://www.hyetech.com/greenfield.html for chasers

    http://www.cartech.com/machining_zone/threading.html info
     
  13. medform-norm

    medform-norm Member

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    Those are nice links Paul. Thanks. They might come in handy. Today our 10$ bargain/suprise Yashica GSN arrived and yes, it has some nasty surprises. Most nasty one we can see now is the filter ring. It looks like it's been slammed into a wall several times after falling down a 10ft concrete stairs: dings galore. We need to get this straightened out in case we need to disassemble the lens to get to the shutter. The super crude thing to do would be to saw off the bad part of the lens barrel, but we like to approach this with a little more subtlety (spelling :confused: ). A new thread repairing adventure is about to start. Any pitfalls on the road ahead of us we need to be warned about?

    Cheers, medform-norm
     
  14. paul ron

    paul ron Member

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    Your camera cost you $10 so don't go and spend another $200 fixing it. It's suposed to be fun restoring it so keep it as cheap as you can. I'd go with straightneing the ring as much as you can by tapping it out with a leather hammer on a round wood plug close to the same diamiter, slightly smaller and of hard wood. I use my carver's lignum vitae malet as my wood plug, the small one is close to 70mm round.

    After you get it nice and round, get a step up ring and make some slots in the threads using a dremel cut off wheel. That will help it cut it's own threads as you force it on. Once it is in place, you have a permenent working filter ring with new threads in place.