Stripped screw head on Hassy film back

Discussion in 'Camera Building, Repairs & Modification' started by jmartin, Oct 1, 2009.

  1. jmartin

    jmartin Member

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    Greetings,

    Well, after successfully opening up several Hasselblad backs without mishap (for the purpose of replacing light seals) I've now managed to strip the head on one of those tiny little screws. Bummer.

    I've looked around a bit and it appears there are some screw extractors available but they all look like they're for larger screws.

    I don't currently have a dremel tool but I could acquire one if there is a small enough attachment for grinding a deeper slot into the head. Or is this not the right approach?

    Anybody have experience with this and can offer advice?

    Thanks,

    James
     
  2. Tom Nutter

    Tom Nutter Member

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    I don't know if you want to grind anything, but if you were to use a very small drill bit and a very gentle touch, you could create enough of a groove where the original slot was by drilling 2-3 spots directly next to each other. You will ruin the screw for sure, but if you are careful, you should at last be able to get it out with firm pressure and a sharp, square screwdriver.

    The other option would be simply to NOT change the light seal ----it's probably okay, unless you are having obvious problems with the back. I've had pieces of the seals fall out of hasselblad backs (when I used Hasselblad) and never experienced a single fogged frame.
     
  3. richard ide

    richard ide Member

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    One thing you could try is to put a very small dab of valve grinding compound on the tip of your screw driver. The abrasive digs in to the metal and helps prevent the screwdriver from slipping. An alternative might be to scrape some abrasive (try 220 grit) fom wet and dry sandpaper and mix with a little grease. This has worked for me on a few occasions.
     
  4. mgb74

    mgb74 Subscriber

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    Another approach (generally last resort) is to try to drill it out with a left hand bit (see micro tools). If you've been a good little boy or girl, Santa will allow the counter clock wise bit to back out the screw enough to grab and turn with pliers. If not so good, then you'll need to drill out the old screw and tap for a larger screw. Another alternative is to drill out the screw head and use glue in that spot instead of a screw (obviously you can't remove that part again).
     
  5. AgX

    AgX Member

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    Is this a drill, an extractor or a combination of both?
    The smallest extractor (conical thread gripping anti-clockwise) around in my workshop needs a drilled hole of at least 2.5mm or so.
     
  6. jmartin

    jmartin Member

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    Thanks, all, for the replies. I think I'll proceed with trying to create a better slot in the head and then perhaps richard's idea of adding some form of grit or compound to provide better grip for the screwdriver.

    Tom, you have been fortunate, indeed. All of my film backs were acquired as used items, and almost every one proved, on its first use by me, to need new seals. (and totally regardless of external appearance, naturally). So now whenever I get another back I immediately change the seals. The parts are pretty cheap, thankfully!

    - james
     
  7. mgb74

    mgb74 Subscriber

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    It's really a combination. For example: http://www.micro-tools.com/store/item_detail.aspx?ItemCode=LHDBSET (they also sell individual bits)
     
  8. AgX

    AgX Member

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    Never saw such before. Thanks.
     
  9. Xmas

    Xmas Member

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    Easy outs (proprietary extractors in England) or special bits are expensive and if an easy out snaps you have a worse problem.

    If you have a drill press and the screw is counter sunk drill into the screw head along the axis of the screw until the counter sink can be snapped off. Use a depth collar on the drill to not counter sink (drill into) the plate.

    Then when you remove the registration plate you can file a screw driver slot in the residue of the screw and unscrew. It should not be tight with out the friction of the counter sunk screw head.

    [not for clumsy] if it is tight and you suspect galling before you damage the head seat a screw driver in the screw and tap the end of the driver with a light hammer this will break some of the adhesion[/not for clumsy]

    Mine were not that tight...

    Zorro
     
  10. John Koehrer

    John Koehrer Subscriber

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    I've used a screwslotting file from micro tools. You just use a corner of the file to make the slot & unscrew the remainder of the screw.
    As I remember, the file ain't cheap, but yes, it is thin enough.
     
  11. resummerfield

    resummerfield Subscriber

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    I learned that technique from an aircraft mechanic, and it really works! Just go slow, and put lots of pressure on a clean, sharp screwdriver. Good luck!
     
  12. jmartin

    jmartin Member

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    I've just looked at that tool at the Micro Tools site and I might go ahead and get one. However, I'm not sure of its application in this case. An important point I failed to mention earlier is that these screws are countersunk down into the plate that forms the inside face of the film magazine. The screws are flat topped, and when completely seated their top surface is just barely below the face of the plate.

    So, in this case perhaps the left hand bit...?

    - jm
     
  13. Greg_E

    Greg_E Member

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    Probably need to drill of the head and hope there is enough left to slot or grab with vise grips to remove the threads. Probably talking something like a 2mm or 3mm (#0 to maybe #2) screw, so there isn't a lot of material to get on.