My nemesis – the broken screw

One of the things that camera restorers (and other people who repair small metal mechanical items) encounters is jammed or broken screws.

For those dealing with larger screws/bolts it can be easily dealt with by using left handed drill bits, or specialized screw extractors. For us dealing with such small metal screws, it becomes more of a challenge. How to deal with a <1mm screw? There is not much material to deal with and there are not many tools for this size job.

I recently acquired a camera in very poor condition. It obviously has been stored in a nasty environment as it was coated in crap and signs of corrosion … one screw had the head broken off, I broke off another screw head while attempting to remove it, and there are a couple of screws that just won’t budge (I stopped before stripping the slotted head).

So … what to do? Get more tools. I am thinking of attacking it in a number of ways:

  1. Drill out the broken headed screws … need to get a drill press for my Dremel.
  2. Use a precision screw extractor … Moody Tools has a tool set for this.
  3. Solder a lever to the heads of the stuck screws.

I will follow up after I attempt any of these … if anyone has another suggestion I would be happy to hear it.

2 thoughts on “My nemesis – the broken screw”

  1. Hi Dennis,

    I’m not sure what the screw material is, but let’s assume it’s some type of steel. If a steel screw has corroded in place, one method is to use heat to expand the thread system and then let the cooling cycle break the corrosion bond.

    Possible heating methods include:

    (1) using a hair-drier. Probably a bit too broad-brush for this situation – you don’t want to cook everything else.

    (2) for the experienced worker a hand-held propane torch with a very small flame moves stuck threads easily. However in the hands of a novice it can be potentially disastrous!

    (3) using a soldering iron to heat the screw head or thread. I would recommend you try that first.

    Before you start clean off all the oil(s) you applied with a solvent as they can form gums and lock up the screw even worse if they get heated past a certain point.

    The idea is to heat the screw just enough to expand it. The rust/corrosion’s bond with the screw fails as it cools down. Apply a WD-40 type fluid as it cools, just not immediately you remove the heat!

    This is not something you can give hard and fast rules for – it’s a technique you have to develop a feel for with lots of practice (read: expect failure at first)

    With regard to a screw with a damaged slot you can:

    (1) file a new slot

    (2) weld, braze or silver-solder a rod to the end of the screw and turn that

    (3) use a pin-vice to grab the outside of the screw head and hopefully turn that if you have enough purchase.

    The very best penetrating oil I have used is a 50-50 mixture of ATF fluid and acetone. When I used to repair vintage cars I had a bath of “oil of wintergreen” which is the magic ingredient in WD-40 or CRC. Soaking 80-year old blocks of rust overnight in the stuff worked wonders.

    If you were able to strip off any parts that could be affected (plastic/bakelite/rubber/leather/vinyl) before soaking the entire unit in ATF/acetone or oil of wintergreen, it could allow you to recover parts or even repair a camera that others have given up as a hopeless case.

  2. Since the screws are all made of brass on this camera a tiny drill bit smaller than the screw will be best to use. After drilling a hole in the center of the screw melt hot solder into the hole to heat the corrosion up
    Drill it once again with a slightly larger bit. Leave the bit in after drilling and let cool for 5 minutes. Using the reverse switch on the drill try and see if the bit comes out with the screw It did for me

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