Should I use light oil to extract a screw?

Laurent · Jan 21, 2022

Hi all,

I have a Canon 50/1.8 lens, "New FD" version, that does not lock properly on the camera.

My guess is that the grease may have solidified (I bought the lens new in '86...) so I tried to remove the chrome ring at the back of the lens, but, of course, out of 3 screws I was only able to get 2 properly.

I have proper screwdrivers, did not remove the screws before the three were unset to avoid having the ring move before everything was unset.

Alas, the third one is stubborn enough not to move at all, to the point that the head is not stripped...

The only thing I can see is putting a drop of very light oil, which is used to get stucked parts unstuck, but I'm not sure
1) this will be enough
2) the oil may not migrate and damage other parts (this oil is not a lubricant)

What would you do?

Don_ih · Jan 21, 2022

I'd use acetone first. Just a droplet on the head of the screw and wait a few minutes. There might be thread-locker.

resummerfield · Jan 21, 2022

First, I’m not a camera repair person. But I’ve disassembled several of my cameras for cleaning, and I know exactly what you’re going through.

First, try the acetone as previously suggested.

If not successful, apply some heat. I use the sharp tip of a soldering iron. These sharp tips are for soldering modern circuit boards. Place this sharp tip of the hot iron on the screw head for a few seconds, maybe 5 to 10, and then try to remove the screw.

Finally, I try to apply some “grit” between the screwdriver tip and the screw head to help bond the screwdriver to the screw. I use some automotive valve grinding compound, but anything with some sharp “grit” to keep the screwdriver from slipping.

Good luck!

Laurent · Jan 21, 2022

Don Heisz said:
I'd use acetone first. Just a droplet on the head of the screw and wait a few minutes. There might be thread-locker.

resummerfield said:
First, I’m not a camera repair person. But I’ve disassembled several of my cameras for cleaning, and I know exactly what you’re going through.

First, try the acetone as previously suggested.

If not successful, apply some heat. I use the sharp tip of a soldering iron. These sharp tips are for soldering modern circuit boards. Place this sharp tip of the hot iron on the screw head for a few seconds, maybe 5 to 10, and then try to remove the screw.

Finally, I try to apply some “grit” between the screwdriver tip and the screw head to help bond the screwdriver to the screw. I use some automotive valve grinding compound, but anything with some sharp “grit” to keep the screwdriver from slipping.

Good luck!

Thankks for your replies, I'll try acetone then heat... will keep you posted of my progress.

I'd really like this lens to get back to normal, it fits my AE1P nicely

Laurent

Tel · Jan 21, 2022

resummerfield said:
First, I’m not a camera repair person. But I’ve disassembled several of my cameras for cleaning, and I know exactly what you’re going through.

First, try the acetone as previously suggested.

If not successful, apply some heat. I use the sharp tip of a soldering iron. These sharp tips are for soldering modern circuit boards. Place this sharp tip of the hot iron on the screw head for a few seconds, maybe 5 to 10, and then try to remove the screw.

Finally, I try to apply some “grit” between the screwdriver tip and the screw head to help bond the screwdriver to the screw. I use some automotive valve grinding compound, but anything with some sharp “grit” to keep the screwdriver from slipping.

Good luck!

+1: I've had good luck with the heat method. (Just make sure to use a clean tip--no solder on it.)

NB23 · Jan 21, 2022

Are they JIS screwdrivers? Those are proper. Anything else is no good and you will run into problems; stripping the screws, difficult to unscrew...

shutterfinger · Jan 21, 2022

Threadlocker that will dissolve with Acetone. You may have to soak it for a few minutes.

NB23 · Jan 21, 2022

Make sure you use a “JIS” screwdriver. Many, many lenses have been scrapped because a phillips was used.

RalphLambrecht · Jan 21, 2022

Don Heisz said:
I'd use acetone first. Just a droplet on the head of the screw and wait a few minutes. There might be thread-locker.

I agree with Don;acetone is worth a try.If that doesn't work,I'd give a light drop of oil a try; after that I'd give up and get another lens.

Light Capture · Jan 21, 2022

Acetone usually works but it might be hard to get past screw head. When it's that stubborn re-applying acetone number of times is needed.
Especially when it needs to penetrate deeper. Acetone dries so quickly that it might evaporate before it gets to the thread locker. That's why applying it multiple times will help.
The best way to apply is needle or dental pick with relatively sharp tip. It will carry small amount of acetone that's just enough to wet the thread.
It's better to apply small amounts at time so it doesn't come into contact with any painted surfaces.

cjbecker · Jan 21, 2022

You can also try giving the butt end of the screwdriver a small wack with a hammer. Will normally get stubborn small screws out.

gone · Jan 21, 2022

I would try acetone, but w/ a little penetrating type of oil. It may be seized tight to prevent anything getting in there though. As cjbecker suggested, good whack on the end of the screwdriver has freed up many a screw from it's hole. A blow dryer that gets really hot can be of help too.

RalphLambrecht · Jan 22, 2022

cjbecker said:
You can also try giving the butt end of the screwdriver a small wack with a hammer. Will normally get stubborn small screws out.

Forever problem there is a hammer big enough

Laurent · Jan 24, 2022

RalphLambrecht said:
Forever problem there is a hammer big enough

May be my hammer was not big enough... seems the head is now stripped beyond repair.

The lens still works, but being unlockable it is not very safe... I guess I'll be on the market for a replacement...

Auer · Jan 24, 2022

Laurent said:
May be my hammer was not big enough... seems the head is now stripped beyond repair.

The lens still works, but being unlockable it is not very safe... I guess I'll be on the market for a replacement...

If you have a drill press or a lathe you can drill out the broken screw and re-thread the hole.

Laurent · Jan 24, 2022

Auer said:
If you have a drill press or a lathe you can drill out the broken screw and re-thread the hole.

I have such tools, but positionning the lens will be quite touchy...
I had success in the past in other contexts by gluing a screwdriver on a stripped screw, so I may try this.

The lens is not of huge value, but I'd be happy to get it back to full functionality.

cjbecker · Jan 24, 2022

If its stripped. You can sometimes get a very sharp flatend screwdriver and tap it till it locks in.

Don_ih · Jan 24, 2022

You don't need anything more special than a regular drill to drill out a screw. However, if you have a dremel and one of those thin cut-off discs, you can use that to cut a standard slot in the screw (it will also cut into the area around the screw a bit, but, at this point, who cares?) and use a standard screwdriver to take the screw out. Phillips and JIS screws are great until they're damaged - then they're garbage.

Laurent · Jan 29, 2022

Well... things get interesting... I was about to try the use of epoxy glue to get this $#@%^ screw out... And discovered the lens know locks properly !

Don't know if it was impressed by my efforts but at least it's back to normal.

I will still try to fix this screw, but there's no more hurry.

Should I use light oil to extract a screw?

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