Jump to content

Loosening a tiny screw


Recommended Posts

I am working on a CLA of my Photomic F Tn finder. I can get all the super tiny screws out except 1, which seems locked in place. Once I get this screw out I can separate the two halves of the meter.

 

This tiny screw will not budge. I have tried soaking (with a q-tip) in 70% Isopropyl Alcohol and it still will not budge. I plan on soaking (carefully) again with a needle bottle this time in 91%.

 

Any other suggestions? Maybe really cold can air to hopefully contract the screw just a wee bit? My biggest fear is stripping the top of the screw head.

 

Much thanks in advance!

Link to comment
Share on other sites

I've had success with PB Blaster. It's often used to free corroded bolts and screws in automotive applications but I've used it on lenses. It typically comes in a spray can, but you could spray some into it's cap and then apply with a Q-tip or something else. You'd want enough around the edges of the screw that it can soak in and work its way down the threads. Give it a few hours to work.
Link to comment
Share on other sites

+ 1 to Conrad's suggestion of applying a soldering iron. Also make sure your screwdriver tip has a good profile. For slotted screws I like to get the screwdriver blade sides parallel by hollow-grinding. Some come with a wedge, which is a sure recipe for slippage and screw damage.

 

Cross-point drivers should be de-burred regularly too, so that the contact edges are sharp cornered and not rounded.

Link to comment
Share on other sites

Screwdriver MUST fit the screw head properly. A loose fit is BAD, and you can mangle the screw head.

Try a drop of lighter fluid. But be VERY careful where it goes, and keep it on the screw. I use it on pens to dissolve old adhesives (some not all adhesives).

The screw may have been installed with a thread lock; paint, varnish, etc. If so, heat may be the solution there.

Caution, too much force on the tiny screw could result in one of several bad results

- strip the head, so the screwdriver no longer can grip the screw

- shear the screw head from the shaft

Link to comment
Share on other sites

I have PB Blaster - I'll try that. Thanks

 

I have lots of different wattage soldering irons - I'll also try that also. Thanks

 

The smallest screwdriver I have is 1.4mm. That might be too big. Maybe I'll look for a smaller head like 1mm. Hard the check the profile without a 10x magnifier. LOL - Thanks

Remember the screws used are JIS - Japanese Industrial Standard screwdrivers should be used, not phillips or pozidrive.

  • Like 2
Link to comment
Share on other sites

Well it looks like I will need to come up with a plan B. I looked with high manification and the top of the screw head is stripped. Because of its tight working area I am not sure what I can use to extract it. Maybe a jeweler can get it out. I will keep soaking and later use heat. Edited by brian_donaldson|3
Link to comment
Share on other sites

It sounds like this may come too late, but my to go to trick is to get the best fitting screwdriver and then -tighten- the screw with force. After this, it usually unscrews. The idea is to get the threads unlocked and that works easier the way the screw went in.

Also, screwdrivers with a good hand grip help a lot. I prefer those even if they are wider than the screw (unless it's a sunk screw of course) than the mini screwdrivers . It's easier to apply force which actually lessens the chance of damaging the head.

Link to comment
Share on other sites

Thanks cees jan de hoog. I had thought of that also but without a good screwdriver, which I seem to lack, that cause more problems.

 

However... drum roll please... a new update.

 

While looking for something totally different I found a set of precision screwdrivers that were made in Japan. The smallest being .9mm and with long, flat profiles. I used the 1.2mm screwdriver, in concert with a continuous bathing of 91% Isopropyl Alcohol and bam! the little sucker started turning free. However, the head is a disaster and I will have to replace that screw.

 

(added - I used a squeeze bottle with a needle to deliver the Isopropyl Alcohol)

 

With much thanks to the community, I will continue my adventure into a CLA of my F Tn meter.

 

p.s. I am still looking for my can of PB Blaster. I know it is around here somewhere. I use it and other thing to work on my dinghy outboard.

Edited by brian_donaldson|3
Link to comment
Share on other sites

I have CLA several FTn finders. First of all do NOT use any type of spray cleaner or lubricant. It will get over everything and cause nothing but trouble. I think the best idea to loosen a small screw is a small soldering iron. And of course it is very important to use the proper screw drivers. The cross head screws are NOT Phillips heads. Using a Phillips head screw driver will strip them. They are JIS screws and require the proper screw driver. A good source for tools is Micro Tools. Good tools may be a little more expensive but will save you time and money in the long run.
  • Like 1
Link to comment
Share on other sites

the top of the screw head is stripped" Brian D.

If this is the case, then you're too late with a "good/proper screwdriver with a good grip".

Drill it out or better yet, after again applying heat, use a 'Pin Vise' to grab the sides of the now marred screw.

This method or when the screw was 'nice', Always Heat these camera/lens screws. Most all of these

PRO go from-the-Sahara-to-the-Antarctic components, used some form of 'Loctite' substance to achieve that claim...

  • Like 1
Link to comment
Share on other sites

Less orthodox answer. Working in RC toy retail my boss there told me: If you see the dentist, try begging for some undead diamonds to use in your Dremel.

Ephraim Kishon wrote in Israel they'd spot industrial spies by watching out which assembly worker puts a screw into each of many holes of the product.

Trying to say: if you are confident the fixed product might be usable without that screw: Behead it! - Especially when there is hope to grab it's remains with some pliers

I also noticed that opticians can be really nice and helpful, when you face tiny screw troubles.

Among the conventional cures mentioned above: Perfect fitting tools and heat from a soldering iron would be my favorites. Recalling the replacing of wheel bearings: Light alloy tends to expand more than steel under heat. That 's why I keep conventional cooking plates, to heat my wheels to about 100°C (a drop of water on them will vaporize) before I start hammering the bearings out, storing fresh ones in the ice box.

Once again: I am neither a watchmaker type nor sure what you are working on.

There are also chemicals to enhance the grip between tool and worn out screw. - I haven't tried them yet.

Link to comment
Share on other sites

Robert, thanks for the Micro Tool suggestion. Now that I have 2x F's and 2x F2's, I think I should really break down and get some decent tools.

 

Gus, after looking at the head of the screw under 25x magnification, the damage is not that bad. For the screwdriver I was originally using, yes, it did do damage. However for the other screwdrivers I found, there is plenty of slot space and I can still move the screw about. The head will probably need a good filing to smooth it out. That is another challenge with a screw that small. But I am up to it. :)

Link to comment
Share on other sites

I'm glad you couldn't find that can of PB Blaster. That stuff shouldn't be allowed within 20 feet of camera gear IMO!

 

Likewise WD40 and suchlike disasters-in-waiting, or in-a-can.

 

Just curious. When applied as I suggested (soak a q-tip and apply it to the screw), what would be the concern? Not seen it melt a screw yet.

 

I've loosened at least 1/2 dozen camera fittings this way. No damage. Now, I agree that spraying it indiscriminately at a lens or camera isn't a great idea. Nor was I suggesting that it be used instead of an appropriate lubricant.

Link to comment
Share on other sites

I have never found a posi-drive screw in a camera. The crosshead screws are JIS. In fact, about the only place I have ever dealt with posi-drive screws are on my old British motorcycles. Using a Phillips head screw driver on JIS or posi-drive will surely bugger them up. I guess that I am sort of ham-handed and whenever I have used any sort of cleaner or lubricant it seems to end up everywhere. I also have the same problem with anti-seize compounds. I usually end up with more on me than on the fastener. I don't know why this is but it always happens. My friends won't let me near the stuff. I am sure that if you are more careful and skillful than I am you can use it but NEVER spray anything into a camera. Follow Tom's advice and use it very sparingly.
Link to comment
Share on other sites

I just thought of something else. As long as you have the finder apart you should clean the resistor ring. It is the large black ring attached to the shutter speed dial. When this ring gets dirty you will have a jumpy meter needle. I cleaned mine with a small paint brush dipped in alcohol. Be careful not to bend the electrical pick ups that rub on the ring. When these meters get jumpy or stop working it is usually because the ring is dirty.
Link to comment
Share on other sites

Some come with a wedge, which is a sure recipe for slippage and screw damage.

 

In my time as a watchmaker, I've spent a LOT of time shaping/"sharpening" screwdriver blades. Learning how to maintain your screwdrivers(your second most important tool next to tweezers) is a fundamental aspect of learning watch repair. Understanding the interaction between the blade and the slot is equally important for maximizing torque, avoiding damage to the screw head, and the all important avoiding slipping.

 

In many cases, you have to custom-tailor your blade to the screw. My screwdrivers are normally sharpened to "American" shapes, which fit 95% of American watches quite well. I have another set of Bergeons stuck back in the bench that I "Swiss sharpened" and will fit most Swiss watches well(the slot depths are different, and I often have to alter my "Swiss" drivers a bit).

 

In any case, I know one watchmaker who was trained at Bulova and sharpens/uses a hollow grind on her blades. Everyone else I know, and all the textbooks, default to a wedge grind. I know watchmakers trained at some of the old factory schools, including Hamilton and Elgin, as well as some trained by other reputable schools. The current SAWTA curriculum(Rolex developed and sponsored) as taught at the big American schools like Lititz Watch Technicum still teaches wedge grinding. In addition, new drivers/replacement blades from Bergeon and Horotec come wedge ground.

 

IF the blade is properly shaped such that it imperceptibly close to the bottom of the slot without touching, the blade will not slip and the driver will not mar the slot. It goes without saying that the blade width should match the slot exactly.

 

In a sense, hollow grinding is a bit more "idiot proof" but also more difficult to get correct. I'll stick with wedge grinding for my own screwdrivers.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...