[AstroDave]

I'm going into my *istD, headed for the sensor so I can de-Bayer it and turn it into a black & white camera (using these great instructions: https://sites.google.com/site/vincenzomiceli/pentax--ist-d-ir-mod; I'm down to step 8 - removing the back plate).

Unfortunately, one of the little screws is seized (stuck - I can't turn it). There is (very) minor corrosion here and there in the camera, so I am suspicious that there may be a little rusting of the threads.

I have applied about as much torque as I dare (with proper JIS screwdrivers). Done some rapping and tapping, trying to jar it loose, and applied a little bit of Kroil (Penetrating-Lubricating Oils). It's still stuck after sitting overnight.

I'll give it another day or two for the Kroil to penetrate (my wife says I have to get the card table I'm working on out of the living room one of these days!) and try again.

I'm prepared to apply additional torque (put a wrench on the screwdriver), to the point of possibly destroying the screw head. I can then drill it out if I have to. I can probably find a replacement screw from the collection I've accumulated from various camera and lens disassemblies.

Before I get that vicious though, any other ideas on what to do from the assembled Forum wisdom? What about a heat gun? JB Weld to attach a substitute screwdriver?

THANKS!

[MikeMcE]

Use a soldering iron to heat the penetrant oil. Tapping and turning are the only other options I know .


Hang up and DRIVE!

[ramseybuckeye]

I was thinking heat also, but it is probably not an area you want to heat.

I think you are doing the best you can, a little penetrant, some time, a little tapping. Walk away a while so you don't get too frustrated. Possibly a vise grip or something on the driver for more torque, if you think the screw can handle it.

Way more drastic may be to super glue the screw diver to the screw head and then use a vise grip on the driver. Problem is then you would need a solvent to separate the driver from the screw, but a more likely outcome would be you'd break the screw.

How small of a drill bit and thread tap do you have?

[ProfessorBuzz]

The screw might be in there with loc-tite or equivalent. Heat a bit might help. I'd be wary of solvents or penetrating oil.

[c.a.m]

These small seized screws are a real challenge, to say the least.

In my experience, I've broken a couple of miniature screws while attempting to remove them -- the heads sheared off when I applied excessive torque. In one case, I attacked the seized screw with a JIS driver and a mini Vise-Grip. In another instance, I had to drill out a couple of screws on a lens mount (Pentax-M lenses are notorious for tight screws on the mount). I ended up drilling out the screw heads but consequently enlarged the tapered screw holes on the mount -- the mount was damaged beyond repair so the non-exotic lens is now for parts.

If the head shears, it's a difficult-to-impossible job to drill out just the shaft or remove it with a micro extractor. If such a job is successful, re-tapping the hole might be necessary.

I would recommend two approaches:

- Continue with small amounts of Kroil for a few more days as you suggested. Patience is the key. (Beg forgiveness for occupying the living room and the tapping sound? )

- Apply heat to the screw head with a low-wattage soldering iron and pencil tip, if it seems reasonably safe at the subject location on the camera. Of course, watch out for non-metallic sections nearby.

- Craig

[AstroDave]

I will try the heat schemes first. Thanks MikeMcE, ProfBuzz, and Ramseye

Possibly a vise grip or something on the driver for more torque, if you think the screw can handle it.

That's in my plan - I've got all sorts of vise grips, not sure what will happen to the screw, though!

Way more drastic may be to super glue the screw diver to the screw head and then use a vise grip on the driver. Problem is then you would need a solvent to separate the driver from the screw, but a more likely outcome would be you'd break the screw.

That's my JB Weld scheme - I don't think superglue will come even close to holding tight enough.

How small of a drill bit and thread tap do you have?

I've got 1/16" drills - I think that will be small enough to not damage the threads, but I'll check. I can get smaller, if I have to. No taps that small! 4-40 is my smallest.

---------- Post added 10-15-20 at 08:28 AM ----------

These small seized screws are a real challenge, to say the least.

I would recommend two approaches:

- Continue with small amounts of Kroil for a few more days as you suggested. Patience is the key. (Beg forgiveness for occupying the living room and the tapping sound? )

- Apply heat to the screw head with a low-wattage soldering iron and pencil tip, if it seems reasonably safe at the subject location on the camera. Of course, watch out for non-metallic sections nearby.

- Craig

Thanks for describing your experience!

I just fixed her mixer and found a missing needle (before the dog did!) - so I have a few day's grace.

I hope all good things come to those who wait. I've got lots of other projects to keep me busy.

[MikeMcE]

Old bench trick is a bicycle inner tube.
Use a length wrapped around the driver body to increase diameter, leverage and grip. I would do this before a vice grip. Many of the screws are sealed with anaerobic liquid on assembly.So Modest amount of heat always helps.




Hang up and DRIVE!

[swanlefitte]

There are left handed drill bits. If you can get it to bite into the screw it will extract the screw before drilling in. Just read about this the other day.

[Not a Number]

There are left handed drill bits. If you can get it to bite into the screw it will extract the screw before drilling in. Just read about this the other day.

Screw extractors - reverse thread tungsten carbide tapered drill bits. You can buy a set or single micro extractors made by companies like Moody Tools.

Central Tools | Search results for: screw extractor

[Viking42]

I'm going into my *istD, headed for the sensor so I can de-Bayer it and turn it into a black & white camera (using these great instructions: https://sites.google.com/site/vincenzomiceli/pentax--ist-d-ir-mod; I'm down to step 8 - removing the back plate).

Unfortunately, one of the little screws is seized (stuck - I can't turn it). There is (very) minor corrosion here and there in the camera, so I am suspicious that there may be a little rusting of the threads.

I have applied about as much torque as I dare (with proper JIS screwdrivers). Done some rapping and tapping, trying to jar it loose, and applied a little bit of Kroil (Penetrating-Lubricating Oils). It's still stuck after sitting overnight.

I'll give it another day or two for the Kroil to penetrate (my wife says I have to get the card table I'm working on out of the living room one of these days!) and try again.

I'm prepared to apply additional torque (put a wrench on the screwdriver), to the point of possibly destroying the screw head. I can then drill it out if I have to. I can probably find a replacement screw from the collection I've accumulated from various camera and lens disassemblies.

Before I get that vicious though, any other ideas on what to do from the assembled Forum wisdom? What about a heat gun? JB Weld to attach a substitute screwdriver?

THANKS!

Dave,
I have used this stuff with success: https://www.amazon.com/MADE-USA-EXTRACTOR-Tightens-Stripped/dp/B08FWKNG52/re...MD4S7ZD85FD9BC

It works by greatly increasing the friction between driver head and screw, preventing slipping and subsequent stripping. It really does work, even on screws I thought were a lost cause because they were so stripped. That said, I've never tried it on a tiny screw like you describe. It seems to be basically fine grit in a gel medium, so I suppose you could try to mix up some of your own using very fine sand blended with, say, gel toothpaste or something similar. Worth a try before you take more drastic measures.

Hope you get it out...

Svend

[c.a.m]

I have used this stuff with success [...]

Good suggestion about making your own gritty compound. Worth a try. Perhaps very fine metal filings might work.

I have also used Screw Grab with success, but only on larger screw heads. I found that its particles are too large for very small screw heads; the grit is not fine enough. At the time, I didn't think of grinding the compound further, so your post has prompted that idea for any future jobs.

In any case, if the screw is really seized, too much torque on the driver could shear the head, especially if the driver is grabbing well with solid purchase.

- Craig

[Viking42]

Good suggestion about making your own gritty compound. Worth a try. Perhaps very fine metal filings might work.

I have also used Screw Grab with success, but only on larger screw heads. I found that its particles are too large for very small screw heads; the grit is not fine enough. At the time, I didn't think of grinding the compound further, so your post has prompted that idea for any future jobs.

In any case, if the screw is really seized, too much torque on the driver could shear the head, especially if the driver is grabbing well with solid purchase.

- Craig

Some good points there Craig. I just walked over to the workshop and rubbed some of the Screw Grab stuff between my fingers, and indeed the grit is quite large so I don't think it would work on a tiny screw. But I like the idea of mixing some metal filings in gel. Or try scraping some grit off of a fine sandpaper sheet with a razor blade - just a tiny bit is all you need. The thing is to prevent the screwdriver from slipping, which is what strips most screw heads.

I think using a penetrant like Kroil, letting it soak in for a few days, then cleaning the screw head with a solvent to get the oil off, following by a drop of grit-in-gel and gentle force on the screwdriver might just do the job. As said, too much force and the head will break off.

[AstroDave]

GOT IT OUT!

Some combination of time, heat, Kroil, and a lot of torque (and maybe phase of the moon - it's new in a couple of days!?) worked. I used pliers to grab the screwdriver, which fortunately did have a very good grab. The screw was very tight until the last half turn or so. It does not appear to be damaged (other than some, actually very slight given how hard I was cranking it, marring of the head). I was wondering if it might have originally been cross-threaded somehow, but that doesn't seem to be the case. I'm not sure whether I will reinstall it when I put the camera back together.

Thanks to all for suggestions. I think the heat may have been a big help. I had my soldering iron on it a couple of times (until the Kroil started to smoke!).

Viking42: I may give the ScrewGrab solution a try for a similar problem - I can't get out the bolts that hold the blades in my jointer - they've been Kroil-ed, but not heated. I'll try some heat, too (soldering GUN for those). I have already tried screw extractors on them. They are about size 10 or 12, so I'm not worried about how much torque they will take!!

[MikeMcE]

Excellent news!


Hang up and DRIVE!

[Viking42]

Great to hear that Dave. I think you could safely put the screw back in if you put a tiny dab of a thin synthetic grease on the threads to prevent siezing again. E.g. I do that on all bolts and fasteners on all our mountain and road bikes, and even the oldest ones after 10 years of rain, mud, grit and wash water I've never had a siezed thread.

BTW, I'm intrigued by your monochrome camera conversion. I will take the time soon to read through your link soon. Thanks for posting that!