Stuck screw…

[tmac1956]

All:

I’m attempting to disassemble an Elgin 16s pocket watch and have encountered a stuborn crown wheel screw. Using a small gauge diabeteic needle, I’ve enjected the area around the screw head with Liquid Wrench penetrating oil. So far (after 24 hours), it’s still stuck and I fear that if I put much more pressure on the thing, I might shear it off. Any suggestions?

Thanks!
tmac

[tmac1956]

Well…. the worst happened and I wrung off the head of the transmission gear screw. Now the question becomes… how do I get the screw shaft out without damaging the threaded hole? Has anyone had luck with using acid such as Bergeon 4503/50 Extract Liquid For Removing Watch Screws?

Thanks!
Tom

[arutha]

It may take a while but pure lemon juice will dissolve steel and not touch the brass. You only have to wait for it to dissolve the screw enough to be ablte to un-do it. Hopefully someone else will have some advice too.

[gerene]

Or maybe this stuf can help:

http://www.jewelerssupplies.com/product9493.html

I never tried it myself, but I came across it lately. It certainly is more expensive than lemon juice

P.S. If you try it, or someone else has, please let me know if it works

Jan

[tmac1956]

All:

I’ll go buy some lemons today and give that a try first. If that doesn’t work I’ll try the CasKerCo stuff. It’s much cheaper than the Bergeon product (naturally). I’ve also looked into screw extractor tools. I found some at Amazon that might work, but they appear to be cheaply made and cost about $20.00. I also found some from an EU supplier that would probably last the rest of my life, but by the time you include shipping, they’re over 50.00 US dollars. Besides, the chemical solution looks like the best way to go.

Thanks eveyone!
tmac

[randy]

If you cannot get the screw out by conventional means then I would recommend soaking the bridge in a solution of alum (aluminum sulfate – available at any grocery store). Leave it overnight and the steel screw will be dissolved due to electrolytic action. If you want to speed up the process you can heat the solution (simmer). This will not harm the brass bridge or its nickel plating.
This is from JimH on the Timezone website, and I’ve seen many others who’ve used it with success.
Look for alum in the shaving section..it’s the old-school way to stop razor nicks.

For the future , there are two products that you can get at auto parts stores.

Evaporust- non toxic, really cool stuff that dissolves rust off of almost anything, without eating most finishes.
You might try it with an old movement plate to be sure,..but I used it on some plated tools last week and it worked great.

‘PB Blaster”” is known amongst the auto crowd as a great lubricant, and a much better rust releaser than Liquid wrench.

Hope one of these helps Tmac

Randy

[tmac1956]

@Randy wrote:

If you cannot get the screw out by conventional means then I would recommend soaking the bridge in a solution of alum (aluminum sulfate – available at any grocery store). Leave it overnight and the steel screw will be dissolved due to electrolytic action. If you want to speed up the process you can heat the solution (simmer). This will not harm the brass bridge or its nickel plating.
This is from JimH on the Timezone website, and I’ve seen many others who’ve used it with success.
Look for alum in the shaving section..it’s the old-school way to stop razor nicks.

For the future , there are two products that you can get at auto parts stores.

Evaporust- non toxic, really cool stuff that dissolves rust off of almost anything, without eating most finishes.
You might try it with an old movement plate to be sure,..but I used it on some plated tools last week and it worked great.

‘PB Blaster”” is known amongst the auto crowd as a great lubricant, and a much better rust releaser than Liquid wrench.

Hope one of these helps Tmac

Randy

Randy:

I’ve got an old bottle of “stipple” used to stop shaving bleeds. I’ll bet that’s alum. I just need to make surre that I remove any other screws before I begin.

Thanks!
tmac

[tmac1956]

Well… I’m soaking it now. I’ll let ya’ll know how it works (nevermind the sophisticated rigging).

Thanks!
Tom

[randy]

Good Luck Tom…we’re all pulling for you !

Randy

BTW…I think your rigging job is just fine..

[arutha]

Good luck, and the rigging is perfect if it does the job

[peterclare]

This is a bit late, and may be stating the obvious, but when you were removing the crown screw were you unscrewing the correct direction?

Crown wheel screws on Elgins (and others) are reverse threaded, generally. I only mention it as I tend to forget occasionally and wonder why they are such a bugger – until I remember…

Regards

Peter in Oz.

[tmac1956]

Peter:

Hmmm…

That might explain things. However, I thought left hand threads were marked thusly with two/three grooves. I guess not.

Well the good news is that the solution disolved the screw. On the down side, it also etched the plate. All of this is ok, as its just a learning piece anyway. Now if I can succesfully replace the cracked pallet fork foot jewel I’ll count this as a successful learning experience.

Thanks!
Tom

[randy]

It might be worth another experiment, as the product you used may have had other chemicals mixed in. Not uncommon in some of the styptic pencils.
You can buy pure alum in bars pretty cheap.
I’ve haven’t seen where others have had etching problems,..that’s what’s got me thinking about your experience.

Randy

[Bob Tascione]

Hi Tom,
Sorry to hear about the broken screw. Peter is correct about most crown wheel screws being left handed and you are also correct about screws with 3 grooves being left handed. Problem is that most left handed screws don’t have these grooves. So when you see these grooves you don’t have to guess whether it’s left or right handed and if you don’t see them well…. One way to check when in doubt (if it’s not a blind hole) is to remove the bridge and take a look at the leading edge of the screw thread from the underside with high mag.
To avoid etching or blemishing I usually use a fairly diluted alum/water (about 6 pts. water to 1 pt. alum) solution to help avoid any etching or discoloring. Usually have great luck and bridges come out with no blemish at all but I still like to test a little on the underside of the plate or bridge before soaking. I usually submerge the entire bridge so that no line is left across the surface in case the solution runs. Just in case.

If it helps any…don’t feel too bad Tom. I’ve snapped my fair share of screw heads off over the years.

Bob

Edit: Hey Randy…I just read your post. You must have posted while I was writing this one. Yes I agree with what you said about alum not etching the finish. I haven’t tried the bars so can’t comment on that but the powder works great.

[tmac1956]

Bob:

Thanks for the specific recommendations. I suspect that the alum that I used might have had other chemicals mixed in with it as Randy suggested. The bottle came from an old barbershop and is probably 75 years old – it’s just what I had on hand.

On a different point, I could sure use some advise on these plate jewels as I’ve run into this several times and I wind up having to ream out the hole and then try to find a bigger jewel with which to replace it. Then I have end shake issues. I do have a pretty decent staking set with the jeweling attachments, but I still have problems actually understanding what I’m doing with this. So far, these friction fit factory jewels have been the most dificult thing I’ve faced.

I’ve read that you can (or could at one time) buy jewel sets with sizes indicated in 1/100 mm that match the reamer sizes in the jeweling set, but I don’t know where one can buy these.

If anything is discouaging me, it’s this issue. Any suggestions here would be greatly appreciated.

Thanks!
Tom

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