Save or scrap?

[mcass]

Well I barely got started disassembling a Hampden 17 jewel movement when the head twisted right off of the transmission gear screw! So I guess my first question can the threaded shaft of the screw be removed, and the screw replaced? If yes, how and with what can it be removed? If no, do I just scrap the whole damn thing? Are parts worth saving for possible future projects?

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[matabog]

You can put the bridge in a nice solution to eat away the thread left in it. It's called ALUM, or something like that.

I can't wait for someone to tell us what it is.

 

Bogdan

[mcass]

You can put the bridge in a nice solution to eat away the thread left in it. It's called ALUM, or something like that.

I can't wait for someone to tell us what it is.

 

Bogdan

Interesting! I hope to hear more input too!


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[mcass]

38 minutes ago, matabog said:

You can put the bridge in a nice solution to eat away the thread left in it. It's called ALUM, or something like that.

I can't wait for someone to tell us what it is.

 

Bogdan

 

That said, I have used tea to restore parts with rust which I think is based on exactly what your talking about now that I am thinking about it. I don't know though whether that would be strong enough to remove the threaded stud or nut.

 

[anilv]

HI mcass,

Try to use a sharp pick and reverse the screw out, you could even try to screw it in deeper and out thru the back but the watch will need to be dismantled for this.. at the very least the barrel bridge needs to come off.

You ARE aware that this particular screw is usually a left-handed thread right? If you weren't, its not surprising you screwed its head off!

Anilv

 

[anilv]

Tea will remove the oxides but leave the metal intact.. at least for the short term(days).. not sure what the effect is for the long term.

This is a good solution to rust of very delicate parts which would not tolerate other means..eg sanding, grinding.

 

Anilv

 

[mcass]

HI mcass,

Try to use a sharp pick and reverse the screw out, you could even try to screw it in deeper and out thru the back but the watch will need to be dismantled for this.. at the very least the barrel bridge needs to come off.

You ARE aware that this particular screw is usually a left-handed thread right? If you weren't, its not surprising you screwed its head off!

Anilv

 

Damn! I do know that but honestly didn't even think about it! Didn't even think about it afterwards either. That explains it though. It didn't even take any force either otherwise I may have.


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[anilv]

Yeah.. left handed screws are usually marked with three lines but some don't.

My pet peeve is Citizen, on some manual watches even the ratchet wheel is attached to the barrel arbor with a left hand thread (WTH Citizen). While they usually do mark them with three lines there are a few which Citizen did not see fit to indicate as such (for god knows why!). Knowing this it still caught me out a few months back...result-broken screw.

Additionally, this makes winding the watch on the bench difficult as the arbor screw will start to unwind before you get close to halfway. You either need to get the winding stuff back in first or jam the ratchet wheel with pegwood.

Anilv

[sperki77]

I believe my dad used to use alum for this, but I don't know the process.  Don't scrap the watch!!!  It is a problem with a solution.  I'll see if I can find more information on this.

Shirley

[sperki77]

Okay, try this link and see if it will work for you:

http://mb.nawcc.org/showthread.php?51819-Broken-screw-removal-ideas

[mcass]

Thanks for the ideas! I'll give it a shot!

I've got another question off topic. After setting that one aside I decided to work on a 1944 Bulova Senator. How are the crystals affixed to the case on old tanks?


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[IllinoisWatch]

That movement is an ST (standard) 1686?  I have about 10 of them in my movement drawer in various "brands". its an ebache movement. you can buy them cheap on ebay, or Dashto.com

[IllinoisWatch]

47 minutes ago, mcass said:

Thanks for the ideas! I'll give it a shot!

I've got another question off topic. After setting that one aside I decided to work on a 1944 Bulova Senator. How are the crystals affixed to the case on old tanks?


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I have that same watch "senator" I'm sure the crystal is just glued in, I need to order a new one for mine, and get it cleaned and ready to sell. GS should have the crystal

[clockboy]

There are a few methods of removing the screw end but I must say the Alum trick has not worked for me. I have used this tool once but it did work a treat (Bergeon 30209). As you become familiar with watch repair breaking screws is a rare occurrence because you just don't over tighten & became familiar with what screws are left hand threads. A good tip when tightening is once the screw bites just tighten further by it the width of the screw head slot.

 

[Marc]

10 hours ago, matabog said:

You can put the bridge in a nice solution to eat away the thread left in it. It's called ALUM, or something like that.

I can't wait for someone to tell us what it is.

 

Bogdan

The alum that is generally available is hydrated potassium aluminium sulfate (KAl(SO₄)₂·12H₂O), or potash alum, and it is one of those wonder compounds that has many uses including;

• post shaving treatment for skin
• deodorant
• fire retardant
• leather tanning
• water purification
• pickling
• dissolving the broken steel threads out of brass watch plates/bridges
• etc

 

Alum also refers to a family of compounds though, all useful stuff but the one you want and which is easiest to get hold of is potash alum.

you need to make sure that there are no other steel components in the plate in addition to those that you want to dissolve, and you need also to use a concentrated solution of the stuff. It also helps if it is warm. Other than that you need a little patience as the process usually takes several hours and can take days. Occasional agitation also helps, and I would imagine that the use of an ultrasonic bath may also be beneficial.

I have the Bergeon extractor referenced by CB and it is a handy bit of kit to have but it is rather pricey (what else?? after all it has "Bergeon" stamped on it). I was fortunate to find mine at a car boot sale, albeit minus the actual pins, but then it only cost me £1 complete with a rather nice canon pinion tightener so I'm not complaining, and I made my own pins on the lathe.  It does only works if the broken screw is in a hole open at both ends though. If it is in a blind hole then it can't be used.

[RyMoeller]

I've used alum a couple of times- once to remove a broken screw and another time to remove a broken stem from a crown.  Works quite well provided you are trying to remove carbon steel.  It seems to me the real key to success was the temperature of the solution- the warmer the better.

[mcass]

I have that same watch "senator" I'm sure the crystal is just glued in, I need to order a new one for mine, and get it cleaned and ready to sell. GS should have the crystal

I still have the Crystal and it's in good shape. As I was polishing The case the Crystal popped off. I just wasn't real sure how to reattach it. This is the first tank I've done.


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[JohnR725]

19 hours ago, matabog said:

You can put the bridge in a nice solution to eat away the thread left in it. It's called ALUM, or something like that.

I can't wait for someone to tell us what it is.

 

Bogdan

If you do a search for Alum is come up several times in the past. I have a link below where someone was requesting where to purchase it.

http://www.watchrepairtalk.com/topic/4870-need-alume/

 

 

 

[ro63rto]

Is this the right stuff?

[Marc]

That should do it.

[RyMoeller]

18 hours ago, ro63rto said:

Is this the right stuff?

I've got a bag like that in my desk drawer too.

My tried and true method:

1. Dissolve about a half teaspoon in a shot glass of water (water will become a bit cloudy)
2. Fill rice cooker with about 1 inch of water and set to warm
3. Place plate (stripped of steel) in glass
4. Set glass in center of rice cooker bath
5. Check in 12 hours or so

The steel you're attempting to extract should turn black and crumbly and you'll be able to work it out of the plate with a sharp bit of pegwood or an old oiler.  It may take more than one bath in the Alum depending on the strength of the solution, temperature, and the surface area of the steel.

[JohnR725]

4 hours ago, RyMoeller said:

My tried and true method:

1. Dissolve about a half teaspoon in a shot glass of water (water will become a bit cloudy)
2. Fill rice cooker with about 1 inch of water and set to warm
3. Place plate (stripped of steel) in glass
4. Set glass in center of rice cooker bath
5. Check in 12 hours or so

To speed up the process increase the concentration and heat. So the method above is basically a double boiler method. I used a pot on the kitchen stove with a Pyrex measuring cup. That I'd heated to a very low boil but you have to keep remembering to add water two both as it of evaporates.

[Paul78]

I tried Alum, I had a watch case with 2 screw snapped in it, left it in the alum solution for about 4 days and it did absolutely nothing. I also had an Omega movement with a setting lever screw with the head rounded which would not budge, this time i bought the very expensive Bergeon tool which has already been mentioned - i found this to be a complete waste of time too! maybe i wasn't using it right, i don't know. I ended up drilling it out! 

[JohnR725]

4 hours ago, Paul78 said:

I tried Alum, I had a watch case with 2 screw snapped in it, left it in the alum solution for about 4 days and it did absolutely nothing. I also had an Omega movement with a setting lever screw with the head rounded which would not budge, this time i bought the very expensive Bergeon tool which has already been mentioned - i found this to be a complete waste of time too! maybe i wasn't using it right, i don't know. I ended up drilling it out! 

I suspect the problem you're having is that the solution really should be hot.

[clockboy]

I think the Alum trick only works with certain metals. I must have been lucky because I have  only had to use the Bergeon tool once & it worked a treat.