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Broken Stem Inside Crown...


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26 minutes ago, jimtone said:

How much alum to how much distilled water? I've seen this advice for dissolving a stem but never a mixture calibration?

No precise mixture is necessary, you can use at saturation.

By the way, we have a section here where most members like to introduce themselves even before asking questions.

 

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  • 4 weeks later...

Thanks, I'll try to find that introduction section. I've soaked the crown (stainless) in alum for 2 weeks with no effect. I've soaked the crown in pure vinegar for 3 weeks with no effect? I really don't want to soak the stem that is in the movement but think that's the only way to know if it is indestructible. 

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1 hour ago, jimtone said:

Thanks, I'll try to find that introduction section. I've soaked the crown (stainless) in alum for 2 weeks with no effect. I've soaked the crown in pure vinegar for 3 weeks with no effect? I really don't want to soak the stem that is in the movement but think that's the only way to know if it is indestructible. 

 Maybe it's a better quality steel in the stem then many old stems. I have done it on several crown. But not all stems rust. Sometimes you have to bite the bullet and buy a new crown. If you can find one? Not the easiest to find for some watches. 

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On 7/31/2018 at 7:53 PM, jimtone said:

Thanks, I'll try to find that introduction section. I've soaked the crown (stainless) in alum for 2 weeks with no effect. I've soaked the crown in pure vinegar for 3 weeks with no effect? I really don't want to soak the stem that is in the movement but think that's the only way to know if it is indestructible. 

If you are UK-based then I can suggest another acid to try.

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  • 6 months later...

is it possible that my stem is stainless?  This is not working at all for me.  i even put a stem extender in to see if it would work but there is no bubbles or anything happening at all.  I used plenty of the Alum and a small amount of water and heated it up and nothing.  any advice?

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I have the same issue.  no amount of soaking seems to dissolve the stem.  No bubbles at all.  Very dissapointed.  I was really pumped when i saw you can use alum to do this and it's not working for my newer watch.  and its going to cost a lot for a new crown.  so far i can't even find one that will match and the manufacturer has been no help.  

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I don't know if such a thing exists, this small, but if attempting to remove broken studs at a slightly larger scale, a left handed twist drill can be a help.

The idea is to use the drilling action to grab the stud as you drill, and when it grabs, it unscrews it.

However, as I said, I'm not sure where you would get a left handed drill bit small enough to attempt this.

I may have just suggested replacing one intractable problem with an equally intractable one, namely finding such a bit. If anybody knows where to source a left handed bit, then we may have a potential solution. 

EDIT: https://www.ebay.co.uk/itm/GUHRING-HSCO-1-0mm-MICRO-PRECISION-DRILL-WATCH-MAKING-QUALITY-LEFT-HAND-LH-301-1/222408832193?hash=item33c89974c1:g:zAAAAOSwtfhYqIzd

EDIT: These things do exist, so first you will need to figure out what size you need.

Next you will need to figure out if they are worth the expense.

Finally you will need to figure out if you can drill that precisely and with sufficient control not to wreck the bit.

You will also need to kill any thread locker, but that has been covered above.

Edited by AndyHull
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The process I described, along with a few other broken stud removal techniques can be seen here.

https://dannysengineportal.com/broken-bolt-and-stud-removing-tips/

 

Some of these will only work at the macro rather than micro level though. I'm pretty sure they don't make helicoils that small, but I guess you might be able to fabricate something similar.

Edited by AndyHull
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One other trick. Get a very sharp screwdriver bit, the same width as the stud. Tappy-tap-tap it in to the end of the stud, till you have a slot. Now tap the head of the screwdriver, and turn at the same time (this is roughly how an impact driver works).

Don't simply try to turn the screwdriver, cos you will simply strip off the end of the stud. You need to tap down as you turn.

Needless to say, the crown needs to be well anchored while you do this. Protect the ornamental end of the crown against being marred as you whack the end of the stud. Similarly, protect the ridges on the crown against whatever you are gripping it with. Don't crush the crown while gripping it. It would be a shame to ruin the crown while attempting to extract the stud.

The screwdriver bit needs to be really sharp, wear safety goggles, cos there is a pretty good chance you will end up breaking the screwdriver bit (hardened steel is not very happy about being whacked). You also stand a good chance of sending the crown flying, and getting hit in the eye by bits of shrapnel is never fun.

Edited by AndyHull
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  • 1 year later...

Hi folks

I've not been on in a while but, got fed up with hoovering and cleaning everything in sight so I decided to find something to fill my time in while we wait to get our lives back.  I bought this Citizen Eco-Drive, it was partly dismantled but seems to be ok. It was missing the stem and crown, hopefully the ones I have ordered from Cousins should be correct, fingers crossed. I have a crown from another with similar case but the stem is snapped off. Am I overly optimistic or is there any chance of ever getting the broken piece out of the crown, it has broken off flush? 

Many thanks

DaveIMG_0332.thumb.jpg.db6cce4d1e19223bd938499d42363c5d.jpgIMG_0333.thumb.jpg.a0351425ffa72e1ec937879a5c897d04.jpgIMG_0335.thumb.jpg.8c523865b49c28ee046f0dc68d09fdef.jpgIMG_0336.thumb.jpg.fabec8da536ede5749f3efe34cb9dc5c.jpg

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Hi   The usual method of removing broken stubs in crowns  is to soak them in Alum (warm) which dissolves steel and leaves the brass intact, from your picture it looks as if the stem is screwed into a steel shaft fitted to the actual crown, so I dont think that method would work,  One could use a screw extractor  which cuts left handed into the screw therfore turning the screw out , the problem being there maybe thread lock or lock tite on the stem .  Heating the stem core will destroy any gaskets in the crown.  Best bet is a new stem and crown        

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usually it's best if you can dissolve it out but?

I don't suppose you give us a picture of what the crown and stem are supposed to look like?

when I started to do the answer I stopped it but because I agreed it look like dissolving would be bad except? Look at the picture carefully we seem to be missing the square? We still have the rest of the stem there I think so that should unscrew. This is where having a picture of the crown and stem separate would be helpful. But otherwise I think you can just unscrew that part that sticking out.

Otherwise there is another way just not on this crown. On a lot of these the brass tube extend considerably out away from the crown. If you're really careful with a watchmaker's lathe you can trim the tube down just a little bit then grab what's left of the stem sticking out and unscrew it usually with a helping of penetrating oil helps.

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Its difficult to say but looking at your pics there might be just enough of the stem left for it to be twisted out with fine pliers or a pin vice. I don't think the Alum trick will work. If it was me and it was not possible to twist out I would file level and drill with a fine drill and then force a larger drill into the hole created and twist out. You might have to add heat because some stems are fitted with loctite. 

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Thanks all for the suggestions. I think the bit that sticks out is actually part of the crown. I have heated it with the tip of a soldering iron and soaked it in acetone, there is not much to get a purchase on. When the new crown and stem arrive I can compare them, I'll post a picture of the new parts. A new crown was only 4 quid to be honest, so not really worth the faff of getting the broken bit out I suppose, but it would still be satisfying. I think fine drills would be the way to go.

Edited by Davey57
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I personally use winegar bath for broken stems in crowns. It takes at least 2-4 days and transforms to black mud. You can check the process works when its bubbling around the stem while waiting to dissolve. Heating up the winegar accelerates the process. 

Edited by Khan
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usually it's best if you can dissolve it out but?
I don't suppose you give us a picture of what the crown and stem are supposed to look like?
when I started to do the answer I stopped it but because I agreed it look like dissolving would be bad except? Look at the picture carefully we seem to be missing the square? We still have the rest of the stem there I think so that should unscrew. This is where having a picture of the crown and stem separate would be helpful. But otherwise I think you can just unscrew that part that sticking out.
Otherwise there is another way just not on this crown. On a lot of these the brass tube extend considerably out away from the crown. If you're really careful with a watchmaker's lathe you can trim the tube down just a little bit then grab what's left of the stem sticking out and unscrew it usually with a helping of penetrating oil helps.

Now that is a good plan. Or drill it out with a very fine bit

Sent from my GT-N5110 using Tapatalk

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Just to satisfy your curiosity, here’s a picture of the new crown.  The one I showed has snapped off flush. Going to try the vinegar on the old one, cheaper than buying a lathe:lol:

Thanks again for all the replies.56EDEF9E-939A-4BD7-8AAC-539F58A25187.thumb.jpeg.09fe9cef5709b5bfc74ea92cf9255dcb.jpeg

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  • 1 month later...

Hello everyone,

Due to some clumsiness, I've broken two stems off in two different Seiko crowns. I've performed a search of the site, and the best methods to salvage the crown seem to be either dissolving the stuck portion of the stem in the crown or using a screw extractor.

Someone please correct me if I'm wrong, but I feel like the acid methodology only works where the material one is intending to dissolve is different from the material one is intending to save? These are Seiko stainless steel crowns I'm trying to save, and I don't know what the material the broken stem is made of. Even if the acid method were to work, I'd need to remove the rubber gaskets from the crown in advance. This feels quite daunting to me. The attractive part of this methodology is its price: Esslinger.com sells Bergeon Vissin Liquid For Extracting Broken Watch Screws Bergeon 4503 for $17.95.

I'm more inclined to try a screw extractor. This method is pricier, but appears to me to be safer for the crown. I'm eyeing the Horofix Aluminum Screwdriver Screw Extractor at $59.95, as the Bergeon tool is significantly more expensive. I believe the 0.40mm blade provided with the Horofix kit will do the trick.

The easy and cheap way to remedy my problem is to (a) stop stupidly breaking stems off in crowns; and (b) take advantage of the readily available supply of Seiko crowns and stems on the market. The problem here is shipping time, with ~30 day waits for a part.

I'd appreciate any advice or insights here. I know that the easy and correct method here is probably just buying a new crown and stem, but I'd like to improve my skills and salvage the two crowns I've broken stems off inside.

Cheers,

Dan

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Hi Dan,

just a few weeks ago, I was faced with exactly the same problem: broken stem for a Seiko 7S36-03J0 case (a Seiko 5 watch).
I also had to get rid of the broken off part sitting in the crown.

For me, the alum procedure worked out perfectly: mix alum-powder in water, keep warm, drop the crown in the liquid and see the stem dissolve...
The process took a few days but worked out perfectly without doing any harm to the crown.

Upfront, I asked myself the same question about the different materials you mentioned, but decided just to give it a try (it‘s not an omega-crown...)

Cost: around 4 bucks for the alum-powder and a bit of patience.

I agree, still to be managed is the task of removing the o-ring from the stem and putting it back on afterwards.

I‘m just a hobbyist, so the pros around here might give more details or additional information.

Hope this might help a little bit.

KR
Thorsten

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Wonderful, thank you for the tips Thoast and Nucejoe. I'm feeling much better about the alum treatment if I can readily slip a new rubber gasket on the crown.

Cheers,

Dan

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