Broken Stem Inside Crown...

[DJW]

I received this watch from a friend to see if I could repair it for him.

The stem was broken at the narrowest point where the set lever rides. I ordered a stem and tried to remove the broken portion left inside the crown. Not paying attention to the amount of force I was using to unscrew the broken stem, I snapped the stem off farther inside the crown. Now I have nothing to "Grab" onto so that I can remove it.

The movement is a Chinese copy of the Venus 175 chronograph movement set inside a replica Panerai watch. I would normally not even touch such a watch as the build quality is usually total junk! But, now I need to remove the stem somehow and replacement parts (crown) are obviously not a possibility.

I though about drilling it out but that would most-likely lead to damaged threads I fear!

 

Any other ideas on how to proceed?

 

 

[Rob]

Put it in a jar of alum for a couple of days. It will dissolve steel. See this thread for details. 

[Geo]

Now that's interesting. If the crown is stainless steel it should do the job OK, but if it is plated brass it might be a disaster.........but I don't know.

I feel an experiment coming on!

Great suggestion by the way. :-)

[DJW]

Put it in a jar of alum for a couple of days. It will dissolve steel. See this thread for details. 

Yep! This looks like a winner! I was also questioning about the effect this would have on the crown as well. But, the crown is stainless steel so  hopefully it will work....we'll see!

[Geo]

Yep! This looks like a winner! I was also questioning about the effect this would have on the crown as well. But, the crown is stainless steel so  hopefully it will work....we'll see!

Remember to let us know how it goes!

[DJW]

OK-After only about 18 hours in the Alum solution (Alum/Water) there is a noticeable difference in the stem. It appears to be dissolving for the inside out. From the looks of it, and comparing the before and after photos, the stem has dissolved down into the crown about 2-3 threads. I actually was able to pull a piece of stem thread out of the crown with my tweezers. You'll notice it sitting next to the crown in the second shot. 

 

Before pic

 

After Pic

 

I'll post updates on the progress!

[DJW]

Well, it does Work! (thanks Rob for the tip!) After less than 3 days the stem is totally dissolved! There was a bit of black grit in the tube, but after a quick ultrasonic bath, the crown has no signs of the broken stem inside!

The only noticeable affect on the crown is a slight darkening/staining of the surface. I'm not sure if this is a result of poor quality stainless steel(cheap Chinese reproduction) or if this will happen to any stainless steel. I d0 think I can clean the surface back to, or close to the original satin finish.

 

One of my other concerns was that this crown has a spring inside to allow for a water-tight seal when the crown is seated home by use of the crown guard lever(remember it is a Panerai replica). As I cannot inspect the spring to check for damage, There does not appear to be any change to the spring strength itself.

 

The process I used was to dissolve about a tablespoon amount of Alum in a small amount of water ( I will not attempt to explain the amounts further in metric or US measurements as I'm sure I will confuse everyone reading! :huh: ) and kept it heated by sitting it on a radiator/heater for the duration. I had to add water once as it will evaporate quickly under these conditions....

 

[Geo]

That's excellent news Don, I'll definitely use that method sometime in the future. Many thanks for keeping us informed.

[Lee]

if you want to speed it up a bit microwave it! shortens the time required considerably!

[Mark]

if you want to speed it up a bit microwave it! shortens the time required considerably!

 

Microwave and metal, is that safe?

 

 

Put it in a jar of alum for a couple of days. It will dissolve steel. See this thread for details. 

 

Is this the stuff? Alum (aluminium potassium sulphate) 250g

I am thinking of giving this a crack myself.

[DJW]

Microwave and metal, is that safe?

 

 

 

Is this the stuff? Alum (aluminium potassium sulphate) 250g

I am thinking of giving this a crack myself.

I wondered the same thing...I warmed up the water in a microwave, but that was the extent of that!

 

As far as the Alum itself, here in the US, she found it in the supermarket. It's used in canning vegitables and pickles! Makes them stay firm and crisp! I believe she only paid a couple of dollars for a a couple of ounces (60g)...

 

Edited April 24, 2014 by DJW

[DJW]

Is this the stuff? Alum (aluminium potassium sulphate) 250g

I am thinking of giving this a crack myself.

Sorry...Yes this is the Stuff!

[Mark]

Sorry...Yes this is the Stuff!

 

Thanks Don :)

[Lee]

Microwave and metal, is that safe?

I don't do safe :startle:

 

I've never had any problem with it, but it certainly gets the old stem fizzing & sometimes you can wait for days & days for the process. since microwaving its usually an overnight job. I just fizz it up every time I go to the loo & also leave the  solution simmering on a chocolate maker!

 

Simple!

 

Lee

[Mark]

Nice one Lee  :thumbsu:

[arkobugg]

Hello Mates,

Had e bendt stem in a Seiko 6309-7290, that I tok up yesterday. And when trying to unscrew it, the male stem broke of inside crown.     See photo...

Im a aware that there are other treads of this issue here befor, but Im only asking if somebody knows where to get at new mal stem part.

I thought I should try the trick with Alum to get out the thread bit inside crown. And replace the mate stem after that.

 

Cheers  from me...

 

[horsetrailer]

Hi. These are available from star time supply and ST supply in the states. I just ordered a crown for a 6309 8900. I also sourced uncut replacement stems for future snafus from Star. I hope this helps. I know your not in the states but it's an option

Sent from my iPhone using Tapatalk

[vinn3]

next time. try heat and penetrating oil.  cheers

[rogart63]

You can find them on Ebay? Found a crown and complete stem for $25 but i think they are aftermarket? And for the same you can get a original NOS male part. 

[sstakoff]

Any advice on how to remove this broken stem?? I don't have any small "easy outs". The crown is a special one for a TW Steel watch so I need to preserve it.

[SSTEEL]

Soak the crown in vinegar or Alum for a few days, this will dissolve the stem.

[ricardopalamino]

I have the same situation right now  . I have been soaking the crown  in Cleaning vinegar for about a week with no noticeable results so far , but I did want to start off easy .  I think I lill soak it in Alum and hot water next to see if I can kick start the action. I am cautious because the first time I used Alum on a broken screw on a base plate the post that the screw was in also dissolved making the part unusable . I am thinking that the stem may have had some loc-tite on it also to keep the crown from unwinding . As soon as I see the part turning black I will soak it in vinegar , put it in the ultra sonic to vibrate it for a bit , and then back into the vinegar again .

[anilv]

If you don't have heat or alum..

It looks like the crown has a really long 'shaft' so I might try to remove a bit of the shaft around the old broken stem piece with a file/dremel, heat the broken bit, then use a pair if 'good' pliers to remove the broken bit. The heat is important as it breaks the hold of whatever is keeping it in place.

Looks like you only need to remove a little bit of the stem to get a good grip on the broken piece.

HTH.

Anil

[anilv]

Looking at your picture again, you may get lucky with just heat and using a pair of fine sidecutters.. hell I've used nailclippers before!

Anil

[Cad101]

I have had success with a pin vice in the past if there is just enough stem to get a purchase on and as anliv says heat it up to break that bond but remove your rubber rings.