Jump to content

Broken Stem Inside Crown...


DJW

Recommended Posts

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?

 

 

post-90-0-01422500-1397914402_thumb.jpg

Link to comment
Share on other sites

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. :-)

Link to comment
Share on other sites

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!

Link to comment
Share on other sites

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!

Link to comment
Share on other sites

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

post-90-0-89203500-1398078520_thumb.jpg

 

After Pic

post-90-0-83668300-1398078518_thumb.jpg

 

I'll post updates on the progress!

  • Like 2
Link to comment
Share on other sites

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....

 

post-90-0-07758300-1398254475_thumb.jpg

  • Like 3
Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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)...

 

post-90-0-44381800-1398340072_thumb.jpg

Edited by DJW
Link to comment
Share on other sites

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!

post-138-0-81988100-1398341620_thumb.jpg

post-138-0-54737900-1398341630_thumb.jpg

post-138-0-83406900-1398341642_thumb.jpg

post-138-0-99846600-1398341675_thumb.jpg

post-138-0-95829300-1398341683_thumb.jpg

post-138-0-15525800-1398341713_thumb.jpg

 

Simple!

 

Lee

  • Like 2
Link to comment
Share on other sites

  • 2 years later...

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...

 

Broken stem.jpg

Link to comment
Share on other sites

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

Link to comment
Share on other sites

  • 1 month later...

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 .

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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.

Link to comment
Share on other sites




  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • That will mean dismantling the gear train, which with 5 pivots to align was a pain. Probably going to have to though. I'm convinced it's something to do with the great wheel. 
    • As far as I know, the only time an epilame treatment has potential drawbacks is when something is rubbing on the treated part w/o lubrication in between creating abrasive dust. That is, I don't believe in the method of "running the watch to make a groove through it first in the pallet stones where the lubrication is then placed". So, I think the rule would be; do not epilame treat parts where rubbing is going on without lubrication. Other than that I don't think we have anything to worry about. That said, I'm not an expert, and I'm always happy to learn more. Has any other repairer than Alex suggested or explained the "making-a-groove" method? My impression is that it's just something he constructed in his mind. I have not perceived it as a generally practiced method. Again, I could be wrong!
    • Post some pictures , some good close ones of the parts you've described. 
    • Ive never used epilame H only information i have read and mentally stored about it mostly from Nicklesilver here and elsewhere ( the fork horns thing ), maybe the residue powder that is removed has some grinding effect ? So probably a good idea to limit its application areas to only the absolute necessary. Yes as far as i know epilame rubs off relatively easy, the technique of running the watch to make a groove through it first in the pallet stones where the lubrication is then placed. This i understand creates the barrier for the lube to sit up to. If i can find a good balance of pros and cons of its use then thats one process i can avoid by using a thixotropic lube on the stones. The epilame i would say allows for a more fluid lubrication to be used that would increase amplitude on low beat movements. The stearic acid powder is extremely cheap, the problem is the fuming process to coat parts, is not selective , the whole part has to treated in this method. If epilame residue can cause wear then thats not good, if I remember the conclusion was not proved entirely just a general assumption between watchmakers. The thread is out there somewhere, the same discussion is also old on a facebook group. Ive never used epilame H only information i have read and mentally stored about it mostly from Nicklesilver here and elsewhere ( the fork horns thing ), maybe the residue powder that is removed has some grinding effect ? So probably a good idea to limit its application areas to only the absolute necessary. Yes as far as i know epilame rubs off relatively easy, the technique of running the watch to make a groove through it first in the pallet stones where the lubrication is then placed. This i understand creates the barrier for the lube to sit up to. If i can find a good balance of pros and cons of its use then thats one process i can avoid by using a thixotropic lube on the stones. The epilame i would say allows for a more fluid lubrication to be used that would increase amplitude on low beat movements. The stearic acid powder is extremely cheap, the problem is the fuming process to coat parts, is not selective , the whole part has to treated in this method. If epilame residue can cause wear then thats not good, if I remember the conclusion was not proved entirely just a general assumption between watchmakers. The thread is out there somewhere, the same discussion is also old on a facebook group. If its a potential problem for amateurs to use then i would prefer not to take the risk .
    • Following on from my question about identifying screws in the AS2063 movement that basically fell out of the case in bits, I’m pleased to report that I’ve got it all back together, and the movement is running pretty well.    But… There’s something wrong with the keyless works and hand setting. It’s fine in winding and quickset date position - these work - but in hand setting position winding the crown turns the whole gear train.  I don’t really understand how it’s meant to work. It doesn’t have a traditional friction fit cannon pinion.  The second wheel is unusual with a pair of smaller pinions on it, which seem to interact with the barrel and the motion works.    Could this be the problem? I must admit I just cleaned it and popped it in place when reassembling the gear train. I’ve lubricated the pivots but didn’t do anything to the extra bits on the second wheel.    Does this make sense and is anyone able to figure out what I’m doing wrong? Thanks in advance, as always.    ETA - the parts list calls it the Great Wheel, not second wheel. 
×
×
  • Create New...