Why does the winding stem keep breaking?

[swordfish]

Gentleman, I'm having the devil's own time trying to replace an Epson VX43E quartz mechanism. I'm able (with grumbling and struggle) to put the mechanism in the case, apply the dial, and even re-attach the oh-so-persnickety hands. I'm able to trim the stem to the proper length and re-attach the crown. I'm able to re-insert the winding stem into place. I can set the time several hours forward or back without trouble. But if I advance the time several days (to get the date and day right), the winding stem breaks within the mechanism. This has happened to me several times. Of course the fragment of the stem within the mechanism cannot be removed, so I have to repeat the whole process with a new mechanism and stem. Do you have any idea what I'm doing wrong?

—Eric (a.k.a. swordfish)

Sent from my iPhone using Tapatalk

[Ishima]

How strange, never had an issue like that.
I can only readily think of two possible causes, the crown has excessive shake in it which is allowing the stem to get bent back and forth too much when in operation.
My other thought is maybe your pin vice is somehow at fault, holding it not quite right, somehow putting forces on the tip as you work the thread that end up weakening it? 

[swordfish]

Thanks for your suggestions, Ishima.  I don't think that they solve the mystery, however.  The winding stem, of course, is constrained both by the stem tube very close to the crown, and (quite distant to that) the close-fitting opening in the mechanism case.  These so constrain the axis of the stem, that I don't see how any wiggle of the stem is possible.  Similarly, when I was filing the snipped-off end of the threaded stem, I did not hold the stem in a pin vise.  I used pliers (held at a right angle to the stem), carefully keeping the working end of the pliers far from the business end of the stem.  

Edited October 10, 2016 by swordfish

[anilv]

Check depth of the movement relative to the case? Eyeball it thru the crown tube. if it is off a bit (too high/too low) the stem will break. Ditto if there is side-to side displacement. If its the original movement then it is unlikely to be out of alignment but if the movement has been replaced with an 'almost similar' sized movement then this can happen.

 

Anil

[oldhippy]

It sounds as if the movement with the stem inserted isn't lined up in the case correctly, its rubbing somewhere.

[ricardopalamino]

  Is it the proper movement for the dial and case ? Do you feel the resistance just before it breaks ?

Do the dial feet align with the dial , and then the dial and movement align properly with the case in depth and side to side alignment as has been mentioned ? Is there a dial washer to help hold the hour wheel down under the dial ? Is the stem fully inserted and locked in by the setting lever

Try moving the mechanism several hours ahead before putting the dial and hands on . Then with the dial and hands on before installing into the case .  I am wondering if the hour wheel isn't somehow lifting and putting a bind either on the cannon pinion or under side of the dial .

Edited October 10, 2016 by ricardopalamino

[BeyondWorld]

From that picture it's broken from the weak point of the stem. 

So this can happen if you put pressure on it when you are cutting it, I always use my gripping device above that point to make sure it's never weakened.

The second possibility is maybe where you got the stem from. If it's a cheap chinese stem, they use really crap steel.