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Removing Crown from stem?

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#2 ·
In my experience ( mostly with PW's and early WW's ) just about all crowns with the exception of some ( many? ) Timex WW's, simply unscrew. I use a pair of flat-nose pliers to grab the winding square, and that's that...crown unscrews. Even in those instances where a bit of thread sealant's been used, the crown doesn't really resist being removed.

Michael.
 
#3 ·
Holding the stem by the winding square while unscrewing the crown risks breaking the stem at the groove for the set lever. I prefer holding with a pin vise at the sturdiest part of the stem, just below the threads.

Most modern watch manufacturers use a thread locker on the crown. I use blue Loctite. It helps to secure the crown without being too difficult to remove.

While we are on the subject, the threaded end of the stem should always be finished flat. Filing the end of the stem to a point or a dome will guarantee that it will come unscrewed.
 
#5 ·
Pin vise gripping the square, and using heat if needed is the way I do this. I've never snapped a stem doing it this way, but of course you have to have a feel for what the stem can take.

Gripping on the rounded portions rather than the square can cause damage to the stem - slightly out of focus but you can see the damage to the round portion here:



This is now a cutting tool, and the raised burrs from someone grabbing it here chewed out both the main plate and the barrel bridge, spreading brass debris throughout the movement.

For installing the crown again, it depends a bit on the crown and stem design if Loctite is required. On some there really is no option, but if the stem is trimmed properly and is sturdy enough that it can be tightened well, it's not needed.

Cheers, Al
 
#7 ·
Archer said:
Pin vise gripping the square, and using heat if needed is the way I do this. I've never snapped a stem doing it this way, but of course you have to have a feel for what the stem can take.

Gripping on the rounded portions rather than the square can cause damage to the stem - slightly out of focus but you can see the damage to the round portion here:



This is now a cutting tool, and the raised burrs from someone grabbing it here chewed out both the main plate and the barrel bridge, spreading brass debris throughout the movement.

For installing the crown again, it depends a bit on the crown and stem design if Loctite is required. On some there really is no option, but if the stem is trimmed properly and is sturdy enough that it can be tightened well, it's not needed.

Cheers, Al
Click to expand...
Thanks Al for ( yet another ) great close-up. Your photo shows why I usually choose the square to grab ahold of, and my flat-nose pliers never leave a mark. I agree that a 'feel' for doing things this way is necessary: once a person's done it a few times, it will quickly become apparent if the crown's on so tightly ( as ccwatchmaker rightly suggests ) that the stem might break before the crown lets go...in which case Jim's preference for a pin vise makes perfect sense.

If I need to dress down the threaded end of a stem, I never leave a ragged edge: I just go around it as gently as possible, and leave a very gentle bevel. Afterwards, if I think the stem is not as tight in the crown as it should be, I just apply a bit of thread sealant, and that's that!

Michael.
 
#8 ·
ccwatchmaker said:
Holding the stem by the winding square while unscrewing the crown risks breaking the stem at the groove for the set lever. I prefer holding with a pin vise at the sturdiest part of the stem, just below the threads.

Most modern watch manufacturers use a thread locker on the crown. I use blue Loctite. It helps to secure the crown without being too difficult to remove.

While we are on the subject, the threaded end of the stem should always be finished flat. Filing the end of the stem to a point or a dome will guarantee that it will come unscrewed.
Click to expand...

FWIW, we were taught to bevel the stem. Back in the day, thread-locking compound was not used...in fact, it was verboten!

Beveling so as to match the bevel of the final drill cut at the base of the threads increases the bearing area where the stem contacts the bottom of the thread in the crown (contact surface actually being a "cone", thus reducing likelihood of backing out. That said, as you point out, a "point" is not good, because only the point is in contact and a "dome" is not good either because the friction contact is a "ring".

All of that said, I bevel then use a permatex superglue for a thread locking compound.

Regards, BG
 
#9 ·
To further complicate matters, if it is a modernish Seiko, there is a good chance it is a one piece unit. The crown and stem are joined together and can't be separated. If you don't see threads, it's because there are none.

A bit of taper on the end will lock it it very tightly. I use purple Loctite for small set screws for insurance. It wouldn't be a bad idea to heat the threaded portion of the crown before trying to remove. I've had a few that would not budge until I heated them a little with a soldering iron. Just slightly past too hot to touch is all you need.
 
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