Hey guys, I need to ask of the forum’s expertise.

I’ve been searching for a correct replacement crown for my Longines 12.68z Sei Tacche.

I recently received a Longines crown that’s supposed to work as a period correct replacement. It fits a “Tap 8” winding stem, according to my watchmaker. This apparently corresponds to a 1.1mm diameter at the external stem tip that goes into the crown.

I also recently bought a NOS 12.68z winding stem from eBay. It engages fine with the movement itself. Unfortunately the stem doesn’t engage the crown I got.

Does anyone know if the 12.68z stems came with different external stem tips that engage in a Tap 8 crown?

Hope this made some sense.



Thanks,
Eric

 

What ref number is your sei tacche, and do you have some pictures

 

Here is the movement picture with the number. These are from prior to losing the original crown

 

Beautiful dial on your Sei Tacche. Just to better understand your issue. Are you saying the crown and stem end are incompatible?

 

Thank you, it’s definitely a favorite of mine.

Yes the crown and stem are incompatible. The crown hole is a touch too big for the stem, the threads don’t engage.

 

Nice looking dial

 

Thank you sir

 

Very nice watch.
I have to ask, how can you be sure the replacement crown was truly for a 12.68 and not a 10.68, 23M, or 27M?
If you are sure it was a 12.68- I can believe there might have been variants.

I know Longines in those years kept introducing innumerable variants to movements and that is a reason why repairs can be complicated.
For example, my watchmaker encountered several types of hairsprings and hairspring stubs and several types of mainsprings for the 8.68 movement.
I also know that Royal Air Force Longines 12.68N watches from 1940-1942 have two different stem diameters, depending on the model of the watch. (That difference was observed by a friend who replicated those crowns for restoration purposes).

If you’d like I can put you in touch with that friend and perhaps he’s got a variety of stems or more info? Feel free to send me a private message.
Cheers

 

Thank you for the info! Very interesting. The person that sent me the crown says it is from a Tre Tacche of similar size. I will PM you for that contact, thanks.


Eric

 

Ok thanks to @Syrte I got in touch with a watchmaker knowledgeable of vintage Longines.

It appears the replacement winding stem I thought was for a 12.68z was probably for a different Longines caliber, maybe a cal 22 which fits a .9mm crown. Just can’t always trust eBay.

Anyways I just ordered another 12.68z stem that measures at 1.1mm, which will fit my crown.

Will post pics once my baby is period correct again!

 

Ha ha, he’s not a watchmaker at all! He’s just a passionate collector who commissioned rare replacement crowns for military Longines, and he had told me about finding different size specs for the stem (or at least the part that goes into the crown) on 12.68N movements so I know he had studied those stems closely.

Glad he could help sort it out though.

I can’t imagine a crown like the one you showed on a cal 22 but those shapes are found on watches of several calibers.... I’d say 10.68, 23M and 27M.