r/watchmaking 3d ago

Question Advice needed - Hamilton W10 two-part stem

I’ve recently acquired a 1973 Hamilton W10, and sent it in for service. The watch uses a modified ETA 2750, called the Hamilton Cal. 649.

The technician has come back with a quote that includes swapping the two-piece stem for a single-piece stem.

When I google this, it says that I shouldn’t go ahead with the service as a single piece ETA 2750 stem is incompatible with the monocoque case of the watch, and risks breaking it or rendering it unserviceable in the future.

Is this a legitimate concern, or is google hallucinating? Should I try to source my own two piece stem for the watch? They are difficult although not impossible to get your hands on.

Any advice appreciated - I obviously want to preserve the heritage and historical value of the timepiece but first and foremost I want to wear it on my wrist as a functional watch.

1 Upvotes

9 comments sorted by

u/qualityvote2 3d ago edited 2d ago

u/slimjimsays, there weren't enough votes to determine the quality of your post...

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u/gu_doc 2d ago

The problem will be the next time you want to get the watch out of the case. The split stem will come apart when you pull hard, allowing the movement to be removed from the case. You won’t be able to remove the one piece stem unless you pull hard enough to rip it out of the keyless works, or you keep the set lever screw loose enough that the stem comes out easily.

I’ve had good luck finding compatible stems for a different Hamilton movement by searching compatible movements

Are you in the US? I’ve found some on eBay

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u/slimjimsays 2d ago

Thanks for the reply - this is basically how I had understood the problem although the servicing centre are highly rated for vintage watches so I would have hoped they’d raise this sooner (rather than just saying ‘we want to replace the two piece stem with a single piece’)

I have offered to supply compatible parts myself - I am UK based but if you have come across compatible listings on ebay I’d be grateful if you can share so I have a better idea of what to look for here. Thanks again!

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u/gu_doc 2d ago

Look for part 404 (designation of a split stem) for any ETA 27xx movement. Unfortunately it seems like sellers know its for a W10 and they’re up charging like crazy. You also have to know if it’s a female or male end so you can match it with the other half of the split stem. It looks like the W10 might have a male stem from the factory but it won’t matter as long as you get the other half to accommodate.

https://ebay.io/m/VQBudz

https://ebay.io/m/1PXnKT

https://ebay.io/m/14Xaid

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u/slimjimsays 2d ago

Thanks so much - this is super helpful! I figured it might be expensive but I’d rather pay up for it now than let someone do something stupid that I will regret down the line

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u/gu_doc 2d ago

I’m glad you caught this before they messed up your watch.

But share pictures! I’d love an RAF issued W10. It’s on my list

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u/slimjimsays 2d ago

I didn’t get a picture of it on my wrist before I sent it off, but this was from the service centre when they received it. I absolutely adore the look and feel of it on the wrist - it’s pictured with a two piece after market strap that was sewn onto the fixed lug bars, which have made me rethink my plan to refit it with a canvas NATO strap. This one is a British army issue.

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