Open a Tissot Savonettes pocket watch?

[qhartman]

I need to replace the battery on this guy, and I can't for the life of me get it open. I assume it's a screw back since there's no notch for a case knife, but I can't get it to go. Can anyone confirm how this thing is put together?

 

Thanks!

 

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[noirrac1j]

a picture would be very helpful.

J

[clockboy]

Most watches require the same opening technics. A pic is required.

[qhartman]

Thanks for taking the time to reply, but there's nothing on the outside of the watch that would be helpful in telling how it opens. Though, I suppose the lack of a tell is a tell that it's a screw back.

Really hoping to hear from someone who has worked on one to just confirm my suspicions, on the off chance that it's a monocoque, which would be weird, but not impossible. I haven't been able to get any useful info from Tissot directly.

I'm to the point of trying to super glue a nut to the back so I can get more torque.

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[qhartman]

Here's a good view:

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[qhartman]

Did manage to get the crystal off. It's just a snap fit retention ring like one would expect. There's no way to get the movement out without removing the stem though, and on this movement the stem release is on the back. The back has to come off somehow...

 

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[WatchMaker]

It does look like the back should come off your pocket watch and these would normally be a snap fit and so be removed by a case knife. I note you've already tried this though so it's probably worth me recounting the story of a quartz pocket watch I once dealt with...

I tend to deal with older mechanical watches but I was asked a while back to fit a new battery into a pocket watch similar in appearance to yours. Battery changing ... easy eh?! However it transpired there was actually no way to get the back off since the case was a single moulded piece! The stem was not a split design and so there was no way to seemingly get at the movement!

The only way to replace the battery was therefore to carefully lift the dial at the battery position (I think at the six o'clock position on the watch I worked on) and then whilst carefully propping up the dial use a pair of tweezers to pull out the old battery and then replace it with a new one. This was not only fiddly work but, even with stem pulled out to time-change mode to maximise the amount I could lift the dial, i was worried about the stress on the stem. The swear box got a top up along the way but I forgot to post that thank you letter to the designers...! 

[qhartman]

Yeah, that's what I'm afraid of here. I have actually glued a nut to the back to get a better bite, but I still can't budge it! Now I'm having trouble groping the sides of the case in my off hand. I have also noticed though that the striping on the back isn't quite straight, which makes me think this back must come off as it looks like it was turned a few degrees further than it was supposed to be turned when it was put on last, presumably at the factory. That would also explain how tight it is.

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[WatchMaker]

Wow - that must be on really tight then! 

Not watch related but when I had a nut on a car that just would not budge I used some Shock & Unlock spray and was amazed when this did the trick. Thinking along similar lines, and before you get too medieval on that case back, I'm wondering if a similar spray (or a plumber's freeze spray) might be enough to contract the steel back for you to then loosen it. Just an idea...!

[qhartman]

So, I've learned a few things. *cue ominous music*

The case is not a screw-back, but it is separate from the rest of the case. Not sure how it's assembled, but I managed to turn it about a quarter turn, and it didn't unthread at all. So for any future searchers, the Tissot Savonettes pocket watch does not have a removable back for all practical purposes. To replace the battery you need to either do the fiddly lift operation described above, or figure out some magical way to remove the stem without access to the back of the movement. I suspect at the factory, they just cut the stem and replace it when they do battery changes.

I also managed to break the crown off the stem during this exercise and lose some of the bushings that were on it. This creates two problems. The first, is that I need to replace the stem, crown, and bushings. Stem should be easy, but crown and bushings will be trickier. Any suggestions there?

The second is that now I can't open the cover (it's a hunter style) to get to the crystal and the rest of the movement! Ideas on that one?