ETA1256/GP 47BF stopping. Barrel to center-wheel?

[MrRoundel]

Greetings all. I just serviced a Girard-Perregaux automatic movement. It seems to run fine, but ends up stopping for reasons unknown. It seems like it may have something to do with the center-wheel contacting the top of the barrel. If there is clearance, it is by very little. It seems to stop most often once the automatic mechanism is replaced. I'm wondering if by tightening the automatic mechanism down to the train-bridge, it's dropping that center-wheel to barrel clearance to nothing, thereby stopping the movement.

Does anyone have experience with this ETA 1256 auto movement that can offer any ideas as to what the issues might be? What do you think would cause the barrel to be so close to the underneath of the center-wheel? Any help is appreciated. Many thanks in advance.  Cheers.

 

[Nucejoe]

If you suspect the autowinder, I just remove the module, normally the two screws that tighten the module to the gear bridhe are darker in color. Yes long screws can be the cause. Also check the ratchet wheel reduction wheel, its arbor drops in jewel hole in barrel bridge.

The movement is vitually a manual wind once the winder module is removed.

We can monitor the patern it stops,which can tell where to look for the faulf.

[MrRoundel]

I don't see anything under the bridge/bridle(?) that would cause stoppage. The screws are both countersunk, and are sitting within their recesses completely. The rotor itself is a bit sloppy, FWIW. DeCarle tells of how to reduce the size of the core by using a modified round file, etc. I don't know if I trust myself to do that one, but might have to resort to it to get rid of the play in the rotor.

The watch had run without stopping for more than an hour so I decided to put the auto mechanism back on. As I lowered it onto the movement, I manipulated the exposed wheel under the auto-mechanism bridge while I go the mechanism itself to sit what seems like a bit more level. The screws are tight now and now stoppage yet. Time will tell if anything I messed with freed things up.

I know that it's best to put the auto-wind stuff back on after casing the watch, but I really don't want to do that now that things seem to be sitting properly. I'll report back if it gives me any more grief. Thanks for your suggestions, Nucejoe. Cheers.

[MrRoundel]

I thought I had it on the run, so to speak, but nope. With a decent hand-wind, the watch seems to run well for 5-7 hours before stopping. The consistent thing is that the center seconds hand is always at 13 seconds when it stops. The hours it runs may vary (I"m running it again today to see how many hours.), and the minutes as well, but the seconds hand is always on the 13 second mark. Jostling it around to take its picture got it to move to where it shows in the image.

I did not replace the mainspring when serviced the watch. This has me thinking that perhaps the second hand is rubbing somewhere, ever-so-slightly, and as the MS gets to a weaker point, it can't make it through it. Other than that, I'm pretty well baffled.

I'm considering ordering mainspring, but have been spending a bit too much out of my budget for watch stuff of late, and it is "just" another watch. It is a very nice looking watch though, and is certainly worth getting in good running condition.

 

[steve1811uk]

Hi, just wondered if you got to the bottom of this as I seem to have an identical issue also with ETA 1256. I think the barrel is tilted and rubbing against the centre seconds wheel  but need to confirm it. Just waiting for the watch to stop.

[ManSkirtBrew]

On 5/27/2019 at 11:26 AM, MrRoundel said:

The consistent thing is that the center seconds hand is always at 13 seconds when it stops.

I know this is an old necro-thread, but just for the record this would have me looking very closely at the teeth on the wheels. It suggests to me that there's some small bit of damage on one or two teeth that the mainspring can overcome with a full wind, but can't as power winds down.

[steve1811uk]

I found that the barrel was tilted and occasionally rubbing against the centre seconds wheel as the clearance there is so small. I made the barrel upright again by using a smoothing broach on one side of the hole in the barrel bridge. This made the hole oval. I then used a small domed punch to make four or five indents on the other side of the hole to take away the ovalness and make more round. In effect I moved the barrel arbor bush in the barrel bridge towards the centre of the watch and made the barrel upright again. This has solved the issue fingers crossed.

[steve1811uk]

On 12/30/2023 at 5:47 PM, steve1811uk said:

I found that the barrel was tilted and occasionally rubbing against the centre seconds wheel as the clearance there is so small. I made the barrel upright again by using a smoothing broach on one side of the hole in the barrel bridge. This made the hole oval. I then used a small domed punch to make four or five indents on the other side of the hole to take away the ovalness and make more round. In effect I moved the barrel arbor bush in the barrel bridge towards the centre of the watch and made the barrel upright again. This has solved the issue fingers crossed.

Update. Watch has not stopped since.

[mikepilk]

As you have found, a common problem is too much play in the barrel arbor bridge hole, allowing the barrel to tilt and touch the bridge or a wheel. 

Also, if the hands have been pushed on too hard, the jewel for the centre seconds or centre wheel can get pushed out a bit, allowing too much end shake on the wheel, resulting in it rubbing on the barrel.