Pocket watch running too fast

[bsoderling]

Hi all,

 

Had a pocket watch coming my way via inheritance. It's an oldish cylinder movement that winds with a separate key.

 

Under the loup it's quite roughly made as I guess many of these were, being the working mans option in those days.

 

I decided to give it it try and soon found that the main spring was broken as well as a chipped balance end stone.

 

These items corrected it runs but too fast...

 

With the timing lever to the slow end it's still fast by several minutes.

 

My thought here is that the HS should be longer to slow down and noting that there is about 10 mm of "unused" HS I'm wondering if I could move the HS end closer to the fixed point? This would obviously turn the balance the same amount and throw the beat off and I would have to compensate for this by rotating the HS collet on the balance staff.

 

Am I going in the right direction here or as off as my movement?

 

I have attached a snap for you to look at.

 

 

 

 

 

 

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[szbalogh]

Right direction

The question is that 10mm lengthening enough to compensate the fast rate? 

 

Edited August 6, 2017 by szbalogh

[roverguybm]

Hello bsoderling!

Couple of questions?

Is it two minutes fast per day in the 12 o' clock up position (assuming this is 'top-up' for this particular pocket watch)? 

When you replaced the mainspring did you use an exact replacement for this calibre of pocket watch? 

How old is the watch...looks like the 1920's from the image but if older then sometimes 2 minutes per day is actually pretty good?

[bsoderling]

Thanks guys for such fast feedback.

The available amount of free HS may not be enough, but at least I know what to expect if I go for it.

The reading off my Iphone timegrapher app ( I do need to upgrade on that part...) isn't too stable but it seems to be more in the 3-5 minutes per 24 hr in the slowest position. It reacts to the setting of the lever and is around 10 minutes at the neutral position.

I measured the mainspring accurately and got a replacement spot on from Cousins. The new however is made in the S-shape that I understand is common these days. Being fresh and "modern" I suppose also means more power. Would you suggest this could be a cause for running fast (I suppose so...)

I really don't know the age of the watch and would appreciate your further thoughts and will upload a couple more snaps for you to review.

I guess it's a quite simple device as it doesn't even have a seconds hand. But the dial is nice without cracks and the size, case and glass are also pleasant.




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[szbalogh]

It can cause the fast rate. Cylinder watches cant have more than 180 degree amplitude. You should hear if it pengs on the safety pin. Or measure the amplitude by marking the balance with a pen.

[roverguybm]

Quote

 

Hello again bsoderling...

The reason for the questions - I was just trying to save you adjusting the hairspring and roller jewel position if possible ...

New spring question - just thinking that maybe the new spring was the wrong thickness, and as this is a cylinder escapement with no pallet fork helping to regulate impulse to the balance staff there maybe a little more direct power going through the train than previously, resulting in it running fast. Since it's an exact, although modern, replacement though, it probably isn't that. What would be great to know is what position the regulator/index was in when you first received the watch...was it in the centre, towards the fast or slow?...if in the centre then this would suggests it was keeping good time prior to the mainspring breaking...although not definitive proof.

The twelve o'clock position questions...a pocket watch is ideally intended to spend most of it's 'time' hung from it's pendent...so timing it laying on it's back for example may not be the correct position to judge it's accuracy...

I like phone apps for measuring accuracy of watches, I have a few on my own phone...but ideally for me accuracy would be best measured over the full 24 hours to allow for the mainspring to run through a cycle (some say you need at least a month to check accuracy!)...but two minutes out...nah, not that...

...10mm of unused hairspring...that seems a lot of spare to me...and as you have written, and szbalogh confirms, 'winding' this extra length back into the available, active length of adjustable hairspring may get things back to acceptable functionality...but then you have a wee bit of delicate work getting everything lined up and in beat again...

I'm also assuming the watch isn't magnetised...doesn't look as if there is any binding coils within the hairspring from the image, but I'd still try demagnetising anyway so that it's ticked off the check list...and sometimes there's a little spare oil that's found it's way onto the hairsprings that can only be seen using a loupe...this can cause things to go fast... 

 

...and please upload some more images...can't get enough of images of pocket watches!!!

[szbalogh]

Yes, good thought. Demagnetize, clean and then tinkering

[oldhippy]

Are you sure, you have the correct strength spring. Letting out the h/spring is the right way of slowing the watch down. Is the h/spring bouncing between the regulators pins, make sure they are, if the pins are very close together you can open them up a little, this will help the watch to slow down.  

[bsoderling]

Thanks for all the valuable feedback!

Oldhippy, I will double check my thickness measurements to be sure I didn't mess that up.

I have cleaned the entire movement and demagnitized as well.

And I can't see any sticking or touching with the HS, even though it's for sure not in perfect shape.

The spring does move between regulator pins but not over the entire regulator swing and I guess this is an indication of the non-perfect shape. I will try to tweak the spring and pins a bit. A thing I note is that I have to be very careful when pushing in the locking pin to secure the HS. It's way too easy to end with a non-flat HS when pushing in the pin. I guess this is all part of the pleasure to work on these oldies [emoji4].

Here's a couple of images of the movement out of its case.


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[oldhippy]

The h/spring should bounce between the regulator pins no matter the position.

The movement is known as a five bar date from around 1890 . Do you have the little cover for the ratchet wheel also the little piece that goes around the hand setting.  

[bsoderling]

Thanks oldhippy, I'll work on the bouncing.

From the general condition I suspected it would be rather old. If you have any links to more info on these and other designs of the period, I would appreciate it very much. I like to have a bit of historical context around the pieces I tinker with.

I do have the parts you mention. Unfortunately all four threaded holes for the ratchet wheel cover are worn out and the thing won't stay in place. I guess the solution will be to step up the thread a size and find larger diameter screws. Don't have the device to create new threads (yet).

Not sure it's visible in the photo but the square stem for the winding key has been filed down to a very small size. I guess this is to counter the rounding off of the corners that might happen if you are using a too large key?

This all leads into another question... is it at all possible to find spares for these things?

I have a couple more of similar design with broken balance pivots etc. and as I just succesfully swapped out balance staffs on a couple of wristwatches, I'm eager to try something on these. But they are all very anonymous...






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[oldhippy]

Thread wear is very common on those parts. I doubt the hand setting square got round shoulders by setting the hands, as far as I can remember they were roughly finished, I had a small box of them and some were not even centre to the spindle. These movements have been manufactured in there thousands, each having something slightly different to the rest. I do not think you will find another that is interchangeable but there’s plenty of spares around, mainly because of them being a cylinder, which is much harder to repair then a leaver escapement. I don’t think you will find a balance that is interchangeable.

[bsoderling]

Correct, the hand setting square looks fine, it's the one for main spring winding that's been reduced. Which I guess makes sense with the force needed to wind the spring.


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[oldhippy]

39 minutes ago, bsoderling said:

Correct, the hand setting square looks fine, it's the one for main spring winding that's been reduced. Which I guess makes sense with the force needed to wind the spring.


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That makes more sence. You find that a lot with clocks.

All down to a poor fitting key. I can never see the sense in people buying old second hand keys from ebay.

[bsoderling]

Hi,

Looks like the watch isn't running too bad with the setting to max slow position. I'll leave it there, in the recommended upright position for a few days and see how it behaves before tampering with the HS. 

Thanks all for improving my knowledge on this.