Movement Number : Now What ?

[frenchie]

Hi,

I have 2 pocket movements with numbers stamped on them : 20656 and 87763.

I googled those numbers but nothing is coming up in the first few pages of results. I don't know who the manufacturer is... One of those has a click system I've never seen before : it doesn't pivot like they usually do, it's more like a spring bar (I'll post pics later when I have time)

I'm trying to find a bit more information just because I'm curious. I'm going to take them apart for cleaning and reassembly (practice watches). Maybe I'll find clues on some of the pieces...

 

Any ideas on where to look ?

[WillFly]

There might be a calibre number or maker's logo hidden away under one of the bridges. Worth a look... any pics you can  post?

[SeikoWatch]

Sometimes Under the balance Wheel.....

[Marc]

Under the dial is always worth a look if nothing any where else.

[frenchie]

Here are pics of the back of the movements. The numbers are under the dial (I don't have pics right now, I'll have to take some later).

The seller said they are french... The golden one runs. The silver one doesn't. It feels gummy, I wonder if it got the cooking oil treatment  :)... the balance moves freely, and there is tension in the mainspring. I'll be good practice to take it to pieces, clean it, and put it back together !

I'll do some work on the silver one this week end, I'll see if anything looks broken...

[frenchie]

A bit more details on the steel colored movement (now mostly taken appart) :

- it's a cylinder escapement. My first one :)  pretty cool.

- there are 2 identical parallel marks on the dial side, I have to take a picture of them. They look like they were stamped on the pilar plate, but I'm not an expert  and they could just be tool marks... I'm secretly hoping it's a manufacturer's stamp that can be easily identified (haha).

 

I cannot figure out how to remove the barrel bridge... :(  As you can see in the picture above, the barrel bridge also holds the center wheel. On the dial side, I can't seem to be able to move the canon pinion, and on the other side, the axle is slightly wider than the hole on the barrel bridge... I'm not sure how hard I can pull on the pinion to remove it, and I'd rather not break anything... And if I do manage to remove it, how do I put it back ?

[frenchie]

2 new pictures :

- the 2 "stamps", close up (numbers ? 2 "ones" ?)

- the dial side of he movement : model number (?) at the bottom of the picture, and the 2 "stamps", on the right hand side of the picture, just above the bottom right blue pilar

 

 

[frenchie]

The saga continues. I found another set of 11 on the back of the barrel bridge. After the parts are clean I'll look for more of those...

 

I tapped out the center wheel arbor with a brass hammer and it came right out. Hurray ! How to tap it back is going to be the next challenge... :(

 

It turns out the mainspring is broken (see picture). There seems to be a lot of those out there, but without a manufacturer or a brand, I'm not sure what to look for... Any advice ?

[frenchie]

I can't edit my post for some reason... anyways... instead of going straight to bay (stupid), googled.... :)

 

The spring is 1.5mm (0.059 inches) wide and around 27cm long (10.75 inches)...

 

I found this chart for american watches : http://www.jewelerssupplies.com/mainspring-size-charts.html

and this explanation of how to figure out lenght, thickness from the barrel size, very handy : http://mb.nawcc.org/showthread.php?36730-determining-correct-mainspring-strength

 

Let's see what I find !

[SeikoWatch]

From http://mb.nawcc.org/...spring-strength

determining correct mainspring strength

A) Take the internal diameter of the mainspring barrel and divide by 100.

B) Take the result of A) and multiply by 26

C) Take the result of A) and multiply by 41

D) Take the difference of C) and B) and divide by 2

E) Take the result of D) and divide by the require number of turns for a full winding

The result of E) is your theoretical thickness.

Next is to determine the length.... From Smith & Smith....

1 Determine the strength of the mainspring required (thickness above)
2 Divide inside diameter of barrel by 2
3 Multiply answer by itself
4 Multiply answer of above by 3.142
5 Divide diameter of barrel arbor by 2
6 Multiply answer by itself
7 Multiply answer of above by 3.142
8 Subtract answer of step 7 from answer of step 4
9 Divide by 2
10 Divide total thickness of spring into answer of step 9
11 Total = length of mainspring

[frenchie]

Thanks !

 

[...] divide by the require number of turns for a full winding [...]

 

I'm not sure how to find this number... can I just say 20 turns ? 

[SeikoWatch]

oh I can't help you Frenchie but at my sens counting the number of turns, ouff !! who knows ? i've never counted this myself !.....and like you, i'm not sure...

[Mark]

If you have the old mainspring (you have) then you can measure it's thickness, the height, the length and the inside diameter of the barrel. Then give these dimensions to your material supplier and they will provide you with a new one (hopefully).

[SeikoWatch]

Mark is right... however, you can also buy one to your watchmaker or an horologist if there's one near you :)

[No8yogi]

If you have the old mainspring (you have) then you can measure it's thickness, the height, the length and the inside diameter of the barrel. Then give these dimensions to your material supplier and they will provide you with a new one (hopefully).

Any recommendations as to where to get one? How accurate do your measurements need to be?

[frenchie]

I ordered mine from ofrei. I could not find and exact match, so I ordered one close enough...

As for measurements, here is what I understand :

the width is important, because the fit inside the barrel must be perfect (too tight and it will not unwind properly, too loose and it can twist inside the barrel)

the length determines how long the watch runs for (less important ?)

the strength (thickness), was tricky to measure for me.... This will determine how strong the spring is (no kidding)... It's how fast the wheels will go when the spring unwinds... a bit of a gamble if your instruments aren't the greatest.

barrel diameter, not sure what that is for, but it's easy to measure.

 

One more thing you'll need is the shape of the end of the spring (the part that attaches to the barrel) : http://www.ofrei.com/page1597.html

(I think I actually screwed that one up, but live and learn... :( )

Edited March 14, 2014 by frenchie

[Geo]

Any recommendations as to where to get one? How accurate do your measurements need to be?

Mark's method has always worked for me. Measure as Mark said using vernier calipers and if the exact size that you require is not produced, go for the next size down to the nearest fraction of a mm. That way you know it will fit into the barrel with the lid on. You may loose a small bit of power, but the watch will at least run and you should still be able to regulate it to reasonable limits.

Edited March 14, 2014 by Geo

[Mark]

Mark's method has always worked for me. Measure as Mark said using vernier calipers and if the exact size that you require is not produced, go for the next size down to the nearest fraction of a mm. That way you know it will fit into the barrel with the lid on. You may loose a small bit of power, but the watch will at least run and you should still be able to regulate it to reasonable limits.

 

I would clarify this further (hope you don't mind Geo):

 

• You can get away with the spring being slightly lower in height, or slightly longer or shorter.

 

• But try your best to get the strength (thickness) exact as this could lose amplitude if it is too weak or cause the balance to knock the banking pins if too strong.

 

• And as Geo said, try not to order one which is slightly higher as it may foul the barrel lid.

 

 

Hope this helps.

[Geo]

I would clarify this further (hope you don't mind Geo):

 

• You can get away with the spring being slightly lower in height, or slightly longer or shorter.

 

• But try your best to get the strength (thickness) exact as this could lose amplitude if it is too weak or cause the balance to knock the banking pins if too strong.

 

• And as Geo said, try not to order one which is slightly higher as it may foul the barrel lid.

 

 

Hope this helps.

I don't mind at all, your the proffesional, I'm here to learn and pass on my own experiences. If I say something that is incorrect I hope someone will correct me.

Keep up the good work!!

[frenchie]

Small update :

Spring seems to fit !!! It was a bit of a paint to fir the harbor back because the loop at the end of the spring was very tight... anyways, that part went well.

 

After that, I proceeded to start putting the watch back together... and the pinion of the center wheel just fell out... ARGH !!! The pinion has a small gear on it ... On the actual center wheel, the part where the smaller gear used to fit looks like it got rusty or corroded somehow, and me banging it out (very very gently) probably didn't help... There is also a small crack on the inside of the center wheel...

SOooooooo

There are tons of replacements on the internets, but how do I figure out which one I need ? Number of teeth and diameter enough ?