AS ST 1950/51

[EdB]

I am currently working on a AS St 1950/51 movement and ran into something I haven't come across before. Is there a special tool to remove the seconds wheel from the gear adjacent to the keyless work? I believe it's part of the motion works. If no special tool is required what is the typical process, it appears to be pressed on; if this is the case when re-installing is there a certain amount of play that should be accounted for? I have attached a couple of pictures for clarification. 

[JohnR725]

I've attached the parts list you'll notice it's the canon pinion. It should pull off if you're careful

1394_AS 1940,1941,1950,1951.pdf

[Nucejoe]

Use a hand remover to pull off this canon pinion.

 

[Xilikon]

Same setup as AS 1920 I came across myself. Use a cannon pinion remover to remove it.

[EdB]

On 4/22/2021 at 3:59 AM, JohnR725 said:

I've attached the parts list you'll notice it's the canon pinion. It should pull off if you're careful

1394_AS 1940,1941,1950,1951.pdf 3.2 MB · 0 downloads

Very useful thank you. 

[EdB]

Ok; all reassembled and running fantastic after some minor adjustments. One this I noticed is that the screw for the ratchet wheel does not screw all the way down there is a visible gap between the screen and the ratchet wheel; possible replaced at one point in time by an incorrect size screw? Or does this movement have a washer that would go between the ratchet wheel and the screw itself? I only make mention of the later due to a video I happened across the repairer stated his had a washer between the ratchet wheel and the head of the screw; seems out of place in my opinion but what do I know.  

[JohnR725]

15 minutes ago, EdB said:

ratchet wheel does not screw all the way down there is a visible gap between the screen and the ratchet wheel; possible replaced at one point in time by an incorrect size screw? Or does this movement have a washer that would go between the ratchet wheel and the screw itself? I

if you look at the PDF parts list I gave you there is a ratchet wheel and there's a specific screw for the ratchet wheel. I'm not seeing any other parts to indicate washer for the ratchet wheel. Then at the picture below you don't see any washer?

A unfortunate problem and watch repair is the older the watch the more likely undesirable things have occurred to it. Specifically in watch repair things get broken things get changed in general bad things can occur to the watch. So compare your screw to the one of the PDF if they don't look the same it's probably been broken replaced.

 

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&AS_1950

 

[Nucejoe]

35 minutes ago, EdB said:

 One this I noticed is that the screw for the ratchet wheel does not screw all the way down there is a visible gap between the screen and the ratchet wheel; 

The wheel with 3 screens is your winding wheel, ratchet wheel has no screen.

 

[clockboy]

1 hour ago, JohnR725 said:

if you look at the PDF parts list I gave you there is a ratchet wheel and there's a specific screw for the ratchet wheel. I'm not seeing any other parts to indicate washer for the ratchet wheel. Then at the picture below you don't see any washer?

A unfortunate problem and watch repair is the older the watch the more likely undesirable things have occurred to it. Specifically in watch repair things get broken things get changed in general bad things can occur to the watch. So compare your screw to the one of the PDF if they don't look the same it's probably been broken replaced.

 

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&AS_1950

 

Agree 100% with your last paragraph John. Vintage pocket watches are a good example 100 years of horological tinkering and changes that are so difficult to trace and correct. 

 

[Nucejoe]

2 hours ago, EdB said:

 the screw for the ratchet wheel does not screw all the way down there is a visible gap between the screen and the ratchet wheel;

 Is ratchet wheel loose ? or level with and properly engages the winding wheel?  

 Screns are on winding wheel which should slightly stand proud of barrel bridge to clear the jewel underneath it, to which jewel screens give you access for oiling.

[Xilikon]

If it's the winding wheel we are talking, I didn't see any washer between the wheel and the screw on AS 1920 (I notice it share a lot of design with AS 1950). There is a thin washer under the wheel. The ratchet wheel screw has no washer too.

Maybe check if those screws got mixed up ? 

Let me tell something : When I disassembled my AS 1920 (in a Girard Perregaux Gyromatic High Frequency Observatory Chronometer, GA9377), I had to do a partial disassembly because i was unable to remove the movement and the stem was split and unable to be reached. I didn't check the screws and mixed all up.

After I cleaned the movement, I decided to do a dry assembly to make sure parts works fine before I order some replacement parts. I did take a guess about screws and the winding section is what gave me some trouble. In the end, I noticed one screw was too long and protruding in the mainplate blocking a wheel so it wasn't possible to wind at all. After disassembling again, i checked the screws and noticed one wasn't polished like others and realized it was the keyless works screw which is shorter than others. After swapping the screws, everything is fine.

I see that screws holding the barrel bridge, ratchet wheel and keyless are all similar size, just different lengths. Bridge screws is a bit longer than the rest.

[jerryvs]

use the upper bridge to avoid to damaging the center wheel 

 

[EdB]

On 4/24/2021 at 2:10 AM, Nucejoe said:

 Is ratchet wheel loose ? or level with and properly engages the winding wheel?  

 Screns are on winding wheel which should slightly stand proud of barrel bridge to clear the jewel underneath it, to which jewel screens give you access for oiling.

Ratchet wheel does not move up or down on it's mounting post at this point in time; I'm sure with a good bump or shock it would move out of position. In current position everything operates as designed. Screws are in the correct places as the winding wheel screw would have a shorter thread and would be reversed as apposed to the ratchet wheel. I'm assuming the ratchet wheel screw currently in the movement had been replaced at one point in time. I have looked over the diagrams for all of the parts and there is no washer shown; so again I am assuming someone changed it down the line. 

[Nucejoe]

1 hour ago, EdB said:

Ratchet wheel does not move up or down on it's mounting post at this point in time; I'm sure with a good bump or shock it would move out of position. In current position everything operates as designed. Screws are in the correct places as the winding wheel screw would have a shorter thread and would be reversed as apposed to the ratchet wheel. I'm assuming the ratchet wheel screw currently in the movement had been replaced at one point in time. I have looked over the diagrams for all of the parts and there is no washer shown; so again I am assuming someone changed it down the line. 

I have a watch here with AS 1950/51 inside, cracked the backplate open, removed and measured the length of ratchet wheel screw from head to tail. that is including the screw head its 1.35mm. 

Hope this helps.