Elgin Grade 315: Runs/stops with dial down/up

[LittleWatchShop]

When turning staffs, a JKA is invaluable and expensive. Fortunately, I inherited mine. There are crude alternatives to a lathe...like chucking something up in a Makita drill motor and using various grit sandpaper to make a pin. Won't turn a staff that way!! But, you can make a pin.

[nevenbekriev]

Please do not file nothing. I have no time this days and am able to write here only in midnight time, so please wait...

[JohnR725]

10 hours ago, docrpm said:

This is probably one of those circumstances where I could use a lathe to reduce the diameter of the pin, right

 I don't use a lathe to reduce the diameter of the pin I use something else but I'm a bit puzzled as to why is it too big in this particular case is that's extremely big? By some chances as the balance bridge off another watch?

[docrpm]

@JohnR725 The balance bridge is from the donor. I don’t think it’s bigger…It’s probably the same diameter but the center is displaced relative to the center of the hole in the baseplate. Not by much, obviously. What I was thinking of doing was just “shaving” off the smallest amount possible from the side of the pin where I think it’s creating friction. But @nevenbekriev wanted me to wait, so…  

[JohnR725]

3 hours ago, docrpm said:

But @nevenbekriev wanted me to wait, so…

He's trying to tell you something like this isn't really a good plan.

Just a reminder of something when they quote something from the other page when I looked up your serial numbers

Estimated Production Year:    1937

Run Quantity:    4,000    
Grade/Model Run:    310 of 329

Estimated Production Year:    1917  
Run Quantity:    2,000    
Grade/Model Run:    127 of 329

You will note that one of your watches was a batch of 2000 made in 1917 and the other was a batch of 4000 made in 1937.

Then did you notice how the main plate has a serial number the complete serial number? Then all the rest of the bridges have a partial of that serial number and typically the serial number is also scribed on the balance wheel. The problem with manufacturing when these watches were made was that there were variations as you can see the balance bridges do not interchange because they're not of the same batch.

Basically what happens is the main plate is made the bridges are made there assembled together and then the holes for the wheels the jewels etc. are done when everything is assembled as this is the only way they have to get all of the alignments absolutely perfect. Then each of the escapement's and balance wheels are adjusted for each watch.

 

[nevenbekriev]

Yes, what I wanted to say is that the cock is part of the main plate, manufactured together with it and not meant to be interchangeable. Even if the other cock gets in place, it is not sure that the balance then will stay upright.

You should use the original cock when it exists and is not destroyed. The adjustment needed by bending it is not irreversible. It is minimal deforming that is needed. No tools are needed. I have pointed to all needed references here for the balance staff endshake checking and correctness confirmation. The only tool needed for the correction is You thumb. The cock must be fixed on the main plate, no need of special plate with holes and so on. If You will feel more confident, then measure with Vernier caliper the height of the top of the cock where the stones are against the main plate bottom when the shim is fitted and try to reach the same height when bending the cock (with no balance in place!!!) Caliper with screw for fixing is perfect.

 

 

[docrpm]

2 hours ago, JohnR725 said:

The problem with manufacturing when these watches were made was that there were variations as you can see the balance bridges do not interchange because they're not of the same batch.

Yep…This makes perfect sense. With that large a gap in the serial numbers, they were almost certainly machined on different equipment, hence one should have no expectation of any cross-batch compatibility. I’ll revert to the original bridge.

Regarding bending the bridge @nevenbekriev, I’ll give it a try, but I may have to buy some better calipers. My Vernier calipers are only accurate to 0.1mm. Not very accurate. 

[JohnR725]

2 hours ago, docrpm said:

Regarding bending the bridge @nevenbekriev, I’ll give it a try, but I may have to buy some better calipers. My Vernier calipers are only accurate to 0.1mm. Not very accurate. 

Just to refresh my memory why do we need calipers for bending the bridge?

[docrpm]

Calipers are so that I can measure how much I’ve bent the bridge (if at all). I plan on being very conservative in my application of force, and if I’m only bending by tenths of a mm, I can easily imagine not applying enough force to bend it at all. 

[nevenbekriev]

You don't need to measure anything. All You need is to adjust the caliper for the 'thickness' when the shim is placed and fix the caliper not to move. Then remove the shim and  adjust the bridge without shim as to be with the same 'thickness', and not to care what the caliper reads at all.

[caseback]

7 hours ago, JohnR725 said:

Just to refresh my memory why do we need calipers for bending the bridge?

The calipers are meant to give you some confidence if your experience doing this is limited. It can help you by giving a visual feedback/result. I kinda doubt if Nev is using calipers himself 

Edited 30 minutes ago by caseback