Full plate watch, Suitable tool for adjusting & testing pallet stones?

[JohnR725]

10 hours ago, mbwatch said:

Yeah - it's a 42 degree lift angle, measured visually. And remarkably it runs with the same amplitude, a weak 175 for >30 hours. Just chugs along and keeps time in 2 positions. I'll figure that one out another time.

One of the problems with watches made before timing machines and vintage watches would be do they really have to have 300+ degrees of amplitude?

 

 

[Randy55]

On 4/27/2025 at 10:09 PM, nevenbekriev said:

This Potence tool is so ingenious, but actually, the traditional way to do the things is much more simple.

Well I would think that depends on many factors. This was the same Potence clip my father made when he attended the Bulova School after WWII, so maybe it's just that different places teach differently

[JohnR725]

1 hour ago, Randy55 said:

This was the same Potence clip my father made when he attended the Bulova School after WWII, so maybe it's just that different places teach differently

I had to go back and verify what were talking about because I wasn't sure with the terminology what exactly you are discussing. Then yes depending upon where you are on the planet and when you are there is all sorts of differences. When I was in school the instructor George showed me how to make one.  Such a simple device to make and so incredibly useful for 18 size full plate watches I wouldn't think of putting one together without it.

[mbwatch]

Update on this project. Where it was left last week, I was not quite getting an unlock on the entry stone and had to start adjusting it inward.

Following Nev's advice to push it all the way back and then gradually move it out until it had correct action with the escape wheel, I moved it not enough on the first two attempts. First time it didn't lock at all, second time it just barely caught the escape tooth and the watch ran with about 10° of amplitude and the balance merely wiggling back & forth.

I attempted to move it again and the front edge of the entry stone fragmented away. It was possibly fractured during the many reassembly rounds. Darn. Well I have a couple of additional Elgin 18s watches made in the same decade that take the same fork and stones (x546 old style) so I swapped in a different fork with good stones. It didn't lock at all, both stones needing to come out. I removed shellac and starting with the exit stone which was worse than entry, and it also fractured as soon as I grasped it with tweezers to pull it out.

So clearly my technique at pulling pallet stones out is poor. I now have 1 fork with a good entry stone and bad exit stone, and another fork with a bad entry stone and good exit stone. Next step is obvious to combine them and hope not to damage another impulse face.

Otto Frei is so far the only source I have found for Elgin pallet stones, but at $30 that is as much as I paid for both my inoperable 18s movements. elginwatchparts.com does not list separate numbers (nor do ofrei) for entry and exit stones on the older Elgin 18s. Does this mean they are the same stone pointing different directions?

On the bright side, I let the watch run with the broken entry stone and it actually did tick at about 100° of amplitude and no lubrication. So I had at least gotten close with positioning the entry stone before I attempted to swap the forks.

[Neverenoughwatches]

35 minutes ago, mbwatch said:

and it also fractured as soon as I grasped it with tweezers to pull it out.

So clearly my technique at pulling pallet stones out is

Is there no room to feed a driver into the rear of the slot ? Twist it to push out the stone.

[mbwatch]

7 minutes ago, Neverenoughwatches said:

Is there no room to feed a driver into the rear of the slot ? Twist it to push out the stone.

Not that I realized, because I have not done this before. Maybe there's a small bevel at the back edge of the slot that would fit a 0.6mm driver when the stone is pushed all the way back. I didn't think of this. The slot does grip the stone very tightly, it is difficult to get any motion from it except when holding tweezers parallel to the slot and pivoting the stone vertically.

One thing that makes these Elgin forks difficult is that they do not lay flat on a bench block with the arbor seated in a hole. They have 2 "layers" so I'll have to find something to support the crossbar if I pushed with a driver blade.

Need more practice...