Help wanted on Kern & Sohne midget, plate 1350...

pgram

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Mar 12, 2011
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I'm trying now to restore a Kern & Sohne midget, plate 1350.
It has been dismounted, mainspring and suspension replaced, and lubed.
It works, but after some time it stops.
I have been trying to raise a bit the fork since the clicks were just 30 degrees on each side and the overswing was only 15 degrees at best.
Now the clicks are very far apart, about 135 degrees on each side, and the overswing is at the beginning nearly 60 degrees, but then reduces gradually.
after 10 - 15 minutes, the clock stops.
I'm attaching a video of the pin escapement working, and of the oscillation of the pendulum.
The hands are not installed yet.
Maybe I raised the fork too much?
Here is a video of the anchor working:
And here is a video of the pendulum while rotating. The clicks are at 135 degrees on each side.
Any advice will be really appreciated!
 

Wayne A

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Sep 24, 2019
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Escapement action looks good to me. I'd lower the fork a little to get more overswing especially if the mainspring if fully wound at this time.
 

KurtinSA

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Nov 24, 2014
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It seems to me that the entrance drop is bigger than on the exit side. Certainly I see the gap between the pallet on the entrance side grow to bigger than when it drops off the exit pallet.

Kurt
 

MuseChaser

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Feb 5, 2019
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It seems to me that the entrance drop is bigger than on the exit side. Certainly I see the gap between the pallet on the entrance side grow to bigger than when it drops off the exit pallet.

Kurt
I noticed that the entrance drop was larger than the exit drop, too, significantly, but I don't have enough experience to know how to best address it on a pin pallet... or even if it's significant enough to need addressing. It also looked like the clock is still slightly out of beat, based upon watching when the spring twist stops and reverses in the video showing the escape... but it's obviously very hard to know that way. As Wayne said, lowering the fork will get you a bit more overswing that may help overcome a small issue, at the expense of a bit of total rotation.
 

Wayne A

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Sep 24, 2019
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Since its a pin pallet and the locks look good I'd not worry to much about the drops since trying to adjust the eccentric to even up the drops will likely cause the locks to suffer and I'm not a fan of bending those pins as an adjustment.

Cannot see the pin position during the escapment action to know if anything need be adjusted there.
 

pgram

NAWCC Member
Mar 12, 2011
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Loiano, Italy
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Hi All,
Thanks for the advice. Lowering the fork solved the problem; it took three attempts to find the right spot.
I prefer not to alter the drops since there is no eccentric, and I'll not bend the peninsula If I can avoid it.
Now the clicks are nearly equidistant (nearly 130 degrees), and the overswing is about 25 degrees on each side; the clock has been running for more than two days with no variation.
Now I'll install the hands and see if there is any variation due to the spring's friction.
Maybe I solved it; now, I'll go for the next...
 
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