What’s wrong with this escapement?

[Crockpot]

Hello everyone, I just serviced this south bend 429 and when I regulated it dial down was -4 seconds per day. Flipped it over and it was like - 1 minute per day. Everything runs well up to the balance but balance was true and concentric. Hairspring sits perfectly between regulator pins.Sufficient endshake. Nothing rubbing. pallet fork snaps back and forth with good snap to either side. I noticed that the balance wheel skips sometimes. With no power on it I spin the balance and it skips and when I flip it over it skips and stops it gets stuck so I have to move turn the balance wheel backwards to get it unstuck. The roller jewel is straight the pallet fork is straight. nothing bent safety dart is straight. It seems like the roller jewel is getting stuck or something. But it’s definitely worse dial up. When I wind it it runs but amplitude and rate drops dramatically dial up. I’ve been trying to figure it out for several days now. I’m stumped! Any help is very appreciated. 

[watchweasol]

sounds odd  can you define the word skips and gets stuck.  how where,   and post a picture for members  to help with the diagnosis     cheers

[kibbler]

Sounds like a jewel, pivot, or end-shake issue to me, but I'm not super experienced.

I'm curious what you mean by "the balance skips sometimes"

It may not be the escapement, if one of the wheels further up the train has an issue, power may not be getting though in some positions.

Edited March 16, 2022 by kibbler

[Crockpot]

The balance wheel gets stuck with no power on the train. It seems like it’s always on the left banking pin when it sticks. The roller  jewel is centered. 0.5 ms beat error. Looking through my 10x loupe the roller jewel is in the pallet fork. Sometimes dial down it doesn’t stick but as soon as I flip it dial up it sticks instantly. The balance wheel spins freely for a few seconds then it stops and bounces a few degrees backwards and sits stuck til a nudge it the other way to free it up. Here’s a picture. My roller jewel is dead center of the banking pins and you can see that the balance arms are cocked to the side when it’s stuck. It’s sticking to the left banking pin when it hangs up. That’s why the balance arms aren’t perpendicular when at rest right now because it’s stuck. It’s really strange.

[watchweasol]

We assume it been cleaned and oiled ?  You have ckeckec the jewels for chip/cracks, the endshake on the pallet/fork and the balance. Is the roller at the right height and not touching the fork.  One thing to try is removing the fork snd check the balance oscillates freely for a few seconds without sticking.  Take the power off brfore removing it.

[Crockpot]

Balance spins freely for about 20 seconds with fork out.Everything looks good I’ve cleaned and oiled it with moebius synthetic oils, and molykote Dx for the keyless works. No cracked jewels. I’m thinking it might be the banking pins making the roller jewel catch at an odd angle or something. I hate to move the pins but tomorrow I might try to bring them out a bit and just see what happens. I’ll let everyone know what happens.thanks

Edited March 17, 2022 by Crockpot

[anilv]

Check that the safety guard on the pallet fork (if it has one) is not touching the roller. Its the middle prong.

Anilv

[Nucejoe]

 Fault at the roller, either the table is not at the height as WW said or even the guard pin as anvil says. 

Excessive end shake also allows the height of roller table vary enough in face up and face down positions  to let the impulse jewel rub on fork.

[Klassiker]

6 hours ago, Crockpot said:

I hate to move the pins

With you there! Did the balance spin freely for 20 sec. dial down and dial up? It sounds to me very much like an endshake / sideshake problem on the balance and / or fork pivots, and almost certainly not the banking pins.

[Nucejoe]

Agree with klassiker, shouldn't touch the bakning pins, not yet anyway, you can easily create new problems .

[Crockpot]

Thanks everyone. Yes it spun well dial up and dial down. I just checked the balance endshake and it’s 0.30 mm by looking with my eye and opening my calipers the same distance I saw balance move. There’s not enough sideshake to even notice.

[Crockpot]

I got the balance endshake Took care of the cap jewels needed tapped in on each side . So endshake is good now. But it still sticks when no power on the train and I move the balance wheel back and forth. Sometimes it freely spins and sometimes it skips a little and sometimes it locks up and I have to turn the balance in the other direction to free it up.  I wound it halfway to see how it does on timegrapher here’s some pictures of what it’s doing. Ones dial up and the other dial down. Amplitudes actually less because of lift angle is 52 degrees and I know the watch is around 42 degrees. I just did it quick to see how it runs.

[watchweasol]

So the mitigating factor is that it sticks when the fork/pallet is in and works ok without the fork, is that a correct assumption. If so then its the relationship between the for/pallet and the inpulse pin roller and balance, Take the power off the watch amd swing the balance and try that du and dd and see if it still sticks. If so its  srrip it down again and just ft balance and fork/pallet and re try.

[Crockpot]

Dial up and dial down pics after moving the right banking Pin just a hair.It might still need a slight adjustment But at least it runs with healthy ticks and tocs now. Thanks everybody for the advice. Hope y’all have a good evening.

[Crockpot]

I think that was making it stick to the left banking pin every time was because the right banking Pin needed to go out just a little. Escapements are very very tricky. i’m sure it’ll go even better when it’s got a full wind.

Edited March 17, 2022 by Crockpot

[Klassiker]

I don't understand why doing what you did worked, but the results speak for themselves. Grandmother and eggs come to mind.

[HectorLooi]

Looking at the regular fluctuations in the trace, I think that there is an issue with the escape wheel.

Maybe the pivot of the escape wheel is bent and when the tooth farthest from the axis reaches the pallet jewel, it doesn't unlock. Moving the banking pin might free it.

[rodabod]

Possibly excessive depth of lock if the banking pin was allowing the pallet stone to enter more deeply than necessary. 
 

It’s worth investigating / observing the depth of lock as it can steal energy from the balance. If you still have issues with the escapement locking up then perform tests to check the “safety action”.