Hermle 341-20 escapement question

jkcab95

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Jul 16, 2020
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Hello,
This will be my first post as I am new to the forum. I have been a member off and on and am typically here for watch repair. I am a bit new to clocks as I have only serviced a Seth Thomas mantel clock from the thirties. This is my second clock and it is for a friend. It is a Linden mantel clock from 1972 according to the number on the Hermle 341-20 movement. When I received the clock it had been to a clock shop about 10 years prior and had a tag on it that said not repairable with a $10.00 charge? When I leveled the clock and swung the pendulum it would run for about a minute and then slow to a stop. I removed the movement and inspected it for missing parts and any damage. I could find nothing wrong except it was dripping with oil.

I decided to disassemble it and clean it. I found 1 pivot hole that appears to have been bushed and the rest looked excellent. all of the pivots were in good order along with all the wheel teeth. the pinons were clean and well polished and looked to be in good order as well. I decided to build a spring winder to do the job properly. I am a machinist mechanic with a well equipped shop and a former cabinet maker (ie I posses some skills). My son and I are both hobbyist watch makers and restore mostly wrist watches from the 20s - 70s.

The Hermle movement has three barrels and two of the are #40s and one is a #41. The #41 for the chimes had a nice spring that was about three times the barrel diameter when removed. The two #40s look to be a bit tired. They were all dripping in oil. I cleaned every thing by hand in Naptha as I did not want to remove any lacquer from the plates. I pegged all the pivot holes and inspected them with a 20x loop. All the wheels and small parts were cleaned in the watch cleaning machine. The springs and barrels were cleaned by hand and lubed with synthetic oil, wound tight in the winder and the excess wiped clean with a lint free cloth then re- inserted into their respective barrels.

I planed to replace the two #40 springs as I suspect they would not have enough reserve as they looked a bit tired. I wanted to make sure the clock would run reliably before investing money in them. I assembled the clock and lubed the hidden pivots as I assembled with HP1000 , it is probably overkill for a clock but it is what I have. It is the appropriate viscosity and a good choice considering the size of the pivots. I made a mount to set the movement in the bench vise for test run and then installed the time barrel only. I leveled the movement, hung the weight and set the pendulum in motion. The pallet fork and escapement look to be in proper alignment and the escape wheel advances as it should.

Now here is the problem. The amplitude seems a bit anemic and it ticks for about a minute as it slows to a stop. The pivot support for the pallet fork and pendulum has two slotted holes for mounting. I assume it is for adjusting the engagement with the escape wheel? I am not sure what the adjustment procedure is for this and or how critical that adjustment is? I was able to return it to the position it was in prior to disassembly as the plate is stained from over oiling and I could see the imprint of where it was. This movement is 11cm and I am not sure if that measurement is from the pivot point to the center of the pendulum or the bottom? I do not know if the height of the pendulum was messed with by someone else and I assume it needs a gross adjustment prior to timing the clock?

I have not oiled the exposed pivots yet as typically we start a watch after cleaning and run it dry for a few minutes to make sure everything is in order before oiling. If you oil a watch and then have to remove something you break the surface tension on the oil and have to clean the parts again and oil again after assembly. I assume it is not as critical for a clock but I like to be precise and through as possible. If you are going to spend the time to restore something I would like the time to reflect some value. A poorly done job is just a waste of valuable time. I would rather have spent the time to do the job completely and only accomplish one thing then to have two jobs done and both are inadequate.

As I mentioned earlier I am not well versed in clocks and am having difficulty finding the appropriate information to aid in diagnosis. I am not sure if this system is specific to Hermle or the proper nomenclature I should use in my search? I have a copy of the service manual but it provides little information of value except what to oil and what to grease!

Any help someone could provide or a direction to head would be greatly appreciated,

Jeff K.
 
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wow

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Jun 24, 2008
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Most of us recommend not using any oil at all on the escapement. Clean it well with naptha and/or denatured alcohol and it should rotate about 2 minutes on its own when mounted in a vice. It must be set in beat like other escapements once back in the clock. Adjusting the forks distance from the wheel is critical also.
 

jkcab95

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Jul 16, 2020
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Most of us recommend not using any oil at all on the escapement. Clean it well with naptha and/or denatured alcohol and it should rotate about 2 minutes on its own when mounted in a vice. It must be set in beat like other escapements once back in the clock. Adjusting the forks distance from the wheel is critical also.
I did not oil any pivots as yet and typically you would not oil the anchor pivots on a watch either. I believe your comment about anchor to escape wheel distance may be the issue. my question is where to start and what does that adjustment look like?
Thanks,
Jeff K.
 

Willie X

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Feb 9, 2008
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Wow,
This is a pendulum clock.

Jeff,
The pallet distance is a straight foward adjustment. It has to be correct and the pallets themselves have to be in good condition. Look up 'adjusting Hermle escapements'.
A Hermle this old would most likely have a lot of wear. The wear can be all the way from the spring barrels to the escape wheel. It's usually 'general wear'. That is, a lot of wear in a few places and moderate to slight wear in a lot of places.
The springs will not the problem. Although at that age they would surely need to be stretched out and cleaned up (serviced).
Good luck, Willie X
 

Dick Feldman

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It is common practice to zero in on escapements and main springs as culprits.
Most commonly, like Willie mentioned, the root problem is lack of power due to loose pivot holes.
Mentioning how much wear is tolerable may bring a firestorm of comments.
I am of the school that no wear is tolerable for a quality, long lasting rebuild.
This board is populated by all levels of clock repair people and you may get some less than quality advice here.
Best of luck with your clock,
Dick
 

jkcab95

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Jul 16, 2020
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Willie,
I find it a bit difficult to quantify the amount of wear as I am not familiar with clocks. That being said I have worked on a few 7 jewel pocket watches and know when they need to be re bushed. What I find interesting is the most wear I see is in the first wheel after the spring barrel in the strike train. The time train looks really good to me. There is very little side shake and sufficient end shake. All the pivot holes in the time train are surprisingly round. I can say that they look better then the pivot holes of the 1938 Seth Thomas clock I did and it has been keeping time for almost three years since I worked on it. I think I had to put a bushing on either side of one pivot. There were a couple that I thought were borderline but thought I would do them on the next service since it was my clock. I will heed your advice and see if I can find some info on adjusting Hermle escapments.

Dick,

I agree in principle but there will always be some acceptable wear. I work on machinery that spans from the 1920s all the way up to a few years ago. Most parts are unobtainum and I need to make them. My work life is about assessing acceptable wear.

Thank You both for your comments. i will keep you abreast of my progress.

Jeff K.
 

Willie X

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Feb 9, 2008
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All the '2nd wheel arbor pivots' are suspect. It's more often bad on the pinion end but can be bad on both ends. The chime side is usually the first to go but there is no set wear pattern.

All 12 mainspring barrel wear points are also suspect.

Maybe you could post some close-up photos? Or, better still, a video of the suspected areas being forced forward and back (using hand pressure) with the main-springs all let down.

Willie X
 

jkcab95

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Jul 16, 2020
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Here is an update on where I am at. First I'd like to say thank you for the help. I did some research on recoil escapements and how to adjust them. I found several pieces of advice that where the same so I gave them a try. First I confirmed I had at least a half tooth of space just prior to drop and I moved the center spacing closer until the exit pallet would not unlock. I then slowly adjusted the anchor up until it just unlocked. It took a few tries to get it right and have equal drop on both sides. Once every thing seemed good and the movement was level and in beat I decided to order new springs from Time Savers. I was a bit disappointed as they did not appear to be alloy springs however they were better then tired springs. I sure am glad I decided to make the spring winder as I got my use out of it already! I ran the clock for 24 hours and all seemed well.
I decided to put the strike and chime train barrels in place and realized I had put the chime second wheel in upside down! I had to do some dis assembly to fix it and was able to finish the assembly. I then oiled everything and gave it another bench test and everything works. I placed it back in the case to run it and regulate it.

Now I am wondering if there is some adjustment I missed and someone might be able to direct me here. When the clock reaches strike time and or time chime on the quarter or hour it strikes two minutes early? The minute hand is square broached and not adjustable. It has a threaded end on the arbor and a nut to hold the the hands on. I can not see how it can be adjusted unless I need to rotate a snail on a shaft?

Thanks,

Jeff K.
 

Willie X

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Feb 9, 2008
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Photos are important. Otherwise you only get guesses.

My guess is: the hand is mounted on a brass hub/collet and can be turned with the right tools.

And, save the original springs, you may need them ... they are likely better than what you just installed. :rolleyes:

Willie X
 
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jkcab95

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Jul 16, 2020
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Ah! You are correct and under the microscope it appears as if someone might have used Locktite instead of re staking it in the correct position. I put it in the ultrasonic and we shall see. I used the square end of a tap in the hand vise and no go. I will try again when it emerges from the ultrasonic I may have to do an acetone soak and then properly stake it and lacquer it when done. They appear to be polished brass.

Thanks
 

jkcab95

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Jul 16, 2020
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Ok,

The ultrasonic did the job and I was able to rotate the collet to the correct position. It is polished cleaned and complete. I just need to regulate but it is keeping good time at the moment. Time will tell! I am attaching a few photos. One is of the over oiled movement at the beginning of dis assembly and tow of it finished.

Thanks again for the help,

Jeff K.

hermle341 20.JPG linden1.JPG linden2.JPG
 
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