Lenzkirch problems. Wrong spring?

berntd

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Hello,
I thought this Lenzkirch clock I repaired was good to go.
I was wrong.

It stops after ~5 days and always 10 past the hour.
The cause is that the strike/chime does not have enough power left to start.

The spring is run down.
I can see that this spring can only wind almost 7 half turns of the key.
However, the clock spring can wind over 13.
Almost double.

I think this has to be the wrong spring.
It has not been shortened as the barrel is very full.

Does anyone know how I can work out the correct spring for this clock strike barrel?

Did Lenzkirch use identical springs for clock and chime/strike?

Both barrels are the same size.

The movement is marked Lenzkirch 52


Best regards
Bernt

20220812_143815.jpg 20220812_143830.jpg 20220812_145615.jpg
 
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shutterbug

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Is the hammer trying to lift during the warning run?
 

Willie X

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The shorter/thicker spring will usually be on the strike and is normally wound less turns (maybe much less turns) than the going train.

If you want to figure it all out, look up 'Willie's turns of power'. Everything to do with the springs can be worked out experimentally.

Willie X
 

berntd

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Thanks Willy.
I will check it out today and see what I come up with.

In the meantime I manually ran the strike for 24 hours and rhe barrel makes exactly 1/2 turn.
So it needs at least 8 half turns for 8 day operation and it currently cannot wind 7 even.
I am sure this is a problem.

To remove that spring, I will have to machine a special thin wall sleeve. None of mine fit because that barrel is very full.

This came to me in poor conditiom with several other previous "repairs" and scratch numbering on barrels wheels etc.

Regards
Bernt
 
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Uhralt

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No. I fixed all those issues already as per my previous thread.
The train not start at all and the spring is completely down.
If the spring is completely down when the strike stops it means it has plenty of power. The strike will probably work well with a weaker spring. I would try a thinner spring and calculate the optimal length using the "Spring Calculator".

Uhralt
 

Willie X

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It can't run until the spring is "completely down".

I think this point needs some clarification.

How many turns are left when the strike stops? There is a completely let down position (with a let down tool) and a position where the striking stops running position.

Willie X
 

berntd

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Willie X
About 1/2 turn is left when I say it is "completely down" by running.
But from let down, full zero, it can only wind almost 7 half turn or 3.5 turns.

Uhralt
I will check that out.

This current spring is very strong.
I will remove the barrel next to obtain dimensions.

Regards
Bernt
 

Willie X

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If you were using 'Willie's turns of power' you would probably be looking for a thinner spring that would provide about 5 full turns of power. The 'turns of power' starts at the point where the spring shuffells in the barrel, when winding from the completely let down position. You can assume about 2 extra full turns, so close to 6 complete turns from fully let down would be about right.

There is a possibility your problem is due to a spring that is simply to long. Any extra spring past the 3/5s full barrel rule will actually shorten the run time. It's certainly worth a try to shorten it to the proper length and recheck. You can cut and try, or use the formula Uhralt mentioned to find a good length for the spring you have there.
Willie X
 

berntd

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I have the barrel out.
Here you can see the spring. The barrel is pretty full.

Too long?

The spring is ~0.50mm thick.

I will make a sleeve next for my winder so I can remove it.

20220814_110925.jpg 20220814_110938.jpg
 

Willie X

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Not off that much. Looks like its been there a while too.

A good experiment would be to see how it goes with the other spring. Many German clocks have a strike spring about 2 thou thicker than the going spring.
Willie X
 

berntd

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Ok, sleeve made and spring removed.
This spring is seriously domed. Someone must have fitted that without a winder.

It definitely has been adapted from something else. I can see file marks and signs

I am not sure what next
?

20220814_122153.jpg 20220814_122201.jpg
 

Willie X

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Measure the thickness of the going spring, or better still, just give it a try as already suggested. Willie X
 

berntd

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Measure the thickness of the going spring, or better still, just give it a try as already suggested. Willie X
Time spring is 0.38 thick.
It looks like this.

I am not sure how to try that in the strike as it also needs the clock to run to rest.

20220814_131248.jpg
 

berntd

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I have swapped the barrels.
Unfortunately the strong strike spring slipped on the barrel pin now and deformed the barrel. It will no longer wind. That is why I hate repeated disassembly. Stuff breaks.

Anyway, as suggested, the original going spring is in the strike.
It starts the train and strikes with just one full turn of winding.
This seems to indicate that this spring could do the job.

It can wind 13 half turns from zero which is 6.5 full turn. That is ample for 8 days.

What now next?.
 
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Willie X

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Just put it on the strike side, you can trigger the strike manually.

If it will run the strike properly, the springs may well have been the same thickness.

To test, with the .38mm spring installed on the strike side. Wind it until you hear/feel the shuffle, then see if it will run the strike (at a decent speed) at the shuffle point. If yes, wind it up fully while counting the turns, this will give you the run time for that spring. That is, 5 full turns will run your strike for 10 days, 4 1/2 full turns 9 days etc.

If it's sluggish at the shuffle point, the spring will need to be a little thicker.
A little thicker would be ~ .42mm.

I'm getting a little ahead of the game but I think you see where this is going ...

Good luck and good night, Willie X
 

berntd

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For interest, I just entered the following into the spring calculator here:
Nawcc Spring Calculator Link

Barrel ID: 1.582
Arbor OD 0.5285"
Turns 6.5

It gives:
Thickness 0.0191" = 0.48mm
Length 45.7" = 11612mm.

Can that be trusted?

The length of what was in there was at least 1450mm. I could not measure the very inside turns.

For thickness, I tend to agree with WIllie that 0.42 is likely enough.
I am not sure how to work out the length for that.
 

Willie X

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Some like calculations, I go completely by actual measurements and experiments.

Facts are, you will need 4 turns of power to run your clock for 8 days, plus about 2 turns to get you into the 'turns of power' region where you have good power. Two turns (estimated) but easily known by experiment (shuffle point, already mentioned).

Question is, how thick does the spring need to be? You know it can't be .50mm, (your actual measurement). So, you will need to go thinner but .48mm is not really noticably thinner ...

You may have the answer right there under your nose, the other spring. Easy to give it a try and see what happens. If it runs the train but slowly, you will need something around 42 to .44mm, any thicker and you will be back in the same box you're in now ...

Willie X
 

berntd

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The problem is determining the new, correct length.
I already know now that I need a .38 or .43 spring.

Best Regards
Bernt
 

Uhralt

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The problem is determining the new, correct length.
I already know now that I need a .38 or .43 spring.

Best Regards
Bernt
Using your barrel dimensions and assuming a thickness of the spring of 0.40 mm the optimal length would be between 1075 and 1350 mm.

Uhralt
 

berntd

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Using your barrel dimensions and assuming a thickness of the spring of 0.40 mm the optimal length would be between 1075 and 1350 mm.

Uhralt
Thank you. could you work that out for a 0.50 mm spring too? Just to see if this here current spring should be shorter.

Regards
BErnt
 

Willie X

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I know I mentioned that your old strike spring might be to long but after seeing the photo, that is not your problem. That spring is toast and meaningless to the conversation.

Did you try the .38mm going spring yet. It needs to be checked anyway, if you plan on putting this clock back into everyday operation. Willie X
 

berntd

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I know I mentioned that your old strike spring might be to long but after seeing the photo, that is not your problem. That spring is toast and meaningless to the conversation.

Did you try the .38mm going spring yet. It needs to be checked anyway, if you plan on putting this clock back into everyday operation. Willie X
Yes I have, as mentioned above in post #19.

That is why I am already trying to work out the length for a new spring.
 
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berntd

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OMG, I just discovered something else - maybe.

How wide should spring be in a barrel?
This old spring is 22.2mm (7/8") wide but the barrel is 24.5mm from bottom to cover on the inside.
Should this then not have a 24mm spring?
 
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Uhralt

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OMG, I just discovered something else - maybe.

How wide should spring be in a barrel?
This old spring is 22.2mm (7/8") wide but the barrel is 24.5mm from bottom to cover on the inside.
Should this then not have a 24mm spring?
This little difference in width wouldn't be significant. Differences in thickness make much more of a difference in power.

Uhralt
 

Willie X

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A good rule is, the spring needs to be 1mm shy of the minimum space available. This is sometimes at the arbor bushing.

The length can be easily calculated but there is NO calculation for the strength/thicknes.

Many of the suppliers charts will give you the necessary barrel size for the spring in question. So, all you need to do is, pick the thickness/strength and look at the barrel sizes. The length and the width are a given.

Willie X
 

berntd

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...So, all you need to do is, pick the thickness/strength and look at the barrel sizes. The length and the width are a given.
Would you go for 22mm or 24mm width? I checked the other barrel spring is 23.3mm wide. Man!.

None of the springs listed on the Timesavers chart are for a 40mm barrel. :-(
Only 43 or 45.

This would not be a problem if I were in the USA and had easy access to stuff.

Regards
Bernt
 

Willie X

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Either would probably be fine. The 45mm barrel one will be a little long but it's easy to cut it back, if necessary. A 10% variance (from the ideal length) will only make a slight difference. A 5% variation, no difference at all. Willie X
 

berntd

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Hello all,
The saga continues...

I have the new spring(s).

This is a 26 x 0.40 x 40 spring. It is for a 40mm barrel.
I opened it up and measured the length. It is 1620mm (!).
This is even longer than the old one that did not work (1500)
The NAWCC spring calculator reckons the spring should be shorter at about 1200 -1300 mm.

I installed it anyway and I can get 12 half turns or 6 full turns out of it from zero to full wind.
It is certainly an improvement.

Should I shorten it?

It is in now and I will try it out but I think it may still not have enough power turns to operate for 8 days.

Regards
Bernt
 

Uhralt

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Hello all,
The saga continues...

I have the new spring(s).

This is a 26 x 0.40 x 40 spring. It is for a 40mm barrel.
I opened it up and measured the length. It is 1620mm (!).
This is even longer than the old one that did not work (1500)
The NAWCC spring calculator reckons the spring should be shorter at about 1200 -1300 mm.

I installed it anyway and I can get 12 half turns or 6 full turns out of it from zero to full wind.
It is certainly an improvement.

Should I shorten it?

It is in now and I will try it out but I think it may still not have enough power turns to operate for 8 days.

Regards
Bernt
Just let it run until it stops. If you get full 8 days of runtime, there is no need to shorten the spring. Otherwise shorten it to 1300 mm.

Uhralt
 

Willie X

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You have to go by how much space is left in the barrel. Though longer, it's also thinner, so you could have more space.

If you post a photo most can tell you if it's to long.

The calculation might be close, or not. So, I wouldn't even think about cutting it back to 1300mm all at once. A little past the 3/5s rule will allow for a couple of repairs, if and when the hole pulls out.

Willie X
 

berntd

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Right now, it is operational. Let's see how long it goes for.
I have it on the Microset Strike test.

It is a vast improvement and it winds beautifully, just like the other side.

Regards
Bernt
 

berntd

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Hello all,
Here is another update:

With the new 0.40mm spring, the clock strike operated correctly for exactly 8 days. It actually stopped in the same hour as when I started the test.

I have now re-assembled it into the case again and it will test for another week.

I am cautiously optimistic.

Another problem with that old spring was the terrible dome. That pushed into the barrel cover hard and wore a groove there over time. This could also have prevented the spring winding further. I have machined that smooth again.

Personally, I would have liked it to go for a it longer than just exactly 8 days. The train has some spots in it where it will just not run with the remaining spring power after 8 days. Not the hammer weight.

Best regards
Bernt
 
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Uhralt

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Hello all,
Here is another update:

With the new 0.40mm spring, the clock strike operated correctly for exactly 8 days. It actually stopped in the same hour as when I started the test.

I have now re-assembled it into the case again and it will test for another week.

I am cautiously optimistic.

Another problem with that old spring was the terrible dome. That pushed into the barrel cover hard and wore a groove there over time. This could also have prevented the spring winding further. I have machined that smooth again.

Personally, I would have liked it to go for a it longer than just exactly 8 days. The train has some spots in it where it will just not run with the remaining spring power after 8 days. Not the hammer weight.

Best regards
Bernt
Shortening the spring about 20 cm should give you more runtime and a little more power.

Uhralt
 

JimmyOz

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Why do you want it to run more than 8 days, anything past 7 days is by design so if you forget to wind it on the 7th day it gives you a bit more time so your clock does not stop, letting it run 8 days or more will give your memory a workout. Whatever day you chose to wind the clock becomes a routine every 7 days.
 
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