Why so slow?

Ken M

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Feb 28, 2009
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I have two clocks now that run like snails, the Kundo basket case and now the Coehler. I get just over 180 rotation, and it takes so long to get there, I'm surprise it keeps going. They are painful to watch. I've been scratching my head on the Kudo for a while, now this one. Why do they run like that? It's like the spring is light and just can't give it a kick that it needs. But it's what the book calls for. Frustrating.
 

KurtinSA

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Know that these clocks typically take 7.5 seconds to go from one stop to the other stop...that works out to be 8 beats in 60 seconds. So, if the distance is only 180 degrees, the speed of the rotation has to be slower to cover that smaller distance in 7.5 seconds. If the rotation distance is 360 degrees, then the speed is going to be faster because it has to cover the total distance in the same 7.5 seconds.

It's not about the speed, it's about making the distance in 7.5 seconds and have a reasonable amount of over swing.

Kurt
 

Ken M

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I'm guessing the strength of the spring and weight of the pendulum determine the speed and distance. My Kerns are very similar to these other two and do just fine. So do ALL Kundos crawl? Coehlers?
 

KurtinSA

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I wouldn't think that they are designed to be that slow. I think it has to do with not extracting enough power to make the clock have more rotation and a faster speed.

Kurt
 

Schatznut

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I did some experiments with a Konrad Mauch I inherited from my grandfather. Per directions in Joseph Rabushka's book, I moved the fork down as far as it would go without fluttering. The clock ran perfectly with no more than about 180 degrees of rotation (that's only a half a turn end to end). Then I moved the fork up as far as it would go and continue to run reliably. It ran well with probably 400-420 degrees of rotation. I backed it down a bit and it is running happily with about 375 degrees of rotation. The constant in all this is the number of beats per minute. Kurt is right - it's about the period of oscillation, not the amplitude, as long as it's in beat and there is sufficient supplementary arc.
 

Ken M

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I did this afternoon, moved the fork way down. Got a little more rotation. I'll try moving it way up tomorrow and see if I can find that happy medium. Without the anchor, it will freewheel on just a few clicks. I wound it up a bit and just let it spin for a while. I think it can do it, it just doesn't want to.
 

Schatznut

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I did this afternoon, moved the fork way down. Got a little more rotation. I'll try moving it way up tomorrow and see if I can find that happy medium. Without the anchor, it will freewheel on just a few clicks. I wound it up a bit and just let it spin for a while. I think it can do it, it just doesn't want to.
I'm sure it wants to, it just can't - something is preventing it. Finding that something is going to be an interesting journey.
It may seem counterintuitive, but moving the fork down decreases the total rotation. See how far down you can go without getting flutter. Then go the other way until it won't run reliably. That's your working range. Pick a point somewhere in the middle.
 

shutterbug

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A couple of things here. The distance of travel on a torsion clock (rotation) doesn't affect time keeping. The rotation time will be the same.
The thickness/width of the suspension spring, it's length, material, and the weight/adjustment of the pendulum are all important. For the most part, an adjustment of .0001" in thickness will change the timing by four minutes per hour. There is usually 4 minutes per hour adjustment on the pendulum too. Thicker will make the clock run faster. Thinner - slower.
Usually, if the suspension spring matches the manufacturer's recommendation, the pendulum is in question - but not always.
Another good thing to know is that raising the fork will increase the rotation amount, but will decrease the over swing. Lowering it has the opposite affect. Fluttering while running usually is because the fork is too low.
 

Ken M

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I raised the fork to the top of the anchor pin, it was no better so I put it way low again. This is as good as it gets, agonizing. I don't believe it will run long like this.
 

Wayne A

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Well that is a little weak but it is running which is kinda impressive. Just have work through the clock to find where the power loss is, or possibly a few small power losses which can add up quick.

Wayne
 

Schatznut

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It's running fast.....?
It may sound counterintuitive, but running fast is a symptom of a clock that has marginal power or excessive drag in the mechanism. When you were into the clock before, what all did you do to it? Did you overhaul the mainspring?
 

shutterbug

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It would help us to know how much time it loses per hour.
 

Ken M

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It's gaining, it runs fast. It's gained 35 minutes since yesterday afternoon. I'm afraid if I make it go any slower, it will just stop. I'll dig into it again. As I said before, the train runs smoothly on just a few clicks without the anchor....guess I need to look at that anchor.
 

marylander

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Hi Ken, the older Kundo clocks normally turn between 180º to 270º. So it is normal if you clock turns only 180º.
From the video you provided, it looks that the pendulum turns less than 180º. I think if you have done all the cleanings and pendulum still turn small angles, you may need to check the following:
a. bent pivot,
b. fork gap too wide or too narrow. Too wide will loss power transfer and too narrow will bind the move.
c. twisted suspension spring. A new suspension spring will give you higher degree turn than twisted spring.

I have heathy late 1940 Kundo clock only turns about 180º.
Ming
 

shutterbug

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What size suspension spring is in it now? Is it a genuine Horolovar?
 

Ken M

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I raised the fork back up to about where the book says. It's running pretty well with about 220 rotation. I don't know why, might just be my perception. Most my clocks are quite active, then something a little slower looks a lot slower...
 

KurtinSA

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How many degrees of over swing do you have? I generally find the book position of the fork to be too high...I usually end up lowering it by at least a couple of mm before I can get a clock to run. The higher the fork, the more power it takes to run.

Kurt
 
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Ken M

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I went and watched the pallets, they were landing on the slant (what do you call it?), so I raised it a little. Looks good, I'm getting about 270 rotation, and about 45 over swing. Looks real good!
 

KurtinSA

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The "slant" is the impulse face of the pallet. Hmmm...I would have lowered pallets to correct that situation.

Nonetheless, 270 degrees of rotation and 45 over swing is pretty darn good!

Kurt
 

Ken M

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I thought about going into the pallets. But earlier when the fork was in a different position, the pallets were landing different. And when I was watching them, they came really close to fluttering. Or are the teeth "landing" on the pallet?
 

shutterbug

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Now that it's running, can we see a pic of the back plate, and please let us know exactly how much time it gains in 24 hours.
 

Ken M

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It looks like 1239 except for that center hole that I don't have.
1627053174080.png
 

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