Pendulum rotation varies hourly

[martinb]

I have recently fixed my first 400 day clock. I think it is an older Haller - it is all metal, no plastic to be seen. It says "Haller" on the dial but the movement just says "Made in Germany". Anyway, having observed the clock for a couple of weeks now, I have noticed that the pendulum rotates further when the minute hand is between 9 and 1 than it does at other times. Apologies if this has been covered before but I searched the forums and couldn't find anything. If I had thought about it, I might have expected greater rotation when the minute hand was descending and a lesser rotation when the clock was working to lift the minute hand. However a peak between quarter to and five past the hour has me scratching my head. Anyone noticed this with their clocks or have an explanation? Something to do with resonance in the spring varying as the minute hand rotates? The only (unsorted) untoward thing I noticed with this clock is that the escape wheel teeth are quite worn. I have attached two videos showing the rotation at different times.

 

[KurtinSA]

Welcome to the message board! I was having a hard time coming up with something that might cause this...just didn't make sense as you indicate about raising the hands. And this is something that seems to happen at a specific range essentially once an hour. But given how power is pushing from the main spring through the wheels up to the escape wheel, it certainly does make sense that when trying to lift the minute hand, the center arbor will have more "work" to do raising the minute hand because it is tied to the minute hand.

Maybe the situation isn't that it turns more between 9 and 1 but rather it is somehow turning less from 3 to 7? I'm thinking there is some interference or binding with the wheels/pinions that interact with the center arbor. That interference is more when the minute hand is going 3 to 7 but less from 9 to 1. The extra interference is drawing additional power so the rotation is less from 3 to 7.

I'm not sure if you took the opportunity to manually move each arbor pair while reassembling the clock. Usually one puts two adjacent arbors between the plates and then gently use your finger to turn the lower arbor to see how they mesh. My guess is that the arbors that mesh with the center one have some tightness. Also, I'm wondering if you were to take the clock apart and randomly put the arbors back in to reassemble the clock, possibly the regions of "extra" rotation might shift?

Anyway, my 0.02!

Kurt

 

[Wayne A]

Somewhere in the gear train, probably in the motion works. Could be burrs on the motion works gears, etc..

Wayne

 

[martinb]

Welcome to the message board! I was having a hard time coming up with something that might cause this...just didn't make sense as you indicate about raising the hands. And this is something that seems to happen at a specific range essentially once an hour. But given how power is pushing from the main spring through the wheels up to the escape wheel, it certainly does make sense that when trying to lift the minute hand, the center arbor will have more "work" to do raising the minute hand because it is tied to the minute hand.

Maybe the situation isn't that it turns more between 9 and 1 but rather it is somehow turning less from 3 to 7? I'm thinking there is some interference or binding with the wheels/pinions that interact with the center arbor. That interference is more when the minute hand is going 3 to 7 but less from 9 to 1. The extra interference is drawing additional power so the rotation is less from 3 to 7.

I'm not sure if you took the opportunity to manually move each arbor pair while reassembling the clock. Usually one puts two adjacent arbors between the plates and then gently use your finger to turn the lower arbor to see how they mesh. My guess is that the arbors that mesh with the center one have some tightness. Also, I'm wondering if you were to take the clock apart and randomly put the arbors back in to reassemble the clock, possibly the regions of "extra" rotation might shift?

Anyway, my 0.02!

Kurt

Thanks. I hadn't thought about it that way. I did spin the arbors by hand as I was reassembling, but only all at once and I didn't notice anything untoward. I will take it apart again and check for binding/tightness more carefully. I'll mark the minute hand position relative to the center arbor before I take it apart and see if the region of "extra" rotation shifts as you suggest.
Sorry the videos didn't make it.

 

[martinb]

Somewhere in the gear train, probably in the motion works. Could be burrs on the motion works gears, etc..

Wayne

Thanks. I will investigate further

 

[martinb]

Links to videos of minimum and maximum rotation

 

[sjaffe]

Try taking the minute hand off and replacing it rotated by 180 degrees. If it behaves the same, it points to the weight of the minute hand which you speculated initially. If it now is the opposite behavior, it is likely something in the gear train (motion works most likely). Hopefully this will help narrow down the possibilities.

Stan

 

[martinb]

Try taking the minute hand off and replacing it rotated by 180 degrees. If it behaves the same, it points to the weight of the minute hand which you speculated initially. If it now is the opposite behavior, it is likely something in the gear train (motion works most likely). Hopefully this will help narrow down the possibilities.

Stan

Good idea thanks. I'll try that first.

 

[TQ60]

Take off all of motion works and see what it does.