Sympathetic Vibration

[Steven Thornberry]

We've had several threads dealing with sympathetic vibration in longcase (grandfather) clocks. Has anyone ever experienced the same in other weight-driven clocks? I am thinking specifically of an S.C. Spring 8-day column and cornice that I have. Periodically, but not always, I find that it stopped after about 6 days. I start it up and it will either remain running until I crank up the weights or stop again after some hours. Although I have not ruled out other causes (e.g., tangled cord, weight scraping backboard), I just wanted to sound out some of the more experienced to see if this might be a case of sympathetic vibration. It currently stands on a small chest that is fairly level front to back, as well as side to side, and the clock is in beat. I have attempted to stabilize temporarily with a piece of thick polystyrene foam, while I hunt out a piece of wood. The movement itself is in good shape, although there may be problems I am unaware of.

 

[doug sinclair]

Over the years I have found that sometimes, worn, loose bearings on the pallet arbor pivots can cause clocks to behave in odd ways. We don't always think of these bearings a wearing out, but they do. And when the pivots are rocking back and forth in their bearings, this robs power that is required to keep the pendulum moving. This problem can be magnified if the case begins to "teeter" a bit.

 

[hoo-boy]

I've been told, read that 2 clocks placed side by side will have their pendulems synchronize with each other , has anyone first hand knowledge of this or is it just....kinda like sympathetic vibration don't cha think?..hoo-boy

 

[shutterbug]

I've been told, read that 2 clocks placed side by side will have their pendulems synchronize with each other , has anyone first hand knowledge of this or is it just....kinda like sympathetic vibration don't cha think?..hoo-boy

Yeah, if memory serves, Harold had an experience like that. Use search, you'll find it

 

[Dave B]

I have a pair of Ogee 30 hour clocks that sit side by side on a bureau. If I run them both at once, they will do that. I suspect what is happening is the bureau is moving ever so slightly.

 

[lamarw]

My question is: Would it affect only one clock or would it have an affect on both clocks stoping at at various times?

In an attempt to explain myself, would you get both clocks running and one would stop and then later when you get both clocks going would the other one stop? Meaning Clock A would be affected by Sumpathetic Vibration and later would Clock B suffer from Sympathetic Vibration.

I guess I am having trouble with this concept.

 

[Scottie-TX]

Of those hanging here, none has exhibited a trace of SV similar to a tall clock. Each has their idiosyncrasies, but none yet, SV.
'Course viennas - and more especially mine on very low power - have VERY small osc. amp. so very little air turbulence can be produced and I'm thinking that turbulence may have a lot to do with what we describe as SV.

 

[Bill Ward]

There was recently an article in the Horological Science Newsletter, where the author measured the motions caused by a a swinging pendulum. The upshot was that sympathetic vibration problems can be caused by very small motions indeed (MUCH to small to be visible with the unaided eye) and that things normally thought to be pretty immovable (like buildings) move a lot more than you might think. For example, some people found that they couldn't work on the upper floors of the World Trade Towers (before they came down) because they got seasick during periods of high winds. I myself witnessed coffee being mysteriously slopped over the side of a cup, sitting on the desk, on the 80th floor. I had no sensation of motion at all. So, just because you don't sense the motion doesn't mean it isn't there.

 

[Scottie-TX]

Can you elaborate: "motions were measured". What kind of motions were measured?