At 04:16 PM 8/1/2007 -0600, you wrote:
>Hi All,    Two new questions from me today.
>
>

>I did a simple test, using various hinges, foil, wire, razor blades and 
>eyebolts.   I could and did see some difference in how long a pendulum 
>would swing free.  I just moved the pendulum 6" and let it go counted the 
>cycles until it stopped.
>Not very accurate, but I could see only about 20 percent different, 
>between what I would call good and better hinges.
>I am not suggesting this test tell the whole story.   So if there is a 
>study I would like to see it or hear about your own testing.   I was 
>surprised there was not a greater different on my test.

Ted,

One possibility that I have heard about in connection with high-performance 
pendulum clocks, is that the mounting points need to be absolutely 
solid.  There can be a considerable loss of energy through 'mushy' 
supports, which might make good hinges appear to perform nearly as badly as 
poor ones.

I would guess that a concrete wall would make a pretty solid mount, though 
a wood one apparently does not.  Or perhaps a rigid steel frame sitting on 
a concrete floor might be good.

Perhaps a year ago someone on the List was doing something similar and 
getting very long decay times, as I recall.

Regards,
Brett


At 04:16 PM 8/1/2007 -0600, you wrote:

Hi
All,    Two new questions from me today.

 

<clip>


I did a
simple test, using various hinges, foil, wire, razor blades and
eyebolts.   I could and did see some difference in how long a
pendulum would swing free.  I just moved the pendulum 6" and
let it go counted the cycles until it stopped.

Not very accurate, but I could see only about
20 percent different, between what I would call good and better
hinges.

I am not suggesting this test tell the whole
story.   So if there is a study I would like to see it or hear
about your own testing.   I was surprised there was not a
greater different on my test.


Ted,


One possibility that I have heard about in connection with
high-performance pendulum clocks, is that the mounting points need to be
absolutely solid.  There can be a considerable loss of energy
through 'mushy' supports, which might make good hinges appear to perform
nearly as badly as poor ones.


I would guess that a concrete wall would make a pretty solid mount,
though a wood one apparently does not.  Or perhaps a rigid steel
frame sitting on a concrete floor might be good.


Perhaps a year ago someone on the List was doing something similar and
getting very long decay times, as I recall.


Regards,

Brett