Topics

Synchronome amplitude


John Haine
 

I don't know if anyone in this group reads "Horological Science News", but 18 months back there was a small furore in that publication arising from some measurements made on the influence of the mass of the bob on the amplitude of swing.  The person who did the measurements used the results to attack the conventional theory that the amplitude depends only on the resistance and is independent of mass.  I got interested in this and did some analysis of his results and concluded that one primary cause of the variation could be small distortions of the frame caused by the weight of the bobs he was using (which varied from 4 to 15 kilograms!).  Some of the measurements included looking at the movement of the support bracket from which I could estimate its stiffness.  Basically a heavier pendulum would move the pallet down relative to the gravity arm, reducing the effective drop and energy increment.

Now I have a Synchronome I'm hoping to make some measurements myself using a dial indicator once the clock is screwed to a wall, but if anyone finds themselves in a position to make such a measurement it would be very interesting.  For reference I've uploaded a copy of my article to the files section.


Tom Van Baak
 

John,

Your theory sounds right. The support & frame does indeed play a large role. I found this out with a free-standing pendulum and was able to increase the Q dramatically by successively adding lead weights on top of the frame, thereby increasing its rigidity. Therefore one has to be very careful about interpreting experiments where only the bob mass is changed.

/tvb

----- Original Message -----
From: John Haine
To: synchronome1@groups.io
Sent: Sunday, January 27, 2019 2:27 AM
Subject: [synchronomeelectricclock] Synchronome amplitude


I don't know if anyone in this group reads "Horological Science News", but 18 months back there was a small furore in that publication arising from some measurements made on the influence of the mass of the bob on the amplitude of swing. The person who did the measurements used the results to attack the conventional theory that the amplitude depends only on the resistance and is independent of mass. I got interested in this and did some analysis of his results and concluded that one primary cause of the variation could be small distortions of the frame caused by the weight of the bobs he was using (which varied from 4 to 15 kilograms!). Some of the measurements included looking at the movement of the support bracket from which I could estimate its stiffness. Basically a heavier pendulum would move the pallet down relative to the gravity arm, reducing the effective drop and energy increment.

Now I have a Synchronome I'm hoping to make some measurements myself using a dial indicator once the clock is screwed to a wall, but if anyone finds themselves in a position to make such a measurement it would be very interesting. For reference I've uploaded a copy of my article to the files section.


Chris
 

It's odd that precision clock cases never settled on the pyramidal form.

Even the Shortt FP used a weird casting balanced on top of a pipe.

On 27/01/2019 19:58, Tom Van Baak wrote:
John,

Your theory sounds right. The support & frame does indeed play a large role. I found this out with a free-standing pendulum and was able to increase the Q dramatically by successively adding lead weights on top of the frame, thereby increasing its rigidity. Therefore one has to be very careful about interpreting experiments where only the bob mass is changed.

/tvb

----- Original Message ----- 
From: John Haine 
To: synchronome1@groups.io 
Sent: Sunday, January 27, 2019 2:27 AM
Subject: [synchronomeelectricclock] Synchronome amplitude


I don't know if anyone in this group reads "Horological Science News", but 18 months back there was a small furore in that publication arising from some measurements made on the influence of the mass of the bob on the amplitude of swing.  The person who did the measurements used the results to attack the conventional theory that the amplitude depends only on the resistance and is independent of mass.  I got interested in this and did some analysis of his results and concluded that one primary cause of the variation could be small distortions of the frame caused by the weight of the bobs he was using (which varied from 4 to 15 kilograms!).  Some of the measurements included looking at the movement of the support bracket from which I could estimate its stiffness.  Basically a heavier pendulum would move the pallet down relative to the gravity arm, reducing the effective drop and energy increment.

Now I have a Synchronome I'm hoping to make some measurements myself using a dial indicator once the clock is screwed to a wall, but if anyone finds themselves in a position to make such a measurement it would be very interesting.  For reference I've uploaded a copy of my article to the files section. 







Brooke Clarke
 

Hi Chris:

It may be that the glass dome was made in high volume for use on Stock Tickers?
Maybe from the 1860s to around 1910.
https://prc68.com/I/StkTckPat.shtml

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.