PSN-L Email List Message

Subject: Re: Anniversary clock spring
From: tchannel1@............
Date: Sat, 15 Dec 2007 17:27:01 -0700

Les,   I think some of the others may answer this better than me, but I =
would suspect this would act the same as other sensors:

The movement of the earth resulting from an earthquake, will move the =
entire apparatuses, and the room it is in.  However the mass at the ends =
of the inverted T will move less, relative to the sensor and the room it =
is in.

Ted
----- Original Message -----=20
From: Les LaZar=20
To: psn-l@.................
Sent: Saturday, December 15, 2007 5:01 PM
Subject: Re: Anniversary clock spring

How would a seismic wave, passing by an inverted T torsional balance, =
impart any torsional motion to the horizontal bar and the masses?  Just =
wondering.

Les LaZar

----- Original Message -----=20
From: Connie and Jim Lehman=20
To: psn-l@.................
Sent: Saturday, December 15, 2007 2:56 PM
Subject: Re: Anniversary clock spring

Ted--there is some neat physics in the inverted T torsional balance. =
The increase of period with increased masses added makes for a nice =
graph in a physics lab, and there are related aspects of interest.  =
Perhaps stability would be a big problem, but set it up with a damping =
mechanism, and give it a try.         Seasons Greetings    Jim Lehman
----- Original Message -----=20
From: tchannel1@...............
To: psn=20
Sent: Saturday, December 15, 2007 1:40 PM
Subject: Anniversary clock spring

Hi Folks,  This is an observation and a question.  I have an =
Anniversary clock, perhaps also called a 500 day clock, as you only need =
to wind it once a year, or so.   I know very little about clocks, but =
have worked on a few clock movements and escapements.   I have some old =
clocks which are 8 day movements.   I wondered why the big difference in =
power consumptions, and spring properties between the two types.

The 8 day movements use a short pendulum which is maybe 1/2 second =
natural period.  The anniversary clock has a short spring, instead of a =
pendulum, which is  like a flat thread.  This spring is fixed at the top =
and has four masses, brass balls on the free end.  One period of this =
spring is about  8 seconds.   The mass in motion, twist the thread like =
spring, until the power of the spring stops the mass, and swings it in =
the opposite direction.  A different coiled mainspring then add a kick =
to the mass and the cycle repeats.

Always looking for different ways to obtain a 20 second period, I =
took a band saw blade, cut it and suspended it from my shop ceiling.  It =
now hangs similar to the thread like movement spring of the anniversary =
clock.  At the bottom of the 72" band saw blade, I attached a 36" =
yardstick.  This now looks like an inverted "T".   I added a mass to =
both ends of the yardstick.  I twisted the spring and released it.   I =
found it rotated back and forth and it period was about 8 seconds.  I =
keep adding equal mass to both end of the yardstick, and the period was =
24 seconds.

The yardstick seems to always come to rest at the same point, as =
the spring wants to untwist.

My question:  Has anyone tried this approach?   If so,  could =
anyone direct me to more information about it on the internet?

Thanks, Ted

Les,   I think some of the = others may=20 answer this better than me, but I would suspect this would act the same = as other=20 sensors:

The movement of the earth resulting = from an=20 earthquake, will move the entire apparatuses, and the room it is = in. =20 However the mass at the ends of the inverted T will move less, relative = to the=20 sensor and the room it is in.

Ted
----- Original Message -----
From:=20 Les=20 LaZar
Sent: Saturday, December 15, = 2007 5:01=20 PM
Subject: Re: Anniversary clock=20 spring

How would a seismic wave, passing by = an inverted=20 T torsional balance, impart any torsional motion to the horizontal bar = and the=20 masses?  Just wondering.

Les LaZar

----- Original Message -----
From:=20 Connie and=20 Jim Lehman
Sent: Saturday, December 15, = 2007 2:56=20 PM
Subject: Re: Anniversary = clock=20 spring

Ted--there is some neat physics in = the inverted=20 T torsional balance.  The increase of period with increased = masses=20 added makes for a nice graph in a physics lab, and there are related = aspects=20 of interest.  Perhaps stability would be a big problem, but set = it up=20 with a damping mechanism, and give it a=20 try.         Seasons=20 Greetings    Jim Lehman
----- Original Message ----- =
From:=20 tchannel1@............ =
To: psn
Sent: Saturday, December = 15, 2007=20 1:40 PM
Subject: Anniversary clock=20 spring

Hi Folks,  This is an observation and a question.  I = have an=20 Anniversary clock, perhaps also called a 500 day clock, as you = only need=20 to wind it once a year, or so.   I know very little = about=20 clocks, but have worked on a few clock movements and=20 escapements.   I have some old clocks which are 8 day=20 movements.   I wondered why the big difference in power=20 consumptions, and spring properties between the two types.

The 8 day movements use a short pendulum which is = maybe 1/2=20 second natural period.  The anniversary clock has a = short=20 spring, instead of a pendulum, which is  like a flat = thread. =20 This spring is fixed at the top and has four masses, brass balls = on the=20 free end.  One period of this spring is about  8=20 seconds.   The mass in motion, twist the thread like = spring,=20 until the power of the spring stops the mass, and swings it in the = opposite direction.  A different coiled mainspring = then add=20 a kick to the mass and the cycle repeats.

Always looking for different ways to obtain a 20 second period, = I took=20 a band saw blade, cut it and suspended it from my shop = ceiling.  It=20 now hangs similar to the thread like movement spring of the = anniversary=20 clock.  At the bottom of the 72" band saw blade, I attached a = 36"=20 yardstick.  This now looks like an inverted "T".   = I added=20 a mass to both ends of the yardstick.  I twisted the spring = and=20 released it.   I found it rotated back and forth and it = period=20 was about 8 seconds.  I keep adding equal mass to both end of = the=20 yardstick, and the period was 24 seconds.

The yardstick seems to always come to rest at the same = point, as=20 the spring wants to untwist.

My question:  Has anyone tried this approach?   = If so,=20  could anyone direct me to more information about it on the=20 internet?

Thanks,=20 Ted

=

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