Hi Ted,

Sorry...I couldn't find anything along the specific line you mention
either..especially the flat ribbon spring variety.  If I read you email
right;
the very height you're using makes it a "giant" representation; and that
likely makes it much more responsive as you're seeing, and
to be fair the stresses involved will likely show all kinds of
metal/structure creep over time which you'll have to adjust for.

A lot of the web sites I've seen, go out of their way to describe such as
antiquated, obsolete, old etc; which is true in the sense
of what is predominately used now.  On the other hand, the torsion aspect
really "does away" with a few of the normal pesky pivot problems
that are found in other seismometers/tiltmeters; and that alone is a good
adjustment and/or labor saving positive.

Yes indeed...explore away.....there is likely a world of different flat
ribbon or round wire sizes material one could try.

Take care, Meredith

On Wed, Oct 1, 2008 at 10:38 PM,  wrote:

>  I am exploring the subject of a torsion spring sensor again.  I say again
> because I have tried this approach before with no success at all.
> I took a long band saw blade cut it to form a long vertical torsion spring.
> Attached both ends and pulled it tight.
> In the middle of this spring I attached a boom. On both ends of the boom I
> attached a mass of equal value.
> This boom would move around the vertical axis with very little effort,
> twisting the spring and then reversing to the other direction, rocking back
> and forth for a very long time.  I don't remember how long but I think it
> was one hour plus.
> The period of oscillation was controlled by moving the masses further out
> on the boom.   Very long periods 30 seconds plus.  To make a long story
> short, it did not record any earthquakes.
>
> I think I did two things wrong.  1. The booms of equal mass cancelled the
> movement of each other. And in this configuration the earthquake would need
> to spin the house to move the masses.
> 2. The torsion spring needed to be tipped, not vertical.
>
> Here is my next attempt.   1.  I removed the boom, which formed a (+) on
> the vertical torsion spring and replace it with a short pendulum boom, this
> time on one side only.
> it looks like a T on its side ( l-)
> 2.  I contained the vertical torsion spring in a strong box about
> 12"x12"x36".  This retains all the parts and I can add tension to the
> spring, and mount the magnet and coil
> 3.  I placed three leveling legs on the base of the box.  Now I can tip the
> vertical spring (Off Vertical).    Similar to tipping a Lehman, pitching up
> or down.
> The spring now at an angle, contains a pendulum which is now (Off
> Horizontal).
>
> The pendulum I am using is only about 6" long, and I get a period of about
> 5 seconds. I could get 20 seconds with a 18" boom. But my box could only
> accommodate a 6" boom.
>
>  It is now running as a test......I will see if it will record earthquakes.
> It is sensitive to me moving around the room, and to drafts and tilts.
>
> I have seen something similar somewhere on the web, but I can't fine it.
> This is all I could find.   If someone has tried this please email me.
> Thanks, Ted
>
> Torsion Seismometer Wood Anderson
>
>
> http://www.data.scec.org/Module/s3inset3.html
>
Hi Ted,

Sorry...I couldn't find anything along the specific line you mention either..especially the flat ribbon spring variety.  If I read you email right;
the very height you're using makes it a "giant" representation; and that likely makes it much more responsive as you're seeing, and

to be fair the stresses involved will likely show all kinds of metal/structure creep over time which you'll have to adjust for.

A lot of the web sites I've seen, go out of their way to describe such as antiquated, obsolete, old etc; which is true in the sense

of what is predominately used now.  On the other hand, the torsion aspect really "does away" with a few of the normal pesky pivot problems
that are found in other seismometers/tiltmeters; and that alone is a good adjustment and/or labor saving positive.


Yes indeed...explore away.....there is likely a world of different flat ribbon or round wire sizes material one could try.

Take care, Meredith
   
On Wed, Oct 1, 2008 at 10:38 PM,  <tchannel1@............> wrote:








I am exploring the subject of a torsion spring 
sensor again.  I say again because I have tried this approach before with 
no success at all.
I took a long band saw blade cut it to form a long 
vertical torsion spring. Attached both ends and pulled it tight.
In the middle of this spring I attached a boom. On 
both ends of the boom I attached a mass of equal value.
This boom would move around the vertical axis with 
very little effort, twisting the spring and then reversing to the other 
direction, rocking back and forth for a very long time.  I don't remember 
how long but I think it was one hour plus.
The period of oscillation was controlled by 
moving the masses further out on the boom.   Very long periods 30 
seconds plus.  To make a long story short, it did not record any 
earthquakes.
 
I think I did two things wrong.  1. The booms 
of equal mass cancelled the movement of each other. And in this 
configuration the earthquake would need to spin the house to move the 
masses.
2. The torsion spring needed to be tipped, not 
vertical.
 
Here is my next attempt.   1.  I 
removed the boom, which formed a (+) on the vertical torsion spring and replace 
it with a short pendulum boom, this time on one side only. 
it looks like a T on its side ( l-)
2.  I contained the vertical torsion spring in 
a strong box about 12"x12"x36".  This retains all the parts and I can add 
tension to the spring, and mount the magnet and coil
3.  I placed three leveling legs on the base 
of the box.  Now I can tip the vertical spring (Off 
Vertical).    Similar to tipping a Lehman, pitching up or 
down.
The spring now at an angle, contains a pendulum 
which is now (Off Horizontal).
 
The pendulum I am using is only about 6" long, and 
I get a period of about 5 seconds. I could get 20 seconds with a 18" 
boom. But my box could only accommodate a 6" boom.
 
 It is now running as a test......I will see 
if it will record earthquakes.
It is sensitive to me moving around the room, and 
to drafts and tilts.
 
I have seen something similar somewhere on the web, 
but I can't fine it.   This is all I could find.   If 
someone has tried this please email me.   Thanks, Ted
 
Torsion Seismometer Wood Anderson
 
 
http://www.data.scec.org/Module/s3inset3.html