Dave, Just to clarify...........on my Lehman's, I use exactly that Chris 
recommended in his drawing. And that works for approx.2 lbs mass,   This 
consist of 4 very strong magnets, again as Chris noted, but I sometime sub. 
the magnets, going thicker, up to 1/4".     The plate I use is Alum about 
1.5" wide 2" long and 3/16" thick.  Thin Alum just doesn't have the body.

 With that arrangement when you move the plate inside the magnets, the eddy 
feels as strong as removing a refrigerator magnet, almost.             On my 
experiments with my 15# mass, I used Chris's arrangement, but 4 even 
stronger magnets, and even a bigger hunk of Alum.  Now this feels more like 
dragging your finger on the table, very strong...........even that was not 
strong enough, but I used it.
I have used copper and Alum.  I use Alum, because it is easier for me to 
get.   You could use whatever, it just needs to be scaled up to do the job. 
Email me for pictures.  tchannel@............

Ted


----- Original Message ----- 
From: "Dave Nelson" 
To: 
Sent: Sunday, July 31, 2011 12:29 AM
Subject: Re: New Seismo


>
> Hi Randall, Brett, John, Ted, Chris and co...
>
> I appreciate ALL the input
>  I really thought that the slice of aluminium  I had between the 
> reasonably strong
> magnets would have been enough  obviously not!
>
>   Ted's comments are valid, I can feel the eddy generated when passing the 
> aluminium between the poles of the magnets but it doesnt feel as strong as
> what Ted is suggesting it should.
>   I had already cut back on the mass to 2 lb instead of the originally 
> planned
> 4lb.  If I have to I will go back to 1 lb
>
>   I think I will also do a bit of a redesign and put the magnet frame for 
> the
> dampening separate ... sitting on the main frame as Chris has done in a 
> couple
> of his units.
> I was waiting to hear back from him as to if there is any advantage 
> having fix
> magnets and the vane moving ie. fixed to the boom, or the other way around 
> like
> I had.
>
>
> cheers
> Dave
>
>
> At 02:40 PM 31/07/2011, you wrote:
>>Dave,
>>Just for laughs, here's the other end of the specturm in regards to mass.
>>They use an effective mass of 19 grams, and don't do badly at all.  Design 
>>by the 'other' Dave Nelson.
>>http://bnordgren.org/seismo/gif_images2.htm
>>Brett
>
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