Hi Sophie,

I haven't built a system using the saw blades, but it looks a bit 
dangerous to me, as the blades would spring up if the weight was removed.

I built a simple system that is pictured here:
http://jclahr.com/science/psn/wooden/index.html
It uses a door spring and is made of wood.  Not the best material for 
a seismic system, but this might be a good design to start with.

Cheers,
John

At 07:09 PM 11/6/2006, you wrote:
>Hi Sophie, the saw design looks interesting however it may take some 
>special tools to build at home. If you are looking for a very simple 
>vertical design, you might also look at 
>http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF
>This design is very simple to construct using common hand tools. All 
>of the materials can be purchased at a local hardware store.
>
>Regards, Steve Hammond PSN San Jose -=- Aptos, California


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