In a message dated 2008/04/04, kwyatt@............. writes:

> So, I am constructing a larger shake table with a 30" base that can hold 
> four buildings.  This lets a class divide up into four teams and then the 
> entire class can watch their buildings shake at once.

Hi Kay,

       Something that size could be quite heavy. Consider foam filled 
buiilding / wall sheet with an Al L angle surround and four vertical foil flexures? 
You can also buy metal + rubber vibration isolation mountings.You can get 
Celotex up to at least 3" thick? This has a thin glass/resin skin.
       Apart from variable speed motors you can also get 'floor shakers', 
which are a very heavy magnet + coil driver system. We use them for testing 
seismometers & geophones. Alternatively, you could use a coil of wire and NdFeB 
magnets. Maybe drive it with a LF oscillator and an audio amplifier?
       The professional shake tables may use an electromagnetic drive 
controlled by a distance transducer. You can vary the frequency and the amplitude.

       Regards,

       Chris Chapman
   
In a me=
ssage dated 2008/04/04, kwyatt@............. writes:



So, I am constructing a larger=20=
shake table with a 30" base that can hold four buildings.  This lets a=20=
class divide up into four teams and then the entire class can watch their bu=
ildings shake at once.




Hi Kay,



       Something that size could be quite heav=
y. Consider foam filled buiilding / wall sheet with an Al L angle surround a=
nd four vertical foil flexures? You can also buy metal + rubber vibration is=
olation mountings.You can get Celotex up to at least 3" thick? This has a th=
in glass/resin skin.

       Apart from variable speed motors you ca=
n also get 'floor shakers', which are a very heavy magnet + coil driver syst=
em. We use them for testing seismometers & geophones. Alternatively, you=
 could use a coil of wire and NdFeB magnets. Maybe drive it with a LF oscill=
ator and an audio amplifier?

       The professional shake tables may use a=
n electromagnetic drive controlled by a distance transducer. You can vary th=
e frequency and the amplitude.



       Regards,



       Chris Chapman