In a message dated 03/08/02, CapAAVSO@....... writes:

> Hi Chris,
> The best I can find is 1/32 thick copper sheet and as a damping magnet it 
> moves more like it is in very watered down treacle. If I stacked four of 
> 

Hi Cap,

       I made a typing error. For #21 please read #31. Sorry about that. The 
price quoted was correct.

       It would probably not be quite as good, but it could be adequate. Thin 
sheet Cu is likely to be harder. One important thing to remember is that the 
Copper needs to extend an appreciable distance beyond the end of the high 
field change region of the magnets. (Prefereably to between 1.5x or 2x the 
magnet width) I have a couple of #31s which are separated by 4 mm and the 
magnets themselves are about 17 mm wide. The magnet pairs are fixed on 5 mm 
thick iron  backing plates (as supplied). The maximum damping is for 
movements parallel to the long axis of the magnets.  The Copper needs to 
extend at least 10 mm on each side of the central magnet junction, making the 
plate over 40 mm wide and extending above and below the magnets themselves. 
My damping plate is a stubby T shape, 50 mm high and about 38 mm wide across 
the column of the T. The free damping movement is about +/- 2.5 mm. 
       You can feel the difference if you slide the magnet pair up and down 
the edge of a Cu sheet and compare this drag with that which you get when you 
put the corner of the sheet through the centre of the gap.  
       Hope that this will help,

       Regards,

       Chris Chapman
In a message dated 03/08/02, CapAAVSO@....... writes:



Hi Chr
is,

The best I can find is 1/32 thick copper sheet and as a damping magnet it moves more like it is in very watered down treacl
e. If I stacked four of these would I get the same damping effect as if I used a 1/8 thick plate?



Hi Cap,



       I made a typing error. For #21 please read #31. Sorry about that. The price quoted was
 correct.



       It would probably not be quite as good, but it could be adequate. Thin sheet Cu is lik
ely to be harder. One important thing to remember is that the Copper needs to extend an appreciable distance beyond the end 
of the high field change region of the magnets. (Prefereably to between 1.5x or 2x the magnet width) I have a couple of #31
s which are separated by 4 mm and the magnets themselves are about 17 mm wide. The magnet pairs are fixed on 5 mm thick iron &n
bsp;backing plates (as supplied). The maximum damping is for movements parallel to the long axis of the magnets.  The Copp
er needs to extend at least 10 mm on each side of the central magnet junction, making the plate over 40 mm wide and extending a
bove and below the magnets themselves. My damping plate is a stubby T shape, 50 mm high and about 38 mm wide across the column 
of the T. The free damping movement is about +/- 2.5 mm. 

       You can feel the difference if you slide the magnet pair up and down the edge of a Cu 
sheet and compare this drag with that which you get when you put the corner of the sheet through the centre of the gap.  

       Hope that this will help,



       Regards,



       Chris Chapman