From ChrisAtUpw@aol.com
Date Mon, 1 Jul 2002 214524 EDT

 

I tried to make a similar system to Bob's small cube magnets with my larger 1/2" magnets, but without success. The V attracting formation is similar to a standard susceptibility apparatus giving essentially cylindrical fields. This produces lift on the lead OK, but I would not have expected it to have a stable central position. The lead should have 'fallen off' the central max lift area and ended up against one pole or the other, which is what I observed. The four magnet reversals which I tried still did not produce a properly stable central position, but it was not so unstable. I think that the central stability with Bob's small magnets is probably either an effect of the curvature of the end field or of the fringe field at the crossover points. If you pass a graphite rod over the end of a 1/4 x 1/4" magnet, there is a definite hump in the central region of the field.

If you want thin iron sheet, I suggest that you buy galvanised iron. I bought some 20 thou thick, but you can get it in a variety of thicknesses. The zinc coat is excessively thin....!

 

4rod.jpg (360681 bytes)

I put just two cylinder magnets on their usual base and put a 0.7 mm x 60 mm lead on top. It overlaps the end and levitates fine, but the position is essentially unstable. However, it is possible to glue a T bar of graphite onto both extreme ends to provide some repulsion. This gives two stable positions with the T bar about 2 mm clear of the end of the magnets at either end. If you now separate the magnets slightly, you can get the rod to centralise with a period of about two seconds. It is never still.  I am not quite sure how useful this is in it's present form, but it does sort of work! The levitation seems to be a bit over 1 mm.

Regards,

Chris

Back