In a message dated 12/11/2007, johnjan@........ writes:

How  about using the hematite magnets that are made to toss in the air and  
rattle?  They are quite hard and polished, though clearly not as strong  and 
NdFeB.
Hi John,
 
    They have a relatively weak maximum field  and a ferocious temperature 
coefficient. 
 
    Moreover, it is simply a matter of better  design to incorporate magnets 
into the magnetic circuit in such a way  that their physical limitations do 
not matter. You might, for  instance, roll the bearing on hardened martensitic 
SS rods connected by  mild steel blocks to flat NdFeB magnets?
 
    Regards,
 
    Chris Chapman






   





In a message dated 12/11/2007, johnjan@........ writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>How=20
  about using the hematite magnets that are made to toss in the air and=20
  rattle?  They are quite hard and polished, though clearly not as stro=
ng=20
  and NdFeB.
Hi John,
 
    They have a relatively weak maximum fi=
eld=20
and a ferocious temperature coefficient. 
 
    Moreover, it is simply a matter of bet=
ter=20
design to incorporate magnets into the magnetic circuit in such a way=20
that their physical limitations do not matter. You might, for=20
instance, roll the bearing on hardened martensitic SS rods connected by=
=20
mild steel blocks to flat NdFeB magnets?
 
    Regards,

 
    Chris Chapman