I=92ve been checking on further sources of carbon and this is what I have=

found so far.  McMaster Carr (or at least my =9293 catalog) has both plai=
n
and copper coated welding carbons up to =BE=94 in diameter and very
inexpensive.  They also sell blocks of carbon/graphite for welding
backups.  Expensive though.  One other source I=92m going to try and
follow up on tomorrow is EDM electrodes.  Tool and die folks use carbon
electrodes to EDM out complex shapes and they can get it in virtually
any size.  I have a contact at a plastic molder where they make their
own molds, and he said he would give me some scrap electrode material.
So I=92ll get some of that material and check it for diamagnetism.  His
comment was that he thought the material from some oil refinery process
is pressed and =91sintered=92 to make the electrode material.  So it come=
s
in different densities and with adders such as copper, i.e., much in the
same way as brushes for motors.

I=92d be interested if anyone has the numbers for diamagnetism for carbon=

vs graphite, if there is a difference.  I would suspect so.  It would
help narrow down our search for materials if we could eliminate the
unsatisfactory forms right off the bat.

Charles R. Patton



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