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Re: Stacking Variacs - shaft material

Hi Eric,

	Any shaft material will be fine.  Mine are aluminum.

There is one "funny little thing" I'll mention if your redesigning the
original variac frame.  The shaft MUST be electrically isolated from the
rotor.  If you were to have a complete electrical loop around the core of
the variac, it would act as a shorted electrical turn.  Low voltage but
very high current.  The shafts are normally well insulated but just don't
try to get too ambitious about adding extra ground wires that could form a
closed electrical loop around the core.  It is possible that it will not
blow a fuse despite the red hot molten metal dripping out the bottom...

Cheers,

	Terry


At 12:42 PM 02/08/2000 -0500, you wrote:
>I want to stack the two 10A variacs I have, and want to know what material
>the shared shaft has to be.  The original shaft is 3/8" aluminum, and I have
>some 3/8" stainless tubing that I think will work, as long as it doesn't
>have to be aluminum.  I figured that plain old (magnetic) steel might not be
>so good for a shaft that goes through the core, no?
>
>I'll ask about the choke I'll need for ganging these later, after I've
>reviewed what I found in the archives.
>
>Eric Forsman
>Baltimore
>