Joseph Gwinn wrote:

(...)
I would be tempted to fabricate the magnetic circuit components by
bolting together four pieces of 1018 steel rectangles: one wide 0.5"
thick piece to form the bottom, two 0.5" thick pieces to form the
outsides, and one 1.0" thick piece to form the center, roughly following
the outline shown in the MagnaBend literature.

This will be a considerable savings on steel material, and on machining
effort.

Bolting-together would be accomplished using hex socket flat head
machine screws through the bottom piece screwed into drilled and tapped
holes in the steel center and side pieces.

I'm concerned about the three additional gaps:
Between each vertical and the base plate
Between the center pole an the base plate
Magnetic flux falls as the cube root of distance, so anything
we can do to reduce reluctance is good.

I'd be tempted to punch many 'E' laminations and
stack them sideways. That design wouldn't have any
additional gaps.
On the ends, I would attach 'C' laminations.
The laminations would attach together as we see in
some older transformers: a long insulated machine
screw with shoulder washers in 4 corners.

http://www.alliedelec.com/Images/Pro...8482_large.jpg

--Winston