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Re: Toroid sizes
At 21:33 22/09/98 -0600, Barton B. Anderson wrote:
>Wow, the craftsmanship of your coil! Looks really great.
>One of the nicest setups I've run across.
Many thanks ;-)
>Your toroid is incredibly smooth! Where did you get it?
Been through this before, but for new members its worth repeating.
This was/is my first coil. Tried all types of suggestions for toroid &
virtually all went into the bin as disasters. The only air-con duct I
could get had a spiral wire outer & was useless.
Anyhow ..... cutting a *very long* story short. These start as metal
'donuts', which have both inner & outer seam welds, the later of which has
to be ground-off and the surface sanded/polished, then a plate welded into
the middle. The two halves are pressed/spun, then welded in a special vice.
Bought the original from a general metal supplier, who sells them mainly to
custom exhaust manufacturers. Theory being they don't know what angle bend
they will need, so if they have 360, they can cut to suit. They are all
regular in size, ie. diameter of torus = centre hole diameter. Can get 1"
to 10" in mild steel "off the shelf". Original toroid was 6" at $80AUS
(just over $40US). They get more expensive above this, the 8" steel being
$300 and the 10" $580.
Aluminium is only "off the shelf" to 6" at $120. The custom 8" of mine was
$580AUS and I got it directly from the manufacturer in Melbourne VIC. This
might seem a lot to some, but you will discover if you try to get one spun
this is really BIG $$$.
Prior to finding these I had phone every sheet-metal shop & spinner in the
phone book. Best quote I got was from spinners at $1500 for the dye alone,
no toroid !!!!!!
The reason for giving the history is it might help you on where to look.
If someone makes these in little ol' Australia, they *MUST* exist in the
US/UK/Europe
For anyone in Aust./NZ see "Tubengineers" in Melbourne.
Cheers,
Mark
http://www.cobweb-dot-com.au/~dkfinnis