On Dec 19, 2007, at 9:42 AM, Dr.Hankenstein wrote:
Tim,
I don't check my email very often, but to answer you question about
the toroids, we keep our eyes open for HV gear being scrapped and
bargain with the scrap guy and then we build a Tesla Coil around our
parts selection. Sometimes it takes years to get just the right
combination to make something worthy of construction. For example, I
don't particularly care for the appearance of chicken wire although
many a good performer has been built with this concept. My coils, as
well as Dr. Sparks coils are built to be beautiful and hopefully last
a life time. In my opinion, it is worth the extra effort to do the
very best work you can and give it your best shot. Sometimes the
results are not as gratifying as expected, but then I've never seen a
good coil built from an armchair.
John Freau occasionally spins some very nice small corona rings. I
have one on my prototype VTTC. Really adds a nice touch. Once in a
while I've heard mention of a "bulk buy" on the larger ones....just
be prepared to spend alot more money! Seems as the size goes up, the
price does exponentially....such as:
http://www.drspark.org/images/wwt6.jpg
Almost a decade ago, I found a metal spinning shop who could make up
to 3n" inch toroids... if I gave them the tooling! So the company I
was working for at the time, which was building and selling Tesla
coils, had the two tools required to make 8"x24" toroids. The tools
had to be made be a tooling company on large lathes from hard rock
maple, with steel mounts for the spinning machine, to the cost of over
$800.
We made some batches of those toroids from fairly thick aluminum, ten
at a time, and we got them down to I think $85 each, including the
cost of the aluminum. But then they had to be sent elsewhere to have
the two halves TIG welded together and the weld bead sanded smooth,
that was another $40 each pair if a batch job was ordered...
These days, I don't know what they would charge me to make ten of
them, but (assuming that little mom-n-pop size company is still
around) I suspect my cost would be $150 - $200, and any sane person
would want to make some money for their trouble on top of that. If
you're doing it as a business, you'd assume your selling price would
be double your "real costs"...
Oh, and those weren't polished, either - they still had the spinning
marks!
I can see why Ross Engineering charges so much for their pretty,
seamless, highly polished corona toroids!
- Bill "Gomez" Lemieux
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