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Re: Touchy toroids

Subject: 
        Re: [Fwd: Touchy toroids]
  Date: 
        Fri, 14 Mar 1997 06:34:50 -0600 (CST)
  From: 
        Bert Pool <nikki-at-fastlane-dot-net>
    To: 
        Tesla List <tesla-at-pupman-dot-com>


At 10:48 PM 3/13/97 -0600, Bob wrote:
[snip]

>Content-Type: text/plain; charset="us-ascii"
>To: tesla-at-pupman-dot-com
>From: tesla-at-america-dot-com (Bob Schumann)
>Subject: Touchy toroids
>
>Howdy coilers
>
>I would like some feedback as to what others have done with 
>their toroid construction using the available aluminum dryer
>ducting from the hardware stores. I am presently on my 5th one.
>
>My last one was my best one but it fell off recently and landed
>on the sharp pointed acrylic inverted-cone primary forms. It was
>toast. The way I had built it was by using some 40 pound monofilamnet
>fishing line and 'chain stiched' the ducting 2 ends together. All
>seemed okay but the fishing line was above the outside surface of the
>seam, so I smoothed aluminum tape around the seam and that seemed ok.
>For the center, I cut out a circle from the center of a cheap pie
>pan and drilled 4 holes in this metal disc at 12, 3, 6 and 9 o'clock.
>I used 4 titanum (free) wires and wrapped each wire around the toroid
>and locked it in place at the center disc with those little screw locks
>used to tighten on automobile throttle cables during adjustment.
>
>I just bought my new ducting. I came of with a stiching method that
>makes the toroid appear seamless. It is very hard to tell where the
>joining took place. There is no need to smmoth aluminum tape over the
>joint.
>
>Ok now for the question (sorry it took so long to get here)
>
>What other methods can I use for a center ?
>
>Someone had told me of 2 pie pans back-to-back but I can't imagine
>how the ducting will stay on the pans' edges. I find my self looking
>in kitchen stores and department stores and hardware stores looking
>for something to jump out at me. Service people at these stores ask me
>'Can I help you find something?' or "What are you looking for?'.
>
>I always tell them that I will know what it is when I see it!
>
>Thanks,
>
>Bob Schumann
>

Bob,

I have found the cheapest and easiest center disk material to be
something
you can find at your local Home Depot, or other similar store.

Look in the department that sells insulation.  You want to buy a 4 foot
by 8
foot sheet of foam core sheathing.  This is a sheet of 3/4 inch thich
styrofoam insulating sheet covered on both sides with aluminum foil. 
You
can cut it beautifully with just a box knife (make that "sharp" box
knife!).
I've made center disks 48 inches in diameter with this stuff.  It is
light,
it is cheap, it is readily available, and it works.  I form my aluminum
duct
around it and use a big hot glue gun to attach the duct to the edge of
the
disk.  My 62 inch diameter toroid is made using this method.  I then run
2
inch aluminum tape across the duct across the disk to the other side -
this
makes sure that I have a good electrical connection between the duct and
the
foil on the disk.  This probably isn't necessary, but I've seen sparks
arc
between poorly connected parts of a toroid and I didn't want the foam
core
to catch fire.


Bert Pool
nikki-at-fastlane-dot-net