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Re: Pseudo Toroid Design
From: Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: Sunday, November 09, 1997 10:00 PM
To: Tesla List
Subject: Re: Pseudo Toroid Design
>
> Imagine that you had two 31.4 foot lengths of thin-wall aluminum pipe
with a 2
> inch
> diameter. If you could "roll" these somehow into two big 10 foot diameter
> circles
> you would have the beginnings of a huge toroid. I say the beginnings,
because
> you could use these two large circles of pipe as a sort of glorified
corona
> guard for a sheet of aluminum 31.4 feet long and say two feet high.
>
> If you do go with aluminum tubing, you can make a simple tubing bender
out of
> sturdy wood, such as two by fours. What you do is build a wooden section
of
> an arc covering several degrees. The tubing is then bent around this arc
> piece by piece, just like with an electrician's tubing bender. Note that
such
> tubing benders have one side designed so that it grasps the pipe during
> bending, but then allows it to slip forward a few inches for the next
bend
> sequence. You are all smart people. Figure out your own modifications.
or check the yellow pages for shops that do "rolling". They have adjustable
rolls and can roll just about any structural element into just about any
radius. I have had 2x2x1/4" steel angle rolled into 30" circles, for
instance. And, one of my clients has 1.5" thinwall steel tubing rolled into
18" circles. Aluminum should be no problem.
They don't go to really tight radii in one step, instead they do several
passes. Essentially, the device consists of 3 rollers, 1 on the inside of
the bend, and 2 on the outside. The rollers have weird notches and such to
accomodate the shape of the structural member (e.g. the leg of an angle).
They have empirically determined what the spacings of the rollers need to
be to produce a given radius of curvature after running through the rolls.
You specify the radius you need, they look up the settings, run your member
through, and, voila, it is bent. I designed a very strange shaped platform
(sort of like an egg with bumps) for a large artificial tornado. The
structural steel fabricator made the edges out of sections of 4x4x1/4"
angle, after measuring the radius of curvature from my drawings.
If you do it yourself... Carve a form with a semicircular notch around the
outside with the appropriate radius of bend. Fill the tube with sand first
(keeps it from kinking and buckling).