Re: Toroid bulk buy

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>


Terry,

That's a good idea about making a toroid that can be separated,
although the smooth welds sure look great.  On some of my small
toroids, the halves fit together so tightly, that I couldn't get them
apart once I pressed them together, so those have no glue at all.
My next step if I had continued would have been to make a special lip with a
ridge so the toroid halves would snap together without glue.  I'm
not sure how they could be pried apart though.  Maybe a type of
glue could be used that would release at a certain fairly low
temperature such as 150 degrees F. or so.  Possibly  a better
way is to use a center fitting, that clamps the halves together, so
no glue is needed at the edge.  The center fitting could be a threaded
type so it can be unscrewed, letting the halves come apart.  I was
working on such a method when I abandoned my spinning operations.
This method may not work so well though if the toroid is too large
and thin-walled.

It should be easy
for a spinning shop to make a nice lip for a smooth fit.  After all,
if I can do it, not being a professional spinner and all.....   :)
It would seem to me that the lip creation would be less work
than the welding, for the company to do.  Possibly the only
problem with the lip idea for a large toroid is that the large
pieces get kind of springy, and that may cause some kind of
weird problems.

Other comments:  I like the idea of fat toroids.  My 4" x 13" toroid
has an aspect ratio of almost 1:3, and I prefer this to the 1:4
aspect ratio.  Fatter toroids are somewhat more difficult to spin
though.  I'm not sure how thin-walled a large toroid can be, and still be
fairly stable.  I'm thinking that 0.080" may be OK using 6061
for a 10" x 30" toroid.  The interesting thing about the 6061 is
that it's not much more dent resistant than 1100 alloy because
the 6061 has to be the untempered type to spin it.  However
I have spun a lot of mine using the tempered type, but it's tricky.
The larger a toroid is, the easier it is to dent it in a way, because
the ROC is flatter.  I'd recomment buying the toroids with a hole
already drilled in some convenient size.  Someone mentioned a
kind of tube to connect the center plates, but I don't really see
any need for that.  It just adds to the complexity and cost.  The
two center plates should just about touch anyway, and the mounting
screw will pull them together, etc.  However, the use of some sort of
center tube or fitting is another way to hold the toroid halves
together in the case of a two piece toroid, as I mentioned above.

Cheers,
John Freau

> 
>  I would suggest one thing.  If at all possible, get the toroids made so
>  that the two halves can be separated!!!  Pulling out a toroid dent from the
>  outside requires about as much effort and high technology as getting that
>  space station arm to bend...  However, if you can get to the inside and
>  push or pound it out, it is 1000 times easier...  Any auto store has the
>  hammers...  This new toroid buy is a perfect time to push the state of the
>  art a little and make repairing a toroid possible when you (and you all
>  know who "you" are :-))) ding them...
>  
>   Terry