Re: Aluminum duct material for toroids

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

Original poster: "Nick Andrews by way of Terry Fritz <twftesla-at-qwest-dot-net>" <nicothefabulous-at-hotmail-dot-com>

When I was installing pellet and gas stoves and fireplace inserts, we used 
several types of flex, both aluminum and stainless, depending on 
application.  We used a lot of 3" and 4" flex, but also got 8" and 10" for 
wood inserts.  The stainless is a lot stiffer to work with, but doesn't dent 
as easily.  We bought it in big rolls like 50 or 100 feet.  Try a local 
fireplace/stove store and see what kind of price they will give you, they 
may have scrap pieces laying around that are too short to use, but would 
work for a toroid...

Nick Andrews
Littleton, CO


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Aluminum duct material for toroids
>Date: Wed, 18 Sep 2002 07:11:43 -0600
>
>Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><Parpp807-at-aol-dot-com>
>
>In a message dated 9/7/02 8:12:55 PM Central Daylight Time, Par pp 807 
>writes:
>
>Hi Ed,
>
>I am posting some recent correspondence on the subject of toroid 
>construction.
>I think it addresses many of your Qs. I hope you find this helpful.
>
>Happy day,
>Ralph Zekelman
>
> > Hi Scott,
> >
> >  Pictures at:
> >  http://hot-streamer-dot-com/temp/RalphsCoil/
> >  Pics include the good, the bad and the  "this was thrown out."  :-(
> >
> >  Enter the 5525K37 into the McMC search and it will take you to the 
>center
> > of the category. Yes, this stuff is seamless. The flex-lok type is made 
>of
>an
> > aluminum strip
> >  around three inches wide. It is wound into a spiral and the seam is
>crimped
> > together.
> >  My first effort at making a 4 x - toroid used this stuff. As you say, 
>it's
> > no good. The
> >  Al is like a thin foil. When I tried to pull it into shape the crimped
>seams
> > just came apart. I made one toroid and threw it out. John Freau uses the
>flex-
> > lok as do most coilers. John makes a very nice toroid with the FL, but 
>he
>has
> > skill. Maybe with
> >  a little practice I could get improved results but the stuff I use is 
>much
> > superior
> >  to the FL. It is of a heavier gauge and it is seamless. It's pricier 
>but
>it'
> > s worth it.
> >  I work it by stretching out the 2.5 ft length to the length of the 8 
>foot
> > bench. I then
> >  bend it into a near circle and fasten the ends. Warning: do not cut the
> > piece; keep it
> >  full. Use one 2.5 ft section per toroid. The ducting is accordion 
>pleated
> > and wound in a spiral. I would like to know how it's manufactured. On my
> > first toroid, I did cut the 2.5 foot section to make two toroids. The
>picture
> > with the aluminum foil covering the seam says it all. Things get messy 
>if
>you
> > cut that edge. The uncut
> >  piece will give you two-flush fitting edges that will produce an 
>invisible
> > seam.
> >  You can work the ducting to the desired diameter simply by squeezing 
>the
> > pleats
> >  back together until you get the correct size. The heavier gauge Al is
>easier
> > to work
> >  without putting a bunch of dents into it. Stainless is too stiff to 
>work
> > with.
> >
> >  I hope this helps. If you try what I am suggesting, please let me know
>what
> > happens.
> >
> >  Happy day,
> >  Ralph
> >
> >  >  In a recent posting to the Tesla list, you mention that the
>McMaster-Carr
> > #
> >  > 5525K37 duct is "seamless", and easier to work with than the 
>Flex-Lock
> > type
> >  > duct. Are you sure that both of these types of ducting are not made 
>from
>a
> >
> >  >  single strip of aluminum, coiled in a helix with some sort of seam? 
>Can
> > you
> >  > describe the differences between the two types of duct material, or
> > provide a
> >  > photo of each? I need to fabricate some small toroids for a magnifier
> > system
> >  > and would like to know what the options are. So far, I have used the
>very
> >  > thin-gage convoluted duct material from Home Depot, which I think is 
>the
> > Flex-
> >  > Lock type. It's so delicate that no matter how carefully the toroids 
>are
> >  > handled, they pick up small dents & dings & soon look pretty ratty.I
>have
> >  > also tried the convoluted stainless steel duct material used for
>re-lining
> >
> >  > chimneys, but its so stiff that the bend radius is impossibly large.
> >  >
> >  >  Regards,
> >  >  Scott Hanson
> >  >
> >