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Stainless steel convoluted duct toriod: my experience
Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>
Jim -
I found Rubber-Cal/Ducting.com in Santa Ana, CA about two years ago,
and stopped in one afternoon. They are primarily a distributor of
industrial hose, and do not stock much duct material that would be
useful for toroid fabrication. They do have an interesting sample
shelf with 1' sections of a lot of different duct & hose products.
Before getting excited, look at the pricing; its outrageous, in my opinion.
Another option is the convoluted stainless-steel duct material used
as chimney liners in the Midwest & East-coast areas. (search the web
for "chimney liner"). It doesn't seem to be widely used on the West
coast. Its available in several different stainless-steel alloys, in
sizes from 3" OD to 16" OD. I think all this stainless steel duct
material is manufactured by only one or two sources, and sold for
different end uses.
I obtained a 6-foot long section of 6" diameter duct, fabricated from
alloy 316, to evaluate its use in damage-resistant toroids. First
off, it is truly crush-proof and dent-proof. I think it would easily
survive all the drops and knocks that quickly turn an aluminum duct
toroid into junk. Whereas the convoluted aluminum ducting is
fabricated from extremely soft alloy, the stainless steel material is
thicker and MUCH, MUCH harder & stiffer. I don't know if the
stainless steel strip starts off as half-hard material, or just
work-hardens during fabrication, but it ends up being like a huge
spring. Its intended use is for basically straight runs lining a
brick or masonry chimney. Trying to form it into a torus of
reasonable diameter is almost impossible, at least with the 6"
diameter material. Larger diameters would be likely be even worse.
First, you'd need a piece at least 1.5X or 2X longer than needed to
form the actual toroid to allow you to form a 1-1/2 turn helix. The
material is so stiff that you can't form the "ends" into a radius,
they just stick out straight. You'd need to form the 1-1/2 turn
helix, cut the straight "ends" off, and then try to find some way to
flatten out the helix so the cut ends could be aligned and joined to
form a torus. The joining process would also take some ingenuity, as
the material is too thin to TIG weld, so some sort of insert would
probably need to be fabricated to align and secure the open ends.
Bottom line is that the stainless-steel duct material itself looks
promising, but the process for converting a length of this stuff into
a presentable toroid needs to be worked out. I just haven't had
enough free time to develop the fabrication process, so my ducting
still sits in a big box gathering dust......
Regards,
Scott Hanson
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, September 04, 2006 10:06 AM
Subject: RE: Toriod ? Bendaway_Plus, stainless, titanium stabilized
Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
Post Script, This company is in Santa Ana, Ca. Anyone near there want to
stop in?
-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Sunday, September 03, 2006 10:40 PM
To: tesla@xxxxxxxxxx
Subject: Toriod ? Bendaway_Plus, stainless, titanium stabilized
Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
Hi,
Has oneone looked into this product before? It claims resilance and looks it
to have it in spades. No bends or dent likely on this excepting extended
drop tests maybe.
It looks to be somewhat smooth too. Coat with alum tape?
I'm wanting to build a 54"x12" toriod. Maybe we can get a sample piece? I
wonder what the wieght is per foot?
Jim Mora
The message is ready to be sent with the following file or link attachments:
Shortcut to: http://www.ducting.com/Bendaway_Plus.html