Re: Toroid Design


The aluminum dryer ducting is very good.  And interestingly, I've
seen two different wall thicknesses for this material.  It is possible that
the thicker-walled stuff is for industrial applications.  The thicker-walled
material I have is duller in appearance than the more shiny looking
thin walled material.  I would be interested to hear if anyone knows
for sure about the different applications and where to obtain each wall
thickness type.

To connect the ends, I carefully cut them so two ridges are left at each
end, (the ridges occur in groups of four).  I then make up a piece of
wood that is specially shaped to fit precisely with the proper curves,
etc.  I place the ducting over the wood, and press in tiny nails through
the ducting and into the wood to hold it all in place.  The result is an
almost invisible joint.  The nails are placed between the ridges, so
the heads are below the surface.  I show this technique on one of
my videotapes, maybe I'll get around to placing a picture at my
webpage.  By using nails, it is possible to open up the joint if needed
in the future to push out any accidental dents that form.  Since the
material is so soft, the dents can easily be pushed out using a
suitably shaped tool.

John Freau