On 6/26/15 5:16 PM, Richard (Rick) Karlquist wrote:
See:
https://www.flickr.com/photos/18794861@N00/2340109594/
The "Mirador"
About 8 years ago when I was at the "Maker Faire"
(by Make Magazine) there was an exhibit of a
tower made out of electrical conduit. Each
conduit had the end flattened with a hole
drilled through it. <snip>
something like 5 feet. I guess this guy assembled
the whole thing in situ at the Faire! He told me
there is some machine tool he used (it had a weird
name) that could either flatten or punch holes in
the ends of the conduit.
A Piranha? (that's a trade name).
I built a geodesic dome out of conduit. Engineer hammer to smash the
ends (faster than crushing in a vice), drill press to drill the holes:
you need sharp bits and a jig to make the holes be in the center: don't
try it with a hand held drill.
The tubes you have sound like "3/4 inch" water
pipe. They are going to be more difficult to flatten
and drill at the end than conduit, which is designed
to be formed.
conduit splits when you crush it: the seam weld is really weak.
Unfortunately, it is dangerous to weld galvanized
material, so you have to fasten it together with
bolts.
Do the welding outdoors with the wind at your back, and the zinc fumes
go downwind. A nice strong fan helps too.
The welders in the effects shop wouldn't weld galvanized indoors, but
outdoors was ok, for small stuff (up to 2" diameter kind of stuff). The
structural welders (welding things like 8" beams) would use blowers and
still hated doing it. But there's a lot more zinc on a galvanized I
beam than there is on galvanized fence rail.
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