[TowerTalk] Homebrew tower...

[Jim Lux]

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.