[drivingpairs] Re: PJ's

> As to the welds, you are looking at heliarc welded joints of VERY high
quality.
> Aluminum does not melt and flow like steel, so the welds look a little
different.
> I have a good friend who recently retired from the aero-space industry
(yes, a
> rocket scientist  <VBG>) and he agrees with me about the quality of
construction.

Usually welding of aluminum is done one of two ways; (1)MIG, or using an
electrode
with an inert gas, such as helium or argon, and the metal being welded as
the second
"half" of the electrical circuit, or, (2) TIG, using a special pair of
Tungsten (alright,
Wolfram, for you really oldtimers) electrodes in the presence of inert gas,
while the
aluminum alloy is fed in by hand.

The TIG process is harder to learn, so is found less often, but when done
correctly,
looks exactly like the best wire-welder welds done in steel. More often a
wire welder
is used, and MIG the process, as just about any wire-feed welder can be made
to
function as a MIG, is used.

What you are seeing that looks a bit rough, is the end of the wire left over
at the
end of the weld, sometimes removed carefully, sometimes not. The best
quality
welds are recognized by their CONSISTENT appearance and the fact that the
proper "penetration" of weld has happened. Smooth edges are the key to a
good
weld.

Take a look at the mid-nineties Sundowner trailers if you want to see real
quality
welds. A recent look at a 2002 Sundowner showed a little lower quality
control
than I am used to, but this was only the cosmetics, not the strength of the
welds.
In the horse compartment, you would expect NOTHING to be left for a horse to
brush against and damage their coat, right?

Alloy also plays a big part in the ability to make pretty welds. The three
highest-
strength alloys used are 2024, 6061 and (rarely) 7075. These have very
different
welding characteristics. So what you are looking at may not be pretty, but
may
be very strong......

Darryl Wright
Boyd, TX

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