On Jun 24, 8:41*am, "
wrote:
It is pretty obvious that this is a cheap way of cutting metal, but
has anyone run across a way of using this technology to weld? *If so
it might open up more options for the impoverished home builder.
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Dear Leon (and the Group),

This causes me to wonder: Where would the thin-walled steel tubing
come from? And, what would it be used for? (within the context of
building on the cheap)

First guess would be bicycle frames as a source of tubing, followed
by EMT.

Second point would be it's use, which would probably be for an engine
mount... perhaps for a pylon. Farther down the list would be landing
gear. Dead last would be a fuselage.

Steel tubing offers the best ratio of strength to weight with the
assumption of welded joints. However, we now have hyper-eutectic
brazing LIQUIDS that are stronger than a mild steel weldment (but not
by much). The tricky bit is that the bicycle tubes are joined using
swaged fittings. The tubing and the fitting are PAINTED with the high-
strength brazing compound (nickle-silver, etc. ) which is then brought
to a red heat and allowed to cool.

As a point of interest neither the VP nor the Teenie Two uses a
conventional engine mount. Both of these designs require welding; the
VP on its wing struts and joy-stick, the T2 on its landing gear, joy-
stick, aileron controls and rudder bar. All of these welds can be
replaced with brazed joints although brazing is usually not accepted
by the CAA because of its historic propensity for cracking. The fact
this is not a problem with modern eutectic brazing materials is of no
interest to the CAA since the people who make the brazing material
have not bothered to have the material tested to CAA standards due to
the lack of a potential aviation market. (The fact high-strength
braze has been used on nuclear subs and the Saturn V rocket, is of
little interest to the CAA (various agencies, depending on which
country we're talking about.) )

I think the point here is that the principle of building on the cheap
tends to avoid welding wherever possible, which raises the possibility
of replacing welded components with riveted, or possibly laminated-
composite, components, such as the engine mount. The other
consideration is to use components that do not require any welding at
all, such as a fixed landing gear leg.

Indeed, if we wanted to get into a useful area of experimentation, the
testing of brazed landing gear components compared to welded
components would seem to be a worth-while area of study. I mention
this here because a gasoline torch does perfectly well for brazing,
although because of safety issues I would prefer to use my tried &
true Naphtha-fueled, solid brass blow torch. (In fact, you need a
couple of these things when gas-welding thick-walled tubing of large
diameter. Such torches are needed to keep the back-side of the joint
NEAR welding temperature when you are welding on the front-side. Of
course, if the weld is for something other than aviation, such as a
dune buggy, trailer frame or whatever, a MIG'er will be more
practical.

As for gasoline torches, one of the best is the fuel tank of a junked
car :-)

-R.S.Hoover