G’day: The easiest way to braze steel - or mild steel - is to
go to the nearest branch of the company which deals in industrial
gases - oxygen, etc and buy a length or two of what they prefer
to call BRONZE WELDING ROD, which they sell in lengths of 36
inches and diameters from 1/16" to 1/4" in sixteenths. (It is
very cheap) The most useful for small jobs is 1/16th. Whilst you
are there buy a small tin of ‘Bronze Welding Flux’, though
’Easyflo’ flux will work too, but isn’t so good at keeping the
surface clear of oxide. You’ll need plenty of heat,
oxygen/propane or oxy/natural gas is sufficient, but other than
for small jobs air-propane isn’t enough. Clean the work with a
file or abrasive, hold the pieces in juxtaposition, and heat to
orange-hot, like Charles says. I rarely bother to flux the work
first, contrary to jeweller’s practices; I just heat the end of
the brazeing rod (don’t melt it!) dip it into the flux powder and
apply it to the orange-hot workpieces at the junction, melting
the flux onto the work. But remember that although it flows
easily, it won’t flow into interstices like silver solder, but is
gap-filling. In fact, you can build up a fillet all around the
work pieces by judicious movement of the flame and frequent
application of the rod. Keep dipping the rod into the flux before
applying it. Actually, brazeing is not very difficult and with a
little practice you’ll soon be a dab hand! Done carefully,
brazeing can be almost as strong as ordinary welding. Oh, and by
the way, I always keep a small stock of brazeing rod handy as I
tend to use it for all sorts of purposes other than brazeing. 
/\
/ / John Burgess, J.O.A.T; M.O.N. (Jack Of All Trades;
/ /
/ //\ johnb@ts.co.nz Master of None)
/ / \ \
/ (___)
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