On Tue, 11 Oct 2005 08:56:49 GMT, SomeBody
wrote:

I'm attempted to do some brazing, never done it before, although I have
soldered some copper pipes before!

I have a piece of 1/4" plate with a hole drilled in it, I have a piece
of 3/4" black iron pipe threaded into a 3/4" ell (elbow?). This pipe will
pass through the hole in the plate and needs to be brazed to seal it up. I
need it to be leak free.

To get some practice, I tried to see if I could braze the threaded pipe
to the 3/4" ell (elbow?), I cleaned the pipe threads and the ell with
acetone and I screwed the pipe into the ell. I got out my small propane
cylinder with a hand held torch tip. I heated the part till it was a light
colored red and try as I may, could not get the brazing rod to flow
worth a dam. Figured I wasn't getting enough heat, so I got out my #20
cylinder of propane and my torch head from my aluminum melting furnace. I
fired it up and blasted the pipe fitting for quite sometime. The brazing
rod was getting soft and would melt, but in globs and would not stick to
the pipe fittings.

Any tips, comments, suggestions?

This is all the equipment I have, no O/A torch kit, don't know nobody
who has one and don't want to pay someone to do this for me. I want to
learn how to do it.

Thanks.

Ron Reil wrote of brazing two cannon balls together with his propane
burner, and people use them to melt brass, so brazing is definitely
possible with your propane burner.

You need to contain the heat. Try making an enclosure out of fire
bricks, or perhaps heating the work in your aluminum melting furnace.
Brazing is done at temps somewhat higher than needed to melt aluminum,
typically about 1600 deg F. Light red isn't hot enough, gotta be
orange. Alloys containing silver work at lower temps (1200 or so,
dull red) but are more expensive. You might have better luck with a
silver-brazing material.

The problem isn't so much propane vs acetylene as it is air/fuel
rather than oxy/fuel . Air is only about 20% oxygen. Your burner
needs to flow a lot of air to burn the propane, and that airflow cools
both the flame and the work. Oxy/propane works well for brazing
but requires an oxy/fuel torch.