Toward a propane/free air brazing torch:
I tried a few things this morning before the rain started. I found a 20' 1/4" ID propane hose I had in storage from a boat stove, UL rated at 350PSI. Thinking about using this for a brazing torch, but I wanted to attach it to an acetylene regulator and gauge and run at maybe 15 PSI. I want a steady regulated pressure. Unfortunately the ends were M and F compression fittings while the regulator was B type left hand thread.
Then I found an old cracked OxyAcet twin hose, no longer useful -- I was hanging on to it for no obvious reason. But of course I now realized the end connectors were still in fine shape, and there were 2 B type left hand connectors on the red hose -- oh boy!

I split the crimped ferrule with a Dremel tool, leaving the end swivel portion intact. As I thought, under the ferrule in the hose was a nice 1/4" hose barb end. So I figured I could mate that lefty B connector with hose barb to my 1/4" propane hose. but unfortunately I didn't have a small enough hose clamp to fit the hose. Actually I want two on this connection for security -- and they need to be the full round type. So couldn't go any further. Maybe I'll go to town and get clamps tomorrow.
Then I thought I'd try firing up my Harbor Freight weed burner and testing it as a brazing torch. It puts out massive heat.
http://www.harborfreight.com/propane-torch-91033.htmlFor the test, I took a piece of 3/8" plate and set a piece of 1/2" water pipe on it. I ground them both clean beforehand. I figured the torch could easily do the job, but after a couple minutes of heating -- even up to the point where the pipe was glowing red in daylight, I couldn't get the braze to flow on the plate -- not sure if it was a fluxing issue or a gas mixture issue. I hadn't used much flux in the joint and hadn't fluxed the rod. It was definitely hot enough to melt the brazing rod, but it stayed on the plate like a little worm. I'll have to repeat that again when the rain stops, with a flux coated rod.
But it was clear the flame was just too massive and spread out to be much good as a brazing torch. Very wasteful. I unscrewed the head, which measured a whopping 2-3/8" ID (!), and checked the bore of the jet, which was .060". Also huge.
I think I'd like to make a torch about 1/2" to 3/4" ID with a much more concentrated flame with a jet orifice somewhere around .040. Also, as I said, with an adjustable regulated propane supply. The weed burner is direct connected to the propane tank.
It does have a good handle, valve, wand, and trigger, so might make a good starter assembly for my brazing torch. But the head will need to be quite different.