View Full Version : propane torch

12-09-2003, 05:43 AM
I got tired of my flame going out when soldering in the confined spaces of the structure I'm building from sheet copper. Problem was that the nozzle was sucking it's own exhaust. I built a new nozzle with an integral air supply tube long enough to avoid this problem. Playing with this tube, I can adjust the ammount of air entering the nozzle, and thus the color and intensity of the flame. Can I use this to advantage? I vaugely remember some talk about a 'reducing' flame, vs an 'oxidizing' flame, something to do with welding or flame cutting. This is only propane, but same principles apply?
By the way, I sure had my fun trying to create an orifice in the range of only a few thou. Anyone have a surefire way of making clean holes in brass down to .002?

Ian B
12-09-2003, 10:33 AM

Sounds like an interesting idea - when you mentioned an air tube, I was thinking of a 3/8" pipe or similar; where does the 2 thou orifice come in? I'm guessing that you're mixing air with the gas after the gas leaves its nozzle?

Have you thought of feeding a bit of oxygen in there? If it's copper and you're soldering it, maybe not...

Any chance of a sketch / photo?



Al Messer
12-09-2003, 11:47 AM
Darryl, make a "Jewelers broach" by stoning 5 or 6 sides on an ordinary sewing needle. This tool will make clean, tiny holes in soft metals such as Brass.

12-09-2003, 02:54 PM
Ian, the orifice is in the nozzle. The propane shoots through this in a jet, sucking air alongside, mixing, and leaving the nozzle looking like a jet, rather than a candle flame. If the orifice isn't right, you get the gas shooting out at different angles, which kills the entire action. Normally, air enters the nozzle through holes near the beginning of the nozzle. What I did was essentially put these holes farther back by adding a tube to the back of the nozzle, and enlarging the holes to overcome the increased resistance to air motion. Air has to come from farther back along the stem leading to the nozzle. Have a look at a standard propane torch to help visualize this. I would include a sketch, but I'm not sure how to. I'm still running IE 4, so I don't know if I can. Maybe I'm missing something, it's probably easy.
Al, thanks for the tip on the jewellers broach. I'll try that out and see how it works.