Cutting Torch Questions

Im a tad ashamed n embarrassed to admit this since Ive owned and used my cutting torch over thirty years and always been able to cut or heat or weld good enough to get by. HOWEVER, Ive never been good at it nor can I cut steel like some buddys (they had much more practice) who make it appear a laser machine has cut it off perfect with no slag.

My first question is what presures to run my fuel and oxygen at using Propane and a tip I believe is No. 2 ??? for cutting maybe 1/4 to 1/2 inch steel??? Seems like I heard of a 5 or 7 to 1 ratio somewhere 5 and 35??

I can cut steel 1/4 to 1/2 decent, but in light metal its welds back together, guess I got too much heat or going too slow?????

I trim my torch so where when you hit the oxygen the flame doesnt change very much, you just get the oxygen blast to blow out the molten metal. That sound anywhere near right???

Reason I brought this up I just installed a new hose and cleaned my torch tips and thoght now as a good time to ask, ESPECIALLY what pressures to run at using Propane????? ?????

Thanks in advance n God Bless yall

John T

Saw your question yesterday and thought you might get some good answers from the experts. I am buy no means an expert but I did work in and have my own welding shop back in the 60s. I always used LP for cutting and brazing while in the shop and still do once in a while. Your LP cutting tip should have a recess in it. I usually run the LP Pressure at #8 to 10 and the oxygen at 30. And on a heavy thick cut I have ran as high as #50 on the oxygen. For thicker metal you can get large tips but they use a lot more oxygen.
When you light the torch your flame will be away from your tip. Pull this flame back until you have a 1/4 to 3/8" gap between the tip and the flames. Then start your oxygen until you have a series of bright blue flames coming from your tip. These should come right back against the tip. The longer these flames the more of a heating tip you have. You want them shorter. You may have to exprement with these. Then when you hit the oxygen lever to cut with you should have a feather come out of the center that is bright blue and about 3 to 4" long. Once you start your cut,hold the top of your torch tip back the opsite way of which you are cutting about 15 to 20 Degrees and make the torch cut from the bottom of your piece. You should see the fire flies coming from the bottom of the metal at an angle and not be getting feed back. The more steady your hand and the more steady you can hold your torch will determine what your cut looks like and the amount of slag to some degree. Dont over feed or you will get blow back. If you are steady enough and practice enough you might get a cut that looks like a lazer cut but I doubt it. I Have made some very clean cuts and I have ran some very bad cuts. That is what they make those 4" hand grinders for!
Dale

I don't know how much of this pertains to propane, but might be a starting point. Hope it helps, or maybe confirm what you are doing is right.

Jon

A guy in our office bought his first Mig Welder. He signed up for a night course at the local community college and has learned all kinds of good tips in the class. He's burning up their steel instead of his own.

J