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So they've told you to go cut some steel....
There are of course lots of ways to cut steel. Make sure you use the proper safety equipment--if there are flying pieces of debris--i.e. if you're using a blade--eye protection is a must. Is getting something done 5 seconds faster with an eye? Or going to the doctor to have a rusty piece of steel cut out of your eyeball? And if you're going to be doing something with flame or electric arc, you'd better be using the specified tinted lenses on your eye protection (light cutting up to 1"=#3-#5. medium to heavy cutting 1"-6" or more=#5 arc tint=#9-#12) Burned corneas will hurt, and in the long run damage your vision. Then you'll be one of those old timers groping around for the cheater lenses. And remember arc welds are high on the u.v. light. It will burn your skin and potentially give you lots and lots of skin cancer. And make you look wrinkley, old and crusty....
1. Put together the torch. Do you have the right equipment? Will the torch hose reach the area where you are going to cut? Is anything obviously broken? Make sure just to snug the fittings, as they are brass--if you over tighten, the threads will be messed up and you'll never get a gas tight fit. Check for leaks, and investigate the smell of leaking gas. Sucks to have a random spark set part of your torch set up on fire. Depending on the type of gas, set the gauges.
Make sure that the torch tip is appropriate for the steel you're cutting. A size 0 is the smallest. The size of the tip is how large the center oxygen hole is--the surrounding holes evenly heat up the area with a combination of oxygen and acetylene mixed in the barrel of the torch, the center hole forces air through the melted steel, giving you your cut. if this center hole is not clean, the air will not be forced out with the correct pressure or in the right direction relative to the heated area. Clean the tip!!!
If you're using a track burner--cake. Make sure you know how to set it up and take it out for a test run on the piece you're going to be cutting before you light it. Make sure the burner isn't going to topple over fall off something when you're through with the cut. The track burner will help you make very, very clean straight cuts with very, very little slag, if you set it up right.
If you don't have a track burner and you're making a long straight cut, think about cheating by using a guide. Get a long straight piece of steel preferably 3/8" or thicker, so the tip won't slip off, and be ready to clamp it by your mark. Don't clamp it on your mark--you will be dragging the tip alongside the edge of the guide. Since the center hole is where the cut will be, you'll need to offset the guide at least the distance between the center of the tip and the edge of the tip. Or if you're really precise, you can try and set it so the edge of the kerf matches the edge of your mark. Also if it's a long cut, make sure you clamp down your piece--the heat will tend to warp the steel so that it will want to curl up. If necessary, tack the steel down until it cools.
ok crack open the acetylene on the torch and light it with a striker. Fuel lighters are not recommended, because the flame might shoot back into the fuel and the whole thing could explode in your hand causing some kind of pain. But if you're into that kind of danger, do what you like. If you aren't able to produce a spark to light the flame, occasionally stop, let the accumulated gases vent and maybe get something that will actually make sparks.
Some guys like to turn on both the oxygen and acetylene and light that. This will make a popping noise. Although this avoids the threads of carbon generated by the acetylene flame--unless you have an idea of what you are doing, what shoots out the end when it lights could also startle you. Better adjustments are made by doing one gas at a time.
The acetylene flame is bright orange, and with a minimum of black soot, and the base should just sit on the tip and not ride away from. Steadily add oxygen. Sometimes at this point the flame will pop out. This could be due to old gas in the hose, and by flushing some oxygen and acetylene through the set up will quickly solve this. When everything is properly lit, there should be a blue flame with white blue flames from the holes around the center of the torch tip. Hit the cutting trigger--the thingy that shoots the oxygen out the center of the tip. While doing this, adjust the oxygen valve so that the white blue flames around the center have clear and pointy tips. If some of them are and some of them aren't, you have a dirty tip. You can cut, but it won't be as pretty...Oh, and you can let go of the cutting trigger now.
You then want to preheat along the cut to be made. This will drive out the moisture from the steel, as well as lessen the shock of the cutting heat. You don't need to get the whole cut cherry red. Just warm it up a little with a few passes. Mostly you'll be concentrating on the place where you are going to start the cut. If this is not a cut that starts at the edge of the steel, for instance, you're cutting precise holes into a sheet--try and start your cut in a place that you're going to discard. Starting in the middle of something can be messy, and if you blow a huge hole, you want it to be in a piece that you can throw away. Get the point that you're going to start cherry red. Then it will start to look melty and kind of a glowing white orange. When this starts to throw out some sparks, hit the cutting lever, and don't be shy. You've got to shove that molten steel all the way through the thickness of your piece, or else that same molten steel will be stopped and come back at you. This is unpleasant. Avoid this.
The gap you have created between the two pieces is called the kerf. The way to make this smooth and even is to move the torch in a smooth and even manner. The reason I like the guide is that I know that I'm on my mark, and I can still check on my kerf. If I'm moving way too slow, the slag will fill back into my cut. If I'm moving way too fast, the cut won't go all the way through. It's nice to travel with the torch tilted a little ahead of your cut, so the leading edge of the flame will preheat the cut a bit, but in line with your cut so that there isn't any unwanted beveling. The hottest part of the flame is the short points of the blue white flame--that is the part that should be riding along the surface of the steel.
The best advice I've gotten most frequently is to be comfortable. This sounds kind of silly, especially if you're cramped into some awkward hole cutting upside down or some kind of nonsense, but it works best. Try and cut from a position that you can move your cutting arm freely, without having to support its weight--maybe prop it with your free arm, or slide it along some surface. If you're pivoting on your elbow, remember that this is an arc movement, and you may have to fight yourself to get a straight cut. When preheating, you can determine how far you can make a cut before having to stop and re-adjust your position, and also see how stable and straight your arm motion is before you start. The less you have to think about where your arm is, and how heavy it's getting, and when is the cut ever going to end, the more you can think about cutting.
Once your about done with the cut, hopefully you've thought about where the piece or the scrap is going to fall. My advice is: not on your toes or on someone else. Either clamp it to something or have a clamp on it tied to something. Even if it's the most beautiful cut known to ironworker-kind, you're still going to look stupid hobbling around after needlessly dropping some steel on yourself.
That's all I could think of at the moment. I think I'll add bending later, if not on another page. If you've got any additional advice or any more questions, e-mail. jeanne@ironworking.com