We wanted to follow up our welding series with some more helpful fabrication tips that any mini-trucker could use. Since this happens to be the first-ever Chicks Special in the history of any custom-truck magazine, what better way to learn a few things about plasma cutting then to have some ladies on hand to actually demonstrate as we learn? We figured you wouldn't mind.
To understand the basics of plasma arc cutting (PAC), let's take a closer look at the setup. PAC is a thermal cutting process that uses a constricted jet of high-temperature plasma gas to melt and separate metal. The plasma arc is formed between a negatively charged electrode inside the torch and a positively charged work-piece. Heat from the transferred arc rapidly melts the metal, and the high-velocity gas jet expels the molten material from the cut. A plasma arc cutting torch has four components: The electrode carries the negative charge from the power supply, the swirl ring spins the plasma gas to create a swirling flow pattern, the nozzle constricts the gas flow and increases the arc energy density, and the shield channels the flow of shielding gas and protects the nozzle from metal spatter.
That's pretty much the long and short of it, so without further ado, sit back, grab a beer, and check out these girls as they school us in the basics of plasma cutting. For more information, contact the company listed in the source box.
1.The first thing you need...
1.The first thing you need is the proper plasma cutter for whatever job you're tackling. The two most important things to keep in mind are the type and thickness of the metal you'll be cutting.
2.Hold the plasma gun approximately...
2.Hold the plasma gun approximately 1/16 inch away from the metal and keep the gun as straight as possible, unless your desired cut is at an angle. The straighter the cut, the less clean-up and grind time you'll need.
3.When you begin the cut,...
3.When you begin the cut, whenever possible you want to start right off the edge of the metal and slowly cut into the edge to get to your desired spot. Replacing the tips can get costly and if you start your cut in the middle of a solid piece of metal you're more likely to get spatter back into the tip. And just like when you're welding, you want to keep the cutter feed consistently paced. If you're getting too many sparks spraying up at you, you're moving too quickly and not cutting all the way through the metal.
4.There are several different...
4.There are several different tips you can use depending on the type of cut you'll be performing. But no matter what, keeping your tip free from debris will yield the best cut possible. If your cut begins to get jagged, it's definitely time to replace the tip.
5.It's almost always easier...
5.It's almost always easier to drag the plasma cutter toward you, rather than trying to push the cut away from you.
6.The easiest way to cut out...
6.The easiest way to cut out a particular shape is to make a template using 18-gauge sheetmetal. After you trace your pattern and cut it out, tack 7/16-inch nuts around the edges. When the template is flipped over, it makes it much easier to pull the plasma around it, since it stands up off the surface of the metal that you're cutting. This gives the head of the plasma a surface to rest against as you drag it along and will yield much cleaner cuts.
7.If you're making a straight cut, aluminum stock works better as a straight edge because the plasma gun will arc to the steel before it will arc to the aluminum. Be careful - it will still cut the aluminum if you cut directly into it.
8.Make sure you use a filter/dryer...
8.Make sure you use a filter/dryer on the airline. This will help preserve cutter tips and produce a cleaner cut.
9.When making any sort of...
9.When making any sort of circular cut, the plasma circle cutting kit is very handy. Using the circle cutter is as easy as drilling a slight starter hole (don't drill through the metal) for it to pivot on, and then all you have to do is set up the gun. Just hold the gun steady and use your other hand to push the cutter around to complete the cut. It's a simple design that uses a roller wheel to deliver a smooth cut every time.
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12.One of the more advanced...
12.One of the more advanced plasma cutting techniques is gouging. This is the process that was developed as a tool for weld removal and weld preparation. Weld defects such as cracks, porosity, and lack of fusion can be gouged out and then repaired with a new, sound weld. With practice, you can achieve a smooth, clean, consistent groove with a plasma-gouging arc. Hold the gun at a 40- to 60-degree angle to the work-piece as the pilot arc is formed and the arc transfers to the plate and move the torch along the plate in a forward motion. Steeper angles and slower speeds cause the arc to penetrate more deeply into the work-piece. Smaller angles and faster speeds remove less material and produce a shallower gouge.
Another practical use of the plasma cutter is the ease of cutting holes (once you're proficient). Whenever a quick hole is needed, the plasma can take a lot less time than the drill press. But don't get lazy and use this technique whenever you need form and function because no matter how good you get with the plasma, the drill press hole will always look better.
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15.Once you get used to having a plasma cutter around, you'll see how much time it saves you. If you do a lot of cutting of brackets, mounts, or anything repetitive one option you might look into (if funds permit) is a CNC plasma. This fancy cutting wizard can really make your life easy and allow you to design some really cool parts.