The most precise tool for cutting shapes out of sheet metal is the plasma cutter. A plasma cutter yields a small precise kerf (width of the cut) and will cut any electrically conductive metal (aluminum, copper, brass or stainless steel). It is able to achieve a smooth, steady cut with the use of a hand-held torch and an air compressor. In addition to cutting straight clean lines, a plasma cutter can gouge, pierce, bevel, cut holes and trace shapes in metal.
Things You'll Need
- Air plasma arc cutting machine
- Air compressor
- Welding safety equipment (welding jacket, gloves, helmet)
- Sheet metal
Make a cardboard template of the shape you wish to cut.
Place the shape template on the sheet metal and trace it with soapstone.
Place the drag shield (the tip of the cutting apparatus) on the metal at the place you wish to begin cutting. Make sure the arc is directed straight down.
Press the trigger. Allow two seconds of preflow air before the pilot arc starts. Move the torch across the metal at a consistent speed once the arc starts.
Adjust the speed so the cutting sparks go through the metal and out the bottom of the cut. If you don not see sparks, you are not penetrating the metal.
Achieve a finer cut by holding the tip of the torch about 1/8 inch from the surface of the work piece. The closer the torch is to the metal the finer the cut will be, and you will get a wider cut if you raise it away from the metal.
Pause briefly at the end of the cut to sever the metal shape from the rest of the sheet.
Tips & Warnings
- Routinely change the air filters on a plasma cutter.
- Low air pressure leads to low performance. The Fabricator recommends setting the source gauge 30 to 40 PSI higher than the pressure gauge on the machine.
- A plasma cutter will produce a post-flow of air for about 20 or 30 seconds in order to cool itself after the trigger has been released. You can, however, resume cutting even if the torch is in its cooling cycle. Just pull the trigger.
- Wear appropriate welding gear when using a plasma cutter.
- Clear the workspace of anything even remotely flammable. This includes protecting your hair from stray sparks; wear a helmet with face protection.