Friday, May 21, 2010

Cut An Oval Shape Into Metal

Cutting an oval in metal requires a tool that has the ability to easily turn corners.

When installing metal roofing or metal HVAC ductwork, you often need to cut an oval shape into the metal for pipe penetrations. The need for an oval or ellipse is required when the round pipe intersects a piece of sheet metal sitting on a slope. Patterns are readily available based on the size of the original circle diameter and the slope or pitch at which the circle will intersect the piece of metal. One tool has the ability to cut various thicknesses of metal, uses no blades or cutting wheels and is available at tool rental retailers. Does this Spark an idea?


1. Lay the piece of metal flat on top of a worktable and place an oval pattern on the surface of the metal.

2. Slide the oval pattern to the location you need to cut the hole.

3. Trace around the oval pattern with soapstone to create a reference line for your cut; remove the pattern from the surface of the metal.

4. Put on tinted cutting glasses and leather work gloves.

5. Set a fire extinguisher near the worktable and connect the ground cable of a plasma cutter to an edge of the metal away from the area you will be cutting.

6. Inspect the end of the plasma cutter. The tip should have a well-defined, round hole surrounded by clean unmelted copper. Unscrew the end of the plasma torch and inspect the copper electrode located beneath the copper tip. It needs to be solid and undamaged to create a clean cut in the metal. Reattach the end of the plasma torch and turn on the plasma cutter.

7. Slide the metal so the outline of the oval overhangs the end of the worktable. You need a clear area below the metal to allow the sparks from the plasma cutter to blow toward the floor or the sparks will fly back at you, which could cause severe burns to your face and body.

8. Align the opening of the plasma tip with the inside of the soapstone line you placed on the surface of the metal in step three. Pull the trigger of the plasma torch and slowly drag the tip of the torch along the soapstone line until the oval drops through the metal.

9. Attach a 60-grit, 4.5-inch flapper wheel to a 4.5-inch angle grinder and clean both sides of the oval hole in the metal with the spinning flapper wheel to remove the slag left from the plasma cutter.

10. Allow the cut and cleaned piece of metal to cool to room temperature before handling to avoid receiving burns from the area around the oval cut.

Tags: plasma cutter, oval pattern, piece metal, plasma torch, surface metal, around oval