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When you have a project that involves cutting metal, an angle grinder can be used to complete the job with speed and precision. Angle grinders fitted with an appropriate wheel can cut through almost any metal, including steel, stainless steel, cast iron, aluminum, and copper.
Using an Angle Grinder to Cut Metal
Before you can start cutting, you will need to prepare your work area and don protective gear. Matching the thickness and abrasive material of your disc to the metal you’re working with will help you avoid discoloration and jagged edges.
Preparing Metal For an Angle Grinder Cut
Before you can start cutting, you have to get the metal prepared. Here are the steps:
- Mark your cut. For pipes, angle iron, and rebar, use a piece of masking tape, wrapping it all the way round the material. This will help you keep the wheel perpendicular to the metal while cutting, and increase the likelihood of a straight and even cut. For sheet metal, use a steel ruler and a permanent marker.
- Unless you are very experienced with an angle grinder, you are likely to produce a slanted or uneven cut. Give yourself a margin for error by cutting an inch longer than required. You can always remove excess material using a grinding wheel.
- Position the metal on your workbench. Make sure there is enough room for the angle grinder disc to pass through the metal without coming into contact with any other surface.
- The section of pipe, angle iron, or rebar marked for cutting should hang over the edge of the workbench. Secure the metal to your workbench using a vise or C-clamps. It should not rotate at all. Do not secure the other end. Sheet metal can be secured on two sawhorses.
- Check the drop-zone. This is the area where the remainder of the pipe will fall, and it should be clean and clear.
- Protect yourself. The type of protection you will need depends on the material you are working with. Cutting steel and titanium creates a shower of sparks, so fire-retardant clothing is necessary. Copper and aluminum do not produce sparks when cut. Steel-toed boots guard against damage from a falling piece of metal. Because discs occasionally shatter, a face shield, glasses, or goggles is essential.ds
Choosing the Right Disc to Cut Metal With an Angle Grinder
Choose a disc that matches the size of your angle grinder — the best 4.5″ angle grinder should only be used with a 4.5″ disc. The maximum RPM listed on the disc should meet or surpass the maximum RPM of your machine.
The grit you choose is dependent on how smooth the surface of the cut needs to be. For faster, rougher cuts, use lower grits. For slower, smoother cuts, choose higher grits.
A soft resin bond is the best choice for cutting metal. As the abrasive materials become dull, a soft bond will let them to fall away, revealing new, sharp abrasive grains.
You will need a cutoff disc or a diamond blade, both of which are thinner than grinding wheels. Different thicknesses may be better suited to specific types of metal.
- For stainless or mild steel, choose a disc that is 1 millimeter or 1.6 millimeters thick.
- To cut quickly and easily through sheet metal, you can use a thinner disc. A 0.8 or 1 millimeter disc will spend less time in contact with the metal, reducing the risk of heat discoloration.
- For thick steel, start the job with a 1.6 or 2.5 millimeter disc. A disc of this thickness will produce a rough cut surface that is likely to need finishing.
Best Abrasive Grinding Disc Material for Different Kinds of Metal
- For copper or cast iron, use silicon carbide.
- To cut steel or stainless steel, choose an aluminum oxide cutting wheel.
- For titanium, ceramic alumina will work well.
- Aluminum has a lower melting point than other metals, making it more susceptible to damage or discoloration from overheating. A slitting disc can be used to create less heat and reduce cut time.
How to Cut Metal With an Angle Grinder
With all of your preparations in place, its now time to use your angle grinder to make the cuts.
- Connect the tool to power. Use compressed air to power pneumatic angle grinders. An electric angle grinder should be plugged into a GFCI outlet. The cord should not cross the drop zone. Take care to arrange the cables so they aren’t a tripping hazard.
- Position the guard so that it will deflect any sparks or projectiles away from your face.
- Turn the angle grinder on and let it get up to full speed by allowing the disc to spin freely for one minute.
- Position the cutting wheel at a 90 degree angle to your cut mark. Bring the cutting wheel into contact with the metal and allow the weight of the angle grinder to do the work. Do not add pressure or try to force the angle grinder through the material.
- Keep the wheel at a 90 degree angle for the entire cut. Angling or tilting the blade mid-cut may cause kickback. The cut should open freely, reducing the chances of getting the blade caught in the material. Allow the remainder to drop away.
- Turn off the angle grinder and wait for the wheel to stop spinning. When it has come to a complete stop, set the tool down in a safe area and unplug it. Clean up the remainder and any debris.
Cutting Thick Pipes With an Angle Grinder
Depending on the size of the angle grinder and the size of the pipe or rebar, you may be able to cut through it with one pass. If you have a larger pipe or a straight cut is essential, plan to make four cuts, one on each face of the pipe.
- Turn the angle grinder off after each cut and allow it to come to a stop before setting it down.
- Rotate the pipe one quarter turn before every cut.
- Cut no further than the middle of the pipe.
- After each cut is complete, carefully remove the blade at the same angle it entered.
While undeniably useful for cutting metal, angle grinders are powerful tools that can become dangerous if used improperly. Always follow safety advice for using cutoff wheels.