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I need to cut out a small section of 1.5mm Stainless steel. Before, when I've made cuts I have used an angle grinder and its resulted in thr stainless becoming scorched/burnt and I can't remove it.

What can i do to cut stainless steel and not have scorch marks?

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As you have implied, heating the metal is actually changing it near the cut and causing it to discolor. There's not soot or anything you can clean off - the metal is changed. You may be able to sand off the surface of the metal near the cuts to remove the discolored metal on the surface, but this will lead to a cut that doesn't look very clean and some discoloration may remain.

The other choice is to cut the metal without heat. Angle grinders don't really cut - they sand their way through the metal creating a massive amount of heat. One tool that actually cuts through the metal is known as a "nibbler". They come in many forms. Hand operated, air powered, electric, and as a small attachment for an electric drill.

They are basically a small punch that nibbles of small bits of metal. They do this very quickly so the result looks like a straigt cut. The issue is that many of the tools that I found top at at 16ga (1.5875mm) or 14ga (1.984375mm) sheet metal. Your 1.5mm sheet is going to be at the top end of their capabilities, but if you choose a quality tool and don't try to move too fast, I think you'll be ok.

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    Or a hacksaw, human-powered. Fancy carbide blade optional, but not a terrible idea with stainless, which is prone to work-hardening. Or, depending on the definition of "small section" and "cut out," a file might be a better approach... Note that most tools rated for X amount of "sheet metal" mean mild steel, and stainless is a very different animal (much harder to cut.) – Ecnerwal Jul 15 at 18:35
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The trick with an angle grinder is not to try to cut the metal with one pass. That way, you are wasting the wheel and effectively heating up the metal, causing distortion and discoloration.

The best way to cut with an angle grinder is to do so in multiple passes, and using the bottom part of the wheel to cut.

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For example, if you are cutting a straight cut on a flat sheet of metal, say 6" long, place the angle grinder on your cutting line, and let the weight of your hand only carry the grinder forward those 6". After that, lift the grinder, and go back to the beginning and use that "track" you just built as your guide, and slowly keep cutting it that way.

This way, you will use much less off your wheel, (which you will notice by the reduced smell and dust in the air), you will cut with minimal discoloration, minimal heat, which will also extremely minimize distortion on thinner gauges metals.

If you still have minimal discoloration you need removed, you can use things such as Zep Polish or a Scotch Brite pad, specially on #4 finish stainless, for example.

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You can cut a stainless steel metal sheet without the burn marks by using a circular saw. It is a handheld saw with a circular blade. Make sure to match the blade with the thickness of your stainless steel sheet (preferably a diamond saw blade because it is stronger than any other circular blades). Make sure to securely clamp your sheets on a working table to be able to cut it precisely without moving.

  • A diamond blade performs the same job as an angle grinder with an abrasive blade. There's still going to be a lot of heat. – JPhi1618 Jul 15 at 19:51
  • And the joy of your diamonds turning into charcoal and then carbon dioxide when they get hot enough (which they will, cutting steel, unless we've gone to a liquid-cooled saw, which was not mentioned.) "Cold saws" use Tungsten Carbide teeth and are a bit much for a home improvement project, though they are again optimized for mild steel (they literally cut away steel "put most of the heat into the chip" thus "cold saw" as opposed to the abrasive type.) – Ecnerwal Jul 16 at 1:55

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