An angle grinder is the fastest way to cut metal in a home workshop — and the easiest tool to make a mess with. Used right, it slices through rebar, angle iron, sheet steel, and bolts with a clean, straight edge. Used wrong, it wanders off the line, overheats the metal, and eats through discs. The difference is rarely the grinder itself. It is the disc you choose, how you hold the tool, and how patient you are with the cut.
The short answer: fit a thin cutting disc rated for metal (1 mm or 1.6 mm for most jobs), clamp the workpiece so it cannot move, mark a clear line, and cut in steady, shallow passes while letting the disc do the work. Never force it, never use a grinding disc to cut, and never cut without eye protection, gloves, and hearing protection.
Choosing the Right Disc
The disc matters more than the grinder. A 115 mm or 125 mm grinder is the standard home-workshop size, and its discs come in types that look similar but behave very differently.
| Disc type | Thickness | Best for | Avoid for |
|---|---|---|---|
| Thin cutting disc (metal) | 1.0–1.6 mm | Most steel, rebar, bolts, angle iron | Grinding or deburring |
| Standard cutting disc | 2.0–2.5 mm | Thicker steel, longer disc life | Fine, precise cuts |
| Grinding disc | 6 mm | Removing welds, beveling edges | Cutting — it binds and overheats |
| Diamond blade (metal) | Varies | Stainless steel, long production runs | Occasional use — costly overkill |
| Flap disc | Varies | Smoothing and deburring after the cut | Cutting through stock |
For most home jobs, a 1 mm or 1.6 mm metal cutting disc is the right call. It removes less material, so it cuts faster, cooler, and straighter, and it puts less strain on a small grinder. The trade-off is that thin discs are more fragile: they snap if you twist them in the cut, so a steady hand matters. Check the disc’s maximum RPM rating and make sure it matches or exceeds your grinder’s speed, and never fit a disc larger than your grinder’s guard is made for.
One rule that is not negotiable: use a disc rated for the material you are cutting. A masonry disc on steel cuts slowly and wears fast; a steel disc on masonry is worse. If the label says “metal” or “inox” for stainless, trust it.
Gear Up Before You Cut
Cutting metal throws sparks, sharp chips, and noise in every direction, and a grinder that kicks back can jump hard. Before the grinder is even switched on, put on safety glasses or a face shield — ordinary spectacles are not enough — plus work gloves, long sleeves, and hearing protection. Sparks bounce off concrete and land on skin, so closed shoes and no loose clothing matter more than they seem to.
Work somewhere sparks cannot reach anything flammable. Sweep sawdust and rags away from the cutting area, keep a fire extinguisher within reach if you are cutting indoors, and never cut near fuel cans or solvents. If you are cutting galvanized steel, the zinc coating gives off fumes that are genuinely unpleasant and harmful in quantity — cut outdoors or with good ventilation, and wear a respirator, not just a dust mask.
Setting Up the Cut
A good cut starts before the trigger is pulled. Mark your line with a permanent marker or a scribe, and if the line needs to be straight, clamp a straightedge or a piece of angle iron alongside it as a guide for the first pass. Clamp the workpiece itself firmly to a bench or a pair of sawhorses. Metal that is free to vibrate or shift will grab the disc, and a piece that drops as the cut finishes can pinch the disc and kick the grinder.
Think about where the offcut will go. Support both sides of the cut so the piece does not sag and trap the disc at the end, and position the work so sparks fly away from you and away from anything flammable. Keep the cord behind you and out of the spark path. Finally, check that the guard is fitted and adjusted so it sits between you and the disc, and give the disc a quick visual check for chips or cracks. A damaged disc goes straight in the bin — never onto the grinder.
The Cutting Technique, Step by Step
Score the line first
Start with a light scoring pass along the mark, barely breaking the surface. This groove gives the disc a track to follow and stops it wandering when you commit to the full-depth cut. It is the single habit that separates clean cuts from wobbly ones.
Let the disc do the work
Hold the grinder with both hands, switch on, and let it reach full speed before touching the metal. Feed it into the cut with gentle, steady pressure and a slight rocking motion — a few centimetres forward, ease back, forward again. Pushing hard does not cut faster; it overheats the disc, glazes the metal, and wears the disc down in minutes. If you see the metal turning blue, you are pushing too hard or dwelling in one spot.
Keep the disc square to the cut
The disc should stay in the same plane as the cut. Twisting or levering it sideways is how thin discs snap, and a snapping disc at 11,000 RPM is dangerous. If the cut starts to drift, stop, re-score, and start again rather than steering the disc back mid-cut.
Cut in passes on thick stock
On anything thicker than about 6 mm, do not try to cut through in one go. Make repeated passes, each a little deeper, and let the disc cool between them. The cut stays straighter, the disc lasts longer, and the metal keeps its temper instead of going soft and blue at the edge.
Cutting Different Kinds of Metal
Rebar and rod
Cut rebar with the bar clamped and the cut point close to the clamp so it cannot vibrate. A thin disc goes through standard rebar in seconds. Cut outdoors if you can — rebar throws a lot of sparks for its size.
Sheet metal
Thin sheet is where beginners struggle, because the disc grabs and the sheet flutters. Clamp the sheet between two boards or along a straightedge, leaving only the cutting line exposed, and use a 1 mm disc. Cut slowly and let the disc score first; a jigsaw with a metal blade is a better choice for long, curved cuts in thin sheet.
Pipe and tubing
Mark the cut all the way around the pipe, not just on one side. Cut partway through, rotate the pipe a quarter turn, and cut again — working around the circumference keeps the end square. For thin-wall tubing, support the pipe close to the cut so it does not crush or vibrate.
Angle iron and flat bar
These are the grinder’s home turf. Clamp the piece, score the line across both faces of the angle if you can, and cut through one leg at a time. Keep the cut square by checking the line on both faces before you start.
Mistakes That Ruin Cuts (or Break Discs)
The most common error is using a grinding disc to cut. It is thick, slow, and prone to binding in the slot, and it leaves a wide, ragged kerf. Next is cutting without clamping — a shifting workpiece is the cause of most wandering cuts and most kickbacks. Third is forcing the grinder, which overheats the metal and wears the disc to a stub. Finally, many people remove the guard for a better view. Do not. The guard is the only thing between you and a disc fragment if one fails, and a grinder without a guard is a tool you should not use.
Also check the disc’s expiry and condition. Cutting discs age, especially in damp workshops, and an old or damp disc can fail without warning. If a disc has been dropped, chipped, or soaked, throw it away — a new disc costs very little compared with the alternative.
After the Cut: Clean Up and Deburr
Fresh-cut metal edges are razor sharp. Run a flap disc or a file lightly along the edge to break the burr, and wipe the piece down to remove metal dust. Check the cut for squareness with a square or by offering the piece up to its mating part — a small error is easier to fix with a file now than after assembly. Sweep up metal chips before they find their way into shoes, tires, or a bare foot, and let the workpiece cool before handling it with bare hands. The edge stays hot longer than you expect.
Frequently Asked Questions
Can I cut metal with a wood cutting disc?
No. Wood discs have the wrong bond and tooth geometry for steel, and they can shatter or grab dangerously. Always use a disc rated for metal, and check the label before fitting it.
What size angle grinder is best for cutting metal?
A 115 mm or 125 mm grinder covers almost every home-workshop job, from bolts to angle iron. Larger 230 mm grinders cut deeper and faster but are heavier, harder to control, and overkill for most DIY work.
Why does my disc keep breaking?
Usually because it is being twisted in the cut, forced through thick stock in one pass, or used without the workpiece clamped. Keep the disc square, cut in passes, clamp the work, and use a fresh disc rated for the job.
Can I cut stainless steel with a normal metal disc?
You can, but a disc rated for inox (stainless) cuts cleaner and avoids contaminating the stainless surface with particles that later rust. For visible stainless work, the inox disc is worth the small extra cost.
Is it safe to cut metal indoors?
Yes, with preparation: clear flammables, protect the floor from sparks, ventilate well, and keep an extinguisher nearby. For galvanized steel, cut outdoors or with a respirator, because zinc fumes are harmful in enclosed spaces.
Bottom Line
Cutting metal with an angle grinder is a skill, not a gamble. Match a thin metal-rated disc to the job, clamp the work, score before you cut, and let the disc work at its own pace. Do that, and the grinder becomes one of the most useful tools in the shop — fast, accurate, and far less dramatic than its reputation suggests.