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An angle grinder does more different jobs than almost any tool in a metal shop: cutting, grinding, deburring, polishing, cleaning welds, removing rust, cutting rebar and tile. It is also the tool most likely to hurt you badly, and that should influence what you buy.

Most tools punish you slowly. A dull blade wastes your afternoon. A weak drill burns out. A grinder punishes you instantly. A wheel spinning at 11,000 rpm holds a surprising amount of energy, and when it binds in a cut it does not stop — it throws the tool, or it throws itself apart. That is why the buying decision here is not really about power or brand. It is about which safety features are present and how well the tool sits in your hand when something goes wrong.

Buy the brake

A grinder wheel spinning at 11,000 rpm keeps spinning for several seconds after you release the trigger. An electric brake stops it in about two. That is the difference between setting the tool down safely and setting a live wheel onto your leg. If a grinder has a brake, buy that one.

Think about how you actually work. You cut, you release, and you reach for the part with your other hand or you set the grinder on the bench so you can reposition a clamp. Nobody stands there counting seconds while the wheel coasts. The brake exists because the gap between “finished the cut” and “put the tool down” is where people get cut. It is the single feature most worth paying for, and it is the reason a mid-priced grinder with a brake beats a more powerful one without.

Paddle switch vs slide switch

Paddle switches are dead-man switches — release and the tool cuts power. Slide switches stay on if the tool is dropped. For anything above light use, paddle is the safer design, and most professional models have moved that way.

The slide switch has one legitimate advantage: you can lock it on and keep grinding for long sessions without hand fatigue, which is why you still see them on bench-bound tools and on grinders used for sustained stock removal. That advantage disappears the moment the tool leaves your grip. A slide-switch grinder that gets knocked off a bench lands running, walks across the floor on its own wheel, and does not stop until it hits something. If you only own one grinder, own a paddle.

How to weigh the buying criteria

Almost every spec sheet leads with amps or volts, and that is the least useful number on the page. Here is a more honest priority order for a tool you will use weekly.

• Electric brake. Non-negotiable if you have the option. Nothing else on the list prevents injury as directly.
• Paddle switch. Second, for the same reason. Both together should filter your shortlist before you look at anything else.
• Body diameter and balance. You control a grinder with your hand wrapped around the motor housing. A slim body you can actually grip beats a fat one with more power every time. This is worth a trip to a store to hold the thing.
• Guard adjustment without tools. A tool-free guard gets repositioned. A guard that needs a wrench gets left in the wrong place, then gets removed. Design determines behaviour.
• Restart protection. If power drops mid-cut and comes back, the tool should stay off until you cycle the switch. Cheap grinders often skip this.
• Motor type. Brushless matters on cordless because it converts battery energy more efficiently and holds speed under load. On corded, it is a nice-to-have.
• Spindle lock and wheel changes. A grinder whose wheel is a nuisance to swap is a grinder you will use the wrong disc on.
• Raw power. Last. Anything in the 7–11A or quality 18V class cuts more steel than most people cut in a month.

What you actually get at each price band

Budget corded

At the bottom of the market you get a motor, a slide switch, a stamped guard and nothing else. No brake, often no restart protection, and a body diameter sized around the motor rather than around a human hand. These tools cut steel perfectly well. They are fine as a second grinder that lives on the bench with a wire cup mounted so you are not swapping discs constantly, and they are fine for a homeowner who will use one twice a year. They are the wrong choice for your only grinder if you work alone, because every safety feature you skipped is one you will need on the day the wheel binds.

Mid-range

This is where the brake and the paddle switch appear, along with a tool-free guard and a body you can wrap a hand around. Bearings are better, gear cases hold up, and the side handle threads into more than one position. For most welders and fabricators this band is the whole answer — buy here, spend the difference on wheels and a proper face shield, and stop reading spec sheets. A mid-range grinder with a brake will outlast three budget ones and will not put you in a hospital.

Professional and cordless flagships

Higher up you are paying for duty cycle and for electronics. Sealed switches that survive grinding dust, kickback sensors that cut power when the tool jerks, anti-vibration handles that matter if you grind for hours, and on cordless, drive electronics that hold wheel speed as the pack drains. If you grind daily, the vibration and dust protection alone justify the cost. If you grind on weekends, this band is a comfort purchase, not a safety one — you already got the safety at mid-range.

Cordless or corded for metal work

Cordless has closed most of the gap. A brushless grinder on a high-output pack cuts plenty of steel before needing a change. Corded still makes more sense if the grinder lives on a bench and runs for long sessions — sustained stock removal drains packs fast.

The real decision is about cords, not watts. Cutting a gate hinge on a fence line, working up a ladder, or trimming something in a car body — a cord is a snag hazard and a nuisance, and cordless wins outright. Standing at a bench blending welds for an hour, the cord is invisible and the battery is a problem. Buy cordless within a battery platform you already own; buying into a new platform for one grinder rarely pays. And be honest about pack size: a small compact battery turns a capable grinder into a tool that stops every few minutes.

Safety, not optional

• ✔ Full face shield, not just safety glasses — wheels shatter
• ✔ Guard stays on, always, positioned between the wheel and your body
• ✔ Wheels rated for the tool rpm, checked before mounting
• ✔ Two hands and the side handle on anything above 4.5″
• ✔ Let the wheel reach speed before touching the work

• ✘ Never use a cracked or dropped wheel
• ✘ Never remove the guard “just for this cut”
• ✘ Never use a cutting wheel for side grinding
• ✘ Never grind near flammables — sparks travel further than you think

The mistakes that keep repeating

Buying too big. A 7-inch grinder looks like more tool for the money. It is more tool than most people can hold onto. Bigger wheels mean more stored energy, more torque reaction, and two hands required for every task. Start at 4.5 or 5 inches.

Cutting with the wheel jammed deep in the kerf. Let the cut open. As the part sags, the kerf closes, the wheel binds and the tool kicks. Support both sides of the cut, or let the offcut fall free.

Standing in line with the wheel. Position your body out of the plane of rotation. If a wheel lets go, it leaves along that plane. Also aim the sparks away from your face and away from anything that can catch — sparks land further than they look, and they smoulder in sawdust and rags for a long time.

Grinding with a cut-off wheel. Thin cut-off wheels are built to take load on the edge only. Lean on the side of one and it will come apart. Use a grinding wheel or a flap disc.

Ignoring the guard position. The guard is not decoration and it is not there just to catch sparks. Rotate it so it sits between the wheel and your body for the cut you are making, and rotate it again when the cut changes.

Cheap wheels and old wheels. Check the rpm rating on every disc against the tool. Check the expiry date on bonded abrasive wheels. Ring-test or at least inspect a wheel that has been dropped, and throw out anything chipped. A wheel is the cheapest part of this system and the part most likely to injure you.

No dust or fume thinking. Grinding steel makes metal dust; cutting masonry makes silica. Ventilate, wear a proper respirator for masonry and for painted or galvanised metal, and do not grind galvanised steel in a closed shop.

Wheels and what they do

Cut-off wheels (1mm–3mm) for slicing bar, tube and rebar. Grinding wheels (6mm) for heavy stock removal. Flap discs for blending welds and finishing — the most useful disc in most shops. Wire cups and knots for rust and mill scale. Diamond blades for tile, block and concrete.

Buy consumables in quantity and buy them decent. Thin cut-off wheels vanish fast, and a good flap disc cuts three times as long as a bargain one while leaving a finish you do not have to redo. Keep a flap disc in something like 40 or 60 grit for knocking down welds and a finer one for finishing, and keep wheels dry — bonded abrasives absorb moisture and lose strength.

Who each option suits

Buy a mid-range cordless with a brake if you already own batteries, work in more than one place, or fabricate away from a bench. It suits most welders now.

Buy a corded 4.5-inch if the grinder lives in a fixed shop, you do long grinding sessions, or you want maximum sustained power per dollar. It is also the right pick if you want a second dedicated tool with a wire cup or flap disc permanently mounted.

Buy a 6-inch or larger only if you routinely cut heavy stock or thick plate and you are prepared to use two hands every time. Skip it as a first grinder.

Skip variable speed unless you polish, work stainless where heat colour matters, or use wire wheels that shed at full rpm.

FAQ

What size should I buy first? 4.5″ or 5″. Wheels are cheap and available everywhere, and the tool is controllable one-handed.

Do I need a variable-speed grinder? Only for polishing and some finishing work. For cutting and grinding, full speed is standard.

Brushless worth it? On cordless, yes. On corded, less critical.

Can I use a 5-inch wheel on a 4.5-inch grinder? No. The guard is sized for the wheel, and an oversized disc will not be covered — which defeats the one thing standing between the wheel and you. Match the wheel to the tool, and check that the wheel’s rpm rating is at or above the grinder’s no-load speed.

How do I stop kickback? Two hands, the side handle fitted, body out of the plane of the wheel, and cuts supported so the kerf cannot pinch. Feed with light steady pressure and let the abrasive work — forcing the tool is what makes it bind.