DeWalt 20-Volt MAX Cordless Brushless 4-1/2 in. Angle Grinder with Slide Switch (Tool Only)

Why I reached for this grinder

I spent the past few weeks putting DeWalt’s 20V brushless 4-1/2 in. grinder through metal, masonry, and auto work—cutting rebar, chasing mortar joints, trimming bolts, and cleaning up welds. I wanted to see whether a compact, cordless grinder could replace my old corded standby for most daily tasks. In short: this DeWalt 20V brushless grinder has the right mix of power, safety, and ergonomics for general use, with a few trade-offs to know before you buy.

Build and ergonomics

At just under 5 lb tool-only, the grinder feels compact but not toy-like. With a 5.0Ah battery installed, the balance sits just aft of the grip, which makes one-handed positioning easy while still leaving enough mass up front to dampen vibration. The slide switch is glove-friendly and has a positive detent—confident enough to avoid accidental activation, but not so stiff that switching on and off becomes a chore. For longer grinding passes, the lock-on function is handy.

The side handle is simple and effective. Threaded positions on both sides of the head let you set up for left- or right-handed work. The head itself is slim enough to get into corners where a bulkier gear case might block access. Overall, the form factor is what I expect from DeWalt’s 20V line: familiar, durable, with no gimmicks.

Power and performance under load

The brushless motor is the hero here. It maintains speed well when you lean into material. On 1/4 in. steel with a Type 27 wheel, I could keep pressure consistent without the audible sag that plagues many compact cordless grinders. For cutting tasks—rebar, angle, and bolt trimming—the motor stayed composed as long as I let the wheel do the work.

Push too hard, and the protection electronics will step in. I saw two kinds of interventions:
- Overload: if you bury the wheel or grind aggressively for extended periods, the tool shuts down to protect itself. Cycle the switch and you’re back in business.
- E-Clutch/Kickback Brake: pinch the wheel and the tool reacts instantly, stopping the spindle and preventing that wrist-jarring spin. It’s confidence-inspiring, especially when cutting in awkward positions.

To be clear, this isn’t a replacement for a 13-amp corded grinder if you live in heavy stock removal. But for typical trades and shop tasks—deburring, edge prep, small to medium cuts—it punches above its size.

Safety features that make a difference

Two things stood out in daily use:

• E-Clutch and Kickback Brake: I intentionally induced a few pinches during test cuts (with PPE and a secure stance). Each time, the tool shut down and the wheel came to a quick halt. That combination turns near misses into non-events, and I wouldn’t buy a modern grinder without it.
• Guards and coverage: The grinder ships with a Type B guard for grinding and a clip-on guard for cutting wheels. The quick-change mechanism makes swapping fast and tool-free, and the clip-on cutting guard adds a welcome layer of spark and fragment control when running Type 1/41 wheels.

Mesh intake screens are another subtle but important safety/durability feature. They reduce the amount of metal and masonry dust that reaches the internals. I made a habit of tapping and blowing them out at the end of the day—worth the extra minute.

Battery strategy and runtime

This tool is sold bare, so plan your battery strategy. Here’s what worked for me:
- 5.0Ah 20V MAX: good balance of weight and runtime; my default.
- 8.0Ah/PowerStack or a compatible FLEXVOLT pack: noticeably more endurance for long grinding sessions, at the cost of extra weight.

Grinding is battery-intensive—no way around it. Cutting is more forgiving, especially with thin kerf wheels. If you’re planning continuous grinding (beveling plate, smoothing welds across a large area), you’ll want at least two batteries rotating on a fast charger.

The tool’s electronics are conservative enough to protect both motor and pack. If it feels like it’s quitting early under punishing load, that’s the overload protection doing its job. Ease off, let it cool for a moment, and continue.

Wheel changes and guard setup

Wheel changes are straightforward: spindle lock, flange, wheel, and nut. The included wrench fits the nut fine, and the spindle lock button has enough depth that I never accidentally released it while tightening. The grinder accepts common 4.5 in. wheels and supports 4–5 in. sizes with the proper guards. I ran Type 27/28 depressed-center grinding wheels and Type 1/41 cutting wheels without compatibility surprises.

The guard mechanism is one of the better quick-change designs. Adjustments are tool-free, and the detents hold position during use. Switching to the clip-on cutting guard is worth the extra few seconds when you’re cutting overhead or near sensitive surfaces—it directs sparks more predictably.

Tip: If you alternate frequently between grinding and cutting, keep both guards set up with their wheels so you’re not reconfiguring flanges mid-task.

Dust, debris, and durability

Grinding and cutting throw debris everywhere; this grinder handles the environment well. The mesh screens do catch a surprising amount of fines. I also appreciate that the head shape doesn’t trap dust in odd pockets—wipe-downs are quick.

Brushless means no brushes to replace, and in my time with it, there were no heat or smell issues even after extended cutting. If the tool feels hot near the gear case after a session of hard grinding, give it a cool-down break; you’ll avoid nuisance trips and extend motor life.

Where it shines

• Metal fabrication and repair: deburring, beveling, rust removal with a flap disc, trimming bolt ends.
• Jobsite cutting: rebar, threaded rod, angle, light plate, and masonry with a diamond wheel.
• Automotive: bracket cleanup, exhaust trimming, and general repair work where a cord is a hassle.

The slide switch and lock-on are excellent for long passes with a flap disc. The compact head and decent balance make it easy to control even in awkward orientations.

Limitations to consider

• Continuous heavy grinding will drain smaller packs quickly and can trigger thermal/overload protection. Plan battery capacity accordingly.
• The slide switch is polarizing. If you work in tight, unpredictable positions all day and prefer a dead-man paddle, this configuration may not be your favorite.
• It’s still a 4-1/2 in. class tool. If you frequently need deep cuts or aggressive material removal, a 5–6 in. high-output grinder (corded or high-voltage cordless) will be faster.

Practical setup tips

• Start with a 5.0Ah or larger battery; keep a second on charge for uninterrupted work.
• Use the clip-on cutting guard for Type 1/41 wheels—better spark control and coverage.
• Blow out the mesh screens routinely; it’s quick insurance against overheating.
• Let the wheel do the work. If you feel the tool bogging, back off slightly—your cuts will be cleaner and your battery will last longer.

Recommendation

I recommend the DeWalt 20V brushless grinder for pros and serious DIYers who value safety, portability, and solid all-around performance in the 4-1/2 in. class. The brushless motor maintains speed under load, the E-Clutch and Kickback Brake add meaningful protection, and the guard system is genuinely user-friendly. Pair it with 5.0Ah or larger batteries and it will handle the vast majority of cutting and grinding tasks you’d expect from a compact grinder. If your day-to-day work is heavy stock removal or you strongly prefer a paddle switch, look elsewhere; otherwise, this is a dependable, well-thought-out cordless grinder that earns a spot in the kit.