DeWalt 20V MAX XR Brushless Cordless 3 in. x 21 in. Belt Sander (Tool Only)

A cordless belt sander that finally feels jobsite-ready

Cordless belt sanding used to mean trading away real material removal and control for convenience. After several weeks with DeWalt’s cordless 3x21 belt sander, I’m comfortable saying it doesn’t feel like a compromise. It’s not a brute like a high-amp corded unit, but it has the torque, dust control, and finesse to live on my cart for everything from flattening subfloors to fine-tuning scribe lines.

Build, balance, and ergonomics

Bare, the tool is reasonably compact and weighs in at just over eight pounds. Add a mid-size 20V pack and it lands in that sweet spot where the belt stays planted without my wrists doing extra work. The auxiliary overmolded handle is a big part of that. It’s positioned high enough to let me steer with the front hand and keep the platen honest, which matters on a belt sander more than most tools.

The platen rides flat and true. If you’re sloppy with your stance it’s still possible to tip the sander and create a dish—physics haven’t changed—but the form factor makes it easy to keep the belt parallel. The front end is compact enough to sneak into corners and along toe kicks, and the side profile lets me get fairly close to a wall.

Battery choice affects the balance appreciably. With a compact 4Ah or a standard 5Ah 20V pack, it feels neutral. With a big FlexVolt pack (9Ah/12Ah), the rear gets heavy and I have to work a bit harder on the front handle to keep the platen flat. That’s manageable, but it’s something to consider if you’re planning to run only high-capacity batteries.

Controls are straightforward. There’s a variable-speed trigger paired with a 25-position speed dial that sets the ceiling. The dial has small but meaningful steps—more granular than most sanders—and I found myself using it to lock in belt speed for different materials rather than riding the trigger. The lock-on button is tucked in enough that I have to be deliberate with gloves on; it’s not a deal-breaker, just less convenient than a proud switch.

Belt changes are quick and drama-free. The lever swings open with good leverage, belts slide off/on without a fight, and tracking dial-in takes just a turn or two. Once set, tracking stayed put for me, even on aggressive grits.

Power and removal rate

This is where the brushless motor earns its keep. Belt speed ranges from a gentle 650 ft/min up to 1050 ft/min, and the tool holds that speed under pressure better than I expected. With 36–60 grit belts, I can flatten OSB subfloor high spots and flush down proud hardwood seams efficiently, in the way I usually reserve for corded sanders. On dense hardwoods (white oak stair treads, for example), dropping to midrange speed cuts chatter and prevents burning while still removing material decisively.

Is it as fast as a big corded 10-amp belt sander when you lean on it? Not quite. But it doesn’t bog unexpectedly, and the consistency of the removal rate is excellent. For controlled stock removal, it’s genuinely satisfying.

Dust collection that keeps up

DeWalt’s dust setup on this sander is one of the highlights. The port can take a 35 mm hose or click into an AirLock setup. Hooked to a DeWalt extractor via AirLock, collection is excellent—on par with the best corded setups I’ve used. I could keep up with a fast removal pace without snowing the room, which makes this much more viable for interior work. The swivel at the port helps keep the hose from fighting you as you move across a floor or benchtop.

The included dust bag is better than most—firm collar, decent capacity—but it’s still a dust bag. It’ll catch a surprising amount if you’re just breaking edges or cleaning up a small patch, but it fills fast when you’re doing real flattening. If you invest in this sander, plan to connect a vac whenever possible. Bonus: if you have DeWalt’s Wireless Tool Control, you can pair the sander with a compatible extractor for auto start/stop. It’s a small convenience that makes a big difference on repetitive tasks.

Runtime and battery strategy

Cordless belt sanders eat batteries. This one is efficient for what it is, and runtime swings with grit, speed, and pressure. With a fresh 5Ah 20V pack, I’m seeing roughly 25–35 minutes of continuous sanding on typical carpentry tasks at midrange speeds. Drop to fine finishing grits and it stretches; crank the speed with a coarse belt and it shortens.

My practical setup for site work is three 5Ah packs in rotation with a fast charger nearby. That keeps me moving without hitting a battery wall. Large FlexVolt packs extend runtime, but, as I mentioned, they skew the balance to the rear. If you’re mostly on flat work like floors or tabletops, that may not bother you; for vertical or overhead work, I prefer the lighter 4–5Ah packs.

Control and finish quality

The platen is flat and the belt rides stable, which makes it easy to get predictable results. I like the way this sander transitions from aggressive hogging to controlled finishing: back off the speed, lighten up your front-hand pressure, and the scratch pattern tightens up cleanly. With 80–120 grit belts, I can go straight to a random orbit sander without a lot of extra time invested in scratch removal.

One nuance worth calling out: the tool rewards good stance and two-handed technique. If you’re lazy with the front handle or let your weight drift to the back, you can create a shallow dip at the trailing edge. The solution is simple—keep even pressure on the front handle and let the weight of the tool do most of the work—but it’s something you feel more if you’re running heavy batteries.

Noise and vibration

For a belt sander, it’s reasonably civilized. DeWalt’s published levels put it in the low 80s dB(A) at the operator position, and that matches my experience. It’s notably quieter than some high-strung corded models, with a smoother pitch. I still wear hearing protection; you should too. Vibration is well controlled, and the overmold doesn’t get hot or buzzy under load.

Setup, accessories, and compatibility

Out of the box you get a dust bag, a dust port swivel, and a single 80-grit belt. The 3x21 belt size is ubiquitous and easy to find in everything from coarse zirconia to fine aluminum oxide. The dust port plays nicely with standard 35 mm hoses and DeWalt’s AirLock system, and the Wireless Tool Control option is there if you already live in that ecosystem. The tool is sold bare, so factor in battery and charger if you’re not already on the platform.

Warranty coverage is DeWalt’s typical 3-year limited plan. I didn’t see anything during my time with the sander that raised durability red flags—tracking holds, guards are rigid, and the belt-change mechanism still snaps with authority.

What I liked

• Strong material removal for a cordless belt sander; holds speed under pressure
• Excellent dust collection with an extractor; hose swivel reduces fighting the hose
• Very granular 25-step speed dial plus variable trigger for dialing in different tasks
• Easy, reliable belt changes and stable tracking
• Comfortable two-handed control; manageable weight with 4–5Ah packs
• Useful integrations: AirLock and optional Wireless Tool Control

What could be better

• Balance shifts noticeably with large high-capacity batteries
• Lock-on button sits a bit recessed and is fiddly with gloves
• The dust bag works, but it fills quickly—plan on a vac for serious work

The bottom line

I reach for this sander far more often than I expected. It has the muscle to do real carpentry jobs—flattening subfloors, trimming proud glue-ups, tuning doors—without tethering me to an outlet or dragging a cord across fresh work. Pair it with a vac and mid-size 20V batteries, and it’s clean, controllable, and genuinely productive.

Recommendation: I recommend this tool to tradespeople and serious DIYers who value cordless convenience but won’t tolerate flimsy performance. If you do all-day beam flattening or constant hogging, a big corded sander still makes sense. For most remodeling, cabinetry, and site carpentry tasks, this cordless 3x21 strikes a smart balance of power, runtime, and control—and its dust collection makes it a better indoor companion than many corded alternatives.