Milwaukee M18 Fuel 2880 Angle Grinder vs Flex 24V FX3171A Variable Speed Angle Grinder

Milwaukee

Milwaukee M18 Fuel 2880 Angle Grinder

$199

4.8★ (2,326)

Flex

$199

Quick take: They live on different battery platforms (Milwaukee M18 vs Flex 24V), so the deciding factor is usually which batteries you already own.

Spec	Milwaukee M18 Fuel 2880 Angle Grinder	Flex 24V FX3171A Variable Speed Angle Grinder
Price (bare tool)	$199	$199
Kit Price	$329	$279
Rating	4.8★ (2,326)	—
Category	Angle Grinder	Angle Grinder
Battery Platform	Milwaukee M18	Flex 24V
Voltage	18V	24V
Motor	Brushless	Brushless
Weight		4.2 lbs (bare)
Released	2020	2021
Wheel Size	4-1/2 / 5 in	4-1/2 / 5 in
No-Load Speed	8,500 RPM	3,500-10,000 RPM, 4 settings
Switch	Paddle, no-lock	Paddle, no lock-on
Spindle	5/8-11	5/8-11 UNC

✓Genuinely replaces an 11A corded grinder for cutting and light fab work — the cordless-parity claim holds in owner use.
✓The Rapid Stop brake halts the wheel in seconds, and crews cite it as the reason safety managers approve this model.
✓Paddle switch with no lock-on satisfies jobsite safety rules that ban lock-on grinders.
✓Tool-free guard adjustment actually stays put under vibration, unlike many rivals' detent guards.
✓Shares batteries with the rest of M18, and it pulls hard on High Output packs without tripping protection.
✓Overload protection prevents the burned-out-armature death that kills corded grinders in heavy use.

✗It devours batteries — sustained grinding drains a 6.0Ah High Output pack fast enough that corded still wins for bench work.
✗Street price around $199 bare is a big step over corded grinders of equal power.
✗No variable speed on this model; you need the 2888 for RPM control on polishing work.
✗Heavier than corded equivalents once a big battery is fitted, which fatigues overhead cutting.
✗The paddle takes acclimation if you're coming from a slide-switch grinder — some owners find long sessions hand-cramping.
✗Wheel-change wrench storage is nonexistent; owners improvise.

✓10,000 RPM top speed leads the cordless 5-inch class - cut-off wheels feel noticeably faster than 8,500-9,000 RPM rivals.
✓Four real speed settings (3,500-10,000 RPM) via touch control make it a legitimate flap-disc, sanding, and polishing tool, which is rare on cordless grinders.
✓Kickback sensor stops the motor automatically if the wheel binds - PTR verified it works.
✓Light for the power class at 4.2 lbs bare, and owners call it well-balanced with low vibration from the suppression handle.
✓24V platform with THERMA-TECH heat management sustains output better than most 18V packs under long grinds.
✓One-step tool-free guard adjustment is faster than the detent systems on most competitors.
✓5-year warranty with registration, and Pro Tool Reviews concluded it 'competes very well against premium professional models'.
✓Kit with 5.0Ah battery and 160W fast charger frequently discounts to around $210.

✗No electric release brake - PTR measured about 2.5 seconds for a Type 27 wheel to spin down after letting go, behind Bosch/Makita brakes.
✗Flex 24V is a young platform in North America with a smaller tool catalog and fewer battery promos than DeWalt/Milwaukee.
✗$199 bare is premium pricing, and 24V batteries are expensive if you are not already invested.
✗Paddle has no lock-on, which fatigues hands on long grinding sessions (the FX3181A side-switch version fixes this).
✗Touch-control speed buttons can be fiddly with gloves compared to a mechanical dial.
✗Sold mainly through Lowe's and specialty dealers - fewer places to handle one in person or get quick warranty swaps.
✗No dust-extraction ecosystem integration like Makita AWS or Bosch's connected modules.