The pick for best overall is the Makita, which finished with the best average
finish of the group at 2.2 across the non-subjective categories. It won both
performance tests outright and not narrowly: 2.98 seconds through 1/2 inch
rebar with a cutoff wheel, and 5.82 seconds grinding through rebar under 20 lb
of force, against 10.4 seconds for the next best tool. Its 13-amp motor held
blade speed where nearly everything else bogged down, and it is also the
quietest grinder here at 88.4 dB, the second smoothest at 70 m/s squared, and
one of the two softest-starting tools in the lineup. The compromises are real
but minor — it is the heaviest tool at 5 lb 9.5 oz, its measured no-load speed
of 9,832 RPM is the second lowest here, and its switch has to be pressed inward
while being slid forward, which is awkward with dirty or wet hands.
For value, the Ridgid at $60 is hard to argue with. It spun faster than any
other tool at 12,065 RPM and converted that into second place in both cutting
tests, 3.8 seconds and 10.4 seconds, beating every 11-amp grinder in the test
and everything else costing more than twice as much. It also carries a lifetime
warranty. Two things to know before buying it: 9 in-lb of startup reaction
torque is the highest here by a wide margin, enough that it flipped itself on
the bench, and its 10-1/4 inch body circumference is the largest in the group,
so it wants two hands and large ones. Above it, the Milwaukee finished second
overall at 3.4 and the Metabo third at 4.8, both tying at 12.6 seconds under
load, with the Milwaukee adding the lightest switch in the test at 3 lb, an
electronic clutch, and overload protection. At the opposite end, the $15
Warrior is a genuinely usable tool for occasional work — 14 seconds through the
rebar and no trouble at 10 lb of grinding force.
The load test is where the buying guidance really sits. Three grinders could
not take 20 lb of force: the Warrior smoked at 15 lb, the Ryobi's brushes burned
out roughly two seconds in, and the Hilti stalled on three consecutive
attempts, its 6-amp motor simply outmatched. That does not make the Ryobi a bad
tool for lighter duty — it recorded around 12 m/s squared of vibration, about
five times smoother than anything else, and earned the best ergonomics rating
of the test — but it is not the grinder for sustained heavy cutting. Comfort
and power pull in opposite directions elsewhere too: the DeWalt vibrated hardest
at 271 m/s squared and the Metabo at 217, while the Hilti's 3.4 second wheel
stop was the fastest of all. Whichever tool is chosen, seven of the eleven run
at or above 98 dB, so hearing protection belongs with all of them.
