What is the quietest car polisher?
The quietest car polisher depends on its type. Among dual action polishers declared to EN62841-2-4, DEWALT's DCM848 states 77 dB(A) at the operator, and among DEWALT's rotary polishers the cordless DCM849 states 78.
A dual action, or random orbit, polisher spins its pad and swings it around an offset at once, while a rotary turns the pad on a fixed axis. EN62841-2-4 covers the first kind; EN60745-2-3, and its successor EN62841-2-3, cover the second. The test loads and set-ups differ, so a 77 from one and a 78 from the other cannot be put in order.
Inside the dual action group, the gap is plain. The DCM848 declares 77 dB(A) for the operator and 88 of sound power; Makita's PO5000C declares 84 and 92 under the same standard. Both makers state a K of 3, and seven decibels is more than twice that.
Makita USA's page for the PO5000C now carries a "DISCONTINUED" label, which leaves the DCM848 as the one current dual action polisher here with a declaration behind it.
Is a rotary or dual action polisher better for a quiet garage?
No maker figure settles that. DEWALT, the one brand here declaring both kinds, lists 77 dB(A) for its dual action DCM848 and 78 for its rotary DCM849, under two standards that cannot be ranked against each other.
So choose the type for the paint first. A dual action is the usual tool for swirls and finishing, because the orbit keeps the pad moving and makes it harder to burn through clear coat. A rotary cuts faster on oxidation and sanding marks but punishes a slow hand.
Once the type is settled, the figures in that group are the ones to compare, and the groups below are set out that way.
How loud are DEWALT's rotary polishers?
DEWALT's rotary polishers declare 78 dB(A) at the operator for the cordless DCM849 and 83.5 or 84.0 for the corded DWP849X, each with a K of 3 under EN60745-2-3, in DEWALT's UK manuals.
Both machines come from one maker, both were declared to the same part of EN 60745, and both carry a 3 dB uncertainty, so the comparison holds. The DCM849 reads five and a half to six decibels lower for the operator, and lower on sound power too, 89 against 94.5 or 95.0.
The DWP849X columns cover the 230 V and 115 V versions of the tool sold in Britain and Europe. Buyers in America get a 120 V DWP849X, a voltage neither column covers, which is why we quote both numbers rather than picking one.
The two are built for different days. The DWP849X runs a 12 Amp motor and takes 7 to 9 in. pads for long sessions on gelcoat or a fleet, while the DCM849 stops at a 180 mm pad and 2200 RPM.
Metabo's North American manual lists the PE 15-20 RT at 80 dB(A) of sound pressure and the PE 15-30 at 90, each with an uncertainty of 3, but names no test or distance for either.
With no standard given, the two Metabo numbers are compared only with each other. Read that way, the gap is large: ten decibels of sound pressure, and ten of sound power, 91 against 101, between machines that share a 1500 W rating and a 7 in. plate.
The PE 15-20 RT is the slower, higher torque tool, stepping from 600 to 1900 rpm with 18 Nm, against 800 to 3000 rpm and 15 Nm for the PE 15-30. The manual also warns that the noise "can exceed 80 dB(A) during operation", a caution about use rather than a declared value.
Is a cordless car polisher quieter than a corded one?
Yes, in both pairs that can fairly be compared here, though the figures do not show why. DEWALT's cordless DCM849 declares less than its corded DWP849X, and its cordless DCM848 less than Makita's corded PO5000C under the same test.
Size and speed also change within each pair. The DWP849X takes bigger pads and spins to 3500 min-1 against 2200 for the DCM849, and the PO5000C orbits up to 6,800 times a minute against 5500 for the DCM848. Any of those differences could account for part of each gap.
A battery polisher brings another advantage off the spec sheet: no cord slapping the panel or snagging a bumper, and no extension lead across the driveway.
Do Rupes, Griot's Garage, FLEX and Milwaukee publish polisher decibels?
No, none of those four printed a decibel figure we could read for a US polisher. Rupes gives a percentage instead of a number, and FLEX, Griot's Garage and Milwaukee give no noise figure at all.
Rupes headlines "NOISE REDUCTION BY 47%" for its BigFoot LHR15 and LHR21 Mark V without saying what the 47% is measured against. Its user manuals sit on a download site that asks for a login, which we did not use.
FLEX's US pages for its FC3321 and FX3321 random orbital polishers describe a gear head built "for reduced high-frequency noise" and stop there. Griot's Garage pages for the G9, G15 and G21 print no figure, and Milwaukee's manuals for the M18 FUEL 2738-20 and the M12 2438-20 have no noise section.
Do I need ear protection when polishing a car?
Yes, by the makers' own instructions. Makita's PO5000C manual says "Wear ear protection", Metabo's polisher manual says "Wear ear protectors!", and every declaration on this page puts 77 dB(A) or more at the operator.
A full correction, with a compound pass, a polish pass and a finishing pass, can keep a polisher running for hours. Over that time the operator figure matters more than sound power, because it is measured where the person polishing stands.
