Guide · Pads and backing plates
5-inch vs 6-inch polisher pads
Which pad size suits your polisher: what Milwaukee and RUPES recommend for 15 mm and 21 mm machines, why a 5-inch pad may measure 5-1/2 inches, and when to use each.
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Short answer
Pick the pad size your machine and backing plate are built around. Milwaukee recommends a 5-inch pad for its 15 mm 2684-20 and a 6-inch pad for its 21 mm 2685-20, with the other size optional on each.[1] A 5-inch pad reaches curves and recesses more easily; a 6-inch pad covers more of a flat panel per pass. Either way, the pad must suit the plate under it.
How pad size follows the machine
| Machine | Orbit | Recommended | Optional | Source |
|---|---|---|---|---|
| Milwaukee 2684-20 | 15 mm | 5-inch | 6-inch | Milwaukee[1] |
| Milwaukee 2685-20 | 21 mm | 6-inch | 5-inch | Milwaukee[1] |
| RUPES LHR15ES | 15 mm | 125 mm (5-inch) plate with 130-150 mm foam pads | Not stated | RUPES[2] |
The pattern is consistent: 15 mm machines are built around 5-inch plates, and the 21 mm machine around a 6-inch one.[3][4] The 15 mm vs 21 mm guide explains why.
"5-inch pad" can mean two things
Pads are often sold by the plate they fit, not their own diameter. RUPES pairs a 125 mm (5-inch) plate with foam pads listed as 130-150 mm, so the pad deliberately overhangs the plate.[2] Makita pairs 5-1/2 inch foam pads with its 5-inch plate in one of its polisher kits. Milwaukee, on the other hand, says the plate diameter should match the pad diameter on its tools.[1]
So read both numbers: the pad's own diameter and the plate it is meant for. Then check your tool maker's rule. The pad and backing-plate guide sets the makers' rules side by side.
When to choose each
5-inch plate and pad
- Most of a car: pillars, bumpers, mirrors and body lines as well as panels.
- Free-spinning machines that tend to stall on curves; a smaller pad sits flatter.
- The default on 15 mm machines.[1]
6-inch plate and pad
- Large flat panels: hoods, roofs, doors on vans and trucks.
- The default on 21 mm machines.[1]
- Less suited to recesses and tight curves.
Both: some machines ship with both plates, which lets you switch without buying a second tool. FLEX supplies its FC3321-Z with 5-inch (FT333) and 6-inch (FT334) plates,[5] and Makita supplies the XOP02Z tool only with a 5-inch (197923-2) and a 6-inch (197929-0) plate.[6]
Pad material is a separate question
Foam, microfiber and wool pads, and their cut levels, are not covered here. We could not verify a maker's pad-family documentation, so we do not rate pads by cut or finish.
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Questions
Can I use 6-inch pads on a 15 mm polisher?
On some machines. Milwaukee lists 6-inch as optional for its 15 mm 2684-20, with 5-inch recommended, and says the plate should match the pad diameter.[1]
Why is my 5-inch pad bigger than 5 inches?
Pads are often named for the plate they fit. RUPES pairs its 125 mm plate with 130-150 mm foam pads, a deliberate overhang. Check your tool maker's rule before mixing brands.[2]
Is a 6-inch pad faster?
It covers more area per pass on a flat panel, but it reaches curves and recesses less easily. We found no independent measurement of correction speed by pad size.
Which pad size does a 21 mm polisher use?
Milwaukee lists 6-inch as the recommended pad diameter for its 21 mm 2685-20, with 5-inch optional.[1]