Brush Diameter for Floor Machines

Determining Diameters of Floor Machine Brushes Block Diameter: Lay the brush on the bristles, block side up.

Measure the actual outside diameter of the block (not the bristle flare).

See photo for reference (measurement B).
A 17" Floor Machine will take a 15" Block Diameter

Center Hole Diameter: Lay the brush on the bristles block side up. Remove mounting hardware, if any.

Measure actual inside diameter of the Center Hole.

5" is most popular, 4" is also used (measurement D).

Pad Drivers will usually extend below the skirt of the floor machine. This allows them to drive a larger pad size.