A power tool (10; 200), comprising: a housing (11; 210); a motor in the housing; a drive shaft (12; 220), a first end portion of the drive shaft (12; 220) being coupled to the motor; a platen (16; 260); a retainer bearing (14; 240) coupled to a first surface of the platen (16; 260); an eccentric sleeve coupled to a second end portion of the drive shaft, the eccentric sleeve being coupled in the retainer bearing to eccentrically couple the drive shaft to the platen; an eccentric mass, including the eccentric sleeve (15; 250), the retainer bearing (14; 240) and the platen (16; 260) coupled to the second end portion of the drive shaft (12; 220); and a counterweight (18; 280) coupled to the second end portion of the drive shaft (12; 240), between the first surface of the platen (16; 260) and the eccentric sleeve (15; 250), wherein the counterweight (18; 280) is positioned such that a counterweight axis defined along a radial centerline of the counterweight is offset by a predetermined angle (θ) with respect to an orbit radius axis of the eccentric mass; wherein the counterweight axis is be defined by a line radially bisecting the counterweight, with an angle θ formed between the orbit radius axis and the counterweight axis; wherein the orbit radius is defined by a distance between the driven shaft centerline and the eccentric mass centerline, with an orbit radius axis defined by a line extending laterally through the longitudinally extending driven shaft centerline and the longitudinally extending eccentric mass centerline; wherein a second surface of the platen (16; 260), opposite the first surface of the platen (16; 260), faces an exterior of the tool, the second surface of the platen being configured to receive an abrasive sheet engaging a finishing surface of a workpiece during operation of the power tool; and wherein the counterweight (18; 280) is configured to counteract forces generated due to interaction between the abrasive sheet and the finishing surface based on the position of the counterweight (18; 280), the position of the counterweight (18; 280) being offset by the predetermined angle with respect to the orbit radius axis, and the counterweight (18; 280) being positioned adjacent to the first surface of the platen (16, 260) and proximate the second surface of the platen (16; 260) and the abrasive sheet coupled thereto; characterised in that the predetermined angle is greater than 3.0 degrees and less than or equal to 9.0 degrees. a housing (11; 210); a motor in the housing; a drive shaft (12; 220), a first end portion of the drive shaft (12; 220) being coupled to the motor; a platen (16; 260); a retainer bearing (14; 240) coupled to a first surface of the platen (16; 260); an eccentric sleeve coupled to a second end portion of the drive shaft, the eccentric sleeve being coupled in the retainer bearing to eccentrically couple the drive shaft to the platen; an eccentric mass, including the eccentric sleeve (15; 250), the retainer bearing (14; 240) and the platen (16; 260) coupled to the second end portion of the drive shaft (12; 220); and a counterweight (18; 280) coupled to the second end portion of the drive shaft (12; 240), between the first surface of the platen (16; 260) and the eccentric sleeve (15; 250), wherein the counterweight (18; 280) is positioned such that a counterweight axis defined along a radial centerline of the counterweight is offset by a predetermined angle (θ) with respect to an orbit radius axis of the eccentric mass; wherein the counterweight axis is be defined by a line radially bisecting the counterweight, with an angle θ formed between the orbit radius axis and the counterweight axis; wherein the orbit radius is defined by a distance between the driven shaft centerline and the eccentric mass centerline, with an orbit radius axis defined by a line extending laterally through the longitudinally extending driven shaft centerline and the longitudinally extending eccentric mass centerline; wherein a second surface of the platen (16; 260), opposite the first surface of the platen (16; 260), faces an exterior of the tool, the second surface of the platen being configured to receive an abrasive sheet engaging a finishing surface of a workpiece during operation of the power tool; and wherein the counterweight (18; 280) is configured to counteract forces generated due to interaction between the abrasive sheet and the finishing surface based on the position of the counterweight (18; 280), the position of the counterweight (18; 280) being offset by the predetermined angle with respect to the orbit radius axis, and the counterweight (18; 280) being positioned adjacent to the first surface of the platen (16, 260) and proximate the second surface of the platen (16; 260) and the abrasive sheet coupled thereto; characterised in that the predetermined angle is greater than 3.0 degrees and less than or equal to 9.0 degrees.