Patent ID: 8371032

Claim:
A power tool, comprising: a motor configured to generate a rotational output, a disk rotatably driven by the motor about a rotational axis, a crank pin eccentrically rotatable by the motor about the rotational axis, a non-rotatable first slider configured to be linearly reciprocated by the crank pin, the first slider being configured to linearly reciprocate a tool, an eccentric pin coupled to the disk and disposed substantially diametrically opposite of the crank pin relative to the rotational axis, the eccentric pin being spaced from the rotational axis so that the eccentric pin does not overlap the rotational axis and being configured to revolve about the rotational axis, a crank disk having the crank pin press-fit therein, the crank disk being rotatably driven by the motor via the eccentric pin, which is rotatable relative to the crank disk, and a non-rotatable second slider configured to be linearly reciprocated by the eccentric pin in a substantially opposite phase from the first slider, the second slider acting as a counterweight to the first slider to reduce vibrations at least in the direction of linear reciprocation, wherein the combination of the disk and eccentric pin have a center of gravity offset from the rotational axis towards the eccentric pin.