An orbital shaker apparatus comprising: a platform further comprising supports for objects to be secured to the platform; a first shaft having a first end and a second end, the first shaft being connected to a first bearing assembly at the first end and having a mounting portion at the second end, the first shaft rotatable about a first shaft axis, the first shaft connected to a motor for rotation, the first bearing assembly mounted on a chassis; a second shaft having a second bearing assembly, a first end of the second shaft being mounted on the mounting portion and the platform being mounted on a second end of the second shaft, the second shaft aligned parallel to the first shaft and offset from the first shaft by a distance R; a counterweight rotor assembly rigidly coupled to the mounting portion, the counterweight rotor assembly rotatable by a belt driven by a pulley connected to a rotating shaft of the motor; and, a shaft slide rigidly coupled to the second shaft at the first end of the second shaft and the shaft slide being coupled to the second end of the first shaft, the shaft slide further comprising an adjustment apparatus; wherein, in use, as the counterweight rotor rotates, the second shaft, second bearing assembly, and platform describes a circular orbit with diameter 2R and wherein the adjustment apparatus operates to change the distance R between the first and second shafts (12, 26), characterized in the counterweight rotor assembly further comprising two counterweight bearings, each of the two counterweight bearings attached to a counterweight wedge, the counterweight bearings rotatable about the rotor assembly and constrained from motion in a direction orthogonal to the plane of rotation by a cap on a pedestal portion rigidly coupled to the first shaft, the two counterweight wedges being positioned symmetrically with respect to a line formed by the intersection of a plane through the first and second shaft axes and the plane of rotation of the counterweight wedges, the counterweight wedges being held in position by a fastener. a platform further comprising supports for objects to be secured to the platform; a first shaft having a first end and a second end, the first shaft being connected to a first bearing assembly at the first end and having a mounting portion at the second end, the first shaft rotatable about a first shaft axis, the first shaft connected to a motor for rotation, the first bearing assembly mounted on a chassis; a second shaft having a second bearing assembly, a first end of the second shaft being mounted on the mounting portion and the platform being mounted on a second end of the second shaft, the second shaft aligned parallel to the first shaft and offset from the first shaft by a distance R; a counterweight rotor assembly rigidly coupled to the mounting portion, the counterweight rotor assembly rotatable by a belt driven by a pulley connected to a rotating shaft of the motor; and, a shaft slide rigidly coupled to the second shaft at the first end of the second shaft and the shaft slide being coupled to the second end of the first shaft, the shaft slide further comprising an adjustment apparatus; wherein, in use, as the counterweight rotor rotates, the second shaft, second bearing assembly, and platform describes a circular orbit with diameter 2R and wherein the adjustment apparatus operates to change the distance R between the first and second shafts (12, 26), characterized in the counterweight rotor assembly further comprising two counterweight bearings, each of the two counterweight bearings attached to a counterweight wedge, the counterweight bearings rotatable about the rotor assembly and constrained from motion in a direction orthogonal to the plane of rotation by a cap on a pedestal portion rigidly coupled to the first shaft, the two counterweight wedges being positioned symmetrically with respect to a line formed by the intersection of a plane through the first and second shaft axes and the plane of rotation of the counterweight wedges, the counterweight wedges being held in position by a fastener.