Adjustable stroke device

An automatic adjustable stroke device for a random orbital machine comprising:

• a housing having a central axis and a wall defining a cavity;
• a counterbalance shaft assembly rotatably disposed at least partially within the cavity and a shaft portion of the counterbalance shaft assembly aligned with the central axis;
• a mounting assembly disposed at least partially within the cavity, the mounting assembly including a workpiece attachment mechanism;
• and
• a stroke adjuster coupling the counterbalance shaft assembly with the mounting assembly, the stroke adjuster assembly enabling the mounting assembly to adjust its stroke upon rotation of the counterbalance shaft assembly and the mounting assembly adjusts a stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing so that the workpiece attachment mechanism dwells to provide a flattened arc travel path portion of the workpiece attachment mechanism during rotation of the shaft, the stroke adjuster including a rotational part automatically adjusting the mounting assembly stroke.