Abstract: Mechanically-adjustable, variable oscillator drive mechanism having fixed locations for a main input shaft, an intermediate shaft, and an output shaft, and including a crank arm member supported by the intermediate input shaft and intermittently oscillated thereby through a fixed rotation, a slidable drive block member carried within a track formed on the crank arm, a positionally-adjustable carrier bracket mounted on the output shaft and pivotally supporting a sector gear segment, the latter also being drivably supported by the drive block member, and a sector pinion gear segment connected to the output shaft and meshed with the sector gear segment. Adjustment of the carrier bracket and connected sector gear segment, relative to the intermittently oscillating crank arm member, varies the angle of oscillation transferred to the sector gear segment, whereby the oscillation of the driven sector pinion gear segment and connected output shaft is adjustably varied.