Abstract: A compact, light-weight machine for throwing balls along a desired trajectory includes a housing with an arcuate track leading inwardly from an opening to an initial ball support station. A throwing arm is rotatably mounted within the housing and is connected to a torsion spring. A crank arm is provided on one end of the shaft to rotate the torsion spring and throwing arm against a stop pin that extends through the housing in the path of the throwing arm. The torsion spring stores energy provided through the crank arm as it is rotated about a central axis. When the spring is sufficiently loaded, the throwing arm will slip from engagement with the stop pin and forcibly move against a ball to move it arcuately around the track and outwardly through the opening. The machine is specially adapted for use with resilient balls that will deform both against the track and against the throwing arm.