A machine and method for machining parts of partial revolution. The machine has a driving sheave rotatable about a first axis and a first driven sheave rotatable about a second axis fixed relative to the first axis. An eccentric link is rotatably connected to the first driven sheave at a pivotal connection that is spaced a predetermined distance from the second axis. A belt is wrapped around the driving sheave and the first driven sheave so that rotation of the driving sheave causes the first driven sheave to rotate. A second driven sheave is rotatable about a third axis fixed relative to the second axis. A second driven sheave contacts with the eccentric link. The eccentric link moves in a reciprocating motion when said first driven sheave is caused to rotate and causes reciprocating rotary motion in the second driven sheave, which is transferred to a part being machined.