Abstract: A jig for cutting a mortise in a workpiece using a drilling tool having a mortising drill bit. The jig includes a base and a guide plate mounted on the base for movement relative to the base. A guide assembly locates the drilling tool. The guide assembly includes at least one rail supported by the guide plate. A guide is mounted on the rails for movement along the rails relative to the guide plate. The guide has an opening therein receiving and positioning the drilling tool. A bushing within the opening in the guide is mounted on the guide for rotation relative to the guide plate. A guide actuator includes a lever operatively mounted on the guide plate and a link connecting the lever to the guide whereby rocking the lever produces linear reciprocating motion of the guide on the rails.