A plunge base for a power tool includes a base plate having a generally flat bottom surface and defining an opening through which a router bit of a router supported by the plunge base extends to engage a workpiece. A carriage support extends vertically upward from the base plate on one side of the opening. A router carriage is slidably retained on the carriage support. The router carriage is slidable toward and away from the base plate between a first position and a second position and is configured to releasably secure a router thereto the router aligned with the opening in the base. A plunge lock mechanism is configured to retain the router carriage at any position between and including the first position and the second position in relation to the carriage support.