A concentric assembly for a portable electric router having a base formed with a cylindrical sleeve terminating in a bottom flange for work engaging. A cylindrical motor housing is axially adjustably disposed within the sleeve. A motor is mounted within the motor housing and has an armature shaft centrally journaled therein. An arcuate pad is formed internally on one side of the sleeve with the arc of its surface set off from a radius substantially equal to the radius measured from the axis of the armature shaft to the outer periphery of the motor housing. A clamping means is connected through the sleeve on the side opposite the pad to force the motor housing against the pad to lock the same in adjusted axial position and to place the motor housing in concentric position. When the clamp is loosened, a rack and pinion mechanism connected between the motor housing and the sleeve can be used to axially position the motor housing to adjust the depth of cut of the router.