a portable electric router having a depth of cut adjustment mechanism including an adjustment ring which engages a screw thread on the motor housing and rotationally engages the router base . there is further provided an arrangement for preventing relative rotation between the motor housing and the base . the adjustment ring is formed as a split ring with projections adjacent opposite sides of the split , each with a frusto - conical camming surface . a circular clamp knob mounted for threaded rotation on a bolt passing through the projections radially with respect to the router motor housing bears against the camming surfaces so as to squeeze the ring in order to effect a clamping action as the knob is moved inwardly . in order to provide limit stops for preset depths of cut , a pair of stop rings are provided which are angularly rotatable on the router base . each of the stop rings includes an interference projection and the adjustment ring has a tab fixedly mounted thereon which extends to a point between the interfering projections . the stop rings may be fixed to the router base to limit the range of angular rotation of the adjustment ring .