A surgical drill for actuating a drill bit , the surgical drill including: a housing , the housing is formed with a distally directed face and so that there is an opening in the distally directed face of the housing; a motor disposed in the housing; a coupling assembly disposed in the housing and adapted to releasable couple a drill bit configured to form a bore in living tissue to the motor so that the drill bit rotates upon actuation of the motor, wherein the coupling assembly is positioned to hold the drill bit to the housing so that drill bit extends forward from the opening in the distally directed face of the housing; and a probe , the probe being slidably mounted to the housing so as to extend forward from the housing and out of the opening in the distal directed face of the housing through which the drill bit extends forward from the housing, the probe having a distal end adapted for placement against tissue or against an implant; characterized in that : the surgical drill further includes a transducer assembly mounted to the housing for producing a signal representative of the distance the housing moves relative to the distal end of the probe when the drill bit is advanced into tissue; wherein the opening through which the drill bit and the probe extend is an opening formed in the transducer assembly ; and wherein, internal to the housing , there is a bushing , said bushing configured to allow the probe to slide while inhibiting lateral movement of the probe over a length of at least 1 cm. a housing , the housing is formed with a distally directed face and so that there is an opening in the distally directed face of the housing; a motor disposed in the housing; a coupling assembly disposed in the housing and adapted to releasable couple a drill bit configured to form a bore in living tissue to the motor so that the drill bit rotates upon actuation of the motor, wherein the coupling assembly is positioned to hold the drill bit to the housing so that drill bit extends forward from the opening in the distally directed face of the housing; and a probe , the probe being slidably mounted to the housing so as to extend forward from the housing and out of the opening in the distal directed face of the housing through which the drill bit extends forward from the housing, the probe having a distal end adapted for placement against tissue or against an implant; characterized in that : the surgical drill further includes a transducer assembly mounted to the housing for producing a signal representative of the distance the housing moves relative to the distal end of the probe when the drill bit is advanced into tissue; wherein the opening through which the drill bit and the probe extend is an opening formed in the transducer assembly ; and wherein, internal to the housing , there is a bushing , said bushing configured to allow the probe to slide while inhibiting lateral movement of the probe over a length of at least 1 cm. the surgical drill further includes a transducer assembly mounted to the housing for producing a signal representative of the distance the housing moves relative to the distal end of the probe when the drill bit is advanced into tissue; wherein the opening through which the drill bit and the probe extend is an opening formed in the transducer assembly ; and wherein, internal to the housing , there is a bushing , said bushing configured to allow the probe to slide while inhibiting lateral movement of the probe over a length of at least 1 cm. <EOS>