A surgical tool assembly for use with an energy applicator to contact tissue of a patient at a surgical site, the energy applicator having a shaft extending along an axis between a proximal end and a distal end, the shaft having an axial-force receiving surface (76, 77), said tool assembly comprising: a support structure to support said energy applicator; an axial connector assembly arranged to engage and releasably lock the energy applicator to said support structure in a locked state, wherein said axial connector assembly comprises a cam member, a locking sleeve, and at least one engagement member; a drive system (66; 200, 250) coupled to said support structure to rotatably drive the shaft of the energy applicator about said axis; a collet assembly cooperating with said axial connector assembly to apply a force to the axial-force receiving surface (76, 77) of the energy applicator when said axial connector assembly engages and releasably locks the energy applicator to said support structure in said locked state; and a reference surface to be contacted by the energy applicator in said locked state, characterized in that said force includes an axial component directing the energy applicator proximally into continuous contact with said reference surface in said locked state, wherein said at least one engagement member is wedged between a sloped surface of the cam member and a sloped surface of the axial-force receiving surface of the shaft, each of the sloped surface of the cam member and the sloped surface of the axial-force receiving surface being arranged at an acute angle (α1, α2) relative to said axis, to apply said axial component of said force to the axial-force receiving surface (76, 77) of the energy applicator when said axial connector assembly is in said locked state. a support structure to support said energy applicator; an axial connector assembly arranged to engage and releasably lock the energy applicator to said support structure in a locked state, wherein said axial connector assembly comprises a cam member, a locking sleeve, and at least one engagement member; a drive system (66; 200, 250) coupled to said support structure to rotatably drive the shaft of the energy applicator about said axis; a collet assembly cooperating with said axial connector assembly to apply a force to the axial-force receiving surface (76, 77) of the energy applicator when said axial connector assembly engages and releasably locks the energy applicator to said support structure in said locked state; and a reference surface to be contacted by the energy applicator in said locked state, characterized in that said force includes an axial component directing the energy applicator proximally into continuous contact with said reference surface in said locked state, wherein said at least one engagement member is wedged between a sloped surface of the cam member and a sloped surface of the axial-force receiving surface of the shaft, each of the sloped surface of the cam member and the sloped surface of the axial-force receiving surface being arranged at an acute angle (α1, α2) relative to said axis, to apply said axial component of said force to the axial-force receiving surface (76, 77) of the energy applicator when said axial connector assembly is in said locked state.