A cutting tool clamping mechanism comprising a first member and a second member; the first member comprising: a front portion at a front end of the first member; and a male portion extending rearwardly from the front portion, the male portion comprising a cylindrical stem having a stem diameter D3; the stem comprising a stem peripheral surface; the second member comprising: a female portion at a front end of the second member, the female portion comprising a front face and a clamping cavity opening out to the front face and formed by the union of an access hole and a gripping bore; and a rear portion extending rearwardly from the female portion;the gripping bore having a circular cross section with a gripping bore diameter D2 in an end view of the female portion, the gripping bore comprising a gripping surface having an arc angle ( α) greater than 180 degrees; the access hole comprising an access bore having a circular cross section with an access bore diameter D1 in the end view of the second member, wherein D1>D3>D2; the access bore and the gripping bore having respective longitudinal axes spaced apart at least along a portion thereof; wherein: the first member is movable between a clamped position and an unclamped position, wherein in the unclamped position the male portion is located in the access hole and in the clamped position, the gripping surface of the gripping bore is in engagement with the stem peripheral surface; characterised in that the clamping cavity comprises an internal coupling recess comprising a drive surface; the access hole further comprises a tooth access hole; the tooth access hole being formed in the front face and extending rearwardly; the male portion further comprises a coupling tooth projecting from the stem peripheral surface and configured to be received in the tooth access hole and in the coupling recess, the coupling tooth comprising a driven surface; and in the clamped position, the driven surface is in engagement with the drive surface. a front portion at a front end of the first member; and a male portion extending rearwardly from the front portion, the male portion comprising a cylindrical stem having a stem diameter D3; the stem comprising a stem peripheral surface; a female portion at a front end of the second member, the female portion comprising a front face and a clamping cavity opening out to the front face and formed by the union of an access hole and a gripping bore; and a rear portion extending rearwardly from the female portion;the gripping bore having a circular cross section with a gripping bore diameter D2 in an end view of the female portion, the gripping bore comprising a gripping surface having an arc angle ( α) greater than 180 degrees; the access hole comprising an access bore having a circular cross section with an access bore diameter D1 in the end view of the second member, wherein D1>D3>D2; the access bore and the gripping bore having respective longitudinal axes spaced apart at least along a portion thereof; the first member is movable between a clamped position and an unclamped position, wherein in the unclamped position the male portion is located in the access hole and in the clamped position, the gripping surface of the gripping bore is in engagement with the stem peripheral surface; characterised in that the clamping cavity comprises an internal coupling recess comprising a drive surface; the access hole further comprises a tooth access hole; the tooth access hole being formed in the front face and extending rearwardly; the male portion further comprises a coupling tooth projecting from the stem peripheral surface and configured to be received in the tooth access hole and in the coupling recess, the coupling tooth comprising a driven surface; and in the clamped position, the driven surface is in engagement with the drive surface.