A head unit for a stop holder for a drilling machine for purposes of compensating for a height displacement between two adjacent components during the introduction and/or machining of a component hole. The stop holder has a front rest section for purposes of resting on the components. The rest section has an axial projection, which forms a second contact surface displaced relative to a first contact surface in the axial direction, i.e., the tool longitudinal direction. Also disclosed is a stop holder, and a method for compensating for a height displacement between two adjacent components during the introduction and/or machining of a component hole.

A manual drilling apparatus equipped with a device for control of advance, which includes a fixed part and a mobile part with movement of translation relative to the fixed part during the drilling, as well as a system for control of the movement of translation of the mobile part relative to the fixed part, wherein the fixed part and the mobile part comprise respectively at least one fixed tube and at least one mobile tube which slide relative to one another, the fixed and mobile tubes being coaxial to the axis of rotation of the tool supported by the apparatus.