The apparatus of the invention enables positioning a drilling guide parallel to the axes of transversal holes in the broach without seeing the holes. To this effect the drilling guide is adjustable with one degree of freedom on a mounting, the adjustment being effected as a function of positional information relating to the axis of the hole and sensed by mechanical feeler means which may be inserted into the broach. After this positioning is done by the apparatus according to the invention, a translation of the drilling guide may be done quickly by any conventional means in order to compensate for the distance between the axis of the drilling guide and the axis of the hole.
