Abstract: The present invention relates to a machining method for obtaining a teeth following a helical curve on the surface of any shape whatsoever, this method being able to be applied to the manufacture of a broach, intended to prepare the intramedullary canal of a bone. The machining method on the surface of any shape whatsoever by a tool provided with a head, following at least one geometrical curve with the shape of a helix is characterised in that it comprises the following stages: tracing the surface normal at a plurality of points taken along the helix, making the helix follow the head of the tool, by orienting the head in such a way that it follows the orientation of the defined normals.