The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.

An accessory tool includes an adapter end having a maximum outer dimension, and a shank coupled to the adapter end. The shank includes a tool engagement portion including a cross section having a maximum outer width, a first reduced portion disposed between the tool engagement portion and the adapter end and having a first minimum outer dimension and a first length, and a second reduced portion formed in the tool engagement portion between the first reduced portion and an end of the shank. The second reduced portion is engaged by the tool to secure the shank to the tool, and has a second minimum outer dimension and a second length. The maximum outer dimension is greater than the maximum outer width. The maximum outer width is greater than the first minimum outer dimension and greater the second minimum outer dimension. The first length is greater than the second length.

The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

A method for fastening a component to a base element, in which method there is produced in the base element a blind bore which defines a depth direction and which has a force transmission surface which has a depth T in the depth direction, wherein the force transmission surface is of frustoconical form with a cone opening half-angle () and a mean diameter (d), wherein the blind bore has a conical blind bore base with a cone opening angle () and, at the edge thereof, a bevel which extends in the depth direction to a bevel depth L, wherein, in the method, a fastening element is anchored in the blind bore by way of the force transmission surface, and wherein the component is held by the fastening element.

A drill bit includes a shank and a body portion defining a plurality of axially stacked, progressively sized steps. The steps include a first step and a terminal step. The first step defines two tip flutes each disposed at a tip flute angle. The body portion defines a body flute extending through the steps. The drill bit also includes an indicator band formed on a portion of the body flute and a portion of an outer surface of one of the plurality of steps.

A drilling tool has a working piece retained by a retainer mounted to a collar. The working piece includes a distal shank and a cutting section and is rotationally fixed relative to the retainer. The retainer may include an engagement protrusion positioned outward of the shank with the protrusion engaging an inner surface of the collar or the collar may include an engagement protrusion with the protrusion engaging an inner surface of the retainer to create a quasi-floating relationship between the retainer and collar. The cutting section may have a distal primary bore cutting sub-section and a proximal counterbore cutting sub-section. The collar includes a lower surface for abutment against a building member during drilling operation to halt axial movement of the tool.

A drill bit includes a shank and a body portion defining a plurality of axially stacked, progressively sized steps. The steps include a first step and a terminal step. The first step defines two tip flutes each disposed at a tip flute angle. The body portion defines a body flute extending through the steps. The drill bit also includes an indicator band formed on a portion of the body flute and a portion of an outer surface of one of the plurality of steps.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The present invention provides a twist drill. A cone portion is provided at a front end of the operating portion, and an exterior surface of the operating portion is provided with a spiral flute for shunting cutting chips. The exterior surface of the cone portion is provided with a plurality of composite cutting blade groups which are sequentially enlarged in diameter from the front end to the rear end of the cone portion. The cone portion is provided with a top blade on the tip. In use, the top blade is used for positioning, and the cutting process is carried out by the top blade and the composite cutting blade groups.