According to one implementation, a drill has at least one cutting edge. A projected shape of a passing area of a ridgeline of the at least one cutting edge when the at least one cutting edge is rotated around a tool axis becomes a line-symmetric and discontinuous line along a parabola, two parabolas, an ellipse or two ellipses. The projected shape is drawn on a projection plane parallel to the tool axis.

A fastener extractor device for removing fasteners and disengaging the extractor from the so engaged fastener. The extractor includes a threaded main body with a hex drive head end portion and oppositely disposed elongated tool engagement hex body with multiple bracing sidewalls with independent contoured fastener engagement channels for fastener insertion and continued rotational removal. A tubular hex surface extractor nut is threadably disposed on the main body member for reversed thread rotation advancement to physically disengage the tool engagement body from the removed fastener.

A drill includes a blade tip part that is formed of diamond and a trunk part that is formed of diamond and is continuous with the blade tip part, the drill rotating about a drill axis, the blade tip part includes N cutting edges where N is an integer of no less than 4, and a proportion of S1 to S2 is no less than 30% and no more than 60%, where S1 is an area of the drill in a cross-section with the drill axis as a normal line, the cross-section including a boundary between the blade tip part and the trunk part, r is a maximum value of a distance from the drill axis to an outer edge of the drill in the cross-section and S2 is an area of a circle with r as a radius.

The invention relates to single-lip drills and double-lip drills, in which one or more depressions are formed in the rake face. The depressions according to the invention are arranged in the longitudinal direction of the tool at a distance from the cutting edge and have a positive influence on chip breaking.

The invention relates to a single-lip drill and a double-lip drill having a plurality of chip-forming devices or depressions in the rake face which are arranged in succession and at a distance from one another. As soon as a cutting edge and/or the associated chip-forming device or the associated depression is worn, the deep hole drill according to the invention can be reground using simple means.

A fastener extractor device for removing fasteners and disengaging the extractor from the so engaged fastener. The extractor includes a threaded main body with a hex drive head end portion and oppositely disposed elongated tool engagement hex body with multiple bracing sidewalls with independent contoured fastener engagement channels for fastener insertion and continued rotational removal. A tubular hex surface extractor nut is threadably disposed on the main body member for reversed thread rotation advancement to physically disengage the tool engagement body from the removed fastener.

The invention involves the extraction process of a glow plug pencil (23) or a broken pencil (23) which is stuck in a cylinder head (13) housing (11) of a glow plug engine comprising a lower (19) and upper (17) part, so that the upper part (17) forms a shoulder (21) with the lower part (19), the pencil (23) being stuck in the lower part (19). The process is remarkable in that it includes a step (a) for drilling a bore in the pencil (23) according to the longitudinal direction of the latter which is performed with the use of a drill bit (1) comprising a drilling part (5) with flutes (7) and a shank (3) respectively having a diameter smaller and greater than the lower part diameter (19) of the housing (11) so that the shank (3) forms a shoulder (9) with the drilling part (5), and in that step a) for drilling the bore includes the drilling of the pencil (23) until the said shoulder (9) of the drill bit (1) is positioned to a stop against the shoulder (21) of the housing (11).

A drilling tool, in particular a rock drilling tool, for a portable machine tool, includes an axis of rotation, at least one spiral path, and at least one wear surface transition. The at least one spiral path is coiled about the axis of rotation along the axis of rotation and includes at least one wear surface having at least one bandwidth. There is a change in the at least one bandwidth of the at least one wear surface at a position of the at least one wear surface transition.

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 invention relates to a single-lip drill and a double-lip drill having a plurality of chip-forming devices or depressions in the rake face which are arranged in succession and at a distance from one another. As soon as a cutting edge and/or the associated chip-forming device or the associated depression is worn, the deep hole drill according to the invention can be reground using simple means.