A deburring chamfer tool has a main body including a working end for engaging a workpiece to be deburred. The working end is of a conical shape and has a first and a second cutting edge respectively extending lengthwise with reference to different slant reference lines which delimit the conical shape. Each of the first and the second cutting edges slope from a first end adjacent to the vertex of the conical shape to a second end adjacent to the base of the conical shape in a first length and a second length respectively. The second length is smaller than the first length.

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.

A deburring chamfer tool has a main body including a working end for engaging a workpiece to be deburred. The working end is of a conical shape and has a first and a second cutting edge respectively extending lengthwise with reference to different slant reference lines which delimit the conical shape. Each of the first and the second cutting edges slope from a first end adjacent to the vertex of the conical shape to a second end adjacent to the base of the conical shape in a first length and a second length respectively. The second length is smaller than the first length.

A hole saw structure, which is cooperated with a hole saw arbor for performing a perforating operation, includes a cylindrical body and a blade set. The cylindrical body has a central chamber and includes an end surface and a peripheral wall. One end portion of the peripheral wall is connected around a circumference of the end surface, the other end portion of the peripheral wall is outwardly folded and overlapped around the peripheral wall so as to form a folded portion, the folded portion includes a folded end, and an inner diameter of the cylindrical body is smaller than an outer diameter of the folded portion. The blade set is disposed on the folded portion and includes at least two cutting teeth and at least two chip discharging notches.

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.