A cutting tool includes a body including a connecting end, a cutting end which includes a space for receiving the work piece, at least one projection with a ridge defining at least one cutting edge for cutting the work piece, and at least one slot for allowing pieces trimmed from the workpiece to exit from the body. The space has a top and a bottom and tapers outwardly from the top to the bottom. The at least one cutting edge has a first end adjacent to the top of the space and a second end adjacent to the bottom of the space and extends from the first end to the second end obliquely. The body is rotatable about a first axis, and the first axis extends longitudinally between the first and second ends of the body.

A spade bit includes a shaft defining an axis about which the spade bit is configured to be rotated. The space bit also includes a blade attached to the shaft and having a first paddle portion and a second paddle portion. In addition, the spade bit includes a tip portion attached to the blade and aligned with the axis. The first paddle portion includes (i) a first leading end portion positioned on a first side of the axis and configured to define a first cutting edge portion, and (ii) a first lateral extension portion configured to define a first sloping surface. The first paddle portion defines a first relief space positioned adjacent to both the first sloping portion and the first leading end portion. The second paddle portion includes (i) a second leading end portion positioned on an opposite second side of the axis and configured to define a second cutting edge portion, and (ii) a second lateral extension portion configured to define a second sloping surface. The second paddle portion defines a second relief space positioned adjacent to both the second sloping portion and the second leading end portion.

A flat drill bit includes a stem body, a cut flute part provided axially from an end of the stem body and being generally flat-shaped, and a threaded guiding part provided axially from an end of the cut flute part. The cut flute part includes two longitudinal wings which are configured to be rotationally symmetrical to each other about a longitudinal central axis (O) of the flat drill bit. Each longitudinal wing is formed with a cutting edge at the end of the cut flute part from which the threaded guiding part extends. A rotating trajectory profile caused by the cutting edge when the flat drill bit rotates is inclined towards the stem body and is at an angle (a) relative to the longitudinal central axis (O), and the angle (a) is in a range between 84° and 86°.

A rotary cutter for cutting damaged threads of a bolt includes a body rotatable about a rotating axis. The body includes a connecting end and an operative end. The body includes an inner periphery delimiting a cutting space extending along the rotating axis from the operative end towards but spaced from the connecting end. A width of the cutting space in a diametric direction perpendicular to the rotating axis gradually reduces from the operative end toward the connecting end to form a conic space. The body further includes at least one cutting blade disposed on the inner periphery. The at least one cutting blade includes a first cutting blade section and a second cutting blade section. The first cutting blade section is arcuate or rectilinear. The second cutting blade section is arcuate or rectilinear. The first and second cutting blade sections are not identical.

A flat drill bit includes a stem body, a cut flute part provided axially from an end of the stem body and being generally flat-shaped, and a threaded guiding part provided axially from an end of the cut flute part. The cut flute part includes two longitudinal wings which are configured to be rotationally symmetrical to each other about a longitudinal central axis (O) of the flat drill bit. Each longitudinal wing is formed with a cutting edge at the end of the cut flute part from which the threaded guiding part extends. A rotating trajectory profile caused by the cutting edge when the flat drill bit rotates is inclined towards the stem body and is at an angle (a) relative to the longitudinal central axis (O), and the angle (a) is in a range between 84° and 86°.

A rotary cutter for cutting damaged threads of a bolt includes a body rotatable about a rotating axis. The body includes a connecting end and an operative end. The body includes an inner periphery delimiting a cutting space extending along the rotating axis from the operative end towards but spaced from the connecting end. A width of the cutting space in a diametric direction perpendicular to the rotating axis gradually reduces from the operative end toward the connecting end to form a conic space. The body further includes at least one cutting blade disposed on the inner periphery. The at least one cutting blade includes a first cutting blade section and a second cutting blade section. The first cutting blade section is arcuate or rectilinear. The second cutting blade section is arcuate or rectilinear. The first and second cutting blade sections are not identical.

A rotational cutting tool includes a connecting end for engaging with a driving tool and a cutting end for engaging with the work piece. The connecting end and the cutting end rotate about the rotation axis upon rotation of the rotational cutting tool. An inner periphery of the cutting end defines a receiving space for receiving the work piece. The receiving space has a conic surface which extends radially and obliquely with respect to the rotation axis. The receiving space includes a first ridge forming at least one cutting edge for trimming the workpiece and at least one slot allowing trimmed pieces from the workpiece to exit from the receiving space. The first cutting edge extends radially and obliquely with respect to the rotation axis. The first cutting edge extends curvedly and has a curved contour.

A rotary cutter for cutting damaged threads of a bolt includes a body rotatable about a rotating axis and having a connecting end and an operative end. A first cutting blade is disposed on an inner periphery of the body facing a cutting space extending along the rotating axis from the operative end towards but spaced from the connecting end. The body further includes a virtual projection plane perpendicular to the rotating axis. A first virtual plane passes through the first cutting blade and extends perpendicularly to the virtual projection plane. A virtual circle and a first virtual reference line are located on the virtual projection plane. The first virtual reference line intersects the rotating axis and passes through an intersection of the first virtual plane and the virtual circle. An angle between the first virtual reference line and the first virtual plane is between 5 and 40.

A rotational cutting tool includes a connecting end for engaging with a driving tool and a cutting end for engaging with the work piece. The connecting end and the cutting end rotate about the rotation axis upon rotation of the rotational cutting tool. An inner periphery of the cutting end defines a receiving space for receiving the work piece. The receiving space has a conic surface which extends radially and obliquely with respect to the rotation axis. The receiving space includes a first ridge forming at least one cutting edge for trimming the workpiece and at least one slot allowing trimmed pieces from the workpiece to exit from the receiving space. The first cutting edge extends radially and obliquely with respect to the rotation axis. The first cutting edge extends curvedly and has a curved contour.

A rotary cutter for cutting damaged threads of a bolt includes a body rotatable about a rotating axis and having a connecting end and an operative end. A first cutting blade is disposed on an inner periphery of the body facing a cutting space extending along the rotating axis from the operative end towards but spaced from the connecting end. The body further includes a virtual projection plane perpendicular to the rotating axis. A first virtual plane passes through the first cutting blade and extends perpendicularly to the virtual projection plane. A virtual circle and a first virtual reference line are located on the virtual projection plane. The first virtual reference line intersects the rotating axis and passes through an intersection of the first virtual plane and the virtual circle. An angle between the first virtual reference line and the first virtual plane is between 5 and 40.