The first upper peripheral surface has a negative clearance angle with respect to the top surface, while the second upper peripheral surface has a positive clearance angle with respect to the top surface.

The positive relief angle is typically less than about 30°, and preferably between about 4° and about 20°.

The second chisel surface defines a second relief angle different from the first relief angle.

The conditioning element may include a horizontal relief angle and/or a vertical relief angle.

The first upper peripheral surface has a negative clearance angle with respect to the top surface, while the second upper peripheral surface has a positive clearance angle with respect to the top surface.

first tool orthogonal clearance

first working orthogonal clearance

The clearance face (526) is at a clearance angle from about 10° to 50°.

tool flank orthogonal plane orientation angle

The first chisel surface defines a first relief angle.

The first frustro-conical internal surface (18) has a draft angle 'A'.

The relief surface and the rake surface form a first angle.

Another embodiment provides positive angle torque shoulders and positive angle load flanks.

The step is provided with an axial angle of relief (53) and/or a radial angle of relief (51), and forms composite blade back combined with the blade back behind the step.

The cutting profile may include a face angle of about 5 degrees, a back angle of about 17 degrees and a gullet angle of 78 degrees (see figure 2).