The rake angles of a cutting tool define the angles at which the tool is presented to the work piece. PDC cutters can have back rake and side rake, each of which can be positive, negative or zero.

Less aggressive back rakes will reduce torque for a given weight-on-bit, but at the expense of penetration rate. Thus the designer is faced with a decision based on conflicting requirements. The majority of ReedHycalog® 'DS' bits have back rakes of 15° to 30°. Although other values have been tested, the 15° to 30° range appears to provide the best balance. Where more torque is available at the bit, such as with Rotary Steerable Systems, more aggressive backrakes are used. As well as increasing ROP, these help to decrease torque for a given ROP, and thus limiting stick-slip.