Page 218 - Demo

216 ISCAR DEEP HOLE DRILLING %u00bd%u0009Practical TipsThe practical tips described below will in many cases help to achieve an optimal result when deep drilling.%u2022 The gap between the drill and the guide bushing or pre hole should be no more than 0.01 mm (0.0004 inches).Pre HoleGAP, max 0.01 mm (0.0004 inches)Guide BushingGAP, max 0.01 mm (0.0004 inches)%u2022 The flat bottom of pre hole is preferable to the V shaped bottom of the%u2022 pre hole in deep drilling operation. A conical surface may cause the drill run-off (%u201cwalking%u201d) and reduce tool life.Pre Hole with Flat Bottom F reactionF net FzF reactionPre Hole with V Shaped BottomF reactionF netFzF reaction