Choosing a Drill

Tech Tips

Choosing The Proper Length Drill:

Always select the shortest drill possible for an application. The increased rigidity will dramatically enhance the number of holes per grind, as well as hole concentricity and location.

Drills over 1" diameter have reduced shanks:

  • 1 1/16" to 1 1/4" sizes have 1" shank
  • 11 5/16" to 1 1/2" have 1 1/4" shank
  • 11 9/16" to 2" have 1 1/2" shank

Choosing Between 118° And 135° Drill Points:

118° point angles are used primarily in softer materials such as mild steels and cast irons.

135° split points should be used to cut harder steel materials and especially in deep holes over 4 times the drill diameter. With a 135° drill point, cutting harder materials will produce thicker chips, minimizing work hardening of the cavity. The length of the lips on a 135° point drill, measured from the axis to the outer corners, is relativity short. This enables quicker penetration into the workpiece and reduces thrust and abrasion along the cutting edges.