Oversize Pitch Diameter

Chip Packing

  • Use spiral point or spiral fluted taps.
  • Reduce number of flutes to provide extra chip room.
  • Use larger hole size.
  • If tapping a blind hole, allow deeper holes where applicable or shorten the thread length of the parts.
  • Use proper lubricant.


  • Apply proper surface treatment such as steam oxide or TiN.
  • Use proper cutting lubricant.
  • Reduce tapping speed.
  • Use proper cutting angle in accordance with material being tapped.
  • Use larger hole size.

Incorrect Tap

  • Use proper GH limits of taps.
  • Use longer chamfered taps

Operating Conditions

  • Apply proper tapping speed.
  • Correct alignment of tap and drilled hole.
  • Use proper tapping speed to avoid torn or rough threads.
  • Use lead screw tapper.
  • Use proper tapping machine with suitable power.
  • Avoid misalignment of the tap and drilled hole from loose spindle or worn holder.

Tool Conditions

  • Obtain proper indexing angle for the flutes at the cutting edge.
  • Grind proper cutting angle and chamfer angle.
  • Avoid too narrow a land width.
  • Remove burrs from regrinding.

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