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External Threading Technical Information

Shop All Dies and Chasers
Basics of... External Threading
Round Adjustable Die82-R Drill, Tap & Reamer GrinderHex Die Thread Chaser Thread Roll

External threading is accomplished by using a variety of cutting tools design for cutting threads on the outside diameter of a workpiece.


Die Types:

Round Adjustable Dies

  • Originates a new thread
  • Ideal for maintenance jobs
  • Will cut external thread when held in a die stock
  • Chamfered on both faces - one side has a 2-3 thread chamfer for threading, the other side has 1 - 1-1/2 thread chamfer for threading close to the shoulder
  • Standard in right hand Unified and American National Thread Form

Hex Rethreading Dies

  • Ideal for maintenance jobs
  • Designed to repair a bruised or rusty thread
  • Can be used in free machining materials
  • Most cost effective rethreading tool available
  • Can be used with a wrench instead of a die holder or die stock

Two Piece Die Blank Systems ( Little Giant® )

  • Collet system designed for greater die adjustability for new threading or thread repair
  • Consists of a cap and a guide(dies not included)


  • Die Stock - Holds round adjustable dies but specifically designed for holding open type adjustment dies
  • Die Adapter - Converts a round die into a hex die. Good for jobs where die stocks can not be used due to lack of space
  • Die Holders - These tools have a straight

Die Materials

HSS - Used for cutting new threads in mild steels and non-ferrous materials
Carbon Steel - Used for rethreading and cleaning of threads

Chasers and Thread Rolls

Thread chasers are used to cut external threads and consist of self-opening die heads and collapsing taps. An advantage of chasing is after cutting the threads, the die head self-opens and retracts eliminating the need to be backed off the work piece. All chasers protrude slightly from the face of the die heads to permit close to the shoulder threading.

  • For machine threading applications
  • Supplied in sets of 4
  • Ground thread for better surface finish and tighter tolerances
  • For use in a variety of ferrous and non-ferrous materials

Chaser Styles:


  • Available in Standard or Projection
  • Projection type offers more regrind life therefore more parts can be produced in between regrinds
  • Will fit styles D, DD, DS, DSA & DJ die heads

H&G Inserts

  • Available in 00 Series or 100 Series
  • 100 Series Chasers will fit 101, 102 and 103 series die heads
  • Used with Carriers that hold the chaser in place. The range of the carrier allows threads of different diameters to be cut

Chasers can be used for:

  • Small or large diameter work on excessively abrasive or hard materials
  • Fast changes on short run jobs or minimum set up changes for long run jobs
  • For single or multiple spindle machine tools

Thread Rolls:

  • Reversible, can be used on both sides
  • Sold in sets of 3
  • Designed for rolling threads from the end of the workpiece
  • Style N - threads diameters from #6 - 1-1�?�4"
  • For rotating or stationary use
  • Available in low or standard helix
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