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Brief note on Dies


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Dies are used for cutting threads on the outside surface on pipe, round rods etc. or threading dies are used to cut external threads on cylindrical work pieces. It is operated with hand and for this purpose die stock is used. These are made of circular and square shape.


Die is made of high speed steel tool, high carbon steel and alloy steel hardened and tempered.


  1. Circular split die or button die :- This has a slot cut to permit slight variation in size. When held in die stock variation, variation in the size can be made by using the adjusting screws ( with the help of screw driver). This permits increasing or decreasing of the depth of cut. When the side screws are tightened the die will close slightly. For adjusting the depth of the cut, the centre screw is advanced and locked in the groove. This type of die stock is called button pattern stock. These dies are used for small jobs. This is generally used on Capstan or turret lathes.
  2. Half die:- Half dies are stronger in construction. Adjustments can be made easily to increase or decrease the depth of the cut. These dies are available in matching pairs and should be used together by adjusting the screw of the die stock, the die pieces can be brought together or can be moved apart. They need a special die holder.
  3. Adjustable screw plate die:- This is another type of a two piece die similar to the half die. This provides greater adjustment then the split die. The two die halves are held securely in a collar by means of a threaded plate (guide plate) which also acts as a guide while threading. When the guide plate is tightened after placing the die pieces in the collar, the die pieces are correctly located and rigidly held. The die pieces can be adjusted using the adjusting screws on the collar. This type of die stock is called quick cut die stock. The better of the die halves is tapered to provide the lead for starting the thread. On one side of each die head, the serial numbers (size) is stamped. Both pieces should have the same serial numbers.
  4. Die nut (Solid die) :- A solid die nut is used to repair a damaged threads but nit to cut a new one. The die nut is turned with a spanner. The die nuts are available for different standards and sizes of threads.
  5. Die plate :- This is a plate made of steel and is hardened and tempered, which has a handle on one side. In this plate, for cutting small threads of different diameters, holes with threads are cut. Threads upto 1/8″ on a screw can be cut with it. Which are used in radio and electrical jobs.


  • Before cutting outer threads, the end of rod should be chamfered with grinder or a file.
  • For cutting threads on a rod or any other round job it should be firmly held in a vice.
  • While fitting die in a job only the side of tapered threads (sides) should be fitted.
  • After fitting the die on the job you should adjust it according to your requirement.
  • Keep on moving the due forward and backwards.
  • Equal pressure should be exerted on the die handle.
  • Jobs of large diameter, threads should be cut after adjusting 2-3 cuts.
  • Proper lubrication should be used while cutting threads.
  • After cutting the threads, it should be properly cleaned and replaced at its proper place.