A die is used to cut a male thread onto a piece of bar, such as you would find on a bolt.
Dies need to be strong and resilient, so we choose dies that are made from high speed steel, which is superior to the high carbon steel that some dies are made from.
How to use dies
The split die fits into a die holder, called a die stock. It is held in place by three securing screws. On the initial cut, the centre screw which is aligned with the split in the die is fully screwed in. This opens up the die as far as it can go, making the initial cut easier as the die is not cutting the full depth of the screw thread first time around.
After the first cut, the screw is released slightly to close the die, allowing a deeper thread to be cut.
Cutting oil should always be used in conjunction with dies.
It also important to ensure that there is a slight chamfer on the end of the bar that is being threaded, to help the cut start.