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What is the difference between internal and external threading tools

Internal and external threading tools are used in metalworking to create threaded holes or external threads on a workpiece. The main difference between the two lies in the direction of the threading operation and the design of the tools:

1. Internal Threading Tools :

Internal threading tools, also known as taps, are used to create threaded holes inside a workpiece. These tools have cutting edges on the flutes that are designed to cut the threads as the tap is rotated into the pre-drilled hole. Internal threading tools come in various types, including hand taps and machine taps.

  • Hand Taps: Hand taps are typically used for manual threading operations. They have a tapered or bottoming design, which determines the depth of the thread. Hand taps are often used for repairing or creating threads in softer materials or for smaller thread sizes.
  • Machine Taps: Machine taps, also called spiral-flute taps, are designed for use in power-driven tools such as drill presses, lathes, or CNC machines. They have a more consistent and uniform thread depth and are suitable for high-production threading operations.

    • 2. External Threading Tools:

    External threading tools, commonly known as dies, are used to create external threads on cylindrical workpieces, such as rods or bolts. These tools are applied to the workpiece to shape the threads. External threading tools come in various types, including hand dies, machine dies, and adjustable dies.

  • Hand Dies: Hand dies are often used for manual threading operations. They are typically held in a die stock or die wrench and manually rotated around the workpiece to cut the threads. Hand dies are commonly used for repair work or for threading smaller-sized bolts or rods.
    • External&Internal Indexable Threading Tool Set, 3/8Inch Shank, 2Pcs
  • Machine Dies: Machine dies, also called solid dies, are used in power-driven threading machines or lathes. They are secured in a die holder or die head, which is then rotated to cut the threads. Machine dies are commonly used in production settings for creating external threads on various workpiece sizes.

    • Adjustable Dies: Adjustable dies, also known as split dies, are used for threading operations where the thread diameter may vary. These dies have an adjustable feature that allows the user to change the size of the threading die to match the workpiece diameter. Adjustable dies are commonly used in repair work or for threading non-standard or custom-sized threads.

    In summary, the primary difference between internal and external threading tools is in their direction of operation and the design of the tools. Internal threading tools (taps) are used to create threads inside a hole, while external threading tools (dies) are used to create threads on the outside of a cylindrical workpiece. Understanding the distinction between these tools is essential for selecting the appropriate tool and technique for specific threading applications.