A threading tap is a unique type of drill that is specifically designed to carve a screw thread on the inside of a pre-drilled hole. All threading taps are designed to complete this simple task, but there is still a huge range of different sizes and styles, all designed to produce a slightly different result. Aspects of the desired screw thread, such as angle, depth, and diameter, can all be customised by opting for the correct type of threading tap. Threading taps come in two main groups: hand taps and machine taps, designed for manual use, and for use on a milling machine, respectively.
Hand Threading Taps
Handheld threading taps are available in three models:
- Taper Hand Tap
The taper tap is sometimes called the ‘first cut tap’ as it is used to start the threading operation. This tap has the gentlest taper of the three and the bottom section is almost completely smooth. Once this tap has been used to start the threading process, the second tap continues the work.
- Second Tap
The second tap, often referred to as a ‘plug tap’, has a steeper taper than the taper tap, allowing it to continue the threading process and engrave the screw thread deeper into the hole. Once the second tap has done its work, the bottom tap can complete the process.
- Bottom Tap
The bottom or bottoming tap has a tiny taper spanning only one or two grooves. It also has a thicker end, which is used to complete the thread by extending it all the way to the bottom of the hole.
Machine Threading Taps
Handheld threading taps aren’t suitable for mass production and are inefficient for use in industrial environments. This is where machine taps come in. A machine tap is simply a threading tap attached to a milling machine. Machine taps are able to mass produce an identical standard and are suitable for a wide range of applications. Machine taps can be used on harder materials than hand taps, as the force of the machine greatly out-performs the force a person can manually produce.
As they work at high speeds and through automated processes, machine taps are designed to direct chips of material away from the machine components, reducing the risk of damage to the workpiece or machinery.
Thread mills are available with through coolant to prevent overheating, which allows for superfast machining. The thread tap is also easily removed from and thread mill for repair or replacement; swapping out a new tap couldn’t be easier.