Taps are tools used for threading holes in materials such as metal, plastic, and wood. They are available in both hand-operated and machine-operated versions, depending on the size of the tap and the size of the hole being threaded. The three different leads on a hand tap refer to the pitch, or the distance between each thread on the tap.
The three lead types are:
1. TAPER: The taper lead is the starting or entry end of the tap, which has a longer lead or distance between threads than the rest of the tap. This taper lead helps to guide the tap into the hole and start the thread more easily.
2. INTERMEDIATE: The second lead is the section that follows the taper lead. It has a shorter lead than the taper lead and is used to continue the threading process further into the hole.
3. BOTTOMING: The bottom lead is the final section of the tap, located at the end of the tap. It has the shortest lead of all three sections, and it is designed to create the finished thread in the hole. Some bottoming taps have a chamfer at the end of the lead to allow for easier threading of the tap into the bottom of a blind hole.
The combination of the three leads on a hand tap helps to ensure that the tap creates a consistent and accurate thread throughout the entire depth of the hole.
Hand taps have a tapered shape with a square or hexagonal shank that allows the user to grip the tap with a tap wrench or pliers to turn it manually. They are commonly used for smaller-sized threads, and are generally slower and less powerful than machine taps. Machine taps, by comparison, have flutes designed to guide chips when threading, parallel shanks for drill insertion, and can therefore operate at higher cutting speeds than hand taps.
Taps are available in a wide range of thread sizes, including:
- Imperial BSW BSP BA UNC UNF BSPF & BSPT
- Metric sizes, Standard Coarse, Metric Fine
In addition, taps are available in a range of special-purpose configurations to suit the specific needs of different applications.
