Taps and Dies are tools used to create screw threads, which is called threading. A tap removes material from a pre-drilled or punched hole. The result of this cutting action produces threads within the drilled hole. These threads are used in conjunction with screws or bolts to hold two pieces of material together. The cutting edges at the front of a tap remove material from the work piece. The chips are stored in the flutes, or pushed forward in front of the tap, or are drawn up along the flutes, removing the chips and cutting fluids from the hole. There are many kinds of taps available in the market. Here are the basics of the UN Thread Taps and the Metric Tap:
Plug taps, like tapering taps, have threads at both the ends of the tap. It assists cutting threads quickly as there are fewer number of threads. They are more efficient when compared to taper taps but it needs steady and patient hands to get the job done. It is easy to work on but, if you are a beginner, stick to taper taps.
Bottoming taps, unlike the plug taps, have ground threads only in the lower ends. They are used after the usage of the plug taps though. Bottom taps can cut threads to the bottom of blind holes although they do not do well at starting threads.
What is the difference between the UN thread taps and metric taps? The techniques are the same. The only difference is in the usage. The British industries use the metric taps whereas the US-based industries opt for the UN thread taps.
What are threading dies?
Carving out external threads is facilitated using threading dies. While the taps are used for external threading, the dies are used for internal purposes. Hand threading dies are generally of two types. They are the “round” and the “hex die nuts”. The round ones are used generally to work with T handles while the other is used on hand tools. Round dies are usually the choice for cutting new threads whereas hex die nuts are commonly used as a chaser to repair existing threads. Round dies also require a holder/handle to use them, whereas hex die nuts do not.
The thread gages
When you are in search of an instrument that will help you measure the pitch and the tolerance levels of the threads, resort to the thread ring gages and the thread plug gages. In case of the external threads, you need the thread ring gages whereas the thread plug gages helps with the internal threads.
When you consider the gages, they do one simple task. Their task is based on the Go and No Go principle. Every gage has a Go and a No Go side and the tool must be able to go through the Go side easily and on the other hand, it must not be the case with the No Go side. It can work for 2 turns and not more than that. The tools that pass this test are the ones certified fit for use in the industry.
These are some of the things one must know before using metric and UN taps.