Features and types of tool
The tap is part of a group of thread cutting tools. This group also includes dies, special heads, rolling dies, cutters, grinding wheels and so on. Its name was obtained from the ancient method of carving. Outwardly it is very similar to a screw, yes, in fact, this is the screw that was turned into a cutting tool.
At its beginning is made a cone, which improves the centering of the end of the screw in the hole and evenly distributes the cutting force between the turns. Also on it there are grooves for removing formed chips. There are also "tapeless" taps - the name speaks for itself.
Taps are manual and machine, and the latter make a cut to the depth of the entire profile, while the taps are divided into several parts. In this regard, hand taps are available in several pieces for the size of one thread. They differ in the number of ring grooves that are applied to the tail - one - the first number, two - the second, etc.
Preparing for operation
The first step in obtaining the desired result from the thread diameter is subtracting the length of its step. For example, with a M20x1 thread, the inner diameter hole should be 19 millimeters. For the beginning there is a rough tapping of the thread, for this there is a special tool, which is easy to determine, thanks to a special ring rim. Work with him should be neat, because he is made of hard, but brittle steel, which increases the risk of breakage.
Tip! Because of the fragility, experts recommend having at least one tap in reserve.
A threaded hole can be made with a drill. Drilling the hole, it is necessary to carefully monitor that the drill goes strictly perpendicular to the surface of the treatment, without any distortions that can completely bring the work to naught. To fix the tap is a special tool - a wrench. If there is not one, then you can use the adjustable wrench. For smooth operation, without distortions and jerks, the surface is lubricated with engine oil. All the chips that are formed in the process are removed by reversing the taps.
Important rules for performing the work of
Now that all the preparatory work has been completed and a roughing tool is cut, it's time to do the main cutting. To properly and accurately carry it out, you need to know certain rules of work.
- Thread tapping in soft metals( copper, babbitt, aluminum) requires periodic twisting and chip removal.
- Cutting is performed alternately using the whole set of taps. Using an average tool without passing a draft, and then finishing, does not accelerate the process, but, on the contrary, will make work more difficult, and the thread will be of poor quality. Finishing and medium are introduced without a wrench, and only after passing through the thread, it is superimposed, and cutting continues.
- The blind threaded hole is made to a greater depth than the depth of the threaded part, with the expectation that the working part of the tap goes out beyond the cut portion. Without this stock, the thread will be incomplete.
Important! During the cutting, it is necessary to check the position of the angle by cutting the cutting position, it must be strictly perpendicular!
- A great role in the quality of work is the choice of lubrication. It is best to use an emulsion, linseed oil, kerosene, turpentine. When working with bronze and cast iron, there is no need to use lubricant.
If these rules are violated during operation, the thread will be defective, and the tap may break and remain in the hole. To pull it out, you need to use a special device, but this is a complex and time-consuming process, and the thread will be completely ruined.
