How to cut the thread?
Technology threading depends on what kind of thread you need - internal or external. In the article we will present several ways how to cut the thread at home. But first, let's talk about the differences, because a single global standard of thread still does not exist. Also, in order to properly cut the thread, you need to know about such characteristics as the diameter of the thread, its pitch and, of course, the type of thread.
Thread metric and inch thread
As you may have guessed from the name, there are two main types of threads that are used in different countries. In English-speaking countries (Great Britain, USA, Canada), inch carving is in effect, which was used in Russia until 1918. Metric thread - the most progressive type of thread - currently operates in more than 150 countries around the world including Russia.
However, problems remain. For example, you can buy a seemingly suitable screw, but at the same time, if you are not sure, you need to specify what kind of production the product is. If English or Canadian - it is better to look for another screw with a suitable diameter, since this screw will almost certainly have an inch thread.On such a screw there will be not only an incorrect diameter and thread pitch, but also the triangular thread profile itself is made at a different angle.
Internal thread and external thread
To distinguish between internal and external threads is very simple. The external thread is cut on the product that needs to be screwed into the hole - it can be a screw, a screw, a threaded bolt or a screw. Internal thread is, respectively, the thread in the hole where you want to tighten the screw or screw. As a rule, the right thread is considered to be the main type of thread, when the screw is screwed in a clockwise direction into the hole.
However, there are constructions that require the use of left-handed thread, in which screwing occurs counterclockwise. This method is attached, for example, the left pedal of the bicycle to the axis of rotation. The pitch and thread diameter are interrelated parameters and together they form the so-called thread size. The standard thread size in Russia is M10, where "M" means "Metric", and 10 is the diameter of the screw, which in this case means 10 mm. With a similar diameter, the standard thread pitch is 1.5 mm. Of course, for smaller or larger parts, other standards are applied with a reduced or increased screw pitch, respectively.
How to thread a tap
The tap is a special tool with which the internal thread is cut, that is, in the hole. External threading is usually not required, since screws and screws are already sold with a finished thread, but there is not always a thread in the hole, so first of all we will tell about internal threading. In addition to taps, we still need a drill. First we drill a hole and remove the chamfer in order to be able to enter the hole with a tap. Recall that a facet is called a bevel at the end of the element or at the very beginning of the hole. For a clear and high-quality thread, we need three taps.
The first tap, which is called the rough, use for the initial entry into the hole. You can check the roughing tap by the risk of shingles at the top of the tap. After a few cycles back and forth, periodically lubricating the rough tap, we make the primary thread finish, then take the middle tap to complete the thread. The middle tap is marked with two risks. They also need to spend several cycles in the hole, lubricating the tap after each cycle.And, finally, for the final threading experts recommend using the so-called fine tap, which already has three risks. After passing through a fine tap, you will receive a full and very clear thread.
Here it is worth noting that two taps are enough for cutting holes with a maximum diameter of 3 mm. In addition, if you cut a blind hole (not the entire thickness of the material), after passing through each cycle, you must not only lubricate the tap, but also remove sawdust that accumulate in its groove with a rag.
Here we need a vise, knob and die with the required diameter and thread pitch. We take the prepared metal rod, firmly clamp it in a vice and remove the chamfer with a file or, for example, with a special velvet file. Then with the aid of the knob we put the plate on the end of the rod, which before this should be abundantly lubricated with engine oil. Now screw the plate onto the rod, lightly pressing it. Having made about one and a half turns, unscrew the plate half a turn back, then again forward one and a half turns and again slightly back until the required depth of the thread is obtained.During this procedure, be careful to avoid any distortions.
Other ways of threading
First, how to cut the thread on the heating pipe. To do this, we use a suitable die and a screw die (a special tool where a die is inserted for threading under conditions when, in addition to torque, a considerable effort is still required to start threading). Without a screw die you will be quite difficult to do because the notches with a chisel that are recommended in these cases do not always help and the die will not cut, but only scrape the end of the heating pipe.
And a few words about how to cut the thread on the machine. It is best to do threading on a lathe-screw machine with special cutters. Depending on the shape of the cut of the thread, you can use rounded cutters, or chisels with a bevel.