The connection of several components using threaded parts is called a threaded connection. What is a thread? These are successive hollows and protrusions on the outer or inner surface of the product, part. This arrangement along a helix provides the connection of two elements.
Threading is done in several ways. In each of them, the thread pitch is of primary importance, therefore, based on this parameter, they distinguish: threaded threads extruded onto products made of thin-walled metal, rolled using special machines. The latter, in addition to being manufactured on lathes, can be cut manually using a tap or die.
For each metal and non-metal product containing threaded elements, there are special and universal tools. Each threaded type needs its own tool, which will provide the necessary thread pitch, its shape, profile and, of course, accuracy.
The control is carried out first of all over the pitch and profile shape, and then over the diameters - internal and external.
How to determine the thread pitch using a vernier caliper and a ruler? Using the above tools, we measure the length of two or three steps of the thread, followed by dividing them by the number of steps.
The internal and external threads can also be measured using a thread gauge. This tool has a scale where the size of the threaded pitch is indicated. By selecting the appropriate plate, we take measurements. It is necessary that the teeth of the plate fit tightly into the measured thread. Clearances are not allowed. And if everything is done according to the instructions, then the standard thread pitch will correspond to the size indicated on the thread gauge plate.
Next, the average threaded diameter is measured. A micrometer can be used for this purpose. Using a set of special tips, various thread diameters are measured. Each tip indicates its maximum size. For example, the mark M 3-4.5 is on the micrometer, which means that with this device you can take measurements of metric threads within a step of 3 to 4.5 mm.
The threaded profile is checked using a template. If there is a need for more precise control, then special microscopes are used.
Conventional thread gauges are used to measure the pitch of the thread in those products and parts where accuracy is not so important. This happens as follows: a normal threaded ring is screwed onto a screw, and, shaking it in different directions, they judge the accuracy of the thread. In this way, the external thread is checked. Now we will consider how to determine the thread pitch of the inner diameter. To do this, you need a normal screw plug (normal is the size). The smooth end of the gauge serves to measure the internal diameter of the thread.
Threads with a high coefficient of accuracy are checked by ultimate threaded gauges. The smooth (through) end of the gauge, as mentioned above, must fully and freely enter the threaded hole. Several threaded turns are applied at the non-bore end, which should not be screwed into the hole.
Manual threading
For manual threading , a threading tool is used. To cut an internal thread, you must first drill a hole in the part. Here it is necessary to take into account the thread pitch on which the size of the drill depends. Then, using a tap, rotating it clockwise, we cut the thread, occasionally twisting the tap back to remove chips and grease it with oil.
Thus, from this article, you learned how to determine the pitch of a thread, how to cut a thread by hand, and what are the threads.