Thread cutting is a very simple and widespread practice in metalworking, but requires a good hand and great precision. It consists of shaping the surface of two elements, the first of which must be cylindrical and the second a hole, in order to join the two solidly via a helical connection.
What are the Elements of Threading?
The thread is the structure that results from a threading job. When the latter is completed on an external surface, the threaded element is called a screw; if the threading involves the inside of a cylinder, the element will instead be called a nut-screw.
During the threading process, the outer surface of the screw, helically shaped, engages with the inner surface of the lead screw by means of a rotary movement: a solid, stable, but reversible coupling is thus generated.
In addition to the cylinder diameter, the pitch is a very important element of the thread: it indicates the distance between two consecutive ridges, and is proportional to the height. The pitch of a thread can be calculated using a special tool, the thread counter.
The Various Types of Threading
As mentioned, a threading job can involve the inner or outer surface of a cylindrical element.
The case of external threading applies mainly to metal rods, rods or cylinders.
Internal threading, on the other hand, are found inside nuts, bolts or ferrules, metal reinforcing rings.
The diameter of the element to be threaded and the thread pitch can be measured in millimetres or in fractions of an inch. The first system is the most common, in which case nuts and screws are marked with an M followed by a number indicating the diameter. When, on the other hand, the diameter is indicated by the abbreviation W, it means that the threading was done on the basis of the Whitworth system, and the measurement indicated is in fractions of an inch.
A helical threading work is also determined by the direction of screwing: the direction can be clockwise or counter-clockwise. The metric thread with right-handed helix direction is the one recognised as the ISO standard.
How to Thread a hole and rod
Three tools are required to fillet a kiln: the deburrer, the intermediate and the finisher.
By means of a special spindle, these three elements must rotate in succession within the hole. To create a thread in a hole, the tools must always be kept in a vertical position.
The threading of a rod or tube, on the other hand, requires a die. This tool is operated by means of a spinner, which must always be kept in a horizontal position. The work involves a very high level of attention and precision.
Bonanomi: Italian leader in precision mechanics
Bonanomi is an Italian mainstay in the precision mechanics sector. With a passionate team of professionals, Bonanomi's range of products and services includes articles for precision mechanics, which can also be purchased off-the-shelf, and mechanical machining for third parties.
The Bonanomi express shop allows you to select the best dressing plates, test benches, squares, cubes and surface plates for your structural needs, supporting your choices with in-depth personalised advice.