Metric tap: sizes and types

Metric tap is a widespread tooling for wood and metalworking machines. This tool is designed to create internal threads in through and blind holes in parts and workpieces. The tap is used mainly in workshops, on production sites, in repair shops, sometimes at home.

For the first time, a thread-cutting tool is mentioned in the history of Ancient Rome and China, as well as in the records of the Mayan peoples. However, such equipment as a manual metric tap appeared only at the end of the Middle Ages (XV-XVI). Until that time, primitive lathes were actively used to form internal threads.

Design Features

The first metric taps had a primitive structure and looked like a rod with four faces on which notches were applied. On the working part in the form of a flat cone, cutting teeth were sawn out. To form the internal thread, the specialist had to screw a tap into a pre-prepared hole. Of course, this method had many disadvantages, for example:

• negative rake angle;
• there is no back surface on the cutting part.

Over time, the design of the tool has become perfect and thought out. Modern taps for metric threads, regardless of size and purpose, have these elements in their structure:

• side grooves that are located along the tool;
• intake cone;
• calibrating working part;
• shank;
• clamping square part (on some models).

All metric taps have a screw shape, but the grooves can be straight and screw depending on the purpose of the tooling.

Tool types

In today's market for construction tools, you can find many metric taps that vary depending on the application. Allocate the main groups:

1. Tooling that is made with a special collar that informs the tool rotation. In most cases, manual fitter taps are available. They are used to form internal threads in housings.
2. Machine and machine-hand tools can be used on machine tools of various types, for example, turning, milling and drilling machines. Taps with a short intake can withstand enormous mechanical stress. Used for cutting internal threads in large workpieces. The equipment is mainly used in workshops, factories, large repair shops.
3. Nut tooling is necessary to create threads in the nuts. After cutting the metric thread with a tap, the nuts are not automatically removed and do not fall, but are moved along the elongated part of the shank, which ensures uninterrupted production (machines have an elongated shape).

Dimensions

In production documents, metric taps are marked with the letter "M" and are measured in millimeters as opposed to inch, which is measured in inches. The profile angle of the thread is 60 °. Metric taps made in accordance with GOST 8724–2002.

Dice

In addition to machine and manual taps for metric threads, dies are actively used in production and repair areas. The most popular in modern production and repair work are dies that are capable of cutting threads with a diameter of 52 mm.

The tooling is a hardened metal nut with axial holes and grooves. The tool can have 3, 4 or 6 holes that serve as a tap for the chips. The cutting part is made in the form of an inner cone. The thickness of the plate can vary from 8 to 10 turns, and the length of 2-3 turns.

The metric die is made in accordance with GOST 24705-2004 and is actively used for cutting external threads in workpieces. To purchase large dies, they must be specially ordered at metal processing plants.

Scope of application

Depending on the area of ​​use, sets of metric taps and dies are divided into the following types:

• household tools that will become suitable in garages, in garden plots, in dachas for restoring torn threads on bolts and nuts;
• manual equipment that is used in workshops for the repair of machinery, automobiles, equipment;
• professional taps and dies, which are used in continuous production lines at enterprises with mass and small-scale production.

Tips for working with taps

In order to improve the working process, namely threading, it is worth using the following recommendations:

1. To minimize the risk of jamming and reduction of resistance during operation, the length of the part for calibration and stripping should be from 6 to 12 steps.
2. To exclude runout during machine threading, it is worth evenly distributing the edges of the cutting part along the circumference.
3. With a manual application of threading, it is recommended to use 2 or 3 taps (draft and finishing taps, accessories for stripping).
4. It must be remembered that the grip under the handle is used only when threading parts on machine tools.
5. The specialist should prepare the hole in advance before forming the thread.
6. It is possible to measure the thread pitch using a thread gauge, and the exact dimensions of the parts can be determined by a caliper.
7. If you just need to adjust the thread, and not create a new one, then you can purchase not a complete but a single tool.

Dial selection

Before acquiring sets of taps and dies for metric threads, it is recommended to determine in advance the scope of work, for which tools are needed. If you need equipment for home use, then professional sets of taps and dies will not work.

Before buying, it is important to carefully inspect the tool, because today in the stores both metric and inch versions are offered, which visually practically do not differ.

When choosing a die, you need to pay attention to the shape of the profile in the last turns, since it should be triangular. It is also worth evaluating the material from which the tool is made. An excellent option for taps and dies will be high-strength carbon steel. The metal has high strength and allows you to quickly and without damage to the workpiece to perform cutting.

Before purchasing special equipment, it is recommended that you familiarize yourself with the general principles of its operation in advance. A set of taps and dies will become an integral part in domestic conditions, during repairs and in production, since the parts that are threaded have mediocre quality.