How to thread tap

How to thread tap

Perhaps the most reliable means of connecting a threaded connection. In the event that any thing breaks, the first thought that comes to mind - to fix broken off part of the bolt. In addition to durability and strength of the threaded connection, it has collapsible property that often plays a crucial role in the selection of this type of compound.

So, before you deal with how to thread tap, let's deal with the types of threads.

The thread is a helical surface disposed on a body of revolution, for example, on the cylinder, as is the case with the bolt. There are two types of threads:

  • Right: helix rises counterclockwise;
  • Left: helix rises clockwise.

Thus, the name of the thread corresponds to the direction of twist. It should be noted that in addition to the twist direction of the thread is divided into the following two types:

  • inside: used in the holes;
  • outer: used on the rods.

Also, each thread is characterized by parameters such as:

Figure 1 - Scheme of general form thread

In everyday life is most often used by right-handed rectangular and buttress thread shown in the figure below.

Figure 2 - and rectangular buttress thread

Tool for threading

Since our goal is to cut the threads yourself at home, you'll use for hand tap.

Figure 3 - Hand taps for tapping

The working part of the tap directly used for threading. It represents the structure of two elements: entrainment and gauge parts. Fence parts are made in the form of a cone and carries out the bulk of thread cutting and calibrating - cleans up the thread and sends the tap.

Figure 4 - a manual tap Design

Dies are used for thread cutting.

The first step in how to thread tap - drilling holes. This step is in fact the most important, because if you make a mistake with the choice of the diameter of the bolt will either hang, or tap can break simply overload. The diameter of the holes is best to pick up on the tables, but you can make a rough estimate: diameter of the hole should be equal to the difference of thread diameter and its pitch. For example, when the outer diameter of 20 mm and a 1 mm step, it is necessary to drill a hole diameter of 19 mm.

Drilling a drill hole of suitable diameter, proceed directly to the tapping. To fix the tap is recommended to use "knob" as shown in the figure below. In the absence of the driver using a conventional wrench.

Figure 5 - Crank to the tap

Figure 6 - Tap tap wrenches and circular dies

Fastener in a vise, adding a little grease in the hole. Next, tap to cut a thread manually perform reciprocating motion: two turns clockwise, one or half a turn - back. Turns in the opposite direction are required to remove the dust from tapping. Coming rough tapping hole, perform the steps described above, the second tap.

It should be noted that often such situations arise when it is required to make thread in a sufficiently thin plate of soft metal, about 3-4 mm thick. In this case, the process can be mechanized using a screwdriver or drill. In this case, instead of the tap in the mounting knob, hold it to the screwdriver.

Rules tapping via the tap:

1. If the opening, wherein the thread is cut deep enough, then periodically turn out of the tap hole. Following this rule, it is necessary to clean the grooves, or tap can easily warp. This applies to a greater extent to soft metals such as copper, aluminum.

2. Use consistently all taps of a set: first draft, then the middle and finally the finish. Otherwise, the thread may get poor quality and taps because of the fragility may burst.

Figure 6 - A set of taps

3. In case to be threaded into a blind hole, the hole depth should be somewhat greater than the planned length of the thread.

4. When processing deep hole plays an important role grease. Experts recommend not to use the engine oil and emulsion, kerosene, or flaxseed oil.

Table diameters for drills for cutting holes metric thread (GOST 19257-73)

We offer you a video showing how to cut tapping.

And another video about how to cut an external thread on the rod.

Cool, I got 5 on technology, ATP KP4)

Excellent article. A lot of useful and background information on one page. Thank you.

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How to cut the threads manually

Threaded joints are widely used in the device of different mechanisms and machines. Bolts, pins, screws, nuts - it is universal, interchangeable fasteners. However, there are times when you want to cut the threads manually. Qualitatively perform this work will help a dedicated tool.

In engineering, there are three basic systems of fixing threads: metric, inch and pipe.

Metric thread is most prevalent. It has a triangular profile with an angle of 60˚. Its basic parameters, the diameter and pitch are expressed in millimeters. Example identification: M16. This means that the metric thread has a diameter of 16 mm with a large pitch of 2.0 mm. If the step is small, then specify its value, for example, M16 * 1.5.

Inch diameters and pipe thread are expressed in inches. Step characterized by the number of threads per inch. These parameters are standardized, so you always have the opportunity to choose the desired instrument.

Cutting threading ram

For threading the thread need the following instruments and materials: die or tubular die stock, plashkoderzhatel, a file, a vise, caliper, machine oil.

The most widely used around the die (chaser). They are in one piece or cut. The diameters of the solid circular plates are standardized. This allows you to choose the appropriate option from a wide range of sizes, for example, M10, M12, M14, M16.

A feature of split dies is possible to adjust the thread cutting diameter in the range 0.25 ... 0.1 mm. However, they have reduced stiffness, which affects the accuracy of the resulting profile.

The plate was placed in plashkoderzhatel suitable size. After that it is fixed with screws. In the case of the outer pipe thread often used plashkoderzhateli ratchet. They provide the convenience of working in confined spaces, such as a wall.

The thickness of the rod is selected to 0.1 ... 0.25 mm less than the outer thread diameter. For example, for the M6 ​​major step is 5.80 ... 5.90 mm; M8 - 7.80 ... 7.90 mm; M10 - 9.75 ... 9.85 mm. Measurements performed with calipers. The diameters of the rods under the metric thread cutting middle class 6g accuracy shown in the table.

To provide the best plunge dies at the end of the rod zapilivajut chamfer. Its width should be 1 - 1.5 mm for M6 ... M18. Workpiece lubricated with machine oil, which facilitates follow-up, and provides a better surface.

The plate was put on the end of the shaft so that its plane is perpendicular to the axis of the bolt being cut. Further, with slight pressure plashkoderzhatel rotate in a clockwise direction (left thread, then counter-clockwise). When the die cuts into the rod for one to two lines, it should be turned half a turn back for a better chip removal. Then again make 1-2 turns in the course of the thread, and 0.5 - in the opposite direction. Acting under this scheme, the bolt is cut to the desired length.

The diameter of the male thread is checked by the conventional nut or ring gage. If necessary, a step control rezbomerom.

Tapping tapping

The following tools and materials for the formation of an internal thread necessary:

  • a hammer punch, drill, the drill bit;
  • set of taps, knob, bench vise;
  • machine oil.

Technology tapping

The first step is to mark the blanks and core center of the future holes. Pick up the drill according to the required diameter of the thread. This can be done using lookup tables or approximately by the formula d = D - P. where D - diameter of the thread, P - its pitch, d - diameter of the drill. For example, for d = 10 M10 - 1.5 = 8.5 mm.

In detail drill hole to the required depth, which must exceed the length of a cut portion. Using drill diameter greater than d, operate at the edge of the hole chamfer. It serves for centering and a better approach of the tap.

On the basic parameters of the thread - diameter and step - pick up the cutting tool. As a rule, use a set of two taps. One draft, another - finishing. On the size of the square tail taps are selected knob.

Detail securely fastened in a vice. Roughing tap and hole lubricated with engine oil. Then place the tap exactly perpendicular to the surface of the parts and by pressing along its axis, rotating the knob on the handle.

Cut into one or two lines of thread, make a quarter turn in the opposite direction. This promotes fragmentation and removal of swarf, prevents jamming of the tool. Continue to work, carrying alternating rotation: ½ turn forward, ¼ - ago. At the same time it must be ensured that there is no misalignment of the tap. One should not use excessive force to it. To avoid jamming, the cutting tool periodically withdrawn and the hole is cleaned from chips.

After tapping on the desired depth in the opening set finishing tap. When he goes in a given direction, it put on a knob and continue to work. Periodically add lubrication.

Thread checked via-plug gauge or bolt. He should be turned effortlessly and swing. If necessary, additional make finishing tap passage.

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Tip 1: How to thread

  • To work need: vise, file, taps, dies, wrenches, lube and desire.

The metric thread diameter and thread pitch measurement in millimeters. In designating a metric thread used alphanumeric marking, e.g. M8h1,5. Figure eight corresponds to the diameter of the thread, and the thread pitch is 1.5, the distance between the coils.

The Whitworth thread, measurements are in inches and the number of threads per inch. One inch equals 2.54 cm., For example 1 inch thread is recorded 1/4 ".

Here is an example excerpt from a table diameter of the shaft under the metric threads:

After selecting the workpiece, it is clamped in a vice, a file is removed from the end chamfer for proper call dies, and rotationally moves the pinch cut thread without forgetting the item lubricated with lubricating oil.

Tapping into the part you need two taps, roughing and finishing.

Tip 2: How to cut an internal thread

  • An electric drill, a set of drills and taps, thread gauge, caliper, table sizes metric threads.

Tip 3: How to thread tap

Before you get started, you need to prepare a hole. If it is too large, the final profile of the thread will be incomplete, and the connection itself - unreliable.

Tip 4: Tapping and dies

Workpiece for threading

The diameter of the rod or threading hole is not equal to the nominal value of the finished product. When cutting external thread is selected rod having a diameter of a few hundredths of a millimeter smaller than the thickness of the finished product. This is due to the fact that when removing the metal chips partially squeezed out, completely filling the threaded profile dies. For tapping a hole is also made with a small allowance down. The exact values ​​of the diameters of workpieces for cutting metric threads are specified in IEC 19257-73.

Before threading on the rod should be noted depth slicing and clamp it vertically in a vise. The surface should be abundantly lubricated with engine oil or lithologic. Die of appropriate size is installed in the holder. Start threading should start side plates. It has a progressively increasing depth of the cutting edge, while on the back side of the die, these edges are reduced fully one and a half turns. The plate was put on the need to produce a rod and kickoff until the high resistance of the metal. In this case, the handle holder must be strictly perpendicular to the workpiece. After kickoff plate should be returned to the third turn back, then you can begin to complete threading slow turning handle holder. Tapped lightly treated with fine sandpaper and cleaned fine metal brush.

The internal thread may be cut in two ways. Through done in one pass, while threading in the deep recess is required to use a roughing and finishing taps used in two successive passes. Detail needed rigidly fix and set the tap spout, lubricate the machine oil in the hole or recess parts. By turning it to one and a half or two turns must perform kickoff, then unscrewed the tap a half turn and continues tapping the full depth. From time to time you may need to completely unscrew the tap to clean the holes from nabivsheysya chips.

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