How to thread a pipe: plugs and dies

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Let’s figure out how to properly cut the external and internal threads on the pipe using die blocks and dies. Threaded joints of metal pipes are strong and airtight, and can also withstand significant pressure. And if you mount the pipes yourself, then threading will be required.

For work you will need tools and materials:

  1. Vernier caliper – for accurate measurement of pipe diameter.
  2. Vise – when using solid dies or tap.
  3. Machine oil or any lubricant.
  4. Rags or sponge.
  5. Protective equipment – glasses, gloves.

A device for tapping a thread, depending on the specific task (solid or sliding dies, electro-lugs, ratchet holders or taps).

Preparation for work

First you need to pick up and, if necessary, cut off a suitable piece of pipe with a grinder or a hacksaw for metal. When cutting, you need to check that the cut is strictly perpendicular to the planes of its walls.

Pipe section

Immediately before cutting the thread, clean the pipe surface from rust or old paint and other foreign deposits using sandpaper and a file. In addition, the end of the pipe must be chamfered with a file in order to make the thread easier. Now let’s move on to preparing for threading.

Preparing the pipe for threading

Major mistakes when threading:

  • the pipe diameter does not match the thread diameter;
  • using an incorrectly centered, rusty or blunt tool;
  • working without lubrication of the tool and pipe leads to cracks or disruption of the threads;
  • excessive physical efforts as a result of a complete lack of work skills lead to thread breakage.

Cutting external threads with a solid die

One-piece dies are often used to cut external threads on pipes. They are a hardened nut with internal cutting edges. This tool is suitable for cutting threads up to 52 millimeters in diameter..

Set of pipe rams with ram holder

It is inexpensive, characterized by good rigidity and accuracy of work, but it does not last long, since it wears out quickly. Working with dies requires some experience, therefore, in order not to damage the tool and the pipe, it is advisable to practice on a pipe section.

The procedure for working with a solid plate is as follows. First of all, you need to select a tool of the appropriate diameter using a vernier caliper. The die is installed in the holder and then fixed with screws. You need to make sure that the die is securely fastened, as otherwise the thread may turn out to be uneven..

The pipe is clamped in a vice or fixed in any other way in a vertical position. Grease or oil is applied to the pipe surface as well as to the die cutters. Lubrication should be performed several times during operation..

Pipe threading with a die

Direct threading is carried out in a plane strictly perpendicular to the direction of the pipe axis, clockwise. If a misalignment occurs, the threads will be torn off or the cutting diameter will change. After cutting several turns, you need to periodically rotate the die in the opposite direction to remove the chips. After that, cutting continues..

Work must be done smoothly and without jerking. In order to cut a high-quality thread, you need to drive it first with a rough die, and only then use a finishing one. You won’t have to cut it for a long time – a thread length of 10 millimeters is quite enough, which is a standard indicator for most of the pipeline networks for household use. After using the die, the grease must be removed from the surface of the pipe and tools. Using a rag, the treated areas are cleared of chips.

Cut thread

Problems can arise when working with stainless steel pipes, since in this case the metal is quite hard. To cut threads on such pipes, you need to select a die from the appropriate steel – for example, with the P18F2 marking. If you use dies made of softer steels, the tool will be hopelessly damaged..

Application of die plates

Unlike one-piece dies, die plates consist of two sliding parts that are fixed in the holder frame. The thread diameter is adjustable. The advantage of die dies is the purity of the resulting thread and increased structural strength.

When working with die-cutting tools, less effort is required than when using conventional dies; in some modifications, the use of a vice is not required. The dies have special guides that simplify the work process and prevent distortions typical for thread cutting with a solid die.

Manual die for cutting threads

To facilitate the work, the klups can be equipped with ratchets. A ratchet wheel is located on the bottom of the heads for replaceable dies of such tools. When the wheel is turned, the head rotates. The disadvantages of systems with dies include higher cost than solid dies, as well as significant weight.

The sequence of actions when using a die plate:

  1. Fixing the pipe in the clamp, while its protruding part should be short, since a long section can bend when cutting.
  2. Insert the die into the holder, and the edge of the pipe into the guide.
  3. Lubricate pipe and tool.
  4. Cut the pipe by rotating the die. Rotate it counterclockwise periodically to free the grooves from chips.

Manual pipe threading

A more expensive, but at the same time quite convenient solution is the electro-lug. However, in terms of economic feasibility, the purchase of such a tool is needed only if pipe threading is performed frequently.

Electroklupp works with an electric motor. As a rule, the tool is completed with high quality tool steel. The dies are inserted into the replaceable head. Klupp of this type allows you to cut threads extremely quickly and efficiently.

Electric thread die

How to work with an electro-lug:

  1. The appropriate head with cutters is selected and fixed in the power drive of the tool.
  2. The pipe is fixed in a special clamp and tightened with a holder. The clamp is fixed on the body of the electrocuppa.
  3. The contact zones of the dies and pipes are treated with a lubricant.
  4. After pressing the start button, threads are cut in seconds.

How to make an internal thread

If an internal thread is required in the pipe, a tap is used – a screw of the corresponding diameter with cutting edges and flutes for chips. The tail of the screw is fixed in the wrench.

Pipe tapered tap

For work, two taps are quite enough – roughing and finishing. The use of a rough tap will allow processing about 70% of the material along the depth of the thread, the rest will have to be done on the finishing tap. Nevertheless, in some cases, the set of tools will have to be increased – to work with titanium pipes, up to five taps will be required.

The selection of a specific tap is made after measuring the diameter of the inner cavity of the pipe. The length of the section protruding from the wall should be several millimeters longer than the cut section. Cutting should only be done with lubricant. The working area must be cleaned of foreign particles and deposits.

Internal threading in a pipe

After installing the tap in the hole, it is necessary to check the strict alignment of its position with the pipe axis. If that’s okay, you can start cutting the pipe. Directly the threading stroke is carried out in the same way as it is done with a die.

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