How to thread a tap in aluminum

Two effective ways to rebuild threads in aluminum

thread, aluminum

Threading a new thread

It is easier to cut bigger threads in aluminum than to recreate the old ones.

Cut new thread and screw in bigger diameter bolt or use repair stud (on the picture above).

But this is not an option for me.

Repairing threads with a repairing insert

The simple and proven way to restore the threads is to use a threaded insert.

Thread it to the outside diameter of the cap and screw it in.

Tapping Threads in Aluminum Spindle

I use threadlocker to make it safe.

Then we safely screw the bolt into the lug. I have seen several times that this method is considered ineffective on the forums.

In my experience I can say that the bolt in the lug holds excellent. In several years of operation, there has never been a case of a bolt in a socket turning or falling out with it.

Useful materials, as well as manuals on car repairs you can find in my group VK. You can join the group by following this link


And what methods do you use to restore the threads? Write in Комментарии и мнения владельцев.

Thank you for your attention, have a nice day!

The composition of the glue

The components that make up the adhesive mass are aimed at creating a homogeneous mixture. Plasticity properties are created due to the epoxy resin. It improves the composition and makes it softer and easier to use. To obtain a single solid component with the metal, metallic substances are added. During the process of pouring and restoration of the chipping polymeric mass of the welding fills the parts that have a defect.

The quality of the mass for welding suggests unique properties. They make cold welding common and attractive to consumers with different professional and construction needs. The weld obtained by cold welding will be inferior in some respects from the standard method, but in terms of speed of work, conditions and simplicity of the procedure will give advantages.

Preparation for threading

Internal threading begins by drilling the desired through hole or blind hole. The main condition: The hole must be smaller than the diameter of the thread. When drilling a hole, it is recommended to choose a drill bit according to the following condition:

  • For M3 threads the drill bit diameter is 2.5 mm;
  • at M4 3.4 mm;
  • at M5 4.2 mm;
  • at M6 5 mm;
  • at M8 6.7 mm;
  • at M10 8.4 mm.
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If larger threads are to be cut, the diameter of the hole is roughly determined by multiplying the thread diameter by 0.8.

The hole for tapping the internal thread is made on a drilling machine or an electric drill. In the latter case the workpiece is clamped in a vice. It must be ensured that the drill bit is guided strictly vertically. On the top edge of the hole a chamfer is removed to facilitate the entry of a tap. It can be made with a drill of larger diameter or a file. After drilling, the hole is thoroughly cleaned of chips, which is especially important for blind holes.

Features of the structure of taps

The tap, which belongs to the group of turnery cutting tools, is shaped like a rod on which the cutting element is made. It is intended for cutting internal threads, that is, inside the hole in various materials, as well as for restoring damaged internal threads.

Set of metal-cutting tools: a. drills, b. countersinks, c. reamers, d. taps, e. dies.

The tools consist of a working part and a tail part. In turn, the working part is divided into a fence (cutting) and calibrating section. The cutting zone is responsible for the basic function of a tap. thread-cutting. and is most commonly tapered. It has chisel-like teeth positioned in a circular pattern. The calibrating section performs the task of final shaping. It is made in the form of a cylinder with teeth that are extensions of the cutting section. This section is significantly longer than the intake section. The working part in the longitudinal direction is cut with grooves, which are designed for the formation of cutters and withdrawal of chips. In taps with a diameter of up to 22 mm, three grooves are made. Devices for special purposes may be manufactured without grooves. Grooves can be straight or screw-shaped.

Tailpiece is shaped like a cylinder. At the end of the section, a square is made to fit into the fastening tool. Diameter markings are stamped into this part. Tool is held in a handhold or machine tool chuck by a shank.

How to thread the internal thread with a tap: threading technology

The main task of the fitter is to create a hole in the metal thickness, followed by the formation of troughs from the inside. They must be made so that the coils fit a bolt, pin or other fastener.

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Threaded element may be needed in the home for the strongest possible connection of the two parts. Here it is necessary to achieve maximum cleanliness. so that there are no chips, deformations, and bent threads. It is also very important to follow GOST standards for the size of the fixture. Diameter must match the screw that will go in.

Many parameters are important. the type of material, its density, as well as its condition, such as temperature, corrosion. First it is necessary to prepare the workpiece. to remove unnecessary dirt. Then you need to choose the right tool, only after that start metalworking in two or three steps. from roughing to finishing.

  • The diameter of the hole;
  • threading depth;
  • the number of threads (these are runs, the most common is the presence of three cavities);
  • pitch, that is, the distance between the two grooves.

How to thread with a tap manually: learn the main

There are quite a few ways to connect parts, but the most common and accessible is still the screw (bolt) fastener. This is exactly the kind of fastener we are going to talk about. precisely, we will look at the types of taps, the technology of threading in holes for screws and bolts of different diameters.


Do not use a drill or other mechanical tools for tapping. An exception is a universal drill press whose speed can be adjusted down to 0.3 per second and which has a reverse function. A simple drill can be damaged, as well as the tap itself.

It is not recommended to deviate from the vertical and perpendicular alignment when drilling, otherwise the drill bit will break. If the same is done to a tap, it can be bent and the alignment given to it at the factory can be disturbed. You can only straighten a tap by using a lathe or drill as a guide. However imperfect, a bit crooked tap immediately leads to poor-quality internal thread in the workpiece. bolts and pins are turned hard or refuse and at all normally tighten.

Preparatory work

A drilled hole that has been threaded with a tap must be turned or countersinked. The diameter of the drill bit should be larger than the internal diameter of the thread, as the material is a bit “squeezed out” while threading. Hard and brittle metals have a smaller difference between these values than soft and ductile metals. For hard, such as 6.7, and 6 for soft ones.8.

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If we drill a hole with the same diameter as the inside of the thread, the teeth of the tap will overheat due to the high friction and build up metal due to the material being squeezed out during tapping. Then we get a broken thread or we break the tap.

If we drill a hole of larger diameter than the required one, we get an incomplete thread.

How to choose a drill bit for tapping threads we have already written in another article

Tables for selecting threaded drill diameters

If internal threads are made, a hole is drilled in advance for them. It does not equal the diameter of the thread because when it is tapped, some of the material is not removed as chips, but is squeezed out, increasing the size of the protrusion. Therefore, before application, the drill bit diameter for the thread must be selected. This can be done according to the tables. They are there for every type of thread, but here are the most popular. metric, inch, pipe.

Metric thread Inch thread Pipe thread
Thread diameter, inches Thread pitch, mm Drill diameter, mm Thread diameter, inches Thread pitch, mm Drill diameter, mm Thread diameter, inches Threaded hole diameter, mm
M1 0.25 0,75 3/16 1.058 3.6 1/8 8,8
M1,4 0,3 1,1 1/4 1.270 5.0 1/4 11,7
M1.7 0,35 1,3 5/16 1.411 6.4 3/8 15,2
M2 0,4 1,6 3/8 1.588 7.8 1/2 18,6
M2.6 0,4 2,2 7/16 1.814 9.2 3/4 24,3
M3 0,5 2,5 1/2 2,117 10,4 1 30,5
M3,5 0,6 2,8 9/16 2,117 11,8
M4 0,7 3,3 5/8 2,309 13,3 11/4 39,2
M5 0,8 4,2 3/4 2,540 16,3 13/8 41,6
M6 1,0 5,0 7/8 2,822 19,1 11/2 45,1
M8 1,25 6,75 1 3,175 21,3
M10 1,5 8,5 11/8 3,629 24,6
M12 1,75 10,25 11/4 3,629 27,6
M14 2,0 11,5 13/8 4,233 30,1
M16 2,0 13,5
M18 2,5 15,25 11/2 4,33 33,2
M20 2,5 17,25 15/8 6,080 35,2
M22 2,6 19 13/4 5,080 34,0
M24 3,0 20,5 17/8 5,644 41,1

Once again, please note that the drill bit diameter is for coarse (standard thread).