Instruments

When installing various equipment, cabinets, clamps and so on, threaded rods are used. It is one thing if these studs have a turnkey hexagon inside, but if there is none, then you have to use stud drivers.

Stud drivers are designed for a specific thread diameter: 6, 8, 10, 12, 14. This is a rather complicated device that has a body in the form of a cylinder, with faces for the key at the end, and inside there are rollers in the form of pins. When turning, the rollers are tightly pressed against the stud thread and hold it when twisting or unscrewing.

Such devices are also used when the bolt breaks off and a piece of thread remains. But they are not cheap. Although it seems to be a universal tool. But for different thicknesses of threads, it must be of appropriate diameter.

Such a tool is not always at hand, so many twist the studs with improvised means, pliers or two nuts, at best, with couplings. However, if a small bolt is screwed into the coupling, then the stud screwed into the coupling will be fixed with the counter screw and it will be possible not only to tighten it, but also to unscrew it.

In addition, when twisting and unscrewing, it is better to use an electric drill with the corresponding bits. Screwing in is not quite difficult, since the bolt previously screwed into the threaded sleeve not only does not allow the pin to be deeply screwed, but also fixes it. Therefore, if necessary, unscrew the hairpin, it holds it.

If you need to remove the clutch, then just hold the clutch with a wrench or pliers and it can be twisted off the stud.

How to unscrew a hairpin? Consider several methods, taking into account the condition of the stud and the existing tool.

How to unscrew a hairpin on a threaded part

If the stud is long enough and the threaded part for 2 or more nuts is available, then we use one of the following methods:

• tighten the nut, screw the second one all the way into the first (it is desirable to use high nuts), then unscrew the pin with a metal tool (wrench or other);
• use a special tool - a hairpin, for the size of a hairpin or universal.

The eccentric hairpin is convenient and effective - the greater the force applied to it, the stronger it clamps the hairpin with the notch of the eccentric.

How to unscrew a hairpin if only 1 nut thread is available? In this case, at least 4 methods are available:

• cut the nut on one side with a hacksaw for metal (the direction of the cut is along the axis of the threaded part), screw it onto the stud, tighten it with a pipe wrench so that the threaded part, choosing the gap in the cut, tightly grips the stud, direct the force in the direction of unscrewing;
• screw the nut onto the thread, weld it to the stud (for example, with a welding semiautomatic device) and unscrew it with a key (or a head with a knob);
• screw the nut onto the thread, drill a recess in the end of the stud (with a diameter approximately half the diameter of the stud), insert the TORX nozzle (E-profile, or another similar with longitudinal ribs) into this recess and unscrew the nozzle shank (this can be helped by the second hand with an open-end wrench or ring spanner that exerts a force on the nut in addition to the main torx force);

In the method with a screwdriver, a large version or a power version with a T-handle is better for this purpose.

How to unscrew a hairpin for a smooth cylindrical part

If only a smooth portion of the stud is available (for example, the threaded portion is broken off), then the following techniques apply;

• clamp the cylindrical part in a suitable tool (in pliers, a pipe wrench, a small vice, a clamp, or others) and apply force in the direction of unscrewing;
• weld a metal bar to the broken end by welding as a T-shaped handle;
• put on a nut of a slightly larger diameter, weld to the stud in a circle and unscrew with a key;
• use a square washer with a thickness of a nut or more, with an inner diameter of the same size as the diameter of the cylindrical part of the stud (ideally, if the washer fits on the cylindrical part of the stud with an interference fit), cut it on one side similar to the nut in the previous subsection, put it on the stud, tighten pipe wrench and unscrew;
• use a die (the one used for threading), turning the end of the stud to a square of the desired size;
• use a hairpin;
• use a hacksaw for metal to cut in the end under a flat screwdriver, with which to remove the pin.

In some cases, if possible, to enhance the impact, at the same time as applying force to the screwdriver or wrench, you can use the second tool (pipe wrench, pliers, etc.) by clamping a smooth side surface and acting in the direction of unscrewing.

How to unscrew a broken hairpin

If the hairpin is broken and there is no part protruding above the surface, then you can unscrew it in the following ways:

• by a welding semiautomatic device, gradually and accurately “build up” a couple of centimeters (if the end of the stud is in the reach of the welding wire) and for this “turn out” to turn out using a clamping tool;
• use a special tool - an extractor (it looks like a tap, the working part is tapered, the direction of the thread is opposite to the thread of the pin): align the protruding end of the pin with a file (or evenly cut it with a hacksaw for metal), pin it exactly in the center, drill a hole of the desired diameter along the pin axis and depth (about 2/3 of the length of the working part of the extractor), insert the extractor and rotate with force until the stud is twisted;
• preparation with drilling as in the previous method, only apply the tap on the left thread of the stud (if the stud is in the right direction) - when the tap, cutting the thread, abuts against the bottom of the drilled recess in the body of the stud, then the chip is often twisted;
• drill the center of the hairpin, thus choosing a diameter so as not to touch the threaded part of the socket, and then remove the remaining metal of the hairpin;
• drill off the broken part of the stud and the threaded socket on the drilling machine or with a hand drill with a larger diameter drill for the repair stud.

Using the method of drilling a recess with driving a torx tip into it carries the risks of strengthening the wedge in the threaded socket due to the expanding deformation of the stud walls. Given the possible complications, we will not recommend it in this situation, despite the fact that it is limited, with certain conditions, and it can be applied.

Difficulty can cause alignment of the end face of the stud if a breakage occurred in depth. In this case, the end burr will provide invaluable assistance.

Another variation for the drilling method. You can use drills with a left direction of rotation and an electric drill with a direction switch and speed control. When drilling at low speeds, the wedged thread loosens and due to the left rotation of the drill, the rest of the stud is easily strained and leaves the threaded socket.

Drilling is often wiser to do in several passes, from a small drill to those that are larger, to the desired diameter.

How to unscrew a stuck hairpin

The acidified hairpin must be twisted with additional tricks, both in terms of tools and in terms of technique.

• apply a few blows with a hammer to the end of the hairpin along its axis without damaging the edge of the thread;
• apply a few light blows from different sides on the lateral surfaces of the stud (screw the nut on the threaded part to prevent damage), without allowing bending;
• apply special penetrating compounds - WD-40, liquid key and their analogues, giving the necessary time in accordance with the instructions for these drugs from their manufacturer before attempting to unscrew;
• use an extension cord to the hand tool to increase the applied force (longer-length wrench or putting a pipe of suitable diameter on the rotatable end of the hand tool;
• when unscrewing a welded nut, use not the open-end wrench, but the Super Lock head, in which the force is applied not to the corners (faces), but to the planes;
• instead of applying physical force and a hand tool, use an impact wrench (if it is not in the home workshop, you can contact the nearest tire service or car service, delivering the part with a stuck stud there);
• with the method of screwing two nuts, the first one is screwed up to the stop with so much force that it cuts into the cylindrical part of the stud, and the second nut should be used not standard but self-locking (this will allow much greater efforts to be applied, reducing the risk of unscrewing the nuts);
• heat several times and allow to cool; at the final stage, heat and unscrew.

Repeated heating is also indispensable for unscrewing the studs, mounted on special compounds - thread locks.

When unscrewing a stuck stud for a welded or wound nut, it is better to use the tool that is more structurally and more solidly covers the perimeter of the nut working surfaces, excluding face licking:

• 6-sided head instead of 12-sided;
• super Lock head instead of the usual;
• spanner wrench;
• a wrench instead of a ratchet.

How to unscrew a hairpin from an exhaust manifold

If the steel stud is stuck in a steel or cast-iron manifold, then it is possible to heat until the metal reddened, using a gas torch, a gas burner from the can, a blowtorch or other suitable equipment.

How to unscrew a hairpin from an exhaust manifold to prevent cracks in cast iron? First of all, it is impossible to artificially intensively cool a cast-iron component. In this case, the collector itself needs to be heated without touching the pin: the collector will warm up and be heard a little in the area of \u200b\u200bthe threaded hole with a soured pin, and the difference in the heating of parts will weaken the stick even more.

How to unscrew a hairpin from an aluminum part

Parts made of aluminum and its alloys cannot be intensely affected by a gas cutter and other powerful equipment due to the risk of fusion of parts or their other damage due to high temperatures. In this case, you can:

• you can only heat the hairpin and then it is not red;
• use a hot air gun (heat gun) to heat the aluminum part or use the blowtorch to a limited extent in a more gentle temperature regime than a gas burner can provide.

How to unscrew a hairpin from the engine block

First of all, when choosing an approach, one must proceed from the material from which the engine block is made. In the case of a cast-iron block, we use the approach with intense heating until the gas burner reddenes. If the block is aluminum, then in the area of \u200b\u200bthe coked stud we warm it carefully with a hot air gun, avoiding damage to the expensive part from high temperatures.

For example, it is often very difficult to unscrew the pin from the engine block ZMZ 402. It is distinguished by systemic problems with twisting out certain studs due to the material of the block and the peculiarities of its heating during operation.

Several cycles of heating and gradual cooling will greatly facilitate the unscrewing of the studs from block 402. Recall that the unscrewing of the studs is carried out in a heated state. It will also be very useful to impact on the hairpin - along its axis or loosening by blows on the sides from different sides.

How to unscrew the broken-off hairpin from the block we described above in a separate subsection, the techniques for this part do not differ in originality.

How to unscrew a hairpin from the cylinder head (cylinder head)

When deciding how to unscrew a hairpin from the cylinder head, one must also proceed from the head material. Cast-iron heads are rare, mainly on older cars, and most often they are made of aluminum alloys.

On the heads of the block often have to deal with stuck, soured hairpins.

To unscrew the hairpin from the cylinder head, the most convenient and effective methods and techniques of the above can be applied. Often this is a two-nut method, using an extractor or drilling. To enhance the impact, it is more advisable to use preliminary loosening tapping on the sides, the use of penetrating compounds, rotation with two tools.

Conclusion

Faced with the question of how to unscrew the stud from the block, head, manifold, starter, wheel hub or other part, you can choose an effective solution to the problem from several methods and techniques, taking into account the available tools and tools. Locksmith tools available in almost any garage can be used, as well as specialized ones, such as a hairpin.

Before you unscrew the hairpin, it is worthwhile to apply shock to it. Also, if the threaded socket in the part is through, and the end of the stud sticks out, then the visible part of the thread should be cleaned of contaminants, which can create additional difficulty when unscrewing. It also facilitates the extraction operation of the preliminary use of penetrating compositions.

In specialized auto repair shops, in production, in construction - everywhere where it is often necessary to work with hairpins, a hairpin is used. Experienced masters who know their job, there is no need to explain its purpose. And the name speaks for itself. However, many may not be clear about the design features of the tool, its appearance, how it works and how much it costs.

Design features of a stud driver, principle of operation

The most famous design of this tool consists of a housing in which three rollers are located. Due to the complex inner surface of the housing during rotation, the rollers tightly clamp the pin, making it turn out even in difficult cases (fasteners for automobile collectors, silencer elements and other places where the thread of the pins “sticks” to the hole of the part into which they are screwed). On the reverse side, the housing, as a rule, has a square hole for the standard size of ratchets (wrenches), as well as the hexagonal shape of the outer surface, for holding with a wrench.

In addition, there are designs, the basic structure of which is similar to the usual three-jaw (collet) cartridge. Chuck jaws during rotation also provide reliable retention of the stud, which makes it possible to unscrew or tighten it with minimal effort. Such a tool is more versatile, since it is supposed to work with studs of different diameters. Some designs, based on the principle of clamping with a rotary cam, also have a certain versatility (the scope is expanded due to the fact that the same tool can be used with different diameters of fasteners).

A lot of designs were invented by those who like to make tooling and auxiliary mechanisms with their own hands - starting from several nuts compressed between each other on the free thread of the stud to relatively complex devices where wedges or eccentrics are used to fix the stud.

If the use is frequent, then it makes sense to purchase not one stud, but a set for different diameters of the studs. Rotation can be carried out either manually or with the help of various power tools - screwdrivers, pneumatic wrenches or drills. After the hairpin is safely twisted, the hairpin, turning in the opposite direction, is removed from it. In fairness, it should be noted that after using this device, the stud thread must be restored using a die (the thread turns out to be somewhat crushed), especially if it is intended to reuse fasteners.

The advantage of using stud drivers

A fairly large number of people today face difficulties in dismantling fastening threaded parts (studs or bolts). If we talk about car service, this is most often associated with the repair of old cars, where some elements of the connection have not been twisted for decades. The advantages of using a special device are as follows:

• with its help, in the vast majority of cases, it is possible to unscrew the bolt with a broken head without damaging the thread in the part;
• the hairpin itself remains practically intact, after running with a die it is suitable for reuse;
• minimum time spent on work;
• made of high-quality steel, the tool is durable and durable;
• in hard-to-reach places it is often more convenient to use a hairpin rather than improvised means.

Simply put, the tool makes it easier and faster. It is no secret that a broken rusted bolt in the absence of special equipment can paralyze all car repair work. A poorly twisted pin can cause the repair time to triple. Therefore, if the hairpin suddenly does not want to get out of a place where its breakage can cause serious problems, it is better to use specially designed tools for this.

Stud Price

For domestic use, a universal stud driver can be quite convenient, which allows you to work with different diameters of threaded parts. For car services or service stations, a special set may be the most functional, including up to a dozen heads of the most common diameters. Moreover, finding and buying a hairpin today is not difficult - these devices are sold both in ordinary stores and on various online sites. Prices are quite affordable - for a universal eccentric mechanism, this is a range from 400 to 1000 rubles. Three-roller stud heads are sold from 300 to 600 rubles apiece, if we consider the most common sizes. Kits can be purchased from 1.5 to 8 thousand rubles, depending on the configuration, quality and manufacturer. In the case of professional use, it is better not to save on the manufacturer, especially since the price difference is not too large.

Hello!

At the beginning of the year, we had a “CV joint replacement season”, “grenades” flew one after another. I have relatives and friends.
All these old parts were in scrap metal, waiting in line.

DIY stud making

For the manufacture of a hairpin, in addition to the SHRUS and a standard set of tools, electric welding is required.

I cut off everything superfluous from the tripoid, cut off the workpiece of the eccentric from the shank.

In the case of the tripoid, he made a slot so that an eccentric was placed in it.

I polished the workpiece.

Using two nuts and a rod, he connected the eccentric to the body. I made a handle out of a broken wrench.

Stud Testing

First test. A bolt tightly clamped in a vice rotates quite easily without additional lever.

Once again, I cleaned everything. A handle from the old cord was useful.
Such a tool should last a long time, because the metal is good, and the teeth are subjected to additional hardening.

And here is a purchased hairpin of a different design. The teeth on the eccentric crumpled on the first hairpin. (not visible in the photo).

About what else can be done from the SHRUS I will tell in my next works. Thanks to all!

In the practice of repairing automotive machinery, it becomes necessary to screw and unscrew the studs - fasteners without turnkey surfaces. For these purposes, a special tool is used - a hairpin or a key for studs. Read about hairpin drivers, their types, work and choice in this article.

What is a hairpin?

Stud (key for studs) - a specialized tool for screwing and unscrewing threaded rods.

A hairpin is a fastener in the form of a rod with a thread at both ends. The stud is screwed into the product in one piece, and a nut is screwed into the second part. In the design of the stud, there are no special surfaces under the thorn (such as, for example, heads on bolts or faces on nuts) or other tools, which greatly complicates the procedure for screwing and unscrewing them. As a result of this, one has to use special tools that are called stud keys or simply stud drivers.

For the correct purchase of a hairpin, you need to understand the existing types of this tool, their features and advantages.

Types, design and principle of work

The main problem of working with studs is to ensure reliable fixation of the cylindrical rod without damaging it and with the force necessary for screwing in or out. Several solutions to this problem are proposed, and according to the method of clamping the studs, the stud drivers are divided into several types:

• Roller
• Eccentric;
• Collet (cam);
• With a wrench and an emphasis.

Moreover, all types of tools can have one of two types:

• A stand-alone tool that works without additional tools;
• Equipment for working with ordinary keys, handles, ratchets and other devices.

The first type of tool is convenient and easy to use, it is always ready to work, however, as a rule, it has a more complex structure and high cost. The second type of tool can have turnkey hexagons or a square of standard size (usually 1/4, 1/2 and 3/4 inches) for a wrench, ratchet, etc. This tool is more versatile, compact and has an affordable cost.

Each of these tools has its own design features and operating principle.

One of the most simple in design and reliable tools. In the general case, it is a cylindrical body, inside of which there are three cylindrical rollers, between which spacer inserts can be additionally installed. The inner surface of the casing has a complex profile (triangular with rounded edges and corners, with elements of an ovoid, etc.), so the rollers rolling around inside the casing can approach and move away from its central axis.

The roller stud works simply. The tool is put on a hairpin and rotated using a key or a screwdriver. When turning, the rollers roll over the hairpin and the inner surface of the body, which leads to jamming of the hairpin - now the force is transferred by hand to it, which allows it to be screwed in or out.

Keys for hairpins of this type are simple, reliable and convenient, however, they have a significant drawback - each hairpin is made for a specific diameter of the hairpin. Only in this case is the necessary clamping of the rollers to the stud and its jamming when turning. Therefore, to work with different studs, you need to have a whole set of roller studs.

A tool of this type is also very simple, while it is more versatile than a roller one. Structurally, this eccentric hairpin is very simple: its base is a case with one or two holes for the studs, on which there is a hinged eccentric - a metal disk with a corrugated rib and the possibility of supplying it to the holes. Also on the case there is a knob or square for installing a knob, ratchet or other device.

The eccentric hairpin works simply: the tool is put on the hairpin, the disk is brought to the hairpin, and the whole tool is rotated - when turned, the eccentric rests on the hairpin, wedges it and allows you to transfer the force necessary for screwing in / out.

Today, two types of eccentric stud drivers are available:

• Universal - with one or two holes that allow you to use the tool to work with studs of different diameters;
• By size - with one hole for working with studs of the same diameter.

It should be noted that there are tools that combine the design features of eccentric and roller stud drivers. In such a tool, there are three small eccentrics covering the hairpin; when turning the tool, the eccentrics jam the hairpin at three points, providing maximum clamping and transmission of high force.

This is a universal tool having a device similar to a collet chuck drill and other tools. The base of this type of screwdriver is a housing, inside of which movable cams are located. When the housing is rotated, the cams converge to the center, clamping the pin, and ensuring the transfer of effort to it by hand.

Collet studs are the most versatile, as they allow you to work with studs of various diameters, even non-standard ones. However, the cams do not always provide the necessary degree of fixation of the tool on the hairpin, therefore this type of hairpin often cannot cope with the fasteners. This is an inexpensive amateur tool that is almost never used in auto repair shops.

Stud with wrench and stop

This tool is quite simple in design, so it is often made in artisanal conditions. The basis of the hairpin is a body with handles, in the lower part of which there is a nut, and in the upper there is a thread for screwing in the screw. In the case opposite the nut, a hole was drilled with a thread for a bolt or screw that secures the nut from turning.

Such a tool works simply. A nut of the required size is installed and bolted into the case, the tool is screwed onto the pin with a nut, then a screw is screwed into the case, it abuts against the end of the pin and is jammed. Now the casing rotates counterclockwise, and the pin, fixed with a nut and a knob, is inverted.

This tool is used, as it is correct, only for turning out hairpins. It, despite the simplicity of design, requires a large number of operations to work with one hairpin, so it is not always convenient. Today, keys for studs of this or similar design are rarely used, they are replaced by simpler and more convenient roller and eccentric stud drivers.

How to choose a hairpin

When choosing a stud driver, it is necessary to take into account the nature of the work that will be performed by this tool, and their frequency.

For use in a garage, when the studs have to be twisted only occasionally, the best solution would be a universal eccentric type stud. Such a tool will allow you to work with studs of various sizes (with it you can turn out and screw the studs of almost all engines - from two-stroke scooters to medium-tonnage trucks, you can also repair other units with studs), it is reliable and easy to use, and has an affordable price. You can also purchase a collet stud, however, it does not always provide the necessary degree of fixation and cannot work with large diameter studs.

For professional use in workshops, the best choice is for roller or eccentric stud drivers. The presence of a tool for a certain size of studs significantly improves the quality and speed of work, and the cost of it pays off in a short time. Although in this case it will not be superfluous to have a universal eccentric tool - with its help you can quickly perform simple work.

With the right choice of a stud driver, you will provide yourself with a reliable tool that will help solve the most complex tasks in the maintenance and repair of vehicles.