During repairs, sometimes trouble happens - something breaks. Sometimes a broken part leads to trouble with a large device. For example, a broken bolt in the cylinder block. A broken bolt causes a lot of trouble. Especially when it broke down in a place where access is limited.
Easy option
The first thing to do is not to panic. Generally. A broken bolt can almost always be removed, the main thing is to act correctly.
Secondly - to examine the "scene". If it breaks when unscrewing - fill it with WD40, brilliant green or brake fluid - it is required that the broken off piece otkis along the thread. You can try to anneal the thread with a blowtorch - you need to look according to the circumstances. Let's see where it broke. When a broken piece sticks out above the part, you are very lucky - you can try to unscrew it. If there is such an opportunity, we wind two nuts, fix the lower one with the upper one. We unscrew the bottom nut - if the broken bolt left the whole thread, it should come out. There is not enough space for two nuts - we try to unscrew the thread with pliers. Another way is to make a cut in the middle with a grinder. As a result, we get a screw that you can try to unscrew with a screwdriver. If it works, the problem is solved. But more often the bolt breaks either flush with the part or inside it.
If it is broken at the detail level, try to unscrew it with your finger. In fact, when a broken bolt is inside the threaded hole, it is clean, and the screw simply broke due to metal fatigue or because it was pulled earlier - it can simply go from the finger. Or we pay attention to a chip - when a piece breaks off, a side always forms on the fracture plane - we substitute a chisel, a screwdriver - we try to unscrew it with light blows.
Such cases often happen when a non-threaded part is attracted to a stud or bolt - for example, a manifold to a cylinder block.
Difficult option
If it didn’t work out in these ways, we will drill. The main thing is that the broken bolt is not hardened. There are several ways to try before trying to drill out a broken bolt. The most elementary - we take a drill with a reverse and a drill. Sometimes such a trick takes place with an ordinary metal screw, with a drill at the end. We press on the broken residue, we try to unscrew it with small turns, accuracy is needed here - you need to turn it “tight”. If these methods fail, we move on to serious actions. When the diameter of the stud is small, you need to determine how to remove the chip - there is not enough space for two options.
Method one. With a small diameter drill, we make two holes in the fragment. Each against the other. We drill shallowly - about 5 - 10 mm, preferably away from the center. Then we take a snap ring puller, narrow-nose pliers, or simply insert two nails, clamp them with pliers - we try to unscrew them.
Method two. You need a special tool - an extractor. It is sold in tool stores. It is something like a cone drill, has a reverse thread, very hard hardened metal. First, we select a drill according to its diameter. Carefully mark the center of the stud with a core, we need it to drill a hole. You don't need to go deep - just drill a little deeper than the length of the extractor. Then we wrap the extractor, trying to unscrew the broken piece.
When none of the methods helped, the most difficult option remains - to drill. This requires several different diameter sharp drills and strong hand. The most important thing is to catch the center of the debris. As accurately as possible, we mark the center with a core, the accuracy of drilling depends on this. Then, with the smallest drill, we drill the broken one through.
It is important to drill exactly along the remainder, parallel to the wall, so that the holes are aligned on both sides. Then we take the next drill diameter and so on until we reach the wall of the hole. If you slightly missed the center of the hole - it happens. The main thing is to stop in time, leaving the whole thread. We take a chisel, a screwdriver or a nail, we crush the rest of the wall of the fragment inward. Then just pull the resulting lump out.
In the process of disassembling battered structures and devices, we sometimes encounter an unpleasant and unexpected situation when the bolt is downright stuck. Absolutely natural in such a situation is the question: how to drill a hardened bolt?
It is possible to list quite understandable and practical ways its extraction. It should be noted that the material from which the product is made, as well as the situation in which the disassembly took place, dictates the choice of one method or another, since the wrong approach can make all your efforts meaningless.
Precautions are the next important component after choosing a bolt extraction method, because in such cases, injuries should be avoided. The bolt is singeed, drilled, twisted or dropped out, poured with acid or alkaline mixtures. So, there are several answers regarding how to drill a hardened bolt or how to remove it from a structure.
The first way is to use gas burner. The surface to which the bolt has stuck is scorched, and then easily unscrewed, because rust and dirty deposits turn into ash, and the softened metal becomes more pliable. And that's all. You can pull out the stuck bolt.
The second method is devoted to how to drill a hardened bolt. With a thin drill, several holes are made, located very close in one row. A chisel is inserted there, several blows are made with a hammer on it - and the body of the nut splits. The bolt can be easily removed. Holes in depth should not be large, otherwise the bolt shaft will be damaged, and then all your efforts to make uniform holes will be in vain.
The third method is associated with the use of acids and alkalis. In household use or in your stash, there is sure to be something caustic. Chemical mixtures that come to hand will dissolve dust and rust between the nut and bolt. Thus, the distance between them will become greater and, using the tool, it will be possible to pull out the bolt. Also, craftsmen advise pouring the compound with soda or soaking it in it. 
According to the fourth method, a stuck bolt can simply be unscrewed. This will help keep the product in good condition. It is necessary to heat the connection with an open fire. The temperature of the metal will gradually rise and it will expand. You can easily remove the nut.
The next method of extracting the bolt is tapping. Actions must be applied using moderate force. Rust will lag a little behind the connection of the nut with the bolt, and this will preserve the integrity of the "fused" elements. Do not overdo it by tapping the product with a hammer.
The sixth way is to cover the bolt with grease that is available. This will ensure good sliding between the nut and bolt. The bolt can be easily removed. Grease, lithol, petroleum jelly, graphite grease, fuel oil can serve as a lubricant.
As a more radical method, you can use a hammer and chisel. With the help of a chisel, serifs are made on the nut itself, and with the help of hammer blows, the nut lends itself to scrolling. This method must be used very carefully, calculating the impact force in this way. To protect the bolt from damage. Having beaten off part of it, you will not come close to success. Careful and calculated actions can guarantee the desired result.
As you can see, there are enough ways to solve the problem with a stuck bolt. You just need to choose the most suitable, and follow all the recommendations. It should be remembered that excessive pressure and zeal can play a trick on you. You should also not use all the methods at the same time, because this can only achieve undesirable consequences: damage to the bolt or bodily injury.
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Video: Drilling out the bolt
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“Everything new is well forgotten old” - this is how the saying goes, and it’s hard not to agree with this. Increasingly, people are returning to the knowledge of their ancestors, and this knowledge is becoming more and more popular every day.
Quite often, when using such fasteners as a bolt, situations arise when the head of the product breaks off, and the hardware itself remains inside. In this case, it becomes necessary to remove this residue without damaging the threads so that the hole can be exploited further. Given this, the topic of how to unscrew a broken bolt is very popular and requires more detailed consideration.
Types of fractures
Typically, such fasteners break at the end of the thread, although there may be exceptions. As a result, the hardware itself can be deepened into the hole, protrude above the surface, or even level with it. Based on this, it is necessary to decide how to unscrew the broken bolt, paying attention to this very moment.
surface break
This type of breakage includes the option when part of the hardware protrudes above the surface. It can be assumed that such a problem is most easily solved without using radical measures. However, before any unscrewing of a broken bolt, it is worth treating the place with kerosene to eliminate carbon deposits and weaken the contact of the surfaces.
- If the protrusion is quite large, then the easiest way is to use tools such as pliers, pliers or clamps, with which you can grab the part and unscrew it along the thread.
- Some experts, answering the question of what to do if a bolt breaks, which sits very tightly in the hole, recommend using welding machine. With it, you can weld a lever to the hardware, which as a result will allow you to get a large shoulder for rotational movement.
- You can also use a drill with a diameter slightly smaller than the bolt itself. With a drill, a hole is made along the central axis of the bolt to the full depth. After that, the remains of the fastener are removed with a hook, trying to unscrew the thread from the very bottom.
Flush break
It is believed that this failure is the most difficult, since it is sometimes very difficult to determine the diameter of the hole, especially if the fastener has been cut. Therefore, in order to determine how to drill out a broken bolt of this type, it is first necessary to clean the surface by determining the gaps.
Quite often, the place of the cliff has very uneven shapes, which, with this arrangement, are very difficult to straighten. Drilling in this state will not work. That is why a core is first used, which prepares a place in the center for working with a drill.
Further steps, describing how to drill out a broken bolt, are described in the paragraph on surface breakage. After making a hole, the remnants of the thread are simply removed with a hook.
Cliff below the surface
Such damage is quite difficult, especially if the part itself is made of soft metal. Therefore, you need to solve the problem of how to unscrew the broken bolt and at the same time not damage the threads in the hole.
First of all, using a core, the center of the hardware is marked. In this case, it is best to use a thin tool from durable metal so as not to accidentally damage the item.
The next step is to purchase a tap with a reverse thread. Its diameter should be less than that of the bolt itself.
After that, a hole for the tap is drilled in the hardware itself, but it is not deepened much. Next, just install the threading tool and turn it along the way, which will lead to twisting. If this does not happen, then the tool is used like a regular bolt, but you should not make too much effort so as not to break it.
Extractor
The most correct answer to the question of how to unscrew a broken bolt is the one in which they suggest using a tool specially designed for this. It is called an extractor and is sold as a set of products of different diameters. Outwardly, it resembles a tap, but without longitudinal slots and with a conical notch for cutting.
To use the extractor, it is enough to drill a hole in the center with a diameter that allows the tool to enter a few turns. Then they begin to turn it all the way, and then until it is completely unscrewed.
Conclusion
There are several options for removing broken bolts from a hole that can be used when certain types damage. However, it is best to purchase a set of extractors in advance, which can be considered the most the best tools for such tasks.
Every motorist knows that car repair is a rather laborious process. Due to the constant loads on different parts, all sorts of little things often break, such as bolts. If a novice driver encounters such a problem, then he is unlikely to cope on his own without knowledge of special techniques. Even This kind of trouble can be dealt with quite easily and quickly.
Most often, bolt failure occurs due to exposure to excessive great strength, and due to rust, it cannot be unscrewed in the usual way. Most often, threaded bolts break, which are constantly exposed to moisture.
How do bolts break?
The worst option is a bolt that has been sheared off flush. Such a screw cannot be unscrewed just like that, without using special devices, such as a drill or welding. It is better if the breakage occurred already during unscrewing, that is, part of the "body" of the bolt is outside. In this case, the bolt is already considered "torn off", since you have already begun to unscrew it. Removing such a bolt is a fairly simple procedure, since in this case you only need a screwdriver or pliers, maximum welding.
Effective ways to unscrew a broken bolt
Before proceeding directly to the removal of a broken bot, you need to conduct a series preparatory activities. The most important thing before starting work is to clean the place where the broken bolt is located from oil, dirt, dust and other foreign contaminants. Then you should treat the junction where the thread is made with a special fluid for greater friction or engine oil. As one option, you can hit the remaining piece of bolt with a hammer several times. You can also try to heat it with a lamp or a soldering iron, but you need to do this only if you are sure that the “neighboring” parts will not suffer from heat.
How to unscrew a bolt if it broke above the threaded surface
Option number 1. If you were able to unscrew the bolt even for a short distance, that is, “break off” the thread, then pliers or an adjustable wrench will be enough to remove such a broken part.
Option number 2. In this case, it will be necessary to use a grinder, a hacksaw or a chisel (it all depends on the size of the bolt). The main thing is not to make too much effort. The essence of this method of removal is to make a transverse hole according to the size of the screwdriver. After you make a hole, you need to try to unscrew the bolt with a screwdriver.
Option number 3. You can use welding. To do this procedure, you can use conventional apparatus for arc welding but best fit welding inverter. In order to pull out a broken bolt, you need to find a suitable nut, weld it to the rest of the bolt from the inside and unscrew it. The welding seam must be done from the inside of the nut, after which you can try to unscrew the bolt. During the use of arc welding, a lot of slag is formed, which fills part of the seam. It is because of this phenomenon that it is recommended to use an inverter. When carrying out welding work, be sure to take care of own protection, as well as provide good ventilation so that the generated heat "leaves".
How to unscrew a broken bolt if it breaks off flush with the surface or below it.
In such situations, more drastic measures will have to be taken. As a tool, you will need a drill with a thin drill. In the body of the bolt, you will need to make 2 - 3 thin holes, then to make one of them, into which you will need to deepen the screwdriver, which will remove the fragments of the bolt. The other way is a little more difficult. If it was not possible to remove the bolt by any of the methods described above, then you need to act even more decisively. In this case, a drill and a tap will be needed.
As part of this method, a hole is drilled inside the bolt, in which a hole is made using a tap. left hand thread. Once the new thread is ready, the broken bolt can be removed using the smaller left bolt that simply needs to be screwed into the new hole.
If the bolt broke exactly at the surface level, then it can be drilled out. This option is the most cardinal, complex and unsafe, since drilling can easily damage the thread pattern. This method uses investment principle: first, a hole is made in the center of the bolt with a thin drill. Then you need to take a thicker drill, which must be screwed into the bolt exactly in the center. And you need to repeat this action until the walls of the broken bolt become so thin that they can simply be broken with tweezers.
The most important thing in this business is not to get excited if you don’t get to remove the broken bolt the first time. If nothing comes out, then it is better to give this job to someone who already has experience in eliminating such defects. So you can save not only the work of your car, but also your own nerves. I wish you success.
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Sooner or later, one of the bolts may break off inside its hole. There are several ways to unlock it. Before buying an expensive extractor kit, try some of the following cheaper methods first.
First, no matter which of the following methods is used, use a special fluid such as WD-40. It is a special fluid with excellent penetrating properties for loosening dirty and rusty fasteners. But it also works well on tight, broken fasteners. If enough of the bolt or stud protrudes from its hole, and it is not too tight, it can often be loosened with pliers or a small pipe wrench. If this does not help, or the fasteners do not protrude enough to securely grip them with pliers or a wrench, try sawing it with a regular wrench or sawing a slot in it for a screwdriver.
If you still can't unscrew it, but know how to use welding, try welding a flat piece of steel or a nut on upper part broken fastener.
If a fastener is broken at or below the top of its hole, have it knocked out with a small, sharp punch.
If that doesn't help, try drilling out the broken fastener with a bit that is only slightly smaller than the inside diameter of the hole. For example, if the hole diameter is 12 mm, then use a drill with a diameter of 11 mm. This will leave a shell that can be knocked out with a sharp chisel. If this does not help, you need to resort to some kind of extractor. Extractors are sold in sets, they can unscrew bolts and studs with sizes of 6-25 mm.
Most extractors are conical, grooved and made of high quality steel. To use an extractor, drill a hole slightly smaller than the outer diameter of the extractor being used (extractor kits include manufacturer's recommendations on which drill size to use with each extractor size); then screw the extractor into the hole and remove it together with the broken screw or pin.
The thread of the extractors is reverse (left), so they will not unscrew when they are pulled out.
LITTLE TIP: Extractors usually save effort and money, but if you are inattentive or in a hurry, it will even cause pain and damage. Drilling the hole for the extractor off center or using one that is too cute or too large drill for a removed bolt or stud will only worsen the situation. Therefore, be careful!
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