An angle grinder, or as it is more popularly called, an angle grinder, is an indispensable and very useful tool in our time. Without him, neither here nor there! And if it suddenly malfunctions, then you have to dodge in every possible way, look for alternatives and think about restoring the instrument. At the same time, you cannot use the grinder for its intended purpose because of what appears to be a simple lining when the disc cannot be unscrewed. Or rather, the nut that holds this disk does not unscrew. Here you can “break the woods”, namely, bend or break the key, damage the locking button, break the case, but still not unscrew that same ill-fated nut. So, we will immediately warn you, if it is not too late... If you suddenly cannot unscrew the nut holding the disk with a wrench, then you need to change tactics. And it is precisely this radical method of unscrewing that our article will be devoted to.
Why does he bite the nut on the grinder that holds the disc?
I will tell, perhaps, a well-known truth. It bites the nuts more often on grinders with a significant disc size, say 150-180 mm or more. The thing is that the resulting torque, in the event of a disk impact at the start of cutting, is significantly greater than for a disk of, say, 125 mm. As a result, the nut is tightened so tightly by inertia that it can be torn off with ordinary and in the usual ways very difficult. Now about special methods.
How to unscrew the nut of an angle grinder (angle grinder) if it is stuck
So, if the key doesn’t work, even if you insert it and hit it lightly with a hammer, then we start using something more serious.
The first thing you can try, but again without fanaticism, is to take a rod, insert it into the holes on the nut and, using a hammer, move the nut in the direction of unscrewing it. The main thing here is not to break the button or tear off the holes, as here
The second thing many people advise is to warm the nut. Warm up the nut. As a result, it is slightly, but physically still obliged to expand. Resizing may or may not help...
There is no need to pull as hard as possible until the lock on the anti-rotation button or the button itself breaks. In this case, it is not the tool you use to unscrew that breaks, but often it is the body of the angle grinder.
The third method is the most effective, and, oddly enough, one of the safest for the grinder herself.
Take and break off the edges of the disk along the nut.
Next, we use a thin metal plate or another disk (thinner), and perhaps a second grinder with a disk. In this case, the broken disk must be turned either with a plate or a disk. We try to sharpen the disk so as not to damage the nuts holding this disk, because they will be useful to us later. We sharpen the entire broken circle in this way until we grind it down and the nut comes off.
This is a matter of 4-5 minutes, no more.
If you use a second disk or metal plate, it is better to insert it into a vice to hold it. Since holding such objects with your hands is dangerous. This method is the most effective!
How to prevent the nut and disc from biting on an angle grinder
And a few words about preventing such unpleasant precedents again. You can use small cardboard spacers, inserting them between the disc and the nut. As a last resort, we use a disk with a smaller diameter, unless, of course, the nut is tightened from above. As a result, you can unscrew such a nut without any problems. It won't pinch, it won't bite on the thread...
And further small video on a topic that I have learned from my own experience.
An angle grinder is a multifunctional, but capricious tool that does not tolerate haste and carelessness. Breakdowns and failures are the result of careless handling or violation of safety precautions. And the most common problem when working with an angle grinder is the jamming of the abrasive tool between the support flange and the clamping nut. How to unscrew a disc on an angle grinder without damaging the parts and the tool itself?
Using an open-end wrench and socket head
Grind the working surface of the key 17 to 4 mm in thickness. On the surface of the 24 mm socket, grind 4 projections so that they fit into the holes in the flange.
The open-end wrench must be placed under the disc. Place the socket head on the grinder nut and use a ratchet to turn it in the direction of rotation of the circle.
Warming up
The clamping nut must be heated with a hot air gun or gas burner so that the metal becomes more pliable. Then unscrew it with a universal wrench or by hand. But the risk of this method is that it can damage plastic parts and gearbox elements.
Using a gas key
When using a gas wrench, the leverage increases, and therefore the moment of force also increases. This tool makes it easier to unscrew jammed connections. But if you try too hard, you risk crushing the flange or breaking the spindle rotation lock.
Using a hammer drill in jackhammer mode
The hammer drill must be switched to chiselling mode without rotation. The 6 mm drill must be placed on the end of the flange or rested against the edge of the hole. The task is to unscrew the nut and move it out of place. After that, unscrew it by hand or with a key. During operation, you need to block the spindle rotation.
Disk corruption
Before unscrewing the nut on the grinder, you will have to completely crumble the disc. If it is already destroyed, you can break it with your hands. Solid circles can be sawed with a hacksaw or a metal blade. The abrasive wheel should leave an inner metal ring and pieces that are not susceptible to mechanical action. Then you need to clamp it in a vice metallic profile or any unnecessary plate whose thickness is less than or equal to the thickness of the disk (but not more). Then turn on the grinder and grind off the remaining abrasive to the landing sleeve. After this, the flange can be easily unscrewed with a universal wrench for angle grinders.
You can make sure in advance that the tool is not jammed in the grinder:
The clamping nut for the angle grinder is included in the delivery set. And the most radical solution to freeing a jammed disk is to saw it and install a new one. You can find such fasteners in all power tool stores.
I’ll say right away, don’t rush into choosing methods and means for unscrewing! Try the following.
If the disk breaks off in the cut during work due to biting, then the nut is almost always tightened tightly. Having placed it on the stopper (pressing the button on the side of the gearbox opposite to the disk), try to unscrew it with a standard wrench with moderate force; if the nut does not work, then there is no need to hit it with a hammer. In general, it is better not to use “impact methods” when unscrewing the nut of an angle grinder. The elements of the grinder gearbox are not suitable for chisels and hammers. You can rip off the stopper, break the standard key, ruin the bearings on the gears, bend the shaft, or even split or make a crack in the aluminum gearbox housing - all these delights do not at all lift your spirits. Yes, the force for which a standard wrench is designed is correlated by the manufacturer with the power of the latch, which is why, armed with a gas wrench No. 3 (for example), we have another problem - a broken latch.
It is well known that screw connections loosen when heated, and the flange nut on a beam is no exception. You can heat the nut with a regular gas burner -
and try to unscrew it with the same standard key.
If you don’t have a burner at hand, you can heat the nut with the engine of the grinder itself. This is done both with a partially broken disk and when the remains of the disk are equal to the nuts and only its central part is clamped between the nuts. We clamp a block of dense wood into the yew (so that it does not “crawl”) Turn on the grinder and rest the edge of the moving nut on the block. Press the nut moderately against the block. Logically, the nut will begin to heat up from friction. Smoke is also possible, but you can heat it without using any heating devices and unscrew it.
The method that helps is to simply press the grinder to the floor, with the disc facing up. Grind off the remains of the disk to the ribs of the nuts, applying the metal flat, and then, using an edge of sheet metal thicker than the disk, grind out its remains from under the nuts.
There is an even more humane way, this is to take a bicycle spoke, sharpen it, bend it with a hook, wrap the other end with a handle (to make it comfortable for your hand) and just sit and pick out the remains of the disk. This also gives results. It won't take long to pick - the width of the clamping part of the nut is approximately 7-10 mm. from the outer edge.
P.S. Finally, I would like to recommend my example. I cut a washer from an old nylon canister (you can make several of them at once) to the size of the clamping nut, 1-1.5 millimeters thick. Using two drops of glue, I glued it to the working surface of the nut (so that it wouldn’t get lost) and forgot that there was such a problem with unscrewing it. When biting the disc and tightening. You can simply use a good lighter to heat the nut or a torch made from a rolled-up newspaper, melt the polyethylene and unscrew it like clockwork, even with your hands (preferably with gloves - it’s hot!)
This simple operation sometimes baffles even experienced mechanics or grinder users. The reason is that the disc is secured with a special nut. The nut has 2 or 4 holes into which a special key is inserted. This key was always included when purchasing an angle grinder. Perhaps it is still included in the kits.
According to the instructions for the grinder, you need to press the latch, which is located on the back of the gearbox. When the shaft is fixed, use a special wrench to unscrew the nut and change the disk. But it is difficult to unscrew the nut if it is not clamped. And he almost always clamps it with such a nut. An attempt to unscrew the disk leads to breakage of the latch behind the gearbox.
- Install a newspaper gasket under the nut;
- Place a gasket from a plastic bottle under the nut;
- Replace the nut with a nut of a different design.
What is a newspaper gasket? This is a paper washer the size of a nut. She puts it on installed disk, and a nut is screwed on top. This piece of paper was a stumbling point, because the safety inspection always spoke about the harmfulness of such a decision.
Representatives of safety authorities treat the installation of gaskets made of any other materials in the same way:
- Cardboard;
- Paronitis;
- Gaskets made of various plastics;
- Rubber gaskets of various thicknesses.
But there is a solution that does not contradict safety requirements and allows you to install and remove the disk normally. This is a special nut that consists of two elements - a nut and a pressure washer. The use of such a nut does not require any shims, because with it the disk does not jam.
If you don’t have a special key at hand, then craftsmen suggest doing without a key. This does not mean that you can do without a key at all, but use a “gas key” or other device. To do this, you need to hold the latch, tighten the nut with a gas wrench and unscrew it. This way you can replace a jammed disk, but this is a very inconvenient operation for one person.
There are also suggestions to hold the disk with your hand and unscrew it. Maybe, but it’s unlikely that you’ll be able to change broken disks this way. It is better to use wrenches that are designed for removing and installing disks.
Some foreign power tool manufacturers, such as Bosh, produce grinders with easily removable nuts. They securely fix the disk on the tool shaft and are easily and quickly removed to replace the disk.
How to remove a bitten disc from an angle grinder + (Video)
The use of new nuts solves the problem of removing the disk, but what to do with an already bitten disk? Even if the disk was installed correctly, it is not always possible to remove it. Practice suggests different ways to solve a problem. You can clamp the clamp and hit the nut holes through the extension in the direction of unwinding. This option is only possible with a working latch. But the latch may not withstand such a solution to the problem and break. 
The second method is more logical. Under the clamping nut and lower support washer there is a gearbox shaft with machined chamfers. The lower support washer is put on them. A standard wrench cannot be installed there - it is very narrow. But you can take a regular open-end wrench set to “17” and sharpen it on both sides. 
The turned key will fit into the gap, fit onto the chamfer of the shaft and secure it. Now, using any wrench, any nut will be unscrewed, and the disk or its remains will be removed from the angle grinder.
How to correctly place a disc on an angle grinder + (Video)
Grinding discs have different diameters, different thicknesses and different purposes. Some are made to work on metal, others work on ceramics, and others work on wood.
The grinder must have a disc of a size that does not exceed the size of the protective casing. The size of the installed disk is indicated in the instructions and on the marking table of the grinder.
The thickness of the disc is selected according to the technological parameters of the material being processed. All discs (grinding wheels) have their own classification. The disc shape, material abrasiveness, grain size, hardness, accuracy class and unbalance class are classified. It is the last value that is responsible for the fact that some disks begin to beat during operation. 
The grinding wheel has a front and back side. The front side is considered to be the one on which the manufacturer’s markings and corporate design are applied. When installing on an angle grinder, the front side should be on top. 
The disk is installed in this way. So that during operation, sparks with particles of the material being processed fly towards the worker. This is due to a safety issue. If the grinder breaks out of your hands, it will not fly towards the employee.
Therefore, when working with an angle grinder, you must wear protective clothing or a thick apron. Eyes and exposed parts of the face should be protected with a mask or at least goggles.