How to place the cut-off wheel on the angle grinder

How to properly place a disc on an angle grinder?

For several years I have been using an angle grinder in my summer cottage, and all this time I have no answer to two questions: which side to put the cutting wheel, and in which direction it should rotate. “I shoveled the entire Internet,” but I could not find a definite answer to these questions. The opinions were divided equally. Both sides give convincing arguments, but at least some authoritative official documents on this topic are silent. Manufacturers are also silent. Today I want to speculate a little on this topic in order to still decide, for a start, with the first question.

So which side to put the cut-off wheel on the angle grinder?

Essence of the question. In the center of the circle (cutting or grinding) there is a galvanized steel ring, which has four punched holes around the circumference, as a rule, with the edges crushed down, to prevent this ring from turning relative to the abrasive. The inner edge of the ring is wrapped inside the circle, into its central hole, and ends flush with the opposite surface of the circle, without going out onto it.

According to manufacturers, this ring is made to protect the shaft that rotates the grinding wheel. “With a high degree of probability,” this is its main function, otherwise the abrasive, when the disc is rotating, will wipe the groove on the shaft of the angle grinder over time, and it will be impossible to center it. Note that in the production of wheels, the ring is riveted during the pressing of the disc from above, after the whole cake of mesh and abrasive has been formed. So, it does not carry any technological function, as it slipped somewhere in the Комментарии и мнения владельцев from an “authoritative” source. I looked at a number of different rollers for the production of wheels, and everywhere the technological process was approximately the same. the ring was pressed into the disk from above already during the compression of the formed disk by the press.

The ring is usually located on the label side of the circle. However, there are circles in which the ring extends to both sides of the circle, and on some circles with a sunken center, it is located only on the side opposite to the label and is located on the sunken side. That is, manufacturers mold rings in different ways. Although, it must be admitted, most of the cup circles still have rings on the convex side, which is “kakbe hint”, that it is preferable to put the discs ring down.

At the very beginning, after buying an angle grinder, I intuitively put the circle with the label out. On that circle, the metal ring in the center was also pressed from the side of the picture. So I sawed, and did not experience any problems. But then I had a cup-shaped circle (with a recessed center), and in it the picture and the ring were on the convex side. I put it with the picture facing out, and it turned out that the circle was scraping on the protective casing. I had to turn the circle over. That’s when I had this question for the first time.

The other day, while watching videos about tools on YouTube, I came across a discussion of this issue, and decided to find out for myself how to set the circle correctly? As I mentioned above, opinions on the Internet are equally divided on this issue. Then I began to develop my own point of view.

  • Rings on circles, including cup rings, are molded from different sides, although more often they are on the convex side from the side of the label.
  • The circles do not indicate the direction of rotation.
  • These points tell us that “with a high degree of probability” circles can be placed by either side.

    Next, I carefully looked at the washer and nut, between which the disc is attached to the shaft of the angle grinder:

    place, cut-off, wheel, angle, grinder

    On the left is a washer that slides over the shaft. It has a ribbed surface and a rubber ring at the inner edge. On the right, the nut, although not polished, has a rather smooth surface, which lies up in the photo. The circle should be clamped between them. At first I thought that the ribbed surface of the washer seemed to be created for engaging the abrasive, and the smooth nut should slide well on the ring so that you can easily tighten it. But the rubber ring was a little embarrassing, which was clearly made in order to cling to a smooth surface, and would probably deteriorate if the sharp edge of the hole from the abrasive side had to be pressed against it often.

    I tried this and that, and so, insert the disc between the washer and the nut, and twist the parts with my hands in order to understand in which case which part clings to the disc better. So, a washer with ribs and an elastic band in any case clings to the disc better, even by the ring, but the nut slides even on the abrasive. I also noticed that it is easier to put the circle on the washer with a ring, since there are burrs on the side of the abrasive that prevent the hole from being loosely put on the neck of the washer. So the results of these experiments clearly support the ring-down setting of the circle on the puck. That is, label down.

    I noticed one more nuance. The clamping surface of the quick-clamping nut has a significant backlash relative to its thread, which allows it to press the wheels, even if there are abrasive irregularities on their surface. In this case, such a disk will be pressed flat. If you turn it over, then it will lie on the washer with an abrasive at a certain angle, and it will have a lateral runout. This is another argument in favor of setting the circle with the ring down, towards the washer.

    Everything that I have listed above follows only from design features. Now a few words about practical convenience.

    Not all angle grinders have a quick-locking nut like mine. If this is a simple nut with wrench holes, then it is easier to tighten it not with a wrench, but with the circle itself. It will be easier if the abrasive clings to this nut. That is, in this case, the circle should also be installed with the ring to the washer. They also say that if the nut adheres to the metal ring, and when biting the circle it clamps, then it becomes much more difficult to unscrew it than if it adhered to the abrasive that is crumbling by nature.

    In general, after much thought, I came to the conclusion that a flat circle should be placed with the ring down, to the washer, and if the disk is cup, then there is only one position it can be placed, regardless of which side it will have ring.

    el_pir sent me a manual for the Metabo WP 850 angle grinder, which says in black and white:

    At the same time, there is no clarification whether this refers to cup circles, or flat. Just detachable. Therefore, to all cut-off. This fully confirms my point of view. Also, in all instructions for Metabo grinders, the corresponding figures are given (although only cup circles are shown there):

    Well, the main picture on the covers of all Metabo grinders’ instructions is also kakbe hint (although the circles there are also cup): Metabo deserves every respect for the quality of its tools, and I think that what is stated in their instructions can be trusted (in the case of a coincidence of the Russian translation with the English and German ones, of course, because there are still translation errors, see the end of clause 6). So I consider this question closed for myself.

    Angle Grinder Safety Chapter 2: Mounting Wheels

    How to install correctly?

    Installing a disk on an UMSH is not so difficult. You can change it simply by following the instructions, although there are some nuances here.

    First of all, you need to install the disc in the correct direction. This is especially important if it is detachable. Usually the side of the disc with the label on which the marking is indicated and, accordingly, the scope of its application, is slightly different from the opposite side. It may not appear immediately, but with prolonged intensive work, the difference will not only be noticeable. it will be obvious.

    On the side on which the label is glued, a wide pressure washer is placed, and the movable nut acts on it when tightening (installing the disc). The nut slides on the polished surface of the washer, without it it will become more difficult to tighten or unscrew, since the abrasive will firmly hold the nut and more effort will be required. This is especially important if a quick replacement of the disc is required or if it breaks down (jamming).

    There is always a chance of disc failure, but installed correctly, it breaks only under heavy loads, the structure of the discs takes into account the difference in loads on both sides.

    With circular saws or other products that have teeth or a significant difference in two sides, there is usually no problem how to set. For example, a grinding disc cannot be fixed on the contrary: it will simply be impossible for them to work.

    Discs for stone, including diamond ones, have a special rotation indicator in the form of an arrow: when installing them, you need to fasten them taking into account where the rod will rotate.

    It is also important to consider the size of the disk when installing. In no case should you neglect safety and remove the protective cover. it is better to choose a disc of the appropriate diameter. Sometimes a worn-out disc from a large unit is placed on a smaller “angle grinder“. However, a worn disc, as a rule, cuts worse, the working surface is limited to about half the radius of the disc, the structure is slightly different. The disc burns faster and does less work. This operation can be justified if the diameter of the stem is the same. But you won’t be able to change it back.

    Debris must not fall under the disc during installation. Of course, the clamping nut may well squeeze small objects, something will press into the surface of the circle. But an imperceptible skew will cause a displacement of the plane of rotation and, as a result, a strong vibration of the entire mechanism, it can cause the destruction of the disc and, of course, you should not hope for an accurate cut in this case.

    Before installing the disc, the “angle grinder” must be disconnected from the mains. this is the main safety requirement, since a sudden turn on at this time is fraught with serious injuries.

    The clamping nut must be unscrewed with the wrench supplied with the tool. To prevent the stem from spinning, it must be locked by pressing a special button. It is necessary to unscrew the nut while keeping the button pressed.

    After twisting the nut, the disc is put on the released stem, with the front side out, and you need to make sure that it is installed exactly in the seat.

    The kit for the new “angle grinder” always includes a certain amount of cardboard spacers. when installing the disc, they must be laid so that they are between the disc and the clamping elements. These gaskets will help unscrew a broken or jammed disc.

    Further, the nut is manually tightened up to the stop and tightened with a special wrench. That’s it, the “angle grinder” is ready to go.

    How to properly place a disc on an angle grinder?

    The disc of the “angle grinder” (angle grinder) is one of its main working parts. It is the disc that determines the use of the instrument. With it, this machine can be used to cut, grind or polish various materials. Discs, depending on the purpose, differ from each other: from abrasive chips. for metal, steel milling cutters and circular saws. for woodworking, with diamond dusting. for stone and tiles, all kinds of brushes, brushes and emery wheels. for polishing various surfaces.

    The disc of the “angle grinder” is a consumable material; you cannot save on it in the process of work. The disc will gradually wear out (burn out) and must be replaced. When planning work, you need to be prepared for this and it is better to stock up on several removable disks in advance.

    How to change a disk if it is jammed?

    What to do if the wheel on the “angle grinder” is stuck? This can happen, for example, when, as a result of work, pieces of the workpiece being cut sharply clamp the rotating disc. This often leads to its destruction.

    To unscrew the nut tightened as a result of rotation, if the circle is bitten, it can be very difficult.

    • One of these methods would be to use two gas keys at once. In this case, the remains of the disc must be broken with pliers. With one key, you need to clamp the part of the stem located under the disc, and with the other, unscrew the flange.
    • Sometimes, in order to gain access of the gas wrench to the rod of the “angle grinder”, you have to disassemble the gearbox.
    • A simple device saves from the problem of a jammed nut. cardboard or tin washers. They are often sold with an “angle grinder“. But over time, they can be lost or become completely unusable. Making homemade washers is not at all difficult. However, it is better not to neglect them.

    In extreme cases, the flange can be sawn with a hacksaw for metal and then replaced with a new one.


    If you had to use a gas wrench, you must remember about the very powerful shoulder of such a wrench and about the effort that is applied to the parts of the “angle grinder”. If you do not act carefully, the spindle lock could be ripped off or the gearbox could be damaged.

    All manipulations with the disc of the angle grinder must be carried out with the power supply completely disconnected (the plug must be removed from the socket). Any inadvertent pressing of the start button will cause the electric motor to turn on, and the rod rotation speed is very high. In this case, injuries cannot be avoided.

    Working with an “angle grinder” involves a lot of waste in the form of metal or wood shavings and dust. Before starting work, you must wear special safety glasses: they will protect your eyes from fragments of the cutting wheel itself in the event of its jamming and destruction.

    Glasses are needed not only as a safety element. If the eyes are protected, more attention can be paid directly to the work of the “angle grinder”, to ensure the correct cut or the choice of the correct mode of operation. This will allow the most efficient use of consumables (cutting wheels), minimizes the occurrence of abnormal situations with a biting disc or its destruction.

    A protective mask that completely covers the face will perfectly replace glasses. this is especially important for a visually impaired master who wears diopter glasses, on which safety glasses cannot be worn.

    The disc on the “angle grinder” can be installed both “away from you” and “towards you”, depending on the direction of rotation and, accordingly, the flow of chips. This does not make a fundamental difference in work. However, the “angle grinder” with a circle “towards itself” when biting the disc tends to jump out of the cut forward, and not on the one who uses it. This is especially important when working with powerful tools, but even a small angle grinder can be a serious hazard.

    A specially mounted extension cord with a plug socket, preferably without grounding, will help to quickly stop the operation of a machine that has escaped from the hands.

    Angle grinder” is a rough processing tool and it is not worth striving to obtain an ideal surface as a result of its work, the main thing is to make a rough cut, which later, if necessary, can be processed in other ways.

    To work without clamps and jamming, it is better not to cut long metal workpieces to the end, leaving 1–2 mm of metal in the cut: they will be easy to break off afterwards, this will practically not affect the quality of the workpiece.

    It is better to place small workpieces in a vice or press them with a clamp to a workbench or other reliable horizontal surface. The quality of the cut and safety depend on the density of pressing.

    How to put the disc on the “angle grinder” can be seen in the following video.

    remove the disc from the angle grinder

    First, figure out which way to unscrew the nut.

    The flange must always be folded in the direction in which the disc rotates.

    For this kind of work, you will need either two gas keys or two clamps.

    Here’s what you need to do: destroy the remnants of the disc, fix the washer located behind the disc with one key, unscrew the flange with the second.

    remove the disc from the angle grinder

    This method is used in extreme cases.

    How To Convert An Angle Grinder for Cut Off Wheels