How To Properly Install The Cutting Wheel On The Grinder

Selection and replacement of discs for grinders
What are the types of grinder discs, their typical sizes. How to correctly change the nozzle on the grinder. What to do if the disc is stuck and the nut won’t loosen?

Dismantling the gearbox

In the event that the retainer is broken, you will have to disassemble the gearbox to remove the tool from the angle grinder. Break off the edges of the remaining abrasive disc with pliers so that you can get to the bolts holding the gear cover. Then unscrew the fasteners and open the gearbox. The cover will be removed together with the pinion shaft. Further, this shaft should be clamped in a vice, having previously laid aluminum gaskets between the steel jaws, and using a gas wrench to unscrew the flange (do not forget to determine the direction of unscrewing).

Using a penetrating lubricant

Liberally spray the flange-shaft connection with WD-40 fluid. It tends to penetrate into inter-threaded spaces and small cracks. After applying the liquid, wait about 5 minutes and try to unscrew the fasteners with a standard wrench.

How to properly change the disc on the grinder

Since the circles for the grinder are consumables, sooner or later they have to be changed. They are attached to the angle grinder spindle using a clamping flange (nut) with an M14 thread. To unscrew it, a special open-end wrench with pins on one side must go to the grinder.

How To Properly Install The Cutting Wheel On The Grinder

So, to replace the tool on the grinder, follow these steps.

  1. De-energize the device by pulling out the plug from the socket.
  2. Lock the spindle of the angle grinder using the button located on the front of the case. When the button is pressed, the stopper enters the hole of the disk installed in the gearbox, which fixes the spindle in a fixed position.
  3. Insert the pins of the key into the holes in the hold-down flange.
  4. While holding the latch with one hand, turn the wrench to the left (counterclockwise) with the other hand until the nut comes loose. Then it can be unscrewed without a key and removed from the shaft. In this case, the angle grinder spindle rotates clockwise. But in which direction to unscrew the nut if your apparatus rotates the shaft counterclockwise? Remember: the clamping flange should always be unscrewed in the direction opposite to the rotation of the shaft.
  5. Now you can change the tool after removing the old one. If you notice that dirt has accumulated inside the casing, then you should remove the bottom flange and use a steel brush to remove dirt from all surfaces.
  • Screw the flange onto the shaft by hand. Tighten the nut until you can no longer turn it without a key. After that, holding the stopper, tighten this nut with a wrench, but no more than a quarter of a turn, otherwise the disc will begin to deform.
  • After performing the above steps, the tool change is considered complete.


    To sharpen the tool, grinding machines (sharpeners) are usually used. But if you do not have the latter, but have a grinder, then you can purchase a sharpening (grinding) wheel for it, with which you can easily sharpen almost any cutting tool.

    Purpose of discs and attachments

    Grinder wheels differ in purpose for:

    • Detachable;
    • Stripping
    • Grinding;
    • Sharpening.

    Heating nut

    The nut can be heated with a gas torch, hot air gun or blowtorch. The heated flange can usually be unscrewed with a standard grinder wrench.

    Grinder discs differ among themselves in the following main features:

    1. Outside diameter;
    2. Disc thickness;
    3. The material from which the disc itself is made;
    4. The characteristic of the maximum rotation speed;
    5. And, of course, the area of ​​the proposed work.

    For a better understanding, let’s look at the main types of grinder discs and give a definition of their application:

    1. Cut-off wheels. These are the most widely used grinder consumables. Their main purpose is to work with metal, stone and wood. A variety of cutting wheels for the grinder are diamond discs. This is a heavy-duty tooling for processing high-strength materials such as reinforced concrete, tiles, porcelain stoneware, marble.
    2. Grinding and roughing wheels. As the name implies, this type of disc is used for grinding various materials, for example, polishing products made of stone, or for removing (roughing) the top layer, for example, removing a layer of rust or old paint coating.

    What to do if the disc is jammed (bitten) on the grinder?

    Everyone who has experience of intensive work with a grinder has probably at least once encountered such a situation.

    Usually, this happens if the disc clamps between the parts, it stops or breaks, and the grinder‘s motor continues to rotate and thus irrevocably tightens the nut.

    So what can you do if you bite a disc on a grinder?

    Each master has his own secrets. Especially for you, we learned a few of them and now we will share the most common ways to get out of the situation.

    The main question: How to choose the right disc for a grinder?

    When choosing equipment for angle grinders, first of all, you should decide on the type of proposed work. The choice of the type of disc will depend on this. We also want to mention that when choosing a consumable, be sure to take into account the power characteristics of each specific model. Examine the labeling. Often, it is printed on the disc itself and includes a set of symbols by which you can determine the relevance of this consumable to perform the intended work.

    Also, focus your attention on such a parameter as the diameter of the disc. In no case should it exceed the size of the protective cover on the particular tool model. The size range of discs is usually represented by the following diameters: 115, 125, 150, 180 and 230 mm. The most common diameters are 125 mm. And 230 mm. They are optimal for most types of work and the capabilities of the tool itself.

    Among the bakelite-based grinding discs, the most popular discs are 6.00 mm thick. This parameter depends on the total diameter of the disc. The relationship is as follows: the larger the disk diameter, the greater its thickness and vice versa.

    How to put the disc on the grinder correctly?

    To put the disc on the grinder correctly, it should first be noted that the disc is installed on the grinder spindle using a special clamping flange with M14 thread. Let’s take a closer look at how to remove a disc from a grinder. In order to unscrew the disc from the grinder, you first need to dismantle the flange. Especially for such purposes, manufacturers complete the grinders with a special open-end wrench. It has a specific shape. The pins located on the arms of this key are inserted into specially provided holes on the flange.

    To unscrew the flange, we fix the spindle. To do this, we clamp the latch, which is usually a button on the top of the case. When pressed, the cotter pin is placed in the hole of the driven disc of the gearbox, and this in turn prevents it from rotating. Next, we insert the pins of the key into the specially provided holes on the flange, pressing the retainer, you must simultaneously turn it counterclockwise and move the flange from its place. If the manipulations were successful and the flange gave in, you can unscrew it by hand and put it aside.

    Now let’s dismantle the disk. Often, in the process of intensive work with the tool, a kind of plaque from small particles of metal and abrasive material forms on the inside of the protective casing. For optimal, stable and durable operation of the grinder, remove the lower part of the flange and clean the casing with a steel brush.

    Cutting wheels for grinders, in turn, have their own subspecies, such as:

    • Cutting wheels for metal work;
    • Abrasive wheels for working with stone;
    • Wheels for woodwork;
    • Diamond discs (mentioned above).

    The purpose of each type of disc usually corresponds to its name.

    Among the grinding discs, there are four main subtypes. Flap, wire, diamond and bakelite-based grinding discs (straight, T41 profile and disc-shaped, T27 profile).

    1. The flap disc is made from sandpaper. Its main purpose is to remove existing coating, such as old paint, primer or paint coat. Also, with disks of this type, wood products are polished.
    2. Wire discs are used by artisans to remove rust. They can also remove other types of stubborn dirt.
    3. Diamond discs are used for stone polishing work.
    4. Disc discs are made of plastic or rubber and are used to polish metal surfaces.

    Method number 2 to remove the disc from the grinder

    This method involves the use of the famous VD-40 grease.

    It is probably like an electrical tape, applicable in all cases of life.

    You need to spray the flange, wait about 5 minutes and try to unscrew it with a wrench.

    Guaranteed even installation on the shaft

    The metal ring increases the footprint. Therefore, when the disc is mounted on the shaft and starts to tighten with the nut, the pressure is evenly distributed. This ensures a smooth fit of the cut-off wheel and reduces the possibility of damage due to skewing.

    Why do you need a metal ring

    The metal washer (ring) is designed to protect the integrity of the disk when it is tightened with a movable flange nut, as well as to increase the bearing surface area. In addition, the metal washer does not allow the cutting wheel to stick to the nut surface, which greatly facilitates the process of replacing it.

    Convenient disk installation

    Installing the abrasive wheel with the face outward provides another advantage. You will always visually see which nozzle (for metal or stone) is installed at a given moment on the grinder. They are not interchangeable and if mistaken, there is a high probability of serious consequences. For example, when trying to use a cutting disc for metal cutting through concrete, it may be destroyed and traumatized by the resulting pieces of the master. Therefore, installing the abrasive wheel with the label facing out will provide not only convenience, but also safety of work.

    Prescribing instructions

    The instructions for many angle grinders, such as the Metabo WP 850, clearly state that “the metal flange of the abrasive cut-off wheels must be in contact with the support flange”. It is not in vain that manufacturers give such recommendations, since they ensure safe operation of the tool, and reduce the risk of serious injury to the master.

    The main difference between the two sides of a circle

    On any cutting disc, two surfaces are clearly visible. One of them (back) is plain, formed by abrasive material. The second (front) has a label containing basic information about the characteristics of the disc. But the main distinguishing feature of the two surfaces is the presence of a metal ring on the front side.

    The advantages of installing a disc with a ring to a grinder

    The cut-off wheels do not have a programmed direction of rotation. Therefore, it does not matter which side will carry out their installation. But as mentioned above, installing the circle with its front side outward makes it easier to replace it (it is much more difficult to unscrew the nut on the abrasive side). In addition, this arrangement provides several other advantages.