Drill, how to change chuck and coal!

Do you know how to fix a drill? Change the drill chuck and coal? The drill is one of the most used automatic tools in any profession. Performing maintenance on power tools is a good source of income for professionals in the World of Electrical. In this article we will show you step by step how to maintain drills. Come on!


Maintenance is a procedure performed on equipment to ensure a good functioning and performance of the equipment, there are different types of maintenance , such as corrective, preventive and periodic maintenance.

Maintenance – Drill

The drill is an electric tool used to drill holes in various materials such as concrete, wood, metal etc. There are several models of drills on the market, such as the bench drill, CNC drill, straight drill, impact drill, industrial drill.

Since all electrical equipment needs maintenance, drills also need maintenance, so let’s see how to change the chuck and coal for an impact drill.

Visually analyzing the drill from the outside, you can see that the funder is very dirty and the chuck is rusty. The drill chuck has not been changed since the tool was purchased and the chuck is also well damaged.

Visually analyzing the drill from the outside.

The drill’s air inlets must always be clean and free, because when the inlets clog the engine it heats up too much, which can damage the engine and greatly reduce its useful life.

Disassembly – Drill

The maintenance processes that we will show you are very simple and can be used for any drill model. The drill is a relatively simple tool, as it is basically a motor , some gears and the activation button. What will change from one drill model to the next are the types of grooves, especially the coal groove.

The first thing is to open the drill, our model has seven screws that hold the plastic housing of the drill, just remove the screws to open the drill. A trick that can help a lot in maintenance is to take a picture before removing the parts from the place, so it is easier to reassemble the equipment at the end of maintenance.

Drill bolt removal.

With the drill open, we will remove the parts, starting with the chuck assembly. Next, we will detach the cable from the motor brushes and remove the carbon holder.

Removing the mandrel and coal holder assembly.

Now we are going to remove the rotor, lifting the motor stator a little bit, which is the widest part of the engine, remove the rotor which is the rotating part of the engine.

Removing the rotor from the drill.

The next step is to remove the bearing from the rotor, which is a piece that looks like a gear with foam around it.

Removed from the drill bearing.

And lastly, just disengage the stator and the drive assembly, which is composed of the button and the cables that are connected to the stator.

Removal of the stator and drive assembly.

Chuck Replacement

We will start the maintenance by changing the chuck and when carrying out the chuck removal, it is important to be very attentive because in the back there is a ball bearing that you cannot miss at all.

Next, we will open the chuck and lubricate the middle of the chuck with degreasing oil. The chuck is fastened using a simple screw thread and since the chuck has been stuck for a long time, the degreasing oil will help when removing the chuck.

To remove the spindle from the gear assembly, we attach the spindle to the vise and using a 7/16 inch inch wrench to unscrew the spindle from the gear assembly.

Changing the old drill chuck.

When we remove and place the old mandrel next to the new one, you can clearly see the difference and see how much the mandrel was worn and damaged.

Comparison between old and new madril.

Before inserting the new chuck, it is good to lubricate the parts with degreasing oil and then just screw the new chuck into the gear assembly. As the drill rotates clockwise to drill it is not necessary to tighten the chuck too much, as over time the chuck will tighten itself with the rotation and the force placed against the wall to drill.

Placing the new chuck in the gear assembly.

However, tightening with the wrench is very important if you are changing the chuck of a reversed drill.

Coal Exchange

The coal is responsible for making the electrical contact with the rotor, causing the rotor to rotate, thereby causing wear on the coals due to the time the drill is used.

The procedure for changing the charcoal is very simple, just remove the charcoal from inside the charcoal holder and then place the new charcoal, the contact for the cable must be outside the charcoal holder for cable connections.

Changing the drill socket.

When comparing a new coal with the used coal from the drill we can see that the coal is already well spent, so it is also necessary to change the coal.

Comparison between new and old pegs.

Maintenance – Cables

The next step is to maintain the electrical part, which is basically to check the condition of the cables and button. The last time the drill was assembled, the person ended up not observing the position of the cable and this caused the cable to be pressed. We can clearly see the marks on the cable in the image below.

Cable pressed by wrong assembly.

The pressed cables are dangerous, because it can cause the cable to break, luckily it was not the case in our drill the cable was only pressed. The cable entering the drill must also be inspected to see if it is not broken and the condition of the plug must also be checked.

Cleaning and lubrication

Cleaning and lubricating the drill parts is essential for proper operation and to maintain the life of the drill.

In the plastic housing you can use a brush to remove coarse dirt and old grease. It is important to remove the grease, as the grease is mixed with dust, wood dust and other things that have been mixing over time.

The plastic cover can be washed with soap and water and the thinner is a great help to remove all grease. In the mechanical parts use anti-corrosion oil to lubricate and protect, the best oil option to lubricate the parts of the motor, rotor and stator are dielectric oils.

Cleaning and lubricating the drill parts.

Drill Reassembly

With the parts replaced, cleaned and lubricated, you can now reassemble the drill. First place the stator with the cables and button in place, make sure the cables are in the correct position so that they are not crushed by the plastic part of the drill when screwing.

Then place the bearing bearing in the original place, then place the rotor inside the stator and fit it in the bearing. Grease the bearing and the rotor tip that fits close to the mandrel. Then place each charcoal holder in place and fit the cables. Do not forget to apply grease to the mandrel assembly.

Reassembling the drill parts.

Now place the mandrel assembly in the right place. Be very careful in this part so as not to forget the ball. And the last part of the assembly is the button to select the hammer, just click it.

Attaching the chuck and hammer button assembly.

Before fitting the plastic housing, it is important to check that all the components are in the correct place, especially the cables so as not to be pressed, after inserting the screws and making the tightening, just test.

Fit the plastic housing, place screws and tighten and test.

Ready, we have a drill ready for use and maintenance in day will certainly be important to ensure the smooth operation of the drill for many years. Below we leave a video of the Mundo da Elétrica channel, showing how to perform electrical maintenance on an industrial mill .

If you have any questions or curiosity about the subject, leave it in the comments and we will answer it!