Electric Drill: Smoke From Tool

The armature is the power-producing unit of the motor. Over-working the drill can cause the armature to break down, burning out the windings. To check the armature for damage and continuity, you will have to remove the armature.

Remove the screws securing both sides of the case together and separate. Remove the brushes by gently lifting up the wires, going to the brush holders, then lift the motor assembly up and separate the armature from the field by pulling it out. Check for a heavy build up of dirt and clean it with electrical contact cleaner. Check the armature for burn marks, indicating a short, causing the smoking. If there are indications of this, the armature is probably bad and will need to be replaced. You can test it for continuity to make sure.

To check for a bad armature, you can perform the 180-degree test. With the armature removed from the unit, stand it up on a bench. With an ohmmeter, attach the two ends to both sides of the commutator to measure the resistance of the windings. As you move it around the commutator, the reading number is not important. You are looking for a consistent reading, indicating the windings are good. If it varies, radically reading zero, or open circuit, then the armature is not good. Another test is reading. If the ohmmeter reads a zero or open circuit, then the armature is not good. The last test is a bar to ground test, which is done by placing on lead of the ohmmeter to the tip of the shaft of the armature and the other end of the ohmmeter to the commutator. If the armature is bad, install a new one.

Install the armature in the field. The field will have a notch, indicating the front. Install the brushes using a small knife, or screwdriver to hold the carbon brushes down, giving you clearance as you install them back in the case. Install the spindle and chuck assembly back in the case. Rejoin the two halves of the case back together.

The carbon brushes ride on the commutator, supplying electricity. As the carbon brushes wear down, they will produce more sparking. This can cause a heavy carbon build up between the brushes and the commutator, causing the drill to smoke. To repair this, you will need to replace the brushes and clean the commutator.

Remove the screws securing the case together and open it. Locate and remove the brush holders from the case. You can remove the holders by gently pulling up on the wire going to the holder. Measure the brush. If it is getting close to 1/8 of an inch, or less, it requires replacement. Press the tab on the side of the holder to release the brush and spring. Clean the holder with electrical contact cleaner, dry and install the spring and new brush in the holder, making sure it locks in place. Remove the chuck and spindle assembly from the case, then lift the motor up and slide out the armature.

Use the electrical contact cleaner on the commutator to clean it, dry then reinstall back in the field. Reinstall the chuck and spindle assembly. Install the brushes using a small knife, or screwdriver, to hold the carbon brushes down, giving you clearance as you install them in the case. Rejoin the two halves of the case back together.

The field is an electromagnet used to generate a magnetic field in an electro-magnetic machine. Over time, this part can build up a lot of heavy dirt, causing excessive heat in the motor, which can lead to shorting out and smoke. To inspect the field, remove the screws securing the case of the drill together and open it. Remove the brush holders by gently pulling the wire up, connected to the brush holders. Remove the spindle and chuck assembly from the drill. Disconnect the electrical connectors at the field then lift the motor assembly out of the case. Pull the armature out of the field to separate it. Clean the field with electrical contact cleaner. Inspect the field for burn marks, indicating sparking and shorting out (perhaps causing the motor to produce smoke). If you notice burn marks on the field, it probably needs to be replaced.

You can perform one simple test on the field, to check for continuity, by using a multimeter. Set the multimeter to an ohmmeter and place a lead on each end of the field. If the reading is infinity, the field is bad and requires replacement. Install the armature in the new field, or the old one if it is good. The field will have a notch on it, indicating the front. Place the motor back in the drill and reattach the electrical connectors. Install the spindle and chuck assembly back in the case. Reinstall the brush holders by using a small blade screwdriver to hold the brush down, allowing you clearance on the commutator. Ensure all wires are tucked inside the channels and out of the way. Close the case back together and secure it tight with the fasteners.

A motor turns electrical energy into kinetic energy. It involved magnets and conductive wire. The electricity creates a current in the wire, which creates a magnetic field, causing the magnets to spin. The motor contains the armature, commutator, brushes and field. If any of these parts fail, they can cause the motor to smoke. To diagnose motors, refer to the symptoms on this page for proper repair procedures.

The switch provides power to the motor, and on some models, changes the direction and controls the speed. If the switch has become worn, it can short out and produce smoke. Signs that a switch is showing wear include working randomly when pushed, problems with direction, variable speed working intermittingly or only on certain speeds. This will eventually worsen with use, to the point it could smoke.

Remove the screws securing the two halves of the case together and separate them. Remove the switch from the drill by unplugging the electrical connectors and removing any screws holding the switch down. Inspect the inside of the switch for burn marks as well as the case for burn marks, where the switch is housed. This will indicate it is shorting out. The switch will need to be replaced as it cannot be repaired. Install the new switch in the housing and reinstall any hold down screws. Reattach the electrical connections and make sure all wires are tucked back in the wire channels. Lastly, reassemble the case back together.

The holder holds the brushes in place on the commutator. If the holders are damaged, they may not be able to hold the brush in the proper position on the commutator, with the correct pressure. This can cause excessive sparking, causing smoke.

Remove the screws securing the case together and separate the two halves. Locate and remove the brush holders. Pull up gently on the wire attached to the brush holder to remove it from the case. Disconnect the electrical connection. Inspect both brush holders for damage and replace as needed, as well as wear on the brushes. Brushes close to 1/8 of an inch, or less, require replacement. If they are in physically good shape, then press the tab down on the side of the holder to release the brush and spring. Clean the holder, brush and spring thoroughly with electrical contact cleaner. Reinstall the brush and spring back in the holder and lock the tab in place. Then, insert them back in the case using a small screwdriver to hold the brush down, giving you clearance during reinstallation. Reconnect the electrical connections and rejoin the two halves of the case back together.