I’ve learnt over the years that a burning smell coming from a drill is usually caused by wear and tear from one of the components. However, it can also sometimes be caused by user error. So what are the most likely causes?
The most common causes why your drill smells like it’s burning are due to issues with the batteries, brushes, motor, switches, cable, or brush holder. User error, such as covering the vent, stops the motor from being able to breathe, which leads to smoking and sparking. Overloading the drill may also cause it to overheat.
In this article, I’m going to help you identify what’s causing your drill to smell like it’s burning and how to fix the problem.
6 Reasons Why Your Drill Smells Like It’s Burning
If your drill smells like it is burning, then it is time to unplug it and find out why. There are several reasons why a drill will begin to smoke, and if you catch it early, you may be able to save your drill.
It is important to pinpoint where the smell or the smoke is coming from to prevent your drill from melting. Common reasons include:
The charging process heats the chemicals in the battery – discharging does the same. Batteries can overheat if you push them from the moment of coming off a charge and running them down to flat.
The contacts of a battery can also short out if you allow them to get wet. A hot battery is dangerous, so it is a good place to start. Unplug it from the drill and see if it smells and feels hot.
Most modern drills use brushless motors, but drills with brushes can burn out. The brushes on older tools that get a lot of use will wear out. You can overheat the brushes while trying to drill hard materials with large bits – reducing their lifespan.
If this happens, you will see smoke coming out from the vents at the side of the drill. Once the brushes burn out, the drill will go silent as no power can get to the motor.
Motors rely on magnets to make them spin, and magnets are fragile. With some larger drills, it may be possible to pull the drill armature out to inspect it for damage. Often the motor, the magnet, and the brushes are one sealed unit.
If the smoke or the smell of burning is coming from this type of motor, stop using it. Unplug the drill, or take the battery out, and wait for it to cool before trying it again.
Trigger switches and mode controls on the drill are avenues for sawdust and powders to get in and between the contacts. This material can heat up or short the contacts, causing the heating or smoking of the switch.
The cables leading into the drill can rub thin or shear from rubbing on sharp materials and overbending. This may thin the cable enough to lead to a short. You may even see sparks along with the smoke.
The brush holder puts pressure on the brushes so that they stay connected with the motor. The wires leading to this holder can loosen from vibrations over time. The holder can also snap from continuous heating and cooling.
How to Fix a Burnt-Out or Smoking Drill?
If you do end up damaging your drill, you need to know what it is you need to replace. If you see sparks, it may be better to replace the tool, but smoke is also a sign that you have been pushing the drill too hard and it needs a rest.
Check the battery for smoke and feel around the base for excessive heat. There is not much that you can do with a dead battery – except replace it.
You can try leaving the battery for an hour to cool down, then try it again to see if it works. But do not use the battery again if it immediately starts to smoke.
Brushes are simple to repair, but it does mean opening up the housing of the drill. Most drills supply spare brushes – if the drills use them. Once you open the drill, you will be able to see the old brushes.
A sign of a burnt brush is a large amount of black powder coating the inside of the drill casing. You may also see large chunks of carbon if the brush has cracks in it.
All-in-one motors are easier, though it does mean buying a new motor. Most drills will have their wires soldered to the motor. To fix it, you will need to be good at soldering, or you will need to take it to a professional.
You might not be able to find a suitable replacement switch for your drill, but you may be able to fix it. You will need to take the drill housing apart to get into the switch mechanism.
Spray thinning oils may make the problem worse and form a sludge inside the switch that you can never get out. You may be able to open the switch and blow out the worst of the dust. The alternative is to find a new switch.
Check and replace the drill’s fuse in the plug – if it has one. Power cables can also smoke if they are on the verge of breaking, they may be faulty.
Check the cable leading from the plug to the drill for exposed copper. You may want to replace the whole cable if there is any damage.
Your drill may not have a brush holder, but if it is broken, it will create sparks. This is not something that you can glue, and you should look for a replacement.
Other Ways That a Drill Can Overheat
You can do certain things to avoid overheating your drill. There are also ways to save your drill if it begins to overheat and smoke while drilling.
Covering the Vent
A common reason for a drill to overheat is something that even professionals do wrong, which is blocking the air vent. As you are drilling, it is tempting to use your spare hand to hold the drill behind the chuck.
You will notice that your drill has an air vent behind the chuck to allow the motor to breathe. If you are drilling or screwing into a tough material, the motor will heat up – it may spark, smoke, and begin to burn your hand.
The best thing is to run the drill with no load and nothing covering the vent for a minute – to allow the motor to spin and cool itself.
Drills do not like it when there are getting full power but not spinning. If you are using the drill as a screwdriver, you may burn out the motor as the screw stops.
Burnouts can also occur if you are slow-running the drill to avoid the screw going too far into a material.