How to Clean Drone Motors?

Like all mechanical components, your drone motors also accumulate dust and dirt over time. This dust can come from flying in a sandy atmosphere or from a recent crash in muddy lands. Whatever the reason is, to keep the motor running efficiently, you need to make sure nothing is hindering its rotary motion. In this blog post, I am going to tell you how to clean drone motors the right way.

The best way to clean your drone motor is by using compressed air (for non-magnetic dirt deposits) or silly putty (for magnetic dirt particles). To clean the motor, open the shaft screw or C-clip to separate the stator and rotor, clean both parts completely and then reassemble gently.

Let’s discuss things in a bit more detail so you know exactly what to do to clean your drone motors.

Why do drone motors need cleaning?

There are many reasons why your drone motors may need to be cleaned. Perhaps you’ve flown in a dirty atmosphere or crashed through muddy land, potentially accumulating dust and dirt on the motor fan. This is quite bad for a number of reasons.

Overheating: The clean airflow over the motor is how it stays cool by dissipating heat, so if there is too much contamination on the rotor’s magnetic surfaces, the heat may not dissipate efficiently. This leads to your motors running hotter than they should.

Excessive friction & wear: When the ceramic particles are crushed between the stator and rotor, they end up creating additional friction and also damage the polished surface. This can damage the drone motors permanently over time.

ESC overloading: The buildup between rotor and stator slows the motor rotation. To compensate, the ESC will send more current to the motor thus increasing the power drain. If the situation gets worse, you might burn your ESC or motor coils. Some high-end drones have preventive software feature that detects blocked motors in case of overload.

Bearing damage: The motor bearing is a critical component and is usually susceptible to mechanical failure. Brushless motor bearings are not 100% sealed so there is a possibility of fine dirt particles going inside the partially sealed bearing and contaminating the lubricating grease. This will result in bearing failure over time.

High noise: A clogged motor will sound like scratching two ceramic or metallic surfaces together. Not fun to hear.

How to clean your drone motors?

To clean your drone motor, follow these easy to do steps to make sure your motor gets cleaned without damaging any of the mechanical parts inside. Before you start, see the below image to familiarise yourself with the main parts of the BLDC (Brushless DC) motor found in majority of drones.

How to Clean Drone Motors?
image courtesy: oscarliang.com

The two major parts are the magnetic rotor assembly and the static coil assembly. When you disassemble the motor, the two parts should come apart. Let’s go step by step:

  1. Remove propeller: Before you can do anything, it is a necessary to remove the propeller since you cannot take out the stator assembly with the propeller on. Follow your drone manufacturer’s guide to remove the properller the right way.
  2. Remove the motor from arm: Although, you can clean your motor without removing it from the drone, removing it makes things a little easier. On some drones, the motors are more closely integrated into the arm so removing it becomes necessary. If you are not sure how to remove your particular drone motor from the arm, check out your drone manual for assembly/disassembly guide. Make sure you don’t break any delicate plastic housing becuase we are going to put the motor back in as it was.
  3. Disassemble the motor: Once the motor is off the arm, its time to open it up. Some motors have a shaft screw at the bottom while others have c-clip ring. The screw can be opened with a screw driver while for the c-clip, you will need a pair of twizers to squeeze the open ends together and take the ring out.
  4. Separate the rotor and stator: Once the screw or c-clip is off, you can open the motor and separate the two main parts. Remember that the permanent magnets used inside the motor are quite powerful so you will need to apply some serious force to separate the two parts.
  5. Examine the parts: Once the two sections are apart, its time to see where the dirt particls have accumulated. There are two types of sand/dust particles. Ferrous and non-ferrous.
    1. Ferrous dirt is bascially rich in iron and other magnetic metals and stick mainly to the magnets inside the rotor. They are hard to get off.
    2. Non-ferrous dirt are common sand or dirt particles accumulated on both rotor and stator surfaces. Since they are not magnetic, they are easy to clean and get off.
  6. Clean the rotor: This is the main part of the drone cleaing. You can either use compressed air cannister or silly putty Both items are easily available online.
    1. If the dust is non-ferrous, you can use the air duster to blow it off. To do that, just hold the nozzel a few inches away at 45 degree angle and blow in short bursts. Remember not to press for too long because the cold air tends to condensate the moisture in the surruounding which is not good for metalic parts. Do this for both the rotor and stator till all the dust and dirt particls are off.
    2. If the dust is ferrous and is sticking to the rotor magnets, the compressed air is not very effective. It will blow the dust off from one place and it will stick to the opposite magnet. In such a case silly putty is very handy. Press the putty inside the rotor spaces and go around the rotor to take out all the particles. You can repeat this for the stator coils as well.
How to Clean Drone Motors?

Once you clean both the rotor and stator, you can put them back and reassemble the motor. During closing the rotor on stator, remember not to let the rotor hit the bearing with a snap. It can damage the bearing. Try to slowly and gently let the rotor down over the stator.

Some tips to remember during motor cleaning

  • You don’t need to oil the bearing area or the rotor/stator assembly. The bearing is partially sealed with lubricating greese inside so it does not need oiling. In fact, oiling will attract more dust and damage the motor instead.
  • In a well balanced motor, the rotor magnets and stator never touch each other so there is no need for oiling here as well.
  • Do not wash the motor parts with water. The residual water can errode the internal parts. If you do wash the motor, make sure you dry it with a compressed air bursts to completely remove the water.
  • Handle the stator coils with case as they are delicate and any rough handling can either damage the wires or the thin plastic insulation over it.