How to fix a broken drone arm [5 options with instructions]

Drone crashes and accidents happen to even the best pilots. Depending on how far up the drone falls from as well as the angle and parts of the drone that hit the ground a drone may be completely destroyed or some of its components may fail before others. Because the arms of a drone stick out from the body they are one of the first things that can get damaged if you crash land or land heavily.

You can fix a broken drone arm by using a combination of wire and glue, an epoxy, a glue such as Loctite, and you can also attempt to weld the plastic together using methyl ethyl ketone. Attempting to fix a drone may void any warranty or refresh plans so use with caution.

In this article, I will go over how to fix a broken drone arm including using glue, epoxy, plastic welding techniques, changing the arm and frame yourself, and when you should just send it into the manufacturer for a complete fix.

To understand the type of fix that will work we need to first understand what type of plastic drones are made from and how you can best fix each type of material.

What materials do Drones use?

Drones need to be made from materials that are lightweight but also impact resistant and able to withstand high operating temperatures due to the fact that the drone electronics can get relatively warm during flight.

The frame

The frame of the drone is typically made up of a magnesium alloy which contains approximately90% magnesium, 9% aluminum and 1% zinc. This can change for each drone but it offers incredible strength and corrosion resistance. It is actually lighter than aluminium by 34% and it is a popular choice for drone frames. It is one of the lightest structural metals in the world which makes it perfect for drones because even the smallest increase in weight can result in a much lower flight time.

The body

On top of the frame, encasing the components, is the body. The material which is used for the body also has to be impact resistant as it is the last shield that is protecting the internal components from any accident or incident which may happen.

Depending on the type of drone the body may be made of high impact polystyrene (HIPS) or Acrylonitrile butadiene styrene (ABS). Let’s take a look at some of the drones that utilise each of these materials.

High impact polystyrene (HIPS)

High impact polystyrene is used in drones such as the DJI Phantom and is typically used on the shell.

Because of the way that styrene does not mix with some other polymers it forms a matrix instead of a complete mix of the materials. This peculiar activity means that when the material is put under stress micro cracks form and the energy of the propagating crack is transferred to rubber particles.

The transfer of energy into the rubber which is mixed into the polystyrene means that it is resistant to impact.

Acrylonitrile butadiene styrene (ABS) – Mavic series drones

ABS is made up by reacting styrene, acrylonitrile, and poly butadiene. These can be mixed together in various ratios giving a different physical property for each mix. The addition of acrylonitrile makes the ABS are stronger than pure polystyrene whilst the acrylonitrile can also contribute to chemical resistance, fatigue resistance, hardness, and rigidity was also providing some protection against the higher temperatures that drones can operate under. The styrene gives the plastic a shiny and impervious surface as well as improving the hardness, rigidity, and improved processing ability.

A lot of drone body materials are created via an injection moulding technique which means that it can be made very quickly in a continuous manufacturing process.

This material can also be used for the drone propellers as it is light and resistant to stress and strain – something that the propellers go under a lot of.

A warning

As drone owners we are often impatient when it comes to trying to get our drone back up in the air as quickly as possible. In the heat of the moment there is no doubt that fixing the drone arm yourself becomes an attractive proposition.

However, if you do not repair the drone properly it will likely crash again and potentially cause more damage to the drone frame, body, and arms. Also, it is likely that any repair that you make to your own drone will void the warranty that the drone manufacturer has placed on your drone.

Sometimes, it is better to take a step back and send your drone to the professionals to be fixed rather than trying to fix it yourself. Sending off your drone to the manufacturer may be the slowest and more expensive option but you are guaranteed to get back a drone which is safe to fly and is unlikely to cause any more damage to itself or other people or property due to a dodgy fix.

Now that we’ve got an understanding of the types of materials that drones use here is how to fix a broken drone arm.

The first thing that people consider when fixing the plastic casing of a drone is glue. Let’s have a look at some of the common options which you can use to glue your drone parts together.

Glue

Glue is a useful tool if the damage is superficial and you want to stop certain parts of the drone vibrating or the damaged part is not a structural component for the drone.

Glue is only as effective as the chemical bond that it can make with the surface of the plastic and therefore you need to select the correct glue and also ensure that the surface is as clean as possible before applying the glue

Clean with IPA first

Before you apply any glue to the surface you must clean the area thoroughly.

Drones always end up with dust, dirt, and grease from handling during use. Making sure that the surface that you’re about to glue his as clean as possible is very important.

Water and soap will not remove some contaminants and therefore you should use isopropyl alcohol to clean the crack and surrounding area thoroughly.

This is how I would clean a crack with isopropyl alcohol:

  • make sure the drone is turned off and the battery is completely disconnected.
  • Use a cotton swab or a microfibre towel and put a small amount of isopropyl alcohol on the surface.
  • Gently sweep over the surface of the crack with the isopropyl alcohol
  • use a toothpick with a small amount of material on it to get into the damage as far as possible.
  • Allow to air dry for at least 10 minutes and use an air puffer (like the ones you use on cameras) to blow out the middle of the crack so that it is completely dry.

Once you have cleaned the area thoroughly (can do more than once) you need to select the appropriate glue or epoxy. Here are a few options which you should consider.

Bondic Liquid plastic

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Bondic liquid plastic is a 100% waterproof and he resistant adhesive which dries clear and can be sanded down afterwards.

The great thing about this glue is that it is a solvent free formula that stays liquid Intel is hardened by the supplied UV light. This means that it will last for ages on your shelf and if you are not happy with the first application you can simply wipe it away and restart again.

Bondic liquid plastic is perfect for drone bodies as well as a lot of other materials so may be good to have around the house.

Loctite

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Loctite superglue plastic bonding system is a two-part bonding system which sets in seconds and develops a lot of strength over a few hours.

It is able to bond to many other materials and is resistant to water, many chemicals, and freezing temperatures.

Plastaid

Plastaid is a two-part epoxy glue that you mix together which consists of a powder and a liquid and results in a strong, hard, long lasting and durable waterproof plastic in about 15 minutes.

Plastaid sticks to many plastics including ABS – which is exactly what drones are made from and it can also mechanically hold on to surfaces such as wood and brick.

It’s natural colour is an off-white colour but you can mix in wood stain or acrylic to change the colour. Do not add too much as it may change the bonding ability.

E6000

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This is an industrial strength craft adhesive that is ideal for bonding together plastics, wood, vinyl, rubber, and a lot of other materials.

The great thing about this material is that it dries completely clear and is nonflammable once it is cured.

Although some of the superficial cracks which you may pick up from a hard landing or a relatively low freefall can be covered up with glue sometimes you need to secure altogether some parts of a drone more securely.

You can combine the physical holding together of a drone part with glue for improved stability and durability. This is particularly important on a drone arm where a lot of forces are acting on the materials during flight.

Wire and glue method

I know, first hand, the power of using a physical method of holding two plastic components together (with wire or floss) and then supporting that connection with glue or epoxy.

My glasses broke right in the middle of the frame and I was able to drill two small holes to pass through some wire. I soldered the wire in place and was able to support the physical connection with glue.

Ever since learning this magical fix I have also fixed a number of other plastic and moments in my house that have failed. The result is that the repaired crack is stronger than the virgin plastic.

This method relies on being able to drill two, or more, small holes in the area next to the damage to past wire through.

This method is perfect if glue isn’t strong enough to provide the level of hold that you need.

  • Drill two small holes – one on each side of the damage big enough to past the wire or floss through.
  • Past the wire, or floss, through the holes – you can go around as many times as you want in order to increase the stability of the physical hold.
  • Repeat for as many places as you wish to provide maximum hold.
  • Deposit glue, or epoxy, through the holes and over the wire or floss.
  • Wait for it to completely cure – sometimes up to 48 hours.

Using this technique, you will be able to provide a really strong hold between two plastic parts.

There is also a technique that does not require any glue or epoxy and may be perfect for your drone accident.

Plastic welding

If you need to join two bits of plastic together you can use a technique called plastic welding.

Plastic welding is a relatively simple task and you can use a solvent-based approach to mount the plastic and then force it together.

Methyl Ethyl Ketone

Methyl Ethyl ketone is a solvent which can dissolve some plastics. It is a toxic solvent so you need to use it in a very well ventilated area and make sure that you follow all of the appropriate solvent safety guidelines.

If you do not want to work with methyl Ethyl ketone you can also use acetone though it is less aggressive and is less toxic.

You may find it hard to come across ethyl ethyl ketone as it is a controlled substance.

This is how you use it:

  • clean the weld area with isopropyl alcohol and allow it to completely dry.
  • Place a small amount of solvent on the area to be welded making sure that the pieces fit together like a jigsaw puzzle.
  • Hold the pieces together for one minute with a relatively high amount of pressure
  • allow the solvent to evaporate completely before using.

Here is a YouTube video which uses a solvent to connect to hard bits of plastic together including ABS plastic.

Change the arm yourself

If your drone incident results in more damage than can be fixed easily with solvent, glue, or wire you should consider changing the entire arm yourself.

This can be a very tricky and finicky process as you will need a number of skills to successfully change the arm yourself.

You will need to be familiar with soldering microelectronics, as well as detaching soldering points and cleaning up with copper ribbon.

I recommend that if you are going to head down this route you should practice on a disposable piece of electronics – you can pick these up any recycling store – before you have a go on your own drone.

Here is a video on how to you can change the arm yourself.

How do I change the arm on my drone?

Changing the arm on your drone requires a number of skills and here is a video which runs you through the most important processes.

You will notice that it is a relatively tricky procedure and you will have to get familiar not only with taking apart the drone without damaging the plastic taps and components are also dealing with small internal and electronic welding.

I recommend that you watch a number of YouTube videos specifically for the model of the drone that you want to repair before attempting it on your own drone.

Send it to DJI for a repair

The last option, and arguably the best, is to send it to the manufacturer for a repair.

If you have the DJI care refresh package you will be able to get up to 3 replacement drones in two years accidental damage and up to 2 new drone for flyaway situations.

The DJI care refresh service is worth if you want peace of mind that your drone will be fixed by the original manufacturer and it means that if they can fix it they will most likely replace children with another one.

If you do not have the DJI care refresh service it has been reported online at drone arm replacements can cost anywhere between US$100 and US$160.

This is much less and the price of a new drone and is done by the original manufacturer. Which should give you a piece of mind.

If you want to know more about whether or not DJI care refresh plan is worth it, check out my other article – is DJI care refresh worth it? [Comparisons and tables] – click here to be taken to article.

Is DJI Care Refresh Worth It?

Summary

In this article, we have covered all of the ways that you can fix a broken drone arm. Having an accident should be the end of the world for your drone and plenty of options for you depending on the type of accident and the type of damage that you have incurred by crashing your drone.

From simple gluing all the way to full replacement – there are plenty of DIY options. However, the DIY options can easily void any of your warranties or DJI care refresh plans and therefore sending it to the original manufacturer may be best option in your case.

Whatever you choose, make sure that you do a full safety check before you relaunch your drone and run through all of the appropriate safety procedures so that you can ensure that your drone is not a risk to people or property nearby.

The Author

Dr Andrew Stapleton is a writer and YouTuber with a PhD in science. He has written and/or produced videos for Science Alert, COSMOS magazine, and Australia's Science Channel among others. Andy started droneflyingpro.com to share his love and the research of all things drone! He has been a drone pilot for many years and has flown many types of drone. His favorite is still the DJI Mavic Air for the portability and functionality packed into a small and portable drone!