We all know propellers are an integral part of flight. And thus, most of us keep an eye out for their overall health. If there’s noticeable wear and tear, we’re quick to replace them.
That’s all well and good, but maintenance for propellers doesn’t just end there.
There’s another important aspect that’s often overlooked (or simply ignored): propeller balance.
Unbalanced propellers can, amongst other things, directly kill your footage by ruining shots. And as you may have expected, the solution is to balance them yourself. Here’s what that typically involves.
You can balance your drone propellers one by one by using a propeller balancer to determine which side is heavier than the other. You can then add weight to the lighter side or remove weight from the heavier side until your propeller is completely balanced.
At the same time, you may find different variations to this method.
In this post, we’ll be going through all of the practical ones that you should know about. You’ll also find the overall process to be surprisingly simple as we cover every step.
A lot of drone pilots neglect regularly balancing their propellers; they deem the process unnecessary. However, there is a true purpose to it. Whether propeller balancing is required or not depends on your application.
The purpose of propeller balancing is to improve performance and reliability by getting rid of excessive vibration. A drone with balanced propellers flies smoothly and, hence, steadily records footage. Similarly, the drone’s internal components last longer since they’re not under additional stress.
So, a relatively shaky drone video likely has to do with unbalanced propellers.
Another indication of propeller imbalance is when your flights start to sound louder.
Now, you may simply class this as an annoyance and look the other way. But the truth is that the noise can potentially relate to more complex problems.
When one blade is heavier than the other, the propeller continuously wobbles as it spins. This unnecessarily burdens its corresponding motor.
And if you don’t attend to an unbalanced propeller over prolonged use, you risk the spread of damage to even more internal components. This includes the bearings, fasteners, and the drone frame itself.
Once the screws start to loosen up and the material begins to fatigue, that’s when you’re really leaving your drone vulnerable to accidents.
But don’t let this scare you! The likelihood of propeller imbalance single-handedly causing a drone to crash is fairly low.
However, I do recommend staying on top of a propeller balancing routine if you value flight performance and product longevity. You can easily fix the drone's wobbling issues by understanding the reasons behind it, as there might be other factors causing it.
There are two ways to go about propeller balancing. One of them is significantly more common in the drone community (and for good reason). Before we get to the whys, take a look at what the methods exactly are.
The two methods of propeller balancing are dynamic balancing and static balancing. In dynamic balancing, the imbalance in a rotating propeller is directly measured using electronic equipment. Static balancing, on the other hand, involves the use of a balancer and the propeller is kept stationary.
Both methods play a role in promoting the long-term use of propellers. However, you may find only one of them being applied in a particular industry.
Let’s expand on dynamic and static balancing so you have a better idea of what their stages involve.
Dynamic balancing is all about technically measuring the vibration of a propeller and locating where the imbalance exists.
This information is obtained by using specialized equipment — primarily an attached, system analyzer consisting of sensors. The propeller, meanwhile, is rotated at a fixed, high speed.
The measurements from the analyzer then allow the technician to develop an appropriate solution by gradually counteracting the imbalance. This is typically done by adding screws, nuts, or bolts.
The complete process is continued until an acceptable magnitude of vibration is reached.
Ultimately, your system will heavily benefit and you’ll notice a much smoother flight.
But here’s the thing: you’ll hardly ever find this method being used in the drone community. Instead, dynamic balancing is a process routinely used in the servicing of airplane propellers.
It simply boils down to the fact that it simply isn’t suitable for the smaller and cheaper propellers that drones use. Dynamic balancing for drone propellers is unnecessarily expensive, complicated, and dangerous (since your propeller needs to be in operation).
The alternative, which we’re getting onto next, offers a more appropriate technique to get to our goal.
This method doesn’t require any fancy devices and is pretty straightforward.
In fact, you may have already deduced the basic idea of the method from its name. It involves horizontally balancing the propeller in the static condition.
So, unlike in dynamic balancing, the propeller is completely isolated from its system and is not in operation. The only accessory you do need is a balancer, which is where the propeller is placed.
The imbalance is countered by either removing material or adding extra weight until the propeller is fully stationary in the horizontal axis and sits level. A balancer is designed for minimal friction and makes this process super easy.
Therefore, it’s something you can comfortably do even if you’re not particularly experienced in repairing drone components. The following section will be going through the exact steps.
You’re now aware of what static balancing consists of and what it’s meant to achieve. Here are a few pointers to make the process for you as simple as possible.
You statically balance a drone propeller by placing it on a propeller balancer with a compatible kit. The blade that sticks up is lighter. You can either add repair tape to the lighter blade or sand off material from the heavier blade until the propeller stops tilting to one side.
If you’re getting your first propeller balancer, make sure the balancing kit it comes with fits your drone propeller. The balancing shaft needs to be the right size to pass through your propeller’s hub.
The Du-Bro 499, for example, is a top-selling propeller balancer. However, the shaft that it comes with won’t facilitate DJI propellers.
Once you’ve gotten hold of a balancer, place it on an even surface before using the kit to mount your unbalanced propeller. Make sure the flow of air is low enough to not interfere with the process.
Now, you can static balance your propeller in one of two ways: either add weight little by little or carefully remove material. Both things are done on the underside of the propeller blade in question.
One thing I will add is that adding counterweights is a lot more beginner-friendly. You can simply remove a piece of tape if you add too much weight. However, reattaching material you sanded off isn’t a possibility.
But if you’re looking for exactly that — a solution that’ll last — removing material is definitely better. The repair tape may eventually come off and you’ll have to redo the whole process.
Regardless of what you choose, the process will be successful as long as you do it correctly.
You’ll know the goal has been achieved when the propeller maintains any position you leave it in. In other words, neither blade should tilt downwards. The propeller can now be unmounted from the balancer.
You’ll also quickly realize that there’s a bit of trial and error to static balancing. But, ultimately, it should only take you around five to ten minutes to balance a propeller.
A reliable propeller balancer will typically set you back around $15. And if you only bring your drone out on occasion, that cost may seem unnecessary to you.
Well, the good news is that you don’t need a specialized balancer. You can technically get the job done with a home-made version of one instead. Take a look.
You can balance drone propellers without a balancer by using cheap tools that you may already have in your house. All you need is a spindle and two cones to secure the propeller. For support, you can use stacks of paper. An actual balancer, however, allows for a more accurate reduction in vibration.
Similarly, it is also designed for convenience. Your makeshift balancer is more likely to frustrate you during the process if you’re seeking the best balancing results.
The example above refers to a minimalist setup that’ll cost you nothing. If you’re hoping to balance a DJI self-tightening propeller, by the way, you won’t even need the two cones.
Now, don’t get me wrong: you can make a much better balancer on your own. Considering you have the resources for it, that is.
One good idea is to use metal construction pieces and assemble them into a typical balancing frame. You may use two small magnets to secure the shaft to the frame and 3D print the cones so they fit perfectly.
The YouTube video below shows what I’m referring to.
Up until now, we had been considering the 2-blade propeller. It’s definitely the most common type of drone propeller but it’s not the only one on the market.
The 3-blade propeller is favored by many drone pilots, particularly because it offers increased thrust. Here’s what balancing looks like for that propeller type.
You balance a 3-blade propeller by using a propeller balancer. Note which blade is middle-weighted and add a little bit of tape to it. Then add tape to the lightest blade (which should now be sticking up completely) until the propeller stays in any position you leave it in.
You may also have to adjust your counterweights by removing a bit of tape, while you repetitively mount and unmount your propeller to check its balance.
Alternatively, you may choose to sand off material from the heavier blades instead.
The process is ultimately pretty similar to balancing a 2-blade propeller. However, it is more tricky. You can expect it to take relatively long to balance a complete set of 3-blade propellers.
If you’re still confused about something, I recommend watching the tutorial video below. It goes through the exact method I’ve described.
To bring things to a close, the best way to balance a set of propellers comes down to preference.
You can balance the propellers on a quadcopter with dynamic or static balancing. The latter is predominantly used. The imbalance is fixed by placing the propeller on a balancer and either adding weight to the lighter side or removing material from the heavier side until all blades weigh the same.
Fortunately enough, you don’t have to go through this process with a new set of propellers since they come factory balanced.
This is also why a lot of drone pilots simply buy a new set. And if you simply can’t get yourself to spend the time and energy on balancing, I recommend you do the same.
Remember that it’s always better to make a replacement instead of pushing on with an unbalanced propeller and having your components prematurely age.