Whether you're a beginner looking for a quadcopter to help you get your feet wet in scratch building, or you're a little more experienced and are just searching for a cheap and reliable frame, look no further than The Ultimate PVC Quadcopter! This is a 450mm frame that is extremely cheap, at around $12 for all the hardware, and is extremely durable as well, mine withstanding dozens of near full speed crashes with nothing more than a couple of broken propellers! The electronics are 100% protected, either inside the PVC arms or underneath the lexan canopy, meaning 1: you'll never have to replace any electronic components and 2: you'll have the flyest (no pun intended :) ) looking DIY quadcopter around! This instructable is going to show you the creation process of this quadcopter and how to make it yourself!
As a kid, I loved playing with PVC pipes and connectors and using them to create anything I could imagine. Many years later, I got a small drone for Christmas, which was lots of fun, but had a very low resolution camera and a short flight time. I wanted to buy a more professional drone, but being only a sophomore in high school there was no way I could have afforded it. I decided to design my own quadcopter to be powerful enough to lift a decent camera, have a more reasonable flight time, and most of all, be cost efficient. Because of my childhood experience with PVC pipes, I concluded that they could be used to construct a simple and durable quadcopter frame. I started to make some sketches and frame prototypes and eventually ended up with the designs above.
This frame uses 1" Schedule 21 PVC because it is thin walled, making it significantly lighter than, but just as sturdy as other pipe of the same size, and at 1" diameter, is wide enough to fit some of the electronics inside for a nice, clean look. Being able to protect the electronics on the inside of the frame is a major benefit of this quadcopter's design, as it saves me money and inconvenience because I don't have to replace any broken parts in the event of a crash. For the electronics plates and canopy I used Lexan polycarbonate because of its strength, lightness, and transparency for aesthetics. The design and choice of materials for this quadcopter stem from the fact that I believe tinkering can be a form of art, and that aesthetics are just as important as, and even compliment, functionality. To me, this quadcopter's appearance possesses the perfect combination of simplicity and complexity. Having the electronics hidden in the PVC arms makes the quadcopter appear elegant and simple, but leaving some wiring visible underneath the clear lexan canopy emphasizes the true intricacy of its design.
Now, without further ado, let's get building!
All drawings and diagrams were created by me either on paper or in Adobe Illustrator for iOS.
Here's what I used to construct this quadcopter. I've broken it down into parts needed for the frame and the power system, as well as the tools required.
For the first step of the frame build, we need to make a place to mount the motors. I flattened the ends of the pipe to create a nice flat area for the motors to mount onto the arms. For the arms I cut the PVC pipe into four 8 1/2” segments. I then marked a line around the pipe 2” away from the end. I heated the pipe over the stove, holding only the 2" area I marked over the burner until that end became soft and malleable. While the pipe was still hot and soft, I flattened it with a cutting board by lining up the edge of the cutting board with the sharpie line from earlier, and pressing down on it until it cooled off and became rigid again. I repeated this process for the 3 remaining arms.
To mount and protect the flight controller and receiver, as well as hold the frame together, the quadcopter needs a system of center plates. I had the 8 x 10" Lexan sheet cut into two circles with diameters of 4 1/2" and 4 1/4" to be the bottom and top plates, respectively. The bottom plate is used as a platform for mounting the flight controller and receiver, and the top plate is a cover to protect them. The plates each have 4 holes drilled in an X pattern so that the four 6 x 32 screws can go through all 4 arms and through both of the plates to hold everything together. The plates are separated by 1" nylon standoffs which the 6 x 32 screws also go through. The screws are secured on top of the top plate with dome nuts.
Now that the motor mounts are flattened and the Lexan plates are installed, it's time to drill the holes for the motor screws. I used a motor mount cross that matched the hole pattern of my motors to mark where the holes should be. After marking the holes with a sharpie, I drilled two holes 19mm across from each other for screws, and 1 large hole between them for clearance of the motor shaft.
It's always a good thing to have something for your quadcopter to land on. For mine, I made landing gear out of a 4" PVC coupler. I used a hacksaw to cut the coupler into four approximately 3/4" wide strips, and then put these strips into a pot of boiling water for about thirty seconds to soften them. I took them out and shaped them by hand into the landing legs. I attached the landing gear to the quadcopter's arms with zip ties. So far this landing gear works extremely well and is very springy, which helps absorb shock during hard landings.
Now that the frame is complete we move on to the quadcopter’s power system. The power system consists of the motors, Electronic Speed Controllers (ESCs), Wire harness, Flight controller, Transmitter, Receiver, and Battery. As shown in the diagram above, the motors connect to the ESCs, the ESCs connect to the wire harness, and the wire harness plugs into the battery. The transmitter (TX) sends a signal wirelessly to the receiver (RX), which sends that signal to the flight controller through the male to male servo wires. The flight controller translates that signal and sends it to the ESCs through the ESCs' servo wires. The ESCs then convert that signal into electric pulses that flow through the motors' phase wires and turn the motors. Now that we know how everything works, we can get started on the power system.
We have to get the motors and ESCs prepared to connect to each other and the wire harness. I soldered male 3.5 mm bullet connectors to each of the motor wires so they could plug into the ESCs, and sealed them with heat shrink. I made a little soldering jig by drilling holes into a plank of wood to hold the bullet connectors while I was soldering. I attached the motors to the arms' motor mounts with M3 screws and screwed them in with an allen wrench.
Since the ESCs came with female bullet connectors already installed, I just soldered male XT60 connectors to the battery end (red and black wires) of each ESC, to allow it to be plugged into the wire harness.
One of the most important electrical components is the wire harness or battery splitter. This distributes power from the battery to all four ESCs and motors. To make the wire harness, I soldered a set (I'm referring to a pair of red and black wire as a set) of 10 gauge wire to a male XT60 connector and stripped the other end of the wires to about half an inch. I then cut and stripped four sets of 12 gauge wire, and soldered them to the set of 10 gauge wire. I soldered female XT60 connectors to the ends of the 12 gauge wires, and insulated everything with heat shrink. I also added a JST connector to the wire harness for an extra power lead just in case I wanted to add any other electronics like FPV gear or LED lights in the future.
Tip: When soldering a wire harness remember that the female connectors go on the "hot" end, or the side that power will flow out from. Male connectors are used on the opposite ends where the power will flow into. Also, remember to slide the heat shrink over the wires before soldering XT60 connectors onto them. If you forget to, you might have to desolder the connector, slide on the heat shrink, and solder the connector back on again which can be a real pain. Trust me, I know.
After making the wire harness I plugged the motors into the ESCs, connected the ESCs to the wire harness, and put the ESCs and wire harness inside the pipe frame. I also drilled holes in the arms for the battery plug from the wire harness and the ESC’s servo wires to come out. To prevent the ESCs from overheating inside the frame, I drilled three holes in the arms near the motor mounts to act as vents to cool the ESCs. The air pushed down by the propellers will flow through the holes and into the pipe to cool the electronics. I also drilled a hole underneath the motor mount to be an entry point to the inside of the pipe for the motors' phase wires to connect to the ESCs.
I mounted the flight controller and receiver to the lexan bottom plate using double sided foam tape. The foam tape works great at both holding the components on, and filtering vibrations before they reach the flight controller. Next, I connected the ESC servo leads to the flight controller.
To connect the ESC wires to the flight controller take the servo wire from each ESC and plug it in to the corresponding pins on the flight controller. For example, the front left motor is Motor 1, so the ESC servo wire from that motor will plug in to the first set of pins on the right side of the board. Motor 2's ESC servo wire will plug in to the second set of pins, Motor 3's the third, and Motor 4's the fourth. There are 8 sets of pins for ESC servo wires on the KK2 flight controller, but because this is a quadcopter with only 4 motors and ESCs, only the first 4 sets of pins will be used.
Motor 1 = front left, Motor 2 = front right, Motor 3 = back right, Motor 4 = back left.
Next, I connected the channels of the receiver to those of the flight controller. On the KK2 Flight Controller the receiver pins are on the left side of the board and the channel pins are Aileron, Elevator, Throttle, Rudder, and Auxiliary in that order, from front to back on the board. I connected the corresponding channels between the flight controller and receiver with male to male servo wires.
Tip: The pins closest to the inside of the flight control board are the signal pins, so the white/yellow wires must plug in to those.
MAKE SURE TO DO THIS STEP WITHOUT PROPELLERS
Before flying, the flight controller needs to be programmed and calibrated. This is one of the easiest steps, but could potentially be the most dangerous. Always make sure the propellers are not installed before configuring the flight controller to avoid injury. On the KK2 board the first thing to do is the receiver test. This makes sure that each stick on the transmitter is changing the correct value on the flight controller. If you find that a stick input is making a backwards output on the controller, (for example, left on the aileron stick shows up as a right aileron input on the flight controller) you can reverse this channel on the transmitter.
Next, is choosing the motor layout. Go to the KK2's main menu and select "Load Motor Layout". Because this drone has 4 motors, with 2 in the front and 2 in the back, select "QuadroCopter X mode". The flight controller will then show the motor layout and the direction the motors should spin. Motor 1 on the front left should spin clockwise, Motor 2 counterclockwise, Motor 3 clockwise, and Motor 4 counterclockwise.
Next calibrate the ESCs.
Next check the motor spin directions. To do this, power up and arm the quadcopter by plugging in the battery, turning on the transmitter, and bringing the throttle stick to the bottom right corner. The board will beep indicating that the quad is armed, meaning the motors are free to spin. Again, MAKE SURE THE PROPELLERS ARE OFF. Turn up the throttle and observe which direction the motors are spinning. Putting a piece of tape on the side of the motors may help with this step. The motors should spin according to the motor layout scheme. If a motor is spinning in the wrong direction, simply unplug and switch any two of the bullet connectors on the motors phase wires that connect to the ESCs, and the motor's spin will be reversed.
Lastly, calibrate the board's accelerometer.
The flight controller is now calibrated and ready for flight!
We're almost done, but before installing the propellers they need to be balanced. There are many benefits to balancing propellers, such as increased motor longevity, "jello" or distortion-free video, and even a quieter quadcopter. Because many prop balancers are expensive, I decided to create my own. My prop balancer consists of a wooden dowel frame, some Neodymium magnets, and a "Fingertip Prop Balancer" I bought for a couple dollars on Amazon. The wooden frame has two booms that are about 6" tall that enable it to fit up to 12" propellers. On the ends of the booms are two Neodymium magnets hot glued to the frame. The fingertip prop balancer fits in between the magnets, only touching one of them, but is kept in place by the magnetic force of the other, resulting in an extremely sensitive and accurate prop balancer.
Balancing the Hub
If the propeller is able to stay in whatever position it is placed in without falling, then it is properly balanced and ready to be installed.
The last step before flight is installing the propellers. Using the motor layout scheme, I installed clockwise propellers on the clockwise spinning motors and vice versa. Clockwise propellers have an "R" printed on them next to the size and pitch (ie. 1045R), while the counterclockwise propellers do not. I put two green propellers at the front and two white ones at the back to help me keep track of the quadcopter's orientation.
Instead of using the standard bells that come with the motors to hold the propellers (you might as well throw those away because they WILL come off in flight and make you crash), I secured my propellers with nylon lock nuts. The lock nuts have a special nylon ring inside of them which ensures that the propellers can never come off during flight. To tighten the lock nuts I used a vise grip. Under the lock nuts I installed a washer to help distribute the pressure from the nut on the propeller more evenly.
The frame is assembled, the electronics are installed, the flight controller is programmed, and the propellers are balanced and ready, so there's only one thing left to do. Take off!
The battery is held on the underside of the quadcopter with a velcro strip, that is sandwiched between the Lexan bottom plate and the PVC cross connector.
The battery voltage alarm is attached to the frame with a velcro adhesive square. Before taking off I plug in the battery's balance connector (white connector) to the battery voltage alarm. Once the battery's voltage drops below 10V during flight, the alarm will go off, telling me to land.
If you're new to flying, fear not! Here is a quick guide on how to take off and more with your new quadcopter.
Whatever you do, don't show off, or try to do anything you're unsure of. With time your controls will become second nature to you, but for now just stick to the basics to avoid crashing.
In conclusion, I can definitely say that I accomplished my goal of creating a cost efficient, durable quadcopter with a reasonable flight time! This build only cost me about $300 (probably even less without having to buy parts for prototyping), which is extremely cheap compared to most other drones of this size on the market. With this setup I can get around 11 minutes of flight time, which is a huge improvement from the flight time of my previous drone. The frame also turned out to be extremely robust, and has endured countless crashes, some at almost full speed into the side of my house or straight into the ground after attempting a flip, with the only damage ever being a couple of broken propellers. For aerial photos and video, this quadcopter can easily carry a video camera, which hangs from my diy camera tray made up of a library card with a camera mount stuck to it. This quadcopter allowed me to take the photos shown above.
I didn't have many big problems, or make any huge mistakes during this project, as I pretty much just came up with a design, and kept improving it until it became as good as I could make it. However, I did learn a few things which I would like to share with you to help you avoid possible issues in the future.
1. Don't go for the cheapest stuff you can find
The saying "you get what you pay for" is really coming to mind right now. Don't buy the cheapest things possible because all it will do is cause you to spend more money later. For example, I started out with a super cheap $8.99 soldering iron thinking it would save me money, only to have to buy a new, more expensive soldering iron later when the cheap one stopped working.
2. Don't be a perfectionist
While it may seem like being absolutely perfect is essential to building a good quadcopter, trust me on this one, all perfectionism will do is cause you to spend extra money, take a longer time to finish your build, and give you unnecessary stress. Of course, being absolutely exact and perfect with everything is nice, but quadcopters are smart enough to fly perfectly fine even if your build is just "good enough".
3. Don't rush
Building a quadcopter is a very exciting thing, but make sure you don't get too excited and jump in too soon. Thoroughly plan out your build first, so that you don't end up buying a ton of parts that you may not even need in the long run. (unless you're prototyping, however, in which buying parts you won't use on the final product is inevitable)
4. Hang in there
Building a drone from scratch is definitely a daunting task, and at times you may want to just give up, but please, don't do it. Do the research, ask for help online if you're confused, take a break, but whatever you do, don't give up, because there is nothing more rewarding than seeing something you built hover right before your eyes.
Thanks for Reading!
I really appreciate you stopping by to read this Instructable, and I hope it inspired you to build this drone, or even design your own! If you have any questions, feel free to ask me in the comments below!