Building a 3D Printed Carbon Fiber Quadcopter

A little while ago, I thought it would be fun and challenging to design and build my own mini-quadcopter using the Mark One 3D printer from MarkForged. While, ideally, I’d like to have one of these quadcopters with GPS and the lift capacity to carry a GoPro, I wisely decided to start small; and never having flown one of these, I bought a Hubsan X4 107C to learn on.

Figure 1.

The X4 shown in Figure 1 is loads of fun to fly, and a remarkable little machine. It’s also quite sturdy, as I found by crashing it numerous times. The frame is injection molded with an upper and lower shell designed to separate upon strong impacts to keep from breaking.

I decided rather than attempting to design and build a larger quadcopter, I’d start small and use the components from the Hubsan; motors, LEDs, and receiver, since they were rather inexpensive and I could use the hand held transmitter I already had.

Now, simply designing a frame to hold the components is not especially difficult, and one can find numerous postings on the Web of people who have done this.

The challenge I set myself: create a frame that was better than the stock one.

While 3D printers are all the rage right now, there’s a dirty little secret: while the typical 3D printer (with care) can make quadcopter parts that meet form and fit requirements, it is a bit more of a challenge for 3D printed parts to meet strength requirements. It can be quite difficult for a 3D printed part to be as strong as a comparable injection molded part; thus, 3D printed parts generally are beefed up and result in a far heavier part. Of course, when designing something that flies, extra weight is something you want to try to avoid.

The Mark One printer’s unique ability to place fiber; fiberglass, Kevlar or carbon fiber, into the part does, however, open the possibility to make a 3D printed part that meet, form, fit and function requirements.

Figure 2.

My first design using Kevlar shown in Figure 2, was a concept to at least prove I could build my own frame. It was a bit lighter than the X4 and did fly; however, it was a bit sluggish in the air and I knew I could improve upon it.

Another advantage of 3D printers is the ease by which new designs can be easily created. So, my next design variation using carbon fiber, shown in Figure 3,  did away with the oval center section, replacing it with a square shaped center section which reduced the weight a bit more.

Figure 3.

I also added a cover for the receiver for protection, my first design had the receiver open. This design flew much better, but I knew I could still do even better. By this time, I knew that the strength met or exceeded the strength of the original Hubsan design; so, my concern now was making it as light weight as possible. A light frame will increase the flight time and, more importantly, it will stress the motors less and prevent them from burning out as fast.

Figure 4.

My last frame design and the one I am currently flying is shown in Figure 4. The arms are a simple X configuration, and it has a receiver cover that fits over it. The motors which previously sat on top of the arms are now sunk a little bit into the arms which raises the center of gravity of the entire quadcopter making it quite agile. I also increased the distance between the motors which make it more stable in the air.

Figure 5.

Figure 5 shows the final quadcopter along with two camera modules; the one by itself is the camera that came with the X4 and allows video to be recorded to a mini-SD card. The camera mounted on the frame is a first person view (FPV) camera that incorporates a transmitter so the camera image can be sent to a video receiver so one can do FPV flying with it. Both camera modules add about 5g to the weight, and most of the time I fly without the cameras.

After a fun iteration process, I am quite happy with how my mini-quadcopter turned out.

Without the camera modules, the entire quad is about 5g lighter than the original X4. When flying the original X4, I found the motors would get quite hot. They never do now. My flight time went from about 5 ½ minutes to around 6 ½, and I can also use a larger battery, which gives me about 8 ½ minutes of flight time.

As important, I never have to worry about the frame breaking in a crash. While the arm thickness of 2mmx7mm does allow them to flex, they are stiff enough to not flex during flight yet bend during a hard crash which allows the force of the impact to be absorbed and released. Finally, by exposing much of the motor they run quite a bit cooler which should allow them to last longer.

Bruce Bodnyk is a menchanical engineer and instructor at 3 HTi. Interested in learning more about 3D printers? Read more here. Or why not contact us?