When it comes radio controlled aerial vehicles, multicopters are more popular than ever. The 3D printing community has gone to great lengths in order to provide for 3D printable replacement parts for these accident prone vehicles–and some designers and developers have gone so far as to create entire 3D printed quadopters, hexacopters, and, in rare cases, even octocopters.
For one New Zealander, named Brendan, 3D printing has been a hobby of his since he got his first 3D printer back in 2013. Around this same time, he was also frequently playing around with quadcopters. He was even part of the group that tested out the 3DR IRIS Quadcopter before it was officially released, and he had also constructed several quadcopters by himself, so it was only his natural progression to begin thinking about how to combine both hobbies: 3D printing and flying robots.
“My initial searches for 3D printed quadcopters turned up designs that essentially mimicked existing off-the-shelf models,” Brendan tells 3DPrint.com. “They didn’t take advantage of some of the benefits of 3D printing – or make allowance for some of its limitations. The first challenge I set for myself was to come up with an improved design for the main arms. The result was the approach that I’ve used in all of my designs – essentially the combination of an ‘I’ beam (that provides vertical strength and rigidity) and a hexagonal ‘tube’ that provided torsional strength while keeping within the 45 degrees maximum overhang rule for 3D printing.”
“All of these designs follow that basic principle of keeping the greatest mass (the batteries) as close to the centre of rotation as possible,” Brendan tells us. “Also, the power electronics and high current wiring is kept down below the battery away from the flight controller to reduce interference with sensors like the magnetometer.”
Brendan’s latest design is probably his most magnificent. It is an octocopter, called the TX8, and it features two motors and two propellers on each of its four arms. It also includes two 4-in-1 ESC motor speed controllers which are wired in such a way that the top and bottom motors are on separate controllers.
“The coaxial design (2 motors on each arm) does reduce the power a bit, compared to an 8 armed octocopter, but only by about 10% and there is a saving in weight, compactness, and overall simplicity that I think are worth it,” Brendan tells us.
- Very light but also powerful
- It is completely 3D printable without the need for any support
- Strong braced tube section arms with plenty of room to conceal the motor wiring
- Arms can be folded down or removed altogether for transport
- Flight controller from 3D Robotics, but it also works fine with other controllers
- Has a RF “invisible” frame instead carbon fiber or aluminium
- The 2 x 5000mah 3S batteries gives it a 15+ minute flight time
- Option of adding larger batteries
- Designed for dual 3S or 4S batteries located near the center of rotation/thrust with room for up to two 6000mah 3S or 4200mah+ 4S batteries
- The floating vibration reducing top plate is designed for the Pixhawk
Brendan has made all of the 3D printable files available to download for free on Thingiverse, and he recommends reading this guide to learn more about setting up the electronics. He also offers some friendly tips for those of you who may want to 3D print your very own TX8. They are as follows:
- Don’t limit yourself to traditional thinking. 3D printers can create all kinds of geometry that is completely internal to the part you are making–for example internal bracing and galleries.
- Don’t create big spaces just to be filled with infill–they don’t provide as much strength as well as thought out “walls” with open space between do.
- Think in terms of threads. If you need strength, try to visualize the threads of plastic wrapping around key points (such as bolts) and then continuing on all the way to the other end of the part. If possible don’t interrupt that journey. One example is the arms in in the TX8–at the motor end on the sides of the “tube” there are small gaps that let some of the threads run all the way from one end of the arm to the other.
- Following on from above, if you need strength, then make sure your layers are oriented in the best way so that if the layers do start to delaminate it has less chance of causing a catastrophic failure.
What do you think about Brendan’s Octocopter? Would you have designed it any differently yourself? Have you tried 3D printing and assembling your own? Discuss in the TX8 Octocopter forum thread on 3DPB.com. Check out another video of the TX8 in action below.
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