One of the ideas with the Crazyflie was to make a simple flying platform and what’s simpler than just attaching the motors directly to the PCB? On our first prototypes we used hot-glue to attach the motors which work out pretty well. The problem was that when you crashed the motors often came loose, and in some cases, so did the wires attached to the motors. Reparing this turned out to be pretty teadious and it makes flying it a lot less fun, since the iteration time for trying new things becomes longer. We did a few tests with different protections, like soldering a ring of piano-wire, but when we decided to make a kit out of the Crazyflie we realized that we needed something that was easier to manufacture.
Since we could not find any off-the-shelf motor mounts we decided to make our own. Our idea is to place the motor in the mount and the mount on the wing. We have tried a few different solutions but the current leading design is one where we feed the cable from the mount out under the wing and to the soldering point for the wire. We have also made a telescopic version so it is possible to adjust the arm length for adjustable flight dynamics or to attach bigger propellers. After some more testing we will decide which one we will go for.
The CAD work is done in an open-source CAD tool named FreeCAD. After struggling for a while with an unstable versions, the 0.12 branch finally became very stable. The images below is the second iteration of prototypes that we have done using Shapeways. It’s is a 3D printing house in the Netherlands that has a great service where you upload models, choose what material you want them printed in, and then two weeks later you receive them in the mail! The durability is pretty good as well. We have only managed to break one, and that’s after a lot of violent crashes and a more fragile design.