Now that the main body is done, the next step is the arms. Now I know exactly how they have to fit into the frame, because I designed the fitting earlier, and the female part of this is already built into the frame centre.
The first problem I noticed is that the radius of the propellers I’ll be using is about 130mm – the same as the length I had set between the body and the motor centre. The frame is angled so that motors this distance from the frame will be equidistant, but I obviously need some clearance between the propellers and the frame, and so I have regretfully extended the arm length to 160mm to allow for this. Because I don’t want to print the body again, this means the motors will form a slight rectangle instead of a square, but I think it will be close enough that it doesn’t really matter.
Here’s the finished CAD render of one of the arms:
The attachment point:
Finally, I added a single layer (0.3mm as it’s the bottom layer) of plastic to the bottom of the arm to help bed adhesion, as it’s printing vertically (this way it looks the best as the curved edge is printed along the Z axis).