The Quest For a Cage

Far too much time was spent this past week trying to figure out how to enclose the air propeller in a protective cage, with a servo motor and air rudders also attached behind the cage. I spent a few days coming up with what seemed like a workable design in OpenSCAD, but when I uploaded the files to 3DHubs I was shocked by the price tag for the work: approximately $1000 CAD. The propeller was almost 10 inches in diameter, so the cage had to be fairly substantial in order to properly enclose it. I was able to reduce the diameter of the enclosure a bit though, and remove some of the material from the sides and back. This helped a fair amount, but the price was still ~ $400 CAD. I would do better to just buy a cheap fan from a hardware store, rip its cage off and epoxy it somehow to the rest of AMOS, the air rudders, and the servo motor. I'm not sure what to do at this point, but I did try splitting up the initial design so that I can print some of the smaller pieces on my own printer. After a few wasted prints (I think the temperature was too low) I now seem to be reliably printing stuff; much better than it had been earlier this year. I'm not 100% sure yet why... perhaps the change in temperature of the extruder or maybe the reduced humidity at this time of year is helping the prints to adhere better to the printer's platform. It will take another day or two to print out the smaller things (pivot joints, air rudders, servo motor holders, etc.) but if these work I may try printing the larger pieces too. I'll have to do it in multiple pieces though and then join them back together somehow.

Here is a picture of the servo motor that I got for controlling the angle of the air rudders:

It is normally used for steering toy remote control cars, but it is supposed to be waterproof, and has a fairly high torque rating: 20 kg-cm, which should be sufficient for controlling the angle of the air rudders. I hooked it up to one of the pulse width modulated (PWM) outputs of the Raspberry Pi and wrote a short program to verify that it turned properly through its specified +/- 90 degree range.