Saturday, 29 March 2014

The Window (beginnings)

Awhile back I made a simple and cheap quadcopter using parts mainly from Hobbyking and the local hardware store, you can read the letsmakerobots writeup I did on it here. A friend of mine also built a similer one using mostly the same parts (we placed one big order with twice the parts needed to make a quad). Fast forward a year or so, and my quadcopter is sitting in parts in a box on my shelf, victim of an upgrade that never quite got finished, and my friend's is also sitting unused on a top shelf. Seeing as the quads were both built with identical electronic parts, and his was also unused, I decided to see if I could buy his off of him, and put the two together to make a octocopter. He conceded, and I was now the proud owner of two disfunctonal quadcopters, plus some extra parts. Step one was to find a suitable octocopter control board that was in my price range and simple enough for me to be able to use. I looked around, and found Hobbyking's KK2.1.5, but more on that in another post. Step 2 was to build a frame, after the sucess I have had with a PVC frame, and the miserable failure I had with a storebought frame, there really wasn't any decision to make. Perhaps later in the future when I become a better multirotor pilot, less prone to crashing, I will invest in a different frame, but for now its 1/2" PVC for me :)

I spent a while with some graph paper, a ruler, and a pencil determining the best frame setup that I could come up with that used only standard pipe fittings,
and after I had sketched a bit I decided on this setup:
With two motors connected to each arm that radiated out of a + fitting, much like my previous quad. A little bit of trigonometry later and I had the legnths of pipe that I would need in order to space everything in a nice octaganal shape, and I also decided to stregnthen the frame a little by connecting the corners to each other, just like this:
I measured and cut all 20 pipe segments, and then faced them and got their legnths perfect on a lathe. 4x 11.85" legnths, 8x 6.5" legnths and 8x 4.25" legnths:
Next up was drilling three holes in the top of each of the 8 motor mount tees for use in fastening down the motors. I found that a very good way to fasten the motors to the frame was by drilling holes in the tee, and affixing the motor to the tee using zip ties. This is a simple, light, easy to repair, and cheap setup, and most importantly, it has a little "give" in it, so if I make an especially hard landing, the zip ties break instead of the motors. I have had that happen several times, and it is much nicer than replacing a motor (my friend decided to screw his motors down, and broke two or three of them in hard landings, I have yet to break one.) This is a picture of my quadcopter's motor mounts, my octocopter will use exactly the same method, except with only 3 zip ties per motor.
Here is all of the pipe and fittings used to make the frame:

And a couple of pictures of the completed frame, it is approximately 3' on diagonal.

 Everywhere that a pipe goes into a pipe fitting, I match drilled a hole and drove a small wood screw into the join to ensure that none of the pipes will pull out or rotate. The frame is very sturdy and has almost no flex. It also happens to look very much like a windowpane, which is where it gets it's name, The Window.
Price: $13
Weight: 1.1 kg
Durability: Dang this thing is durable, it would take a lot to break it, and if it does, parts are cheap and avalible at the local hardware store.
Looks: So apparently some people find this to be important. I have never understood humans. In other words, Dat Pipe :)

Well, that's all for now, updates will come sometime.

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