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Folding Drone Build

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Drones are an addiction. You start with something small to learn on, then move on to something bigger like a 3D Robotics drone. You build your it, you fly it, and it’s awesome. Then you crash it and turn your $600 quadcopter into a an unrecognizable pile of parts. At least that’s what happened to me. This is the last recorded footage of my “old” drone before I stuffed it into the roof of the Henry Ford Museum at Maker Faire Detroit last year. A very large man was dispatched to retrieve it (they wouldn’t let me up there, I asked) and after 30 minutes, he lowered a box and a bucket down to me containing what used to be my drone. It was a sad day – I took no pictures and just shoved the whole thing into my trunk.

What goes up must come down and what comes down can sometimes go back up. When I got home I examined the wreckage. The airframe was tangled mess of fiberglass and aluminum but somehow most of the electronics survived intact. Two of the motors were broken, the APM had a crack in the case but was otherwise functional, and everything else including my GoPro checked out (the case was shattered but the camera still worked.) Now, I had never been a huge fan of the 3D Robotics frame. Yes it was rigid and light but it was rather big. It was a pain to store and difficult to transport in my car or anywhere else. I decided I was going to rebuild my drone and solve this issue in time for Maker Faire NY 2013.

Design Goals

  • Overall frame size must be similar to the original (I didn’t want to recalibrate the APM.)
  • The drone must fold up and fit into a carry-on suitcase.
  • Reuse as many parts as possible from the old drone.
  • Have plenty of room for FPV equipment (if I ever wanted to go that route.)
  • Be darn strong for when I crashed again.
  • Us easily replaceable parts.

Before the crash I was looking at other DIY frames and came across a guy on the on the RC Groups forums that build something called the Fold-A-Quad. I really liked the looks of it but unfortunately he didn’t post his design files. No worries, I loaded up Vectric’s Aspire and started to work on my own version. I decided to make the top and bottom plates interchangeable for simplicity. I somehow managed to fit these plates, motor mounts, and camera riser onto 1 – 24″ x 12″ sheet of 0.063″ G10 fiberglass. I considered 3/4″ square aluminum tubing for the arms but I was concerned about weight – especially if this thing was going to carry FPV gear. I went to Home Depot for inspiration and found it in the bathroom isle. They had some 24″ aluminum towel bars that were cheap, light, and fairly strong. I love finding stuff locally – makes it easier to find a replacement when your break it.

I originally considered using nylon screws to keep the frame together but after seeing the prices on McMaster Carr I opted for traditional M3 screws and lock nuts. I also priced standoffs but wow – those things are pricey! I started thinking about alternatives and went down to the workbench. I had some small poly tubing so cut off several pieces to try to get a consistent length. That didn’t work. Then I thought – “hey, I have a 3D printer – I’ll CAD some up and print them!” So I did. And they worked!

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Files

  • 3D Printed Parts (2 Legs, 20 Standoffs (print standoffs with skirt)) – GitHub
  • Frame – GitHub
  • Arms – GitHub

BOM

Frame

Electronics

Here’s some footage taken by the folding drone at Maker Faire NY 2013. I did a little FPV flying as well with my DIY FPV setup – that will be another post.

Overall I’m happy with the folding drone frame, however I would make an improvement or two, mostly with the arms. I found that friction didn’t keep the arms in place and I ended up using a drill press with a 1/8″ bit to drill straight through the frame-arm-frame sandwich to put in a pin in each leg. In the next version I’d like to make a locking system of some kind.