Foldable 3D Printed Drone

Introduction

I only started this project as an experiment, to see if current desktop 3D printing could be a viable option for a drone frame, and also to take advantage of the fully custom nature and make it a little out of the ordinary.

There are many affordable carbon fiber frames readily available, but only a few are foldable, and most of these are kind of large and not in the micro-drone scale that is becoming very popular. So, I went about designing my own:

Well, I have been extremely surprised by the results. Normally, 3D printed structures are have too much flex to be viable for drone frames, but modern PLA filament has come a long way in just the last year or so, and at this scale, the frame is surprisingly good, and very light weight.

The all-up-weight of my one is 184 grams. The typical flight time is around 17 minutes, which is amazing for this size drone. And, thanks to recent micro HD cameras, like the Caddx Turtle, it takes very smooth 1080p 60fps video.

Audience

This project is mostly intended for people already familiar with DIY racing-style drones, although could be completed by a novice with some additional reading, which I will provide links to.

Most DIY drone builds use a range of flight controllers which are based around the STM32 family of processors, like the F4. The flight controllers run a number of open source firmwares, like Betaflight. There is an easy to use Configurator program for setting up the particulars of your build. Just go to https://betaflight.com for info.

Printing the frame

Just go to this thingiverse link to download the STL files: https://www.thingiverse.com/thing:3997199

The default print settings are fine for this build. I used Cura for the slicing, at 20% infill, 0.2mm layer height. If you want slightly better strength/quality, you can try 0.15mm, and 25%. I use PLA filament from https://3dfillies.com/

The arms are all identical, so you just print 4x. There are, however two types of arm STL files you can choose from. One is for 110x (or the H1304) motors, for the 9mm hole spacing. The other is slightly longer and has 12mm hole spacing for 1306 motors, and 4.5 inch props.

You can also build for two different main body heights. Either 20mm or 25mm. My build uses 25mm standoffs, but you may want to use 20mm ones for a slightly smaller build. The Caddx camera only fits when using the 25mm height.

The assembly is very easy. You just need 4x 14 to 16mm M3 bolts, and 4x 7 to 9mm bolts to hold everything together:

You can optionally print the front and rear braces for added stiffness:

Finishing touches

You may need to use some sandpaper on the round ends of the arms which slot into the swivels, to get the right fit. You want the fit to be very snug, though, as the arms just stay in place by friction. Tighten the longer bolts so that the friction is adequate, but donot over-tighten as you may crush the PLA and weaken the arm.

The front holes for mounting the camera posts will probably need to be filed slightly, with a square-end file, until the fit snugly.

Installing electronics

The bottom plate of the frame has mount holes towards the front for a 20x20mm stack. This is a very popular size for flight controllers and 4-in-1 ESCs. You typically mount the 4-in-1 ESCs at the bottom, then solder the 4 motors to the 12 pads (3 for each motor). Then the flight controller on top, then the HD camera board on top of that:

If you are new to DIY drones, Oscar Liang has very good guides on how to do the basics: https://oscarliang.com/build-racing-drone-fpv-quadcopter/

IMPORTANT: to prevent the arms gradually folding inwards during flight, you MUST mount the propellers in the reverse direction, and configure Betaflight like below:

The results

The resulting build has really surprised me, and has become my go-to drone. I usually keep it (and my Jumper T8SG radio), in my backpack. I hardly notice it there. At any time I can get decent video, with a range of about 1.5km, and long flight time. Not band at only about $180 (AUD) in parts.