Pi Drone Assembly Part 1 – base pi drone frame

In this first post of a series about the Raspberry Pi Drone Project, I’ll show you how I started to build my drone. The series will be broken up into many short(ish) posts to make it easier to follow along. I’ll loosely be following along with this instructable (which I recommend you read for extra info) throughout the series. In this part we’ll be covering how to make the basic pi drone frame. We’ll start by talking about the things you need before you get started (and that you need to be able to do).

Prerequisites for the project as a whole

  • Around £200 (I will update this price when everything is tested and finished).
  • Basic tools like screwdrivers and a pencil.
  • A saw or hacksaw.
  • A phone running a recent version of Android – there isn’t an app for iOS (or at least not yet).
  • Lots and lots of time – research and assembly both take a long time.
  • Good organisational skills – there’s a lot to keep track of here and a lot to do to make sure everything works.
  • The ability to use a soldering iron, and a good iron.
    • (a little 10W iron might not heat things up very easily).
    • Preferably you’d have interchangeable tips as well – some of the soldering later on involves quite small components.

Parts used in this post

  • A large piece of 0.5cm thick plywood for the frame.
    • I got a large sheet of plywood (610×1220 mm) from B&Q for roughly £12.
    • It ended up being far too much, but that’s ideal because then you can re-cut if needed.
    • You’ll need to cut 4 arms, each being 21.5cm long and 4cm wide.
    • You’ll also need to cut 2 12cm squares of wood for the centre of the drone.
  • Some screws to fix the pieces of the frame together.
    • I bought a small bag of miscellaneous screws and nuts from B&Q at the same time as the frame for around £2.50 per bag.
    • The screws need to be a bit longer than 1cm – the combined width of the overlapping plywood – to be able to secure it well.

Pi Drone Frame Assembly

Cutting out the basic pieces of the frame

First off, you need to mark out the lengths of wood you need to cut with a pencil. Remember that you need to cut 4 arms, each being 21.5cm long and 4cm wide, and 2 12cm squares of wood for the centre of the drone. I recommend using a set square and/or a compass to try to make sure you cut at right angles.

It’s worth trying to do this without wasting much wood, but if you bought some excess that’s good because it means you can re-cut if you need to. Here’s how I marked it up.

The plywood marked up ready to cut
The plywood marked up ready to cut

The image is a bit faint, but hopefully you get the idea. These are fairly simple shapes so cutting them is quite easy with a saw (what I did), but using a hacksaw will probably make it slightly more accurate.

You won’t need the second piece for the base for a little while, so put it somewhere safe for now. This is what my pieces looked like:

The pieces that make up the drone frame
The pieces that make up the drone frame

Fixing the pi drone frame together

NOTE: In my case, I found that I needed to make a little modification to the arms, and take the corners off to make more space for the standoffs for the power distribution board. I don’t recommend you do this though, because it makes the arms weaker, and isn’t necessary as I later found out (details coming later on).

So to fix the arms, you want to do each one at a time, making sure they’re centered and aligned with each side of the base, or the drone won’t fly well. To make sure the joins are strong enough, I recommend that you overlap the arms with the base by at least 4cm. A little more couldn’t hurt, just as long as you have room for the standoffs for the power distribution board.

Mark up regular intervals where you want the screws on the arms (not too close to the edge of the arms!), then line everything up, fix in place, and drill through both the arm and base at once with an appropriately-sized wood drill bit. You can make the screws staggered as I have, or in a straight line – it shouldn’t matter much.

Once done, you should have something that looks a bit like this, and that is roughly 55cm in diameter (depending on the overlap you chose).

The first part of the drone frame assembled
The first part of the drone frame assembled

Note that I accidentally drilled in the wrong place first time for one arm. It doesn’t seem to matter too much though – don’t worry. If you need to, you can always cut another arm because plywood is very inexpensive. The arms should all be very close to 90 degrees from the sides of the centre, and the diameters should be within a few mm of each other if you’ve done a really good job. If it’s slightly off it’s probably not a huge deal though – the flight controller we’ll be using is quite resilient to imperfect frames.

Part 1 Summary

We didn’t do too much here, but it’s solid progress. In the next part (which may be a bit longer) we will cover power and connecting the motors. Have a look at the project page to see the current status of my drone.

That’s all for now but stay tuned for more posts coming soon.

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About Hamish McIntyre-Bhatty

I'm currently studying for a Computing and IT degree with the Open University, and am a software developer as well. I enjoy coding in Python, C++ (still learning), and Java. Having written 4 open-source programs (hosted on launchpad.net), set up my own website, and started volunteering at Wimborne Model Town to work on their river control system, I still find the time to enjoy cycling, acting, photography, and playing bass guitar. I go climbing every now and then as well. More recently, I wrote my first commercial program, Disk Verifier, and created a PSID Unlocker GUI for Parted Magic. I also create tutorial and other informative videos for Parted Magic LLC.

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