Build Your Own 3D Printed Mini Racing Quadcopter

WARNING: Spinning propellers are dangerous! Do not put the blades on your quad until you are ready to fly. A 700 degree soldering iron also does a pretty good number on human skin before you even know you touched it. Ask me how I know!

I found this project on thingiverse and decided I had to give it a try. Hovership has created a 3d printable mini racer quadcopter called the MHQ2 and has posted the 3d printable STL files and even a nice build guide online for free. This copter was also featured in a recent issue of MAKE: Magazine. Enough people had already built these that the bugs are already worked out of it. The entire thing shouldn't take more than a weekend of work. You could probably put it together completely in 1 day if you had everything ready to go.

Since the copter itself is very small it does not use very much filament. I printed the entire frame in about 2 days. A couple of the frame plates are very large however and I had to print at least one of them diagonally on my Ultimaker 2 in order for it to fit. There are also a lot of additional or remixed parts on thingiverse to suit different people's needs.

The cost for this entire build (assuming you already have a radio controller) not including FPV camera gear, is about $225. Of course it's always possible to spend more or less than that but that was the total for the components I chose.

So, warm up your 3D printer and let's get building!

Electronics:

These are the parts I chose, but that doesn't necessarily mean they are the fastest, best, cheapest, etc.

• Naze32 Acro flight controller ($25)
• Emax MT2204 2300KV Brushless Motors (set of 4, 2 CW & 2 CCW) ($60)
• Zippy Compact 1300mah 3S 25C LiPo battery ($9 each)
• Favourite Sky 3 Quattro 4 x 12A Brushless Quadcopter ESC 2-4S ($31)
• FrSky D4R-II 4 Channel 2-way Telemetry Receiver ($30)
• Gemfan 5040/5040R 5x4 props ($4 per set. Buy lots of extras!)

Optional:

• Video transmitter ($25)
• GoPro or Mobius camera ($60-500) - There are cheaper FPV cameras but this frame is setup for a GoPro. Remixes exist on thingiverse that should allow you to try other camera types.
• Video Receiver/display ($60-500) - Lots of options here from inexpensive LCDs to Fatshark FPV headsets.

Hardware

You can actually order the build kit directly from hovership ($16) if you don't want to find and order these parts individually. Since I was building more than 1 of these I ordered all these parts in bulk, mostly from mcmaster-carr.

• 4x M3 20mm screws
• 8x M3 18mm screws
• 4x M3 12mm screws
• 12x M3 5mm screws
• 4x M3 5mm nylon screws (for mounting flight controller)
• 6x 35mm black nylon standoffs (you could use metal but the nylon ones are far cheaper, especially on eBay)
• 4x 6mm M3 white nylon spacer (for mounting flight controller)
• 4x M3 white nylon nuts (for mounting flight controller)
• 16x M3 Locknuts
• 8x M3 nylon washers (2 per motor arm)
• 8x M3 metal washers (2 per motor arm)
• 6x 7mm size vibration dampeners

Misc

You'll need a few other random parts to finish this build.

• Battery Strap - I got an 8" which was a bit too long but worked well after trimming an inch or two off it ($3)
• Antenna tubing - one piece is plenty. ($2)
• Small Zip Ties
• Heat Shrink Tubing ($5)
• 2mm Bullet Connectors ($6)
• Power connector ($1)
• Servo connectors and wire or a servo cable you can hack up (rx to flight controller connection) ($5)

You can get the parts on the MHQ2 thingiverse page.

• If you do not yet own a 3D printer (I'm sure you want one by now!) you can get the parts made by someone in your area using 3dhubs.com. When that person inevitably wants to build one of these copters too you can point them to this instructable. :)
• Most of the parts are very thin and do not use a lot of filament.
• I printed all my parts in ABS in .2mm layers. ABS allows the parts to bend a bit without snapping. ABS can also handle higher temperatures than PLA so it shouldn't warp in the sun, which is important in this application.
• I printed 2 of the motor mounts and the front landing gear in green to help identify the front of the copter. I also printed the large plate of the "clean section" in the same green to give it some color.
• The motor mounts and landing gear should be printed with 100% fill so they're strong. All these parts are so thin there's not much room for infill anyway so you're not saving much plastic or weight.
• At the speeds I was printing it took me about 2 days to finish all the parts.
• If you want to run 6" props you can use the extended arms instead of the standard ones
• There are also lots of other remixed or accessory parts for this copter on thingiverse if you search for MHQ2.

After you get all the parts printed you will need to clean them up. If you printed in ABS you may have brim material to remove from all the holes in the plates. An x-acto knife makes quick work of this.

Once all your parts have finally arrived it is time to begin construction. By this time I'm sure that your local UPS delivery guy and USPS mail carrier are wondering what you're up to.

This copter is quite easy to build. You could probably figure out how to put the frame together without my video or any instructions at all. I recommend watching my video above and also referring to Hovership's MHQ2 Build Guide.

Your steps will quite likely vary depending on the flight controller and ESCs that you choose!

At this point you should have your copter all wired up and ready to configure. If you are using the naze32 acro you will need to install baseflight. It is a Google Chrome browser add-on. Once you get that program started you can connect your flight controller to your computer via USB. The above video covers almost all of the flight controller configuration. It is very simple.

Other things you will need to do that vary depending on your hardware:

1. Bind your receiver to your radio. In my case I am using a Taranis and this is fairly simple. Loads of videos exist to cover just this topic by itself so I won't go into detail here.
2. Calibrate your ESCs. This teaches the speed controllers the range of the throttle it should expect from your receiver and ensures that all motors are configured to run at the same speed. This generally involves a simple procedure similar to the following: Turning your throttle all the way up, then powering up the flight controller and ESCs (no props installed!). This means you'll need a battery. Your ESCs will make some music then you turn the throttle down to the minimum position and they will probably make more noise. Then you can turn it off. You should check the instructions for your particular hardware as it may be entirely different.
3. Configure your flight modes. As you will see in my video above I was not expecting "acro" mode by default and ended up crashing. Unless you are experienced with this flight mode you will want to change it or set up a switch on your radio to choose the one you want.
4. Setup your telemetry or at least a flight timer. LiPo batteries don't like it when you drain them completely. Copters also don't fly very well with a dead battery so you don't want to let it get to that point. By setting up battery monitoring or at least a flight timer you will avoid losing track of time and finding yourself way up in the air with a dead battery.

If you made it through everything successfully you should be ready to go test fly it. This thing is pretty fast and potentially difficult to control due to its small size and weight. If you don't have experience flying quadcopters you might want to practice using a small toy or a simulator first. The controls should be the same.

Pre-flight checklist:

1. Make sure you have the correct props on the correct motors based on which way they spin!
2. Make sure you tested your controller and that the flight controls seem to be controlled by the proper sticks. if these are switched around or backwards you will probably crash before you realize the problem. (been there done that!)
3. Check over everything to make sure things are connected and that no wires are at risk of getting hit by a propeller. Yes I've done that too. :)
4. Make sure you have plenty of space to fly. The last thing you need is to worry about hitting something before you have full control over the copter. Maybe I should rename this to the "stupid things I've done" list.
5. Make sure your camera is recording!!!

Hopefully you can learn from some of these mistakes I've made without having to make them yourself.

Maiden Flight

To arm the copter hold your throttle (left) stick to the bottom right for a few seconds. Your props should spin slowly when it is armed. Slowly bring the throttle up until the copter takes off.

To disarm it move the throttle stick to the bottom left for a few seconds.

Next Steps:

• Install an FPV video transmitter and fly this thing via first person view!

Good luck and safe flying!