The Hummingbird: 3D Printable Freestyle FPV Drone (3.5 Inch)

What this instructable will show you:

This instructable will show you how to build a 3.5 inch freestyle FPV drone that is cost effective, easily repairable, and fully customizable using 3D printing.

Freestyle FPV drones are all about agility and durability, but commercial frames are often expensive, hard to repair, and not easily customizable. A 3D printed frame provides an affordable and crash-friendly alternative that lets you experiment with tricks, learn FPV without a fear of waiting weeks for replacement parts, or try a completely new frame style if you're already an experienced pilot!

My goals for the design of this freestyle drone:

1. Make the frame as modular and repairable as possible
2. Ensure durability in crashes
3. Make the frame easy to assemble and work on
4. Use common FPV components
5. Do flips, barrel rolls, and other tricks
6. Make videos while airborn

Specifications:

1. ~4.5 minutes of flight time
2. ~280 grams dry weight
3. ~370 grams with battery
4. 3.5 inch propellers

Note:

This build shares common tools, supplies, and some assembly steps with my previous project Heatseeker. Only build-specific instructions differ.

3D Printing Supplies:

1. PA6-CF Carbon Fiber Filament:
2. Used for durability and stiffness
3. PLA can be used, but your frame will be less stiff
4. Used for the main frame of the drone
5. ABS Filament
6. Used for durability and impact resistance
7. PLA can be used, but your frame will be less durable
8. Used in the drone's canopy
9. TPU Filament
10. Used for flexibility and shock absorbance
11. Used in mounts for electronics, spacers, and landing gear
12. Filament Drier
13. Used to dry filament after they have absorbed moisture
14. 3D Printer

Soldering Supplies:

1. Soldering Iron
2. Used to heat up solder and make electrical connections
3. Solder
4. Heated up to make electrical connections
5. Flux
6. Removes oxidation from solder joint and spreads solder evenly
7. Wire Strippers
8. Remove insulation from the wire

FPV Equipment:

1. ISDT 608AC Lipo/Li-ion Battery Charger
2. Used to charge batteries once they are depleted
3. Eachine EV800D FPV Goggles
4. Used to see out of the drone's camera while in flight
5. Radiomaster Pocket ELRS
6. Used to control the drone

Electronics:

1. Runcam Phoenix 2 Camera
2. Provides live video footage (any fpv camera with a width of 19mm would work)
3. SpeedyBee F405 Mini Stack
4. Used as the brain of the drone
5. Includes the Flight Controller, Power Distribution board, and ESCs
6. HGLRC Zeus Nano 350mW Video Transmitter
7. Used to transmit video to the FPV goggles
8. SpeedyBee Nano 2.4G ELRS Transmitter
9. Used to connect your drone to your controller
10. Emax ECO II Series 2004-3000kv Motors
11. Used to spin propellers and make the drone fly
12. OVONIC 4S 850mAh Lithium Polymer Battery XT30
13. Used to provide power to the drone
14. XT30 Male Connector
15. Used to connect the ESC (electronic speed controller) to the battery

Additional Hardware:

1. Gemfan Hurricane 3520 3.5X2X3 3-Blade PC Propellers
2. Used to generate lift
3. 20mmx200mm FPV Velcro Battery Straps
4. Used to hold the battery in place on top of the drone
5. Heat set inserts
6. Used to allow screws to be used in the 3D prints
7. Screws
8. Used to assemble the drone frame and hold electronics in place
9. Double sided tape
10. Used to secure small components

Optional:

1. SpeedyBee FPV Soldering Practice Board
2. Used to practice soldering before soldering the final components

Note:

You can swap out any component you want, but you may need to adjust the 3D model with CAD to fit the new dimensions or mounting points.

Files:

All part files can be found on this printables page. All files are in the STEP, allowing you to modify them after downloading.

Notes:

1. Files that begin with a number (ex: 4xArm-PA6-CF.step) indicate how many times that part should be printed
2. Each file ends in the recommended print material
3. When printing this I used PA6-CF for the main body and ABS for the canopy of the drone for their elevated durability and heat resistance.
4. These can both be printed in PLA but the results will be less durable.
5. PA6-CF and ABS produce harmful particles, so it is recomended to print in a well-ventilated area.
6. A heating chamber benefits these materials as it reduces warping
7. PA6-CF must be kept dry with a filament dryer for optimal print quality.
8. No supports were needed for the TPU parts.

Introduction to heat-set inserts:

Heat-set inserts are small brass threaded tubes with knurls on the outside which you melt into prints with a heated soldering iron. This allows reusable threads and strong connections.

Instructions:

Take any part and use the given diagram to determine which insert goes into which hole. Heat up your soldering iron and place the heat insert on top of the hole. Once the soldering iron is heated, place the tip into the threaded hole and push down so that the insert melts into the plastic. If it does not push in, increase the temperature.

The following method is used for all heat-set inserts in this frame.

Once all heat set inserts are installed, allow the printed parts to cool completely before assembly.

Notes:

The heat-set insert types in my diagrams are classified by insert thread size x insert depth x insert outer diameter

1. ex: M3x3x5 = M3 thread x 3mm length x 5mm outer diameter

Different heat settings for your soldering iron will be used for different 3D printer filaments. From my experience the following settings worked but you may have to experiment:

1. PA6-CF: 600° F
2. ABS: 500° F

It is better to have a lower temperature than a higher temperature, as a high temperature can cause the insert to go in too far and weaken the surrounding plastic.

I recomend practicing on a test print to figure out the proper temperature and timing.

Sometimes some plastic will bulge at the top as you push the insert in.

1. You can trim it with flush cutters/filament cutters once the part cools.
2. Make sure the insert is flush with the surface of the part.

Instructions:

1. Slide all 4 arms into the grooves on the central frame block.
2. Use m2x10mm screws for the arm's side mounting points and m2.5x10mm screws on the bottom mounting points. You will need 3 screws per arm, 12 screws in total.
3. Place the electronics deck on top of the central frame block. Line up the flight controller mounting holes and ensure the side mounting points are aligned.
4. Screw the electronics deck to the central frame block with m2.5x10mm screws.

Notes:

1. Do not overtighten the screws into the plastic inserts, make them just tight enough for a strong connection.
2. Longer screws are acceptable for this step.

Recommendation:

Before trying this on real electronics, I recomend you order an FPV practice board to get comfortable with using a soldering iron.

If this is your first time soldering, you should watch this video. Some vocabulary you will need to know is:

1. Tinning: Tinning is applying solder onto a pad or wire to make it easier to bond them together later
2. Flux: Flux is a chemical cleaning agent used to remove oxidation from a solder joint. It also helps keep heat distribution even and leads to cleaner solder joints.

Instructions:

1. Tin the top and bottom of the large ESC pads.
2. Solder the battery lead (XT30 connector) and capacitor to the large pads on the ESC. Remember that the capacitor's long leg is positive (+) and the short leg is negative (+). I reccomend soldering it onto the bottom side of the ESC. Reversing the polarity of the capacitor can destroy the ESC.
3. I have provided a wiring diagram as well as a picture of my own solder above. Ensure that your capacitor is going the same direction as the XT30 connector. The XT30 connector must be soldered at an angle similar to that shown on my picture so that the capacitor can fit in between the wires.
4. Tin the motor pads.
5. Attach the flight controller ribbon cable to the ESC.
6. Push the ESC down into the electronics deck and make the XT30 connector face the rear of the craft. I used m2 screws to temporarily secure the ESC while soldering the following components. Any length above 10mm will work as this is temporary.
7. Insert the landing gear into the bottom of each arm. Place the motor on top of the arm and secure both the motor and landing gear with the m2x12mm motor screws, passing the screws through the landing gear first, arm second, and screwing into the motor last.
8. Ziptie the motor wires to the lower beam of the arm in order to prevent them getting tangled in the propellers during flight.
9. Route the motor wires through the rounded rectangular slots to get them to the ESC.
10. Cut the motor wires to length and strip off some of the insulation. Tin the wires.Route the motor wires through the
11. Connect the motor wires to the ESC motor pads as shown on the wiring diagram. The order of the wires does not matter. Repeat this with all 4 motors.

Notes:

1. Do not overtighten the screws into the plastic inserts, make them just tight enough for a strong connection.
2. Only solder the components you have. You will likely not have to tin all the pads.
3. If you are using a different ESC, use the manufacturer's wiring diagrams.

Instructions:

1. Use m3x10mm screws and put them through the centeral mounting points from above as shown in the image attached. The top side is the one with the VTx antenna connector.
2. Push the VTX spacers onto the screws from below.
3. Screw the VTX into the two rear inserts with the antenna connection facing rearwards.
4. Remove the placeholder screws used on the ESC to temporarily secure it and place the flight controller on top of the ESC. Ensure the arrow on the flight controller faces towards the front of the frame.
5. Push m2x25mm screws through both the ESC and Flight controller and screw them into the four inserts on the centeral frame block.
6. Connect the ribbon cable from the ESC to the flight controller.
7. Follow the wiring diagram for the flight controller to solder wires to the VTx. Twist the VTx wires into a coil. This will help minimize clutter and intereference, resulting in higher image quality and repairability.
8. Take the unsoldered ends of the VTx wires and cut them to length. Tin the wires and solder them to the flight controller as instructed on the wiring diagram. I have attached the Speedybee F405 Mini's diagram above.
9. Attach the VTx Antenna that came with the VTx onto it.

Notes:

1. Only solder the components you have. You will likely not have to tin all the pads.
2. If you are using a different VTx or flight controller, use the manufacturer's wiring diagrams.

Instructions:

1. Use m2.5x5 screws to secure the camera/elrs antenna mount onto the electronics deck. Longer screws are acceptable.
2. Push the two sides of the mount apart and push the T-shaped ELRS antenna into the large circles. Push it back together. Place the camera into the front of the mount and align the camera's screw holes with the small holes on the mount. Use the m2 screws that arrived with your camera, in my case m2.4, to partially screw into it through the mount.
3. Adjust the camera to your desired angle and screw it in completely. Do not overtighten the screws into the camera. Too much pressure on TPU can cause layer seperation. You will be able to change the camera angle with the canopy attached so it does not have to be finalized now.
4. Take out the wire with a plug that came with your camera and cut it to length. Give it some extra wire so you can change camera rotation if desired in the future.
5. Tin the wire and solder it onto the flight controller following the wiring diagram. The wiring diagram for the Speedybee F405 mini is attached above.
6. Once the soldering is completed, take the end of the wire with the plug and twist it into a coil once again. This follows the same rationale as with the VTx. Plug into the camera.
7. Take out your ELRS receiver. Tin the pads on the chip and solder the wires that came with it to the chip.
8. Attach it to the antenna to the chip and use double sided tape to mount it in the area next to the VTx and behind the flight controller. Use the above picture for reference.
9. Coil the wires from the ELRS receiver and cut to length. Strip their insulation, tin them, and solder them to the flight controller.

Notes:

1. Do not overtighten the screws into the plastic inserts, make them just tight enough for a strong connection.
2. Only solder the components you have. You will likely not have to tin all the pads.
3. If you are using a different flight controller, use the manufacturer's wiring diagrams.

Instructions:

1. Take the canopy and align it with the electronics deck. Do not secure it yet.
2. Pass the VTx antenna through the rearmost hole and pass the XT30 connector through the forward hole.
3. Take the VTx antenna mount and pull the antenna through the center hole until it is a snug fit. Push it down into its slot and screw it in with two m2.5x10mm screws. Ensure the VTx antenna is not under tension and exits straight up from the canopy.
4. Press the canopy onto the electronics deck and screw into both of the rear canopy inserts through the holes in the electronics deck aligned with the inserts. Use m2.5x10mm screws.
5. Turn to the truss-like structure on the side of the electronics deck. Locate the circular hole that should now be aligned with the canopy's inserts and screw into it with more m2.5x10mm screws. Do this for both sides of the electronics deck.
6. Verify that the canopy sits flush on the electronics deck, all screws are securely tightened, and no wires are pinched between parts.

Notes:

1. Do not overtighten the screws into the plastic inserts, make them just tight enough for a strong connection.

WARNING:

1. Remove propellers before connecting the battery or USB. Propellers must remain OFF for the entire Betaflight setup.

Checklist:

1. Flash new firmware
2. Calibrate accelerometer
3. Ports Configuration
4. Verify Receiver Inputs
5. Modes Setup
6. ESC Flashing
7. Motor Direction Test (PROPELLERS OFF)
8. VTx Setup
9. OSD Setup
10. Failsafe Check
11. Save Settings

Instructions:

1. For this stage of the setup, I followed this video. Skip to 2:10:30 to get to the configuration portion of the build.
2. Use the attached two images in order to assist with motor direction setup. This build uses the props-in motor direction layout (first image), but props-out (second image) is also calid as long as your motor directions match in betaflight.

Notes:

1. After software setup you may screw your propellers tightly onto the motors. Use the screws that came with your motor. Ensure your screws are not too large for your specific propellers.
2. Make sure the leading edge of your propeller faces the direction of rotation.
3. Propeller direction images from Betaflight

Instructions:

1. Plug and unplug your battery onto the drone 2 times and then plug it in as fast as you can. This will put your flight controller and receivers/transmitters into binding mode.
2. In Betaflight, open the VTx tab and confirm the band, channel, and power level match those in your goggles.
3. For the Eachine EV800Ds, use the channel/band button on your goggles to get onto the right channel and band. Hold down the button to transition between the two modes.
4. For the Radiomaster pocket, click the SYS button to enter the tools menu and click the scroll wheel when ExpressLRS is highlighted in black. After this you will want to scroll down until you find the Bind option, in which case you will click the scroll wheel again to put it in bind mode.

Notes:

1. Refer to the user manual or online resources to find the connection instructions for your specific FPV goggles and controller.

Instructions:

1. Ensure all screws are secure and snug, not overtightened.
2. Motors must spin freely by hand with no rubbing or binding .
3. Propellers direction is correct and they are tightened.
4. VTx and ELRS antennas are installed correctly and securely.
5. Receiver inputs work correctly.
6. Motor direction and order are correct (Props off when testing).

Instructions:

1. Charge your batteries and equipment pre-flight.
2. Check all screws and mounts to make sure nothing is loose, especially the propellers.
3. Go to a safe location to fly, ideally a wide and open area.
4. Arm your drone, try hovering and test out basic controls.

Notes:

1. Do not keep the drone powered on while stationary for extended periods, the VTx can overheat without airflow.
2. Don't be afraid of crashing! That's why the drone is 3D printable!