The aim of this project is to maximize the flight time/ battery life of the very famous Hubsan X4 quad-copter. This will show how you build your own for very low cost, simple to build and fun to play with. The 3D print is 100% designed by me for use with spare parts from the Hubsan H107L model. It consists of a chassis that fit a receiver, four 7x20mm motors, four 3mm LED´s and a clip to hold the battery.

The weight of this chassis is only 4.18g plus battery clip 0.49g. The whole quadcopter including chassis, clip, LED's, motors, propellers and receiver is only 21g. Excluding battery, that is 25% lighter than the original H107L model which weight is 27.8g. Even loaded with a 380mAh battery it´s just 3.5g heavier than H107L without its battery.

With battery: 31.35g compared to commercial 38.15g.

Continuous flight time with a 380mAh battery was measured to 11.5 minutes. I don´t have a H107L to compare with but I think it´s maximum 10min. Please let me know it you have one!

The 2 gram circuit board is quite advanced for its small size. It has a built-in radio receiver, 4 Motor + 4 LED drivers (which also signals low battery level), 6-Axis Flight Control with automatic or remote gyro calibration, 4-Way Flip support, and both Beginners & Advance Mode for different range of performance. The radio transmitter can be calibrated as well with adjusted sensitivity, flight control fine tuning and remotely turn off LEDs. Fligh performance can be set during the flight as well as enabling/disabling flip-mode.

Due to its low weight it´s also very quick and reactive. A great fun to play with. It´s robust enough to fly with but don't expect it to take too serious damage. It´s optimized for weight, not robustness. Maybe if you print it with 100% infill and another material it could take more damage.

All 3D printable files are downloaded from my build at http://www.thingiverse.com/thing:681232

I include the original Rhino CAD file if anyone wants to modify the construction for improvements. It could easily be converted for the stronger 8mm motors for example. For more details of what parts to buy and how to actually build it, please read further!

Step 1: Materials and Equipment

Prices can differ but you can find everything needed at Ebay. I will not provide with URLs as they change over time. Look for Hubsan h107c, except for the motors that must be for h107L. If you don´t already have a transmitter it´s probably more cheap to buy a whole quadrocopter with it included and take the parts from that.

Materials

3D printed chassis and battery clip: Files downloaded from http://www.thingiverse.com/thing:681232
1x Radio transmitter: Hubsan H107C-19 4-Channel 2.4GHz [$24]
1x Radio receiver+flight control: Hubsan H107-A34 [$19]
4x Motors: Hubsan 7x20mm (2x CW, 2x CCW) for H107L [$7]
4x LED: Hubsan H107L & H107C LED (2x Red, 2x Blue, 3mm diameter) [$6]
4x Propellers: Hubsan H107-A02-PRO (2x TypeA, 2x TypeB) [$2]
1x Battery: HUBSAN HS-H107-A24 3.7V 380mAh Li-Po Battery [$9]
1x Charger: Hubsan 3.7V Usb Charger [$2]
2x screws: Hubsan Part H107-A07 Screw set [$2]

Total cost (without transmitter): $47

Equipment

3D printer (I used a Wanhao Duplicator 4x, similar to Makerbot)
Soldering iron
Screwdriver
1mm drill or a sharp tool

Step 2: 3D Printing

For the print I used a Wanhao Duplicator 4x printer. It´s similar to makerbot. For filament material i choose PLA because it´s easiest to use for beginners. If you want more rugged construction you better choose a different material. For slicing software I use Simplify3D, very easy to use and creates very good prints. It cost a bit of money but it´s worth it in the end. I manually defined the support structure for example and you find that in the images.

You can find all settings in my images but here is the most important ones for the body:

Filament: PLA
Nozzle width: 0.4mm
Extrusion width: 0.46mm
Layer height: 0.1mm
Top solid layers: 5
Bottom solid layers: 5
Shells: 1
Infill: 10% with 50% extrusion width @ 75 & -25 degrees
Support infill: 30% and offset 0,25mm
Temp extruder: 218C
Temp bed: 60C

For a more robust body I recommend 100% infill and 2 shells. For the battery clip you can use same settings except extrusion width which I set to 0.42 to get a better fit on the body. For bed adhesion I used regular painters tape.

Printing time: 2.5h
Material cost: 0.25 dollars

Step 3: Construction and Soldering

The construction is very basic and I made it plus the soldering in just an hour (including taking photographs). The circuit board has a clever design where it´s almost impossible to connect wrong motor to wrong connections, but please look at my images to make sure you put the motors in correct place! There are two different type of motors and two different type of propellers, clockwise (CW) and counter clockwise (CCW).

Help Table:

Propeller A = CW: Red=plus, Blue=minus
Propeller B = CCW: White=plus, Black=minus
Blue LED = Front: Red=plus, yellow=minus
Red LED = Rear: Red=plus, yellow=minus

Construction:

Place the circuit board in the chassis
1. Make sure the holes in the circuit boards is on top of the two fix
2. Drill two small 1mm holes in the chassis using the circuit board as reference
3. Use two small screws to fixate the board
Place the LED´s first in the small holes pointing to the ground (if you want to fly high)
1. Make sure Blue LED´s are in the front and red led´s in the rear end
2. The circuit board power cable indicates rear end of quadcopter
3. Put the LED cables through both slits so it will go beneath the motor
4. Use a small tool to bend the cable correctly beneath the motor before you place the motors
Place the motors and make sure the cable fits into small slit beneath the motor together with LED cable
You can fix the cable in the long slits under the arms later using a bit of glue

Soldering:

Do NOT cut the cables, they already have correct length
Set soldering iron to 180C (too high temp can damage the circuits)
Use the help table above to get polarization right
1. All LED and motor connections are closest to the correct LEDs and motors
Heat each connection just a few seconds, if you miss let it cool and try again to avoid damages.
Fixate all cables with small bits of glue

You can now place the battery beneath the chassis using the clip and you are ready for a flight!
Place the quadcopter on flat surface and calibrate the gyro from the controller by holding throttle in it´s lower right position and switching fast right pad left/right/left/right a couple of times until you hear a sound and the LED´s flashes one time.

Step 4: Specs and Results

I´m satisfied with the result and it´s really fast and fun to play with. Lighter, faster and longer battery life than original but maybe a little less robust. You may want to fly over grass and not full speed into a stone wall! Thus main reason to build it "because you can" and "3D printing is fun" =)

Weight Stats:

Chassis: 4.18g
Battery clip: 0.49g
LEDs: 0.68g
Motors: 13.6g
Circuit board: 2.05g
Battery: 10.35g

Total weight without battery: 21g (25% lighter than original)
Total weight with battery: 31.35g (18% lighter than original)

Hubsan H107L weight without battery: 27.8g
Hubsan H107L weight with battery: 38.15g

Battery Life

Continious flight time measured to 11.5 minutes!

Dimensions:

Motors CC: 64mm (1mm smaller than original)
Max diagonal outer fan-fan: 145mm
Max height: 30mm
Body center height: 5.5mm

Other:

Remote distance: 100m
Motors: 50000 rpm, 7x20mm, 1mm shaft
Circuit board: Radio receiver, 4 Motor + 4 LED drivers, 6-Axis Flight Control, 4-Way Flip support and Both Beginners & Advance Mode For Different Range of Performance