This is a fully parametric, fully printable, quadrocopter frame design done with Inventor. With this design you can print a quadrocopter with a 160-260mm motor to motor distance, giving enough room to accommodate props from 101.6mm (4") to 177.8mm (7").
Motivation: I wanted to build a quadrocopter which I could use to learn with, a basic requirement of this being that I need to be able to fix it with minimal cost and difficulty. So its a good job I have a 3d printer!
Draft: I started this design with the intention of squeezing all the electronics into the centre of the hub area, in the same plane as the arms. I completed a draft with this in mind, but I wasn't happy with how much plastic it consumed and I also hadn't given any though to how I would route cables around the frame. In addition to this, I based the design on "guestimate" dimensions, it was always going to need some sort of reworking.
Revision 1 (Pictured): The draft design gave me some good ideas to move forward with, it also gave me the confidence to buy the parts I'd need to eventually get this thing into the air. For this revision I moved the electronics to a more standard location on top of the hub area. There are fixing holes for the electronics on a square of 45mm about the centre, this can be varied. Another variable dimension is the motor to motor distance, which for this revision is set at 180mm allowing for a 10.16-12.7mm (4-5") prop.
With this revision I gave a little thought to routing of wires and came up with the "power layer". This component stacks with the hub of the quadrocopter and allows the esc's and battery to plug into the frame. Many quadrocopters suffer from the "flying spaghetti monster" problem, this solution goes some way to alleviate that.
This is the design I have printed, as it turns out I was being a bit ambitious with the prop size, all things accounted for it weighs about 450g. I calculate about 600g of thrust with this set up meaning its going to have to run at over 3/4 throttle to fly. Whilst not a show stopper its certainly going to strain the motors and esc's, and I doubt its going to be manoeuvrable.
Landing gear has also been added, not sure how it will perform but it certainly looks the part.
Revision 2: This design incorporates some lessons I learned from the previous revision. The arms are thinner, making them lighter per unit length, and allowing for greater prop sizes up to 177.8mm (7"). The thinner arms also mean the hub area uses less plastic, more weight saving. The minimum thickness of all components has also been reduced slightly in an attempt to remove some more redundant plastic. Due to the allowance for larger props I hope to achieve over 1kg of thrust with this design, giving much more acceptable performance.
motor_to_motor = Distance between motor centers, dictates arm length which is limited by build platform size.
arm_width = Self explanatory
arm_height = Self explanatory
mounting_square = The side length of the square who's corners lie at the center of the mounting holes.
hub_square = Width of the hub.
pinch_gap = Width of the gap between the top and bottom hub components.
power_thickness = The max thickness of your power distribution circuit.
battery_width = Self explanatory
battery_thickness = Self explanatory
structural_cover = The minimum thickness of any section.
Please take note, I havent flown this yet. I ordered a receiver that as incompatible with my transmitter and am waiting for a replacement from chine (boo). I shall update this thing with pictures and hopefully videos when I get the last bits in place.
I'm open to any suggestions as to how I can improve this design further. Moving forward, I'm going to experiment with different thickness's in an attempt to find a good trade off between weight and strength.
Some info on the electronics was requested. There is an awful lot of choice in this respect, you ultimately need to decide on a control unit and a drive system. For my control unit (not pictured) I use an Arduino nano, "All in one" sensor board which can be found on ebay, and a fly sky 6 channel receiver (FS-R6B) to go with my fly sky transmitter (FS-TH9X). Such a control system will work for any quad configuration. The drive system is dependent on the quadrocopter weight and maximum allowable prop diameter, this choice is non trivial and I suggest you visit some quadrocopter forums where you will find a huge amount of sadvice and suggestions.
There is a wealth of further information at Aeroquad.com and multiwii.com
I have uploaded 2 zip files, one containing the Inventor files and one containing STL files for the current final configuration. If you are unable to edit Inventor files and wish to have changes made to the design please ask in comments.
There's nothing too drastic to print here, no overhangs, just some slightly thin walls. When printing the arm and landing gear, make sure you have them angled 45 degrees across the build platform so that they fit. At 25mm/s feed rate I printed a full set in about 6-7 hours
To keep everything strong this is designed with zero tolerance for fits, your going to have to either calibrate your machine and add tolerances or file the parts like I did.
Hopefully its obvious how this goes together, 4 arms are inserted into the hub top and bottom, the power layer and battery mount stack underneath this. Secure with bolts(m3x30 bolt diameter is variable) and nyloc nuts.
For the power distribution circuit I used 2mm (variable) male bullet connectors which are secured in their groves with epoxy. The bullet connectors, battery connector and electronics power connector are wired to 2 copper plates one for positive and one for negative. The copper plates must then be insulated from each other. There is a gap allowed for the battery connector and electronics power connector to enter the power layer, the size of this gap is variable.
Landing gear slots onto the battery mount, you can either force fit this or add some epoxy.
I would suggest mounting the electronics with vibration damping stand-offs.
The motor mounts are designed for the 3 bolt mounts I have. I'm happy to knock up a more standard 4 bolt version if its requested.