Wanted to play around with angled arms on a mini quad so figured it was a good excuse to play with openSCAD some more.
I keep modifying the design as I fly and crash this thing so this is very much a work in progress. For the most up to date files be sure to checkout my github project where I've tracked the development. I don't always update the files here with every little change since I make so many so often.
I've built and flown this in several variations and confirmed it's a pretty fun little quad.
I fly and recommend dRonin because I love it's autotune:
First flight with the original PLA center and acrylic plates ended about how I expected it to:
The new PETG center and lexan plates have proven VERY durable and are why I now feel this is finished enough to be worth sharing.
I've posted an Instructable with details about this build and more details on making your own which I've also entered into the Drones Contest 2016 - if you like this even a little I would really appreciate your vote! http://www.instructables.com/id/Ultra-Budget-Mini-Quad
You can also find even more details about the design and build process on my forum thread at Flite Test where I documented this project as I worked on it.
Folger Tech 2020 Prusa i3
I've printed this in PLA and PETG - I would NOT recommend PLA for the center section as it's too brittle and will likely break in any kind of crash. PETG however has held up great in even some hard fast crashes into pavement.
For the infill I used slic3r and a custom modifier STL (included in my github repo linked above) to do 80% infill in the center of the center section but only 10% around the arms to save weight. With 4 perimeters this has proven to give plenty of strength but still have enough flex to absorb the energy of most crashes. If you can't or don't want to do variable infill I'd stick with about 60%-80% for strength.
To attach Motors
16 - m3 x 22mm bolts for motors (Can be adjusted by modifying the motor mount openscad definition)
For attaching Arms
8 - m3 x 30mm bolts for arm mounting. May revise design to use only 4 bolts or maybe 4 m4 bolts.
16 - m3 washers for arm mounting bolts. (or 8 if only using 1 bolt per arm)
8 - m3 nylocs for arm mounting bolts (or 4 if only using 1 bolt per arm)
For Flight Controller Mounting
4 - 3mm tall m3 M/F nylon (or printed) standoffs.
4 - m3 O-rings (optional for some setups - helps minimize vibrations to flight controller)
4 - m3 nylon (or printed) nuts
4 - m3 x 12mm nylon (or printed) screws
Top Bottom Plates
2 - 4" x 4" pieces of 3mm polycarbonate or Carbon Fiber - DXF files included for use as templates or with a laser cutter or CNC. 1/8" plywood would also work and be lighter but is opaque - I tried 1/16" ply and it worked but did crack in crashes. I also tried acrylic but it proved too brittle and I would not suggest it.
openSCAD! I'm still working on making the design more parameterized and would love to turn it into a customizer...but I doubt there's enough interest in it to be worth the time. I may still do it juts for kicks someday but unless this proves popular I wouldn't hold my breath waiting for me.