Hello all.
New to the forum but not multi's.
Since losing my 1st build APM , dead cat frame with gimble and action cam .Money and my wife's understanding have been stretched a little 
I started out again with 4 emax 2204 motors and ESC's a CC3D .This was swapped across seveal frames over the past 16 months or so .
The last 250 I built was just under 220gr inc FPV gear ,without battery.
It flew like a flying buddies 4S night hawk pro but on 3S .

Alas my poor piloting skills and one too many crashes caught up with me .
Snapped an arm and the lower plate after it dropped from the air on a fast run.

The ESC for one motor had blown , so swapped the ESC and the motor wouldn't spin up until around 1300 .
I didn't want to add a new motor to 3x 12 months plus old motors . Took a deep breath and ordered 4 motors and ESC's to put on a new frame.

This left me with 3x Emax 2204's and the calibrate when they feel like it bheli Emax 12A ESC's .
I have an SP3 for my next quad build ,so the CC3D was unused . 

Tri -copter then , lots of Googling a pencil and some paper .
The arms come from a piece of 10mm aluminium from a DIY shop cost £5 per meter ( carbon would be nice but I wanted to make it as cheap as possible).
 

I never throw any thing away so scanned my broken parts bin for bits of frame for F/C mounting ect .
After struggling with the maths of rotor distance I came across this great little app that does all the geometry and maths for you .

http://tcoptercalculator.co.nf/

Also this page and vid was really helpful

http://www.flitetest.com/articles/symmet...ign-theory

So plans drawn arms cut and holes drilled , easy .Then came the tail servo ( a new thing to me servo's).There are many clever and simple designs for the tilt rotor on a Tri and I toyed with many of them .
In the end I cheated   looking through google images at tri servo tails this came up .

 https://www.hobbyking.com/en_us/rotorbit...black.html
Ready made and fits 10mm cross section arms .

Wish I had found rotor bits earlier in my multi career . I large selection of motor holders and frame connectors for various sizes of square and round carbon or aluminium DIY frames .

Back to the build .After sketching out plans drilling and working out what was going where , I reached this stage .


 



It's got bit from 3 different frames   and weighs a whopping 328gr( 10mm carbon fibre for the arms would remove a lot of this) without batt . 
Since upgrading too Win10 my FTDI adapter won't work (must be a clone driver issues).
So the CC3D is running Librepilot which has little support or features for tri copters .
Despite this managed to get her air borne today after a few flips smashed props and panick attacks  .Still Need to sort out some servo judder and still needs some PID work .
But to my amazement it test flew really well . 
I'll post a vid when some 6inch props arrive and the tuning is sorted .
If you have 3 old motors in your box of bit's and are in the dark Northern hemisphere give a DIY  tri a try .
It will keep you busy on dark wet nights .
Cheers.

Great Project - also thinking of Building a tri. Planned to get a Baby tri from rcexplorer.se and reuse motors laying around. But gettin just some 10*10 Square tubes Isolde also work... Anyways you may could Flash your cc3d with the https://github.com/lkaino/Triflight/releases/tag/0.5 to get some better response and Support for the Tail ...

P.S.: rotorbits Looks ok but still im towards http://rcexplorer.se/product/tricopter-t...top-piece/

(05-Nov-2016, 08:09 AM)Clemens Patocki Wrote: Great Project - also thinking of Building a tri. Planned to get a Baby tri from rcexplorer.se and reuse motors laying around. But gettin just some 10*10 Square tubes Isolde also work... Anyways you may could Flash your cc3d with the https://github.com/lkaino/Triflight/releases/tag/0.5 to get some better response and Support for the Tail ...

P.S.: rotorbits Looks ok but still im towards http://rcexplorer.se/product/tricopter-t...top-piece/

Hiya Clemens .
I tried flashing cleanflight to the CC3D but it would not work . It looks like I will need a new FTDI adapter to achieve this .
And yes the rcexplorer tilt mechanism looks far more simpler with the direct connection of servo to the motor plate .
The gear mech on the rotorbits is a ratio of 1:1 so over complicated for no reason .