Building a quad is a pretty time-consuming project that requires good soldering skills and decent electronics knowledge. This, however, makes the final product so much more rewarding!
*NOTE: I have built SEVERAL quadcopters following the creation of this post and have learned a lot more about them. This is a great beginner setup but I would personally recommend different parts now that I have much more experience in the hobby
Order your parts from a reputable RC gear dealer such as Hobby King or getfpv. I chose to get many of my parts from Ready To Fly Quads and I was very happy with everything except the motors. I will be replacing my motors with Emax motors shortly.
To minimize shipping costs, remember everything you need so you can order everything in one shipment.
Quadcopters use different propeller directions to control yaw movement, so we need 4 sets of Motors and ESCs -- two that are spinning counter clock-wise, and two that are spinning clock-wise.
Start with the motors..
Cut the leads to a reasonable length, but not too short. Then, tin the leads.
Once you have done this on all four motors, cut the heatshrink off of all four ESCs and desolder the pre-existing leads. Keep the heatsinks as we will put them back on later!
Then, solder all 4 motors to the ESCs, but on two of the motors switch any two of the leads. This will reverse those motors' directions.
Now, test all the motors to make sure that you have two spinning in each direction.
Now, if you wish you can heatshrink the ESCs to protect them, but make sure to remember to put the heatsinks back on.
I, however, decided to cut the heatshrink off later and heatshrink the escs directly to the carbon fiber arms.
Now, screw the motors onto the 4 arms. Make sure that when you screw in the motors the screw does not jam into the motor windings.
At this point, I Heatshrinked the ESCs to the arms and labeled them according to which way they were spinning.
Now, we get to start putting things together to achieve a final product.
First, lets build the power distribution and flight controller sandwich. This will mount to the frame and provide us with a mounting surface for our two PCBs that are being mounted on our quad. For this I used 8 1cm aluminum standoffs with m3 threads. I took the two sets of four and sandwiched the power distribution board from Hobby King in between them. The size of your PDB should match the size of your flight controller if you want to organize your build this way. You should also solder on some power leads at this point which will be used to power the entire build. I chose an XT-60 connector as is the standard for most small 3S batteries.
Now, before putting the flight controller on top of this, we have to prepare it by soldering the pins on.
Now we can start to see where everything will be when the build is done:
Now we start to piece together to puzzle. Do this one arm at a time. I just used the top section of the bottom plate to hold the arms in place as I routed the wires and soldered them to the power distribution board.
Make sure, that as you are placing the arms, that the motors with the right rotation are going where they are supposed to. This varies from flight controller to flight controller, but the X quad standard is:
Top right: CCW Top left: CW Bottom Left: CCW Bottom right: CW
Also make sure to keep track of which ESC signal wire belongs to each ESC.
For a clean-looking build I routed as many wires I could in between the two sections of the bottom plate. Keep in mind that this only provides about 3mm of room, so don't go crazy. This meant that I would have less wires visible on top, and therefore more room for mounting cameras and other accessories.
Here I soldered all the power leads to all 4 ESCs to the power distribution board, which will provide all the ESCs with power from the battery when it is plugged in.
Before installing the bottom plate, don't forget to install the aluminum standoffs for the top plate, as the screws for these will not be able to be accessed once the bottom plate is screwed down to secure the arms.
It is at this point that you will want to route all the wires you can/want through the center hole in the frame. Then, screw the bottom plate in, securing the entire lower portion of the frame and arms.
OPTIONAL STEP: Depending on your ESCs this step is optional or required. Each ESC is equiped with a BEC (battery elimination circuit) which supplies 5v through the red and black wires of the servo lead. If all 4 BECs are connected to the flight controller, this can either cause excess heat generation or kill your ESCs/flight controller. This is wht at this point many people snip the red and black wires on 3 of their ESCs, leaving just the signal wire on all ESCs but one.
There are two sets of wires going to your flight controller. The first are the wires from your receiver, and these will be clearly labeled on both the receiver and the flight controller. This is as simple as matching "aileron" to "aileron" and "elevator" to "elevator".
The second set of wires goes from your flight controller to your ESCs. For this you will have to refer to the manual for your flight controller. Make sure you get this right or else your quad will not fly. Also make sure to follow any instructions regarding channel reversal depending on the FC.
After these are connected, you can finally install your fligh controller ontop of your PDB. Make sure it is facing the right way!
At this point, give all your connections a double check, and test everything! Make sure your receiver is bound to your transmitter and make sure the Multiwii goes through its self check successfully.
After a succesful check, see if you can spin up the motors by arming the quad and slowly throttling up. MAKE SURE THERE ARE NO PROPELLERS ON THE QUAD AT THIS STAGE.
If all is well and all motors are spinning the right way, then you can install the top plate!
YOU ARE DONE! At this point I recommend that you connect to your multiwii via Multiwii WinGui and calibrate your accelerometer and magnometer, as well as to set up flight modes. As a beginner you may want to fly in Angle mode (self-leveling mode) or Horizon mode (Angle mode with higher sensitivity as the sticks go past a certain point) and experienced pilots can fly in Acro (acrobatic) mode.
When installing your propellers, keep in mind that some of the motors spin in different directions. You want the propellers to pull air from above the blades and push them down.
Before actually taking off, bring the throttle up to about 5-10% (where the motors jsut start spinning) and test out the controls, making sure that the quad responds in the correct manner (left side lifts up, front lifts up, etc)
If you get into a bad situation, make sure you cut the throttle. If your quad crashes and the motors are unable to spin, you must make sure you zero out your throttle or disarm the quad, as if the motors try to spin and they can't you will kill your ESCs.
Pretty cool, huh? You have build a carbon fiber framed quadcopter. Don't be afraid to crash! As long as you are in a field with a soft surface, you have NOTHING to worry about. Speaking from personal experience, it is really hard to start flying, ESPECIALLY in acrobatic mode.
Enjoy your quads, be safe, and have fun!