Simple Quad Scratch Build

Hi! I know this isn't Flitetest's scratch build, but I was looking for build thread of a simple quad for a long time, so I decided to do it myself.

Here I'm going to show you complete build of my quad-copter (simple quad)

Note: I'm just a 14 years old boy, so don't judge me if you find any mistakes.

   Here is a list of the components and parts I've used:

Motor: 4 hexTronik DT750 Brushless Outrunner 750kv

ESC: 4 TURNIGY Plush 25amp Speed Controller

Control board: 1 Hobbyking KK2.0 Multi-rotor LCD Flight Control Board

1 TURNIGY BESC Programming Card

2 PolyMax 3.5mm Gold Connectors 10 PAIRS

1 10x4.5 SF Props 2pc Standard Rotation/2 pc RH Rotation (Red)

1 10x4.5 SF Props 2pc Standard Rotation/2 pc RH Rotation (Black)

1 Hex locknuts M4 10pc

1 On Board Lipoly Low Voltage Alarm (2s~4s)

1 XT60 to 4 X 3.5mm power breakout cable

1 MPX Connector Male/Female (10pairs/set)

1 10CM Male to Male Servo Lead (JR) 26AWG (10pcs/set)

Note: When I was ordering at HK they didn't have  it in stock so I soldered my own cables from Servo Terminals and 15CM Servo Lead Extension.

For battery I suggest 2200mAh 25C Turnigy battery. I already have some 3 cell batteries lying around so I haven't order new ones.

Later I realized that somehow I haven't ordered breakout cable, so I had to solder it by myself. I used multiplex connectors instead of XT60's.

   Frame Building:

To make frame as simple as possible I decided  to do it from 4mm plywood and 10mm (0.393 inch) square spruce sticks, which could be found in any DIY store.

 First cut two arms on length 60cm (23.62) with handsaw. At half (30cm) measure 5mm on each side and cut 5mm deep slot. Make sure that both together fit perfect. If not sand edges until it is OK.

Then cut two square pieces out of 4mm plywood with dimensions 12cm*12cm (4.72*4.72). These will be used for reinforcement.

Now when you got all parts cut out and they fit together perfectly it's time to glue all parts together. I use wood glue, because all parts are wooden and it allows mistakes (you got a lot of time to make sure that arms are perpendicular).

First glue arms and again make sure it's perpendicular.

Wait for about 10 minutes that glue barely sticks and glue your upper plate on.  Try to fix corners of the plate in the middle of the sticks. Make sure it's still perpendicular. If it isn't try hard to fix that problem. 

After about 10 minutes glue the other plate on.

Well our frame is done.

Now it's time to paint your frame (to look better and protect wood from water and dirt) if you want. I decided to paint mine white, because I had some white acrylic paint lying around from other projects.

The total weight of unpainted frame should be somewhere around 110g.

That is 3.8 ounces.

   Installation of motors:

Well as tape wasn't self-adhesive I decided to hot-glue it on frame.

   Programming ESC's:

In this step you should take your ESC's connect them into programming card (BEC plug) and connect battery. Then turn the brake off, select Ni-XX type (that ESC's don't switch off motors in mid-air) and set low voltage cut off.

   Balancing props:

This is an important step to get your quad stable. You need a prop balancer some tape and of course props. As there is already article about ways to balance props I guess that I don't have to show you how to do it.

   Connecting everything together:

Now get your motors into the mountings and connect them to ESC's.

Then put a zip-tie around wires to fix ESC's in place

Later connect your receiver with KK2 board as seen on the picture

Now connect one of the ESC's in M1 plug. This plug powers up flight controller and receiver. Then keep pressing the Down button until you get to the Select configuration menu. Select X-Quad configuration. Then go to show configuration and connect ESC's where they should be.

 Turn on the receiver and test if motors are spinning in right direction. If they aren't switch two wires on motor.

Now it's time to put your props on, fix your battery and test it.

Some photos with new camera ;)

And finaly first flight!

And after more than fifty flights... finaly a broken prop!

After lots of flights (and crashes) I have to say I'm pretty impressed with quad-copters. They're so stable and durable. Here is a table of downsides and good sides of my simple quad:

Advantages:

1. Durability (wooden frame, shortened axle)
2. Cheap electronics
3. Cheap light and durable frame
4. Weight (pretty light)
5. Absorbs some of vibrations (wooden frame)

Disadvantages:

1. lots of twisting on arms (I recommend using thicker sticks for frame)
2. Battery is on the bottom (possibility to damage it)
3. Weight (could be lighter from carbon fiber)
4. Not suitable for carrying a camera (Board and receiver on top, battery on bottom)
5. If you bend an axle on DT750 it's hard to find replacement