fredag den 20. november 2015

DIY H4 home made frame

See the DIY frame in action, no tweeking done on the FC, flown by one of my students who is a complete novice and has no experience with quadcopters.

You might also want to read this article on the CC3D

Well was a bit bored so I decided to make a home made frame and see how it faired compared to buying a Ebay frame. So I went to the local hardware store and purchased a piece of 15mm x 15mm square wood measuring 2 meters in length. The length was a bit overkill, but could not find a shorter length, so i guess the rest will be used to repair the arms, when it eventually breaks. I also purchased a small square plastic box that is used by electricians to mount and combine electrical wires

Measured and drilled four holes for the mounting plate used four plastic bolts and fastened the mounting plate with plastic nuts.

Mounted 4 plastic bolts at the top of the mount and tighten with a thin plastic screw. The screw will act as a stand-off.

Slotted the power distribution board on the mounting plate

used 4 plastic stand-offs to fasten the board and drilled four holes at the bottom for the power cables to the ESC´s.

Soldered the main power cables to the PDB,There is a small switch under the board which enables the power to be switched on/off. The board worked on its maiden flight but suddenly cut off and i could not reinitiate any 12 volts, i did not test why, but simply resolved the issue by resoldering and connecting the main power cables to one of the + and - from the ESC's, bypassing the on/off switch and making the 12 volts live at all times. This PDB is not sold with a manual so the Internet and common sense was the way i had to go by setting it up.

Soldered a JST XH connector to the LED pins, this will deliver 12 volts to the LED light strip that I will mount at a later stage.

I then soldered 4 positive and 4 negative wires using each corner and fed the wires through the holes in the housing. These wires will be later hooked up to four ESC's on the quad.
The ESC's power cables are now done, was a bit of a hassle as the soldering plates on the PDB are small and close together, make sure to check that your cables are not shorting.

Powering the CC3D can be done in two ways, I chose to use a UBEC, I soldered the + and - to the second LED pins/pads. The UBEC will convert the 12v from the PDB to 5v for the CC3D. The second method of powering the CC3D is by using the BEC on the ESC and plugging it directly to one of the motor pins on the CC3D.
 Method 1. using the UBEC, The + and - wire leads from the UBEC

 Plug it into motor channel 1, remember to get the polarity right + is the middle rail, - is the bottom rail closest to the edge of the board and the top rail is the signal cable to the ESC.

Method 2. Using the BEC from the ESC. Simply power the CC3D using the BEC of the ESC. It plugs into the one of motor channel, giving the CC3D the required 5v.
Mounted the CC3D and tightened it down with 4 plastic bolts.
Cut two sleeves and fed the signal cables to the CC3D.
Mount the cable for the reciever port, this will later connect to the radio reciever.
The cable for the main port, if you are going to be using other units like GPS, telemetry and so on. My setup is not using additional units, so this cable was removed.

Solder a female 3.5 mm banana plug on each of the power cables for the ESC's and cover it with shink tube  

Drill four holes in each corner of the housing, this will be used to mount the housing on the frame.
At this point you now have a almost ready to fly housing that can be removed on the fly and be used on another unit without too much hassle. Stage 1 done.

Building the frame.

 Cut two pieces of wood mine were 41.5 cm, try to keep the edges as straight as possible.

Drill two holes on each shaft, making sure that there is equal space on both sides. The more centered the housing is the better the center of gravity.

Using 25mm bolts mount the housing on the frame.

Tighten the screws firmly. 

To stop the frame from flexing too much, you will need to cut out and mount an adequate plate, using some thin light weight hobby wood. I used som Carbon that i had left over from a hobbyking H4. I cut the frame and drilled the necessary holes and tied it all together. if you don´t have an old frame, find something that is light weight. The length of the plate can be much shorter. Make sure to check the flex on the frame.

The top side. 

Both bottom flex plates mounted

Cut two more pieces of wood, They will make the arms.

Again measure an drill two holes, making sure that the arm is bang in the middle. You are going to need a top plate to stabilize the arm.

Mount the second arm in the same manor as the first. 

Make a flex plate for the top. 

Mount four motor mounts and a motor, one on each arm.

Connect each ESC to one of the power outlets from the housing, and feed the signal cable from the ESC up though the sleeve in to the housing 

Solder a header pin on to the signal cables or you can make your own header pins if you have the required tools

Mount the four signal wires from the motors accordingly

Mount the cables from the reciever port to the reciever.

Had to cut the lid of the housing as the wires stuck to far up. Anyways, not entirely done, the cabling needs to be done properly, for now the unit is ready for testing.

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