|Good news!! The MK build review now has a new section on PID settings. This is a relatively tricky endeavour if you don't understand what is happening with PID setting so we took the time to explain the art of setting PIDs in easy to digest terms. We still recommend that you get all the configuration and flying know-how needed from the two main forums on the MK (RCGroups & MK Forum US). Next GPS, MK Tools....
This is essentially a review in progress, and I will add to this over the coming weeks as I progress this build.
I decided to make an MK (MikroKopter) from scratch and document the journey for the benefit of all those who are considering embarking on a similar journey with the MK and like me, are not necessarily endowed with copious levels of electronics/computing/physics knowledge.
Why the MK? Well because it is probably the best featured, most professional kit system available currently by popular opinion. Anyone who has venture to spend a little time looking into the MK and its variants will immediately realise that this is not a small project. Apart from the time & care required in assembly, there is the very real (and time consuming) task of getting to know the MKTool. The MKTool is the configuration & tuning tool used to get the MK flying.
So having built a Quad or two successfully in the past, I decided that if I was going to put one of these things together and write about it, it may as well be something a little more exotic like a Hexa with all the trimmings. Where I digressed from the recommended MK components was in the choice of landing gear, props and motors. Everything else was as supplied by the MikroController shop guys.
Why did I go for the different landing gear & motors?
1) Motors: I have come to totally rely on the KDA20-22L motors as they are just about bullet proof with the power/current ratio that suits my flying.
2) Landing Gear: Well I just don't like the MK gear and prefer to use my own adaptation. This my personal preference and I do not draw issue here.
2) Props: Again, i prefer to use the APC product. In my mind the APC props are more robust and seem to be better balanced on average.
So beginning with the build:
I expressly ordered the components individually rather than in a kit for the reasons stated above and experienced no problems with the exception of my big doh!! moment when I realised I had forgotten to order the pressure sensor. Of course, this happened after I had built the frame and assembled the power distro board so I had to wait for the missing part to arrive before I could proceed.
Building the Hexa frame was nothing short of a pleasure with absolutely no problems - The frame assembly information on the MK WIKI is pretty much spot on and easy to understand. If their English translation seems a little inaccurate at times, they more than make up for the deficiency with the copious amounts of high quality pictures showing the sequential progress of the build on the site. I do emphasise though that it pays to read ahead! When I began assembling the frame, I looked at all the pictures first ot get an idea of what is being done at what stage so I would not end up with unwanted surprises.
In short, the frame build went like this:
- Cut 6 x 3 (18 lengths of 60cm ) silicon wire
- Soldered the wires to the motors and applied heat shrink
- Fastened the motors directly to the arms with a little added thread lock
- Threaded the motor wires through the arms (about 20cm overhang but I think it is better to have too much)
- Assembled the frame with base plates by using the steel screws/locknuts in the centre and nylon screws around the perimeter
- Attached supplied base-plate spacers
- Attached landing gear and battery support brackets (my own)
Power Distro & BL controllers
Once the frame was assembled with the motors and landing gear, I turned to assembling the I2C BL controllers (ESCs) and mounting them on the power distribution board.
This proved to be a very easy exercise involving two stages -
- Completing the assembly of the BL controllers by:
a) soldering an electrolytic capacitor to the BL controller
b) setting the address of the BL controller by creating a solder bridge
- Attaching the BL controllers to the power distribution board through wire bridges.
With the power distribution board there is one huge note of caution:- Look at the assembly photos carefully!! You need to thread the capacitor leads through the power distro board first before soldering the leads so this can turn out to be a nasty surprise if you are not aware of the process. This approach is necessary because the soldered leads form part of the structure. Rather clever really.
Once all six BL controllers had been soldered in all that remained to be done was the soldering of the leads for the battery and power supply to the Flight Controller. I also attached some LED adhesive strips to the arms so I soldered power leads for these as well.