I have started building an APM 2.52 Quadcopter with ST360 kit.

I am a total n00b and will require lots of help. Got some of the parts and rest are on the way. I am not sure if I know all the parts which are required. I plan to document my build in this thread so that it becomes easy for people who plan to build a similar quad in the future.

Here are the parts I'm staring with:

1. APM 2.52 => http://www.quadkopters.com/product/flight-controllers/apm-2-52/
2. ST360 kit => http://www.quadkopters.com/product/rtf-kit-and-frames/st360-kit/ .This includes the frame, 4 motors, 4 propellers etc.
3. uBlox 6M GPS With Cover => http://www.quadkopters.com/product/flight-controllers/ublox-6m-gps-with-cover/
4. Multirotor 4IN1 ESC(4*30A) => http://rcmumbai.com/index.php/product/multirotor-4in1-esc430a/
5. Flysky 9x 2.4GHz 9CH Transmitter WITH RECEIVER => http://rcmumbai.com/index.php/product/flysky-9x-2-4ghz-9ch-transmitter/
6. Power Distribution Board => http://www.quadkopters.com/product/flight-controllers/power-distribution-board-100a/
(is this required with the 4-in-1 ESC? Or is it surplus?)
7. Turnigy 2200 mAH 3S 25C Lipo pack
8. IMAX B6 Skyrc => http://rcmumbai.com/index.php/product/imax-b6-skyrc-original/
9. Velcro Hook and Loops, Zip ties
10. Hex screw driver => http://www.ebay.in/itm/271568037218?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
(there's no hex screw driver with the kit...so I'm unable to start without one)

That's all the parts I have got so far. I have no idea whether I'd require anything else, particularly connectors and cables. Once I start building, I'd like to have all the parts at hand. So I require suggestion whether I require anything else. Also please clarify the following points.

(i) Whether I'd require the Power Distribution Board at all, given that I am using a 4-in-1 ESC? If so, how do I connect it?
(ii) Do I need an APM power module like http://www.quadkopters.com/product/flight-controllers/apm-power-module-with-bec-xt60-black/ ? If so, what do I connect it with? Is it essential?
(iii) There is no stand for GPS. Do I need to get one? e.g. http://www.quadkopters.com/product/flight-controllers/gps-folding-base-antenna-stand/
(iv) Do I mount the APM controller directly on the plate or is there any requirement to add anything to minimize vibration?
(v) Is a 2200 mAH 25C battery sufficient for this setup?
(vi) Do I mount the APM controller on the top plate and the 4-in-1 ESC on the bottom or vice versa? If Power distribution board is required, where do I mount it?
(vii) Is there any way to extend the mounting plates later if I plan to add telemetry and gimbal later? There seems to be a lack of space. Are such extended mounting plates available?
(viii) Do I need servo cables and XT60 connectors? I did not notice these in the kit.
(ix) Anything else that I'd require before I start?

Thanks in advance.

If this is your first experience with quadcopters, then maybe starting out with an APM will be a steep learning curve. Maybe setting up and flying a KK board first woild have made things easier. But dont let my words discourage you, if you feel confident then go for it.
The 360 frame is a bit small for all the bits and bobs of the APM, so it will be a tight squeeze.

1. A power distribution board will make things neat and easy to connect( + to +, - to -)
2. Not required unless telemetry will be used.
3. Not required if it can be placed away from other electronics.
4  you can mount the FC directly if your motor and props are balanced and there is nominal vibrations, but that situation comes rarely so damping is advised.
5. Battery is sufficient to fly but not for very long.
6. Depends on the build.
7. Upgrading to bigger frame would be less hassle.
8. Male to male servo leads will be required as well as a female XT60 connector.
9. Heat-shrink, a good soldering iron, drivers, Patience and refreshments depending on age.


Ashim.

1st a simple advice ............. read and see videos.

You could have saved a lot and chosen better options ( as per your condition (noob)) if you had done a bit of research.

Have a look here .... i too was a noob in Quad so selected the items to suit my needs & expense.
As per me & Net NAZA is the best choice to lift quad with min of tuning.

http://www.rcindia.org/multirotors/scratch-built-quad/msg229598/#msg229598

@santanucus

I have exactly the same stuff bought from exactly the same links.
http://www.rcindia.org/multirotors/st-360-quad-with-apm-2-6/msg211030/#msg211030

Please do tell us how much experience you have with aeromodeling or RC in general so that we know how to proceed with helping you.

For now;

1) You do not need the power distribution board as you already have a 4-in-1 ESC.

2) The power module is needed for monitoring LiPo voltage via telemetry. It isn't essential but proves helpful.  And, as you do not have a telemetry kit, it won't be of much use anyways.

3) A GPS stand is difficult to work with. You should rather get PCB 'stand-offs' or spacers. That will help you fix the APM box as well as the GPS module.

4) The ST-360 frame isn't vibration proof and you'll certainly need to add vibration protection to avoid erratic flight behaviour.

5) With my setup, a 2200mAh gives a maximum flight time of 13 minutes.

6) The ESC is to be mounted on the top plate, the APM above it and the battery below the bottom plate. This is because the CG lies above the top plate.

7) Mounting plates can be easily made out of copper-clad boards or acrylic and are definitely needed with this frame.

8.) You do need servo cables, m3 nut-bolts, extra bullet connectors and an XT-60 for the ESC.

9) Buy spare props and prepare a testing rig for tethering the quad for first flight and tuning. You'll also need a good soldering iron, hot glue gun, drilling-machine etc if you plan to add telemetry, camera or other modules.

Thanks everyone for the detailed responses.

@rastsaurabh
As I had mentioned in other threads, I went for APM because of my future requirements of FPV, Telemetry and GPS. I chose ST360 to keep the quad small and portable as I plan to carry it along during my travel. Most of the members had suggested APM and that's why I chose it. NAZA would have been better but it exceeds my budget. I checked out many videos but could not find specific ones which use ST360 kit with APM and GPS. I am confident of doing the calibration, flashing and software related settings of APM. What I am not confident of is the hardware part. The videos don't provide the details on all aspects. Who would have guessed that I'd also require hex screwdrivers of god-knows-what size. That's why even after procuring most of the major components, I am unable to start due to the lack of minor components like cables and connectors and screws. Even if I had chosen the KK board, I would have faced the same problems.

@ashimda
Thanks for the encouragement. Have some more queries for you.

- regarding point 5, I can understand that the bigger the mAH of the battery, the better, subject to the weight. But is 25C enough to provide the required current for this setup?
- I'd order male-to-male servo leads rightaway, heat-shrink and XT60 female connector. Will there be a requirement for one or more XT60 male connectors?
- which bigger frame do you suggest? Will I get more mounting space on a F450 frame or is mounting space the same and only the frame arms are longer?

@Swapnil
I have seen your thread. I'd require further help from you as I proceed. I have zero RC building experience. I have flown small RTF quads like Syma X5C and Hubsan and have made some repairs, change or motors and range mods in them.

Regarding your answers,

- On point 6...do you mean I can mount ESC on the top plate and attach the APM right over it? If I mount battery below the bottom plate, what lies over the bottom plate?
- Do you have a photo of your quad without the "Alien Inside" cover so that the inside is visible?
- what is your experience about the quality of the motors and the props that come with the kit? Suppose if one motor fails, is there a replacement available? I'm afraid that if one or more motors fail, it would be hard to get exactly the same motor as its sort of unbranded.
- Do I need wires too?
- most importantly, are all the motors the same or are  there CW and CCW pairs?  

Thanks.

Quote from: santanucus on July 02, 2015, 08:37:42 PM
...Most importantly, are all the motors the same or are  there CW and CCW pairs? 

I'm surprised you haven't found the answer to this question yet. Most hobby motors aren't optimized for a particular direction of rotation. I suppose you had the 12V casette player motors in the back of your mind while asking this.

But, I'm more worried about the following quotes.

1) Who would have guessed that I'd also require hex screwdrivers of god-knows-what size...

That's preposterous! Any decent hobbyist has a hex screw-driver set.

2)  But is 25C enough to provide the required current for this setup?

Another basic question. One you're expected to answer yourself.

It's simple queries like these that make people refrain from replying. Now these might be singular instances given that you say you've done the basic 'reading and videos'. But it seems you need to brush up your basics.

This might seem rude but it's like going to a gun shop and asking where to put the bullets. This is an expensive hobby and if aren't prepared to go through the basic concepts then you'll end up hurting your wallet and head before you complete your project.

3) Will there be a requirement for one or more XT60 male connectors?

Only one male XT-60 is required for the ESC even if you are planning to add telemetry and other modules.

4) Will I get more mounting space on a F450 frame...

The ST-360 can easily handle all the modules you have and are planning to mount in the future.

5) What lies over the bottom plate?

All the wiring. There isn't enough space for the LiPo after adding support spacers.

6) What is your experience about the quality of the motors and the props that come with the kit?

The motors are of mediocre quality but work great (unless you mis-handle them). The props seem flimsy but can take a lot of damage.

I am unable to start due to the lack of minor components like cables and connectors and screws....

Now, most RC 'enthusiasts' have  all the basic components and tools stored in nicely labeled boxes (or lying around their bedroom/ garage). It isn't expected of a newbie to have everything. And, so, it'll be easier for you if you go through videos about working with BLDCs, ESCs, LiPos, connectors etc before you buy anything else.

Swapnil Admire your patience!!!

Thanks for you patience.

By the way, I have mentioned at the start that I am a n00b. Not someone who can be called a "hobbyist" yet. My only experience is fixing a Syma X5C which had CW and CCW motors but no cassette player motors. Even in the case of some hobby motors I have read that there are threads oriented towards a particular direction. Hence the question.

1. I am not a "decent" hobbyist. I am a wannabe hobbyist. I did not have a quad frame previously and everywhere else, including in the RTF models I have handled, there were screws which required 4 headed phillips screwdrivers. There are hardly any videos or texts which discuss types of screws. When I ordered a frame, I did not anticipate that screws would be hex. This is probably not as preposterous as it sounds.

2. Yes...I have some idea about how to calculate the current supplied by a 25C battery of a certain mAH and am aware of the calculations about how much powers are drawn by the motors. But I am not sure about the current drawn by the APM FC or the GPS module or the ESC. I only required a rough idea from those who obviously have more idea than me. A one liner reply would have sufficed.

The whole idea of a discussion board is to gain knowledge from those who know more. I run and code and administer a few of such boards since 2005...so I know. And I answer simple queries too or redirect them to the FAQ that I have made for simple queries.  I am obviously capable of building a quad without making a single post here. But that would probably delay it by a couple of weeks. That's why I asked questions. As the nature of discussion boards go, no one is obligated to answer "simple questions" or any questions for that matter. But there are always some people who answer simple questions. I hope to remain one of them when I learn enough.

Nice to see you took it all in good spirit!

1) There are hardly any videos or texts which discuss types of screws. When I ordered a frame, I did not anticipate that screws would be hex. This is probably not as preposterous as it sounds.

These kits generally come with hex screws. You'd have known that if you'd done a bit of background research. There are not only long build videos for quads in general but also for the ST-360 specifically.

2) I have some idea about how to calculate the current supplied by a 25C battery of a certain mAH...

So do all the 14 year olds on this forum. It's not difficult to find out the current consumption of FCs and GPS modules, just check their websites. 25 C is the minimum C rating that one would go for with your setup considering that a quad isn't flown at full throttle all the time.

3) By the way, I have mentioned at the start that I am a n00b. Not someone who can be called a "hobbyist" yet. My only experience is fixing a Syma X5C which had CW and CCW motors but no cassette player motors. Even in the case of some hobby motors I have read that there are threads oriented towards a particular direction. Hence the question.

You've stated that more than once here. But if you'd cared to read just a little bit more, you would have realized that most BLDCs (almost all available locally) aren't optimized for a particular direction.

Most importantly, you missed the big point. You NEED to read more about all the electronic components involved. We'll happily answer all your simple queries here. But it'll do you much more good if you were to do it yourself initially. There's a lot of newbies here asking a lot of questions about everything. Even if it seems discouraging, we ask all of them to read more and come back with specific queries.

See how I answered questions '3' to '6' in reply #4? Those were good questions even if they were simple and you can always expect good answers in return.
But asking whether BLDCs come in CW and CCW seems just silly to us as that makes it clear that you know almost nothing about them.

Honestly, I'd have loved to answer your questions in a nice straight-forward manner. But, that wouldn't have done you any good. Your worries regarding hex screws and direction of motors are going to seem silly compared to the problems you are going to face during the build.

Again, and I can't stress this strongly enough, please read everything you can about all the stuff you've purchased. Also, check out some airplane build videos for getting familiar with the electronic components.
   

Straight to your queries,
Purchase a good set of hex drivers , which at least include 1mm , 1.5mm , 2mm , 2.5mm , 3mm hex drivers . or you can also get Allen keys , but you will find that a good set of hex drivers are better than Allen keys in terms of long run and easy to use.

About battery, I haven't looked in to the current draw of motors in this kit, but a 2200 mah 25C is more than enough to supply the needed current for this setup. The current drawn by flight controller and other accessories are negligible to the total current draw of motors , so you don't have to worry about that , still it is better to keep a battery that can provide more than the max. Estimated current draw. Regarding selection of batteries there are lots information in this forum itself , if you want more info with exact facts and figures I can link you to some other threads or websites.

Regarding CW and CCW motors - in a multirotor we use cw and ccw rotating motors and appropriate props (if you don't know why please feel free to ask ). A brushless motor can be made to rotate in any direction , I am not going in to theory here , you just have to swap any two of the three wires from motor to ESC for reversing the rotation direction of a BLDC. But few manufacturers produce multirotor specific bldc motors with CW and CCW threaded shafts and prop adapters - this is help full because the chance for prop to become loose is very less ( give you the chance to think why ! ) , still it doesn't mean that a CCW threaded motor cant be rotated in CW direction . I will have look in this st360 kit to see whether your motors come with different threads.

Just looked at the st360 quad kit in QK , from the pictures in website it doesn't seem the motors included are with cw and ccw threaded prop adapters - those motors have a non threaded shaft and collet type prop adapters.

Thanks sooraj for resolving my queries.

I have ordered hex drivers already. Learnt it the hard way

I'd purchase additional batteries. When I do, I'd get the ones with more C rating in the future.

I also had the impression that BLDC motors don't come in CW and CCW pairs. But I saw some sellers selling BLDC motors with CW and CCW threads. So I got confused. In ST360 kit, the motors are unbranded and the details are not quite available anywhere. In the absence of information I can assume that any motor in this kit can be used as CW and CCW. By the way, I am using some brushed CW motors in a RTF model as CCW and these are still working...although some people say that their life will be short.

Anyway..thanks for all the help folks. I have got all the parts (hopefully) and waiting for the hex screwdrivers to arrive. Once they arrive, I'd start building the quad and post the updates. I'd post a revised list of parts so that beginners will not face problems in assembling a quad.

I created this thread to keep a log for building the quadcopter. This is meant for beginners as well as for my own reference later.

While waiting for the hex screwdrivers to arrive, I started the initial setup of the APM Flight Controller, which can be done by connecting it to a computer using a USB to Micro-USB cable which are used to connect most mobile phones these days.

The process is explained in details in the video



The process involves downloading the Mission Planner from http://ardupilot.com/wp-content/plugins/download-monitor/download.php?id=82 and installing it. The configuration details are explained in the video. The only thing that one has to carefully note is to place the APM Flight Controller in an absolutely level table. I placed it on my computer table which I thought was levelled but after the accelerometer calibration produced erratic results in "flight data", I tested with a bubble level measure and found that the table is not horizontal. I again did the calibration in a horizontal place and it was perfect. Please note that the "UP" side of the APM is the side with the pins. Also be careful about the "forward" direction (marked with arrow) as right/left etc. are relative to the forward direction.

Next I attached the external Compass cum GPS module in order to carry out the compass calibration. The video shows the APM 2.5 which includes a compass. So this will be different as APM 2.6 does not include internal compass. One cable from the GPS/Compass module goes to the socket on APM FC marked "GPS". Another (smaller one) goes to one marked I2C, which is the compass. While calibrating the compass, instead of rotating the APM FC as shown in the video, the GPS module has to be rotated.

Problems: As in the video, I started in Mission planner with "install Firmware" option. After downloading latest updates, Mission Planner reported that "this board is retired" and apparently installed an older firmware. I am aware that this APM FC is a clone and not the original one. I think it would have been better if I did not install firmware in it and left it with the default one. Now, in the "terminal" tab, when I connect to APM, it shows junk characters. Maybe this one had a custom firmware? Although other functions and calibrations are going on well, I am apprehensive about it.

If somebody has updated firmware on the APM FC ( http://www.quadkopters.com/product/flight-controllers/apm-2-52/ ) bought from Quadkopters.com, please share your experience on this issue. I am posting a screenshot.

After the hex screwdriver set arrived, I started assembling the frame. I got the screwdrivers real cheap from eBay. http://www.ebay.in/itm/271568037218?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

But the black socket head hex screws in the ST360 kits are real bad. The heads lose their hex shape and erode as you turn the screw and become circular. And then the driver simply rotates and screws won't turn. After trashing a couple of screws, I managed to assemble part of the frame.

I hate hex screws. I don't know why hex screws are used in this hobby. Maybe its a legacy of the old times when people used to build RC planes only. Most RTF models have switched over to 4-headed philips screws which are used everywhere. In fact I'd suggest people who use this frame to get similar sized 4-headed screws. I figure, I'd be having a tough time unscrewing these screws when an arm requires to be replaced or upper plate needs to be taken off to install additional components.

@ santanucus,
Accelerometer calibration need to be done after mounting apm on frame. That help the apm to calculate level /offsets between apm and copter.

Latest firmware that can be installed in apm is 3.2.1, this hardware is discontinued after releasing pixhawk and no further firmwares are supported even if you brought from 3dr.

Also the issue about the terminal tab can be ignored, that will happen if you connected through telemetry or osd data reports enabled,  the CLI interface is in the stage of deprecation and will disappear soon.

Yeah the board from quadkopters, is retired and won't install the latest firmware, but it will work just fine with the old one

Dude the board is just fine, many people are getting the same error with many of the same boards. There is a same video by painless360 too, he too discuss the same problem and the solution and also explain about the affects if any (which is none)

Thanks all ! Good to know that the board is ok.

@akhilzid
You are right. I'd do a recalibration after I complete the mounting.

@ Immanual, the problem is not with the board from QK, its a common problem with whole APM hardware platform,
And the latest firmware(3.3 or above) is for Pixhawk, current latest firmware for apm is V3.2.1.
Read here. http://copter.ardupilot.com/wiki/common-autopilots/common-apm25-and-26-overview/

@Santanucus,
And the problems that you stared is not actually a problem, and this one works perfectly with all current features.

Connecting and calibrating the Radio

So I am back with further configurations. Progress is slow, as due to engagements I can work on it only on the weekends.

Today I attached the 5 servo cables with the Channels 1-5 of the APM board. 4 of these went to the corresponding channel pins of the Flysky Radio receiver. The cable from channel 5 of the board went to the Channel 6 pin of the receiver. This was done as per the guidelines in the following video. Although its related to Turnigy 9x, it should be applicable to Flysky 9x radio too.

Although servo leads of the cables would smoothly go into the pins only one way, care should be taken about attaching the cable. Basically, the yellow cable pin should be upwards when attached to the printed side of the receiver. On the APM board, yellow cable pin should be on the left when seen from the pinned side of the board up and the input pins on the right.



I was under the impression that the receiver will not power up with the USB power. But it did. No binding of the radio with the receiver was required and the movement of the sticks were shown on the mission planner.

When I turned on the radio, it showed "switch error". This can be resolved by following this video:



Basically, before switching on the radio, you need to push all the switches upwards. That would resolve the problem.

Adding 8 batteries in the Flysky 9x radio is a big hassle. And now the battery cover would not close. I have to think what to do with this later. Maybe a battery mod by attaching LiPo battery in the socket can be considered. There is also a video on this mod.

Next, I calibrated the sticks using mission planner and it went on smoothly. This is explained in http://copter.ardupilot.com/wiki/initial-setup/configuring-hardware/#calibrate_radio_control and also demonstrated in the APM 2.5/2.6 Simple Installation and overview video that I posted in my earlier post.

I have attached some photos and screenshots.

Sorry guys, I taught that the apm people released a new board, and so the old one is being shown as retired, my bad , been a while since i have browsed through the ardupilot forumns ,but the qk board works great, I flown with it in near the beach and stuff with high winds under auto, it works great

Flight Mode Configuration

Well, I thought it would be easy. But it is somewhat challenging part. The reason is that Channels 1-4 of the APM FC are related to throttle, yaw, roll and pitch  (may not be in that order), but you need to configure Channel 5 (auxiliary channel), what it will do and which buttons in the radio it will use.

Before that, you need to know what each mode in APM is supposed to do. I selected certain modes as per my requirement. See this video for more on flight modes:



As I said before, when you connect APM Input Pin 5 to the Receiver, connect the corresponding servo cable to Channel 6.

In this case, I plan to use 6 flight modes using the Gear and the Aux-3 (Flight Mode) switch. The Aux-3 switch has 3 states and Gear switch has 2 states...so there are 6 states in total. For 3 flight modes, only the Aux-3 switch would have been sufficient. It is possible to configure other switches for this purpose. It depends on your convenience. Switches are shown in the attached picture.

Next refer to this video. It explains the process in details. To carry this out, you need to connect the APM FC with the Receiver with Mission Planner through USB. Then you need to start the Radio (Flysky 9x in my case). All the configuration needs to be done on the Radio itself but you need to refer to the parameters shown in the Flight modes option in the Mission Planner.



As shown in the video, I changed my vehicle type to "Acro" in the Radio. That required re-calibrating the controllers although I had done the same in the "helicopter" mode earlier. After that, one needs to follow the procedure shown in the video to set up the switches and the positions and their values in respect of the Auxiliary channel.

One point to note is that the current PWM value from the transmitter radio is shown in the Flight Modes option like Current PWM: 5: 1052. Here 5 means channel 5 and the current PWM value is 1052. That lies between 0-1230...so is in Mode-1. You need to change the PWM value so that each state of the switches send signals of different PWM value. The ranges between which the PWM values corresponding to each flight mode should lie is shown in the Flight Modes option. Do not blindly copy the values shown in the video (although its fairly ok). Just calculate the value at the centre of the range i.e. (max-min)/2 and set value accordingly.

Configuring the flight modes with the Radio is the most important thing in this section. The actual 6 flight modes that you select and their order can be changed any time. The modes which I have selected can be seen on the attached screenshot. You can refer to the wiki at http://copter.ardupilot.com/wiki/flying-arducopter/flight-modes/ for essential and additional flight modes. Later, I may change the modes as well as their orders for convenience.

Configuring Failsafe

As per the (1/8) video on setting up the APM FC which I posted earlier, I only changed the battery voltage to 10.5 and set the RTL option and also set "Enabled always RTL" when PWL value falls below 975 (default) so that the quadcopter returns to home location and lands when signal goes below certain level. Of course, good GPS lock is needed for RTL mode. So before launching, always ensure that GPS lock has been acquired. I am not sure whether anything more needs to be done in the failsafe option. I'd configure it later if something else needs to be done. RTL specs will be configured later.

Connecting the ESC

ESCs control the speed of rotation of the motors. Most people use 4 ESCs but here I have used a 4-in-1 ESC from Emax. It is cheaper than 4 ESCs. On the flip side, it takes up space on the centre of the quad while separate ESCs can be attached on the arms. Also, if this ESC gets damaged, the whole thing has to be replaced. There are supposed to be modules inside for replacement but parts are not available in India.

This ESC comes with 12 wires with female bullet connectors which are kept in a separate packet. You need to insert these in sockets meant for 4 motors. Each socket has 3 holes with screws. You need to insert one wire in each hole and tighten the corresponding screw. The ESC also has a pair of power cables (red/black) without a connector, where I'd solder an XT60 male connector. The battery is attached here. Since the battery has a XT60 female connector, the connector to be soldered with the ESC has to be male. It also has for some wires with connectors for connecting to output pins of the APM flight controller.

I have to solder male bullet connectors with the motors since in this ST360 kit, the motors come without connectors.

I have attached the photos of the ESC from top and from bottom after connecting the wires with bullet connectors.

I'd be back after soldering and calibrating the ESC. I don't plan to mount anything until after all the connections are tested and calibrated.

Soldering XT60 Male connector to ESC and bullet connectors to the motors

This was the toughest job for me as I don't have much experience of soldering. Having a bad and old soldering iron did not help either. I did a shoddy job in connecting the XT60 connector. Luckily, I purchased several pairs although only one is necessary. The plastic kept melting and the connector pins detached as a result. After losing several connectors (which don't appear to be of great quality either), I managed to connect one with the ESC power connectors. Attaching the bullet connectors (which came with the frame kit) with the motors was a relatively easy task.

The heat shrink that I purchased was too narrow to fit. I should have purchased a wider one. I used a 3M Micropore tape to insulate the joints. Hope these are insulators ! 

The XT60 connector that I soldered with the ESC won't last long. Maybe I'd purchase a readymade one so that I won't have to detach this particular connector repeatedly.

For soldering techniques, the following two videos helped





The technique to solder the bullet connectors was particularly effective.

Next comes the job of connecting the ESC with the motor, battery, APM Flight Controller and calibrating the ESC.

Calibrating 4-in-1 Emax ESC

This is an important step before the final assembly. But hardly any good video is available which specifically addresses calibrating a 4-in-1 ESC. There is one video which shows how to do it but after assembling the quad. The wire connections are not visible clearly and they did not explain the whole process. So I had to work upon it. Here is the video for initial reference.



4-in-1 ESCs have a bunch of red/white/black cables (ref. photos posted earlier) which are meant for connecting to the output pins of APM. But during calibration of the ESC, we will not connect them to the output pin fully. Here are the steps for the 4-in-1 ESC calibration.

1. The ESC has red/black/white cables. One is a three pin cable (one red, one white and one yellow). There are three other white cables with a one pin connector. The white wire is for signal. The black is ground and the red one for power.
2. Detach battery from ESC, if connected. Also USB cable should not be connected to the APM. Take out the channel 3 servo wire on the radio receiver which is connected with the APM. Then plug the 3 pin wire of the ESC in Channel 3 of the receiver.
3. Switch on the transmitter. Push the throttle to the top.
4. Connect the battery to the ESC.  You'd see red and blue lights flash alternatively in the APM like a police car. Detach the battery.
5. Again plug in the battery. As soon as you hear two beeps, pull down the throttle in the transmitter to the minimum. You would hear a series of musical beeps and tones. When its completed, ESC is calibrated for one motor. Now push the throttle up and one of the motors will spin. Switch off the transmitter and detach the battery.
6. Next, you have to carry out the same process in respect of the other motors. Problem is that in respect of other motors, there is one pin with white wire only. This can't supply power to the APM. So attach the three pin wire to Pin-1 of the output of APM. Now power will be supplied to the APM from the ESC. Time to calibrate other motors.
7. Now insert one pin of one of the other 3 white wires to a Signal Pin (S) of channel three of the receiver. Power on the transmitter and push throttle to the maximum. Connect battery. Check the attached photos.
8. As soon as you hear two beeps, pull down throttle to the minimum. Then you hear a series of beeps and tones and calibration will complete for this motor. Push throttle up and one motor will spin. Switch off transmitter and unplug battery.
9. Repeat the process from step-7 with two other single connector white wires for calibrating the remaining two motors.

That ends ESC calibration.

Those who are not using 4-in-1 ESC but 4 different ESCs may refer to the following video:



A general idea on what ESC is about is given in this video



I have tested, configured and calibrated almost whole of the quadcopter system without attaching them to the frame. That makes it easier to get photos which might be helpful for beginners. Actual assembly will be the lest step.

Next, I'd insert all the red/white/black wires from the ESC to the output pins of the APM Flight Controller in such a way so that the front two motors of the quad spin in inward direction (towards each other) and back motors in outward direction (away from each other). That would enable stability and lift of the quadcopter.