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Step 25: Balance Props

Balancing the quadcopter props is an extremely important step in minimizing the vibrations produced by the spinning motors. Minimizing vibration improves battery life, the life of the craft itself, and video quality.

Now the only components left to attach to the quadcopter are the props. Before we attach the props to the motors though, we need to balance the props. By balance the props, I mean we need to make sure that each blade weighs exactly the same. Unbalanced props cause three main issues during flight. First, unbalanced props can cause intense vibration since the props spin extremely fast. This vibration can interfere with the accelerometer as well as loosen screws or damage components. Second, if you are doing aerial videography with your quadcopter, the vibrations caused by unbalanced props will cause the infamous jello effect in your video (or, to use the correct terminology, the rolling shutter effect). Third and last, since some of the energy put into the motors is wasted on vibration when you quadcopter has unbalanced props, balancing the props can increase battery life slightly.

To balance our props, we will use a special tool called, unsurprisingly, a prop balancer. A prop balancer consists of a metal shaft suspended by two magnets. By using magnetic suspension, there is practically zero friction, which means, when we test our props, even the slightest difference in the weight of the two sides of the prop will be noticeable.

Let’s balance our props. First, select one of the props and mount it in the prop balancer by slipping the metal shaft through the hole in the prop and sliding the rubber pieces to the middle so that the prop will be held in the center of the shaft. Then, hold the prop in a horizontal position and, taking care that your fingers do not bump the the prop one way or the other, carefully let the prop go. Unless your prop is already balanced, which, unless you opted to by very high quality props, is unlikely, one side of the prop should fall. Repeat this test several times to make sure the result is reliable. The side of the prop that falls is, obviously, the heavier side. So, cut a very small piece of electrical tape and apply it to the light side (the side that went up) of the prop. Then re-test the balance of your prop. If the original heavy side still falls, move the piece of tape further from the center of the prop. Otherwise, if the side to which you applied tape now falls, move the tape closer to the hub, or cut it smaller.

It will probably take some fiddling, even quite a lot of fiddling, but you will know your prop is balanced when, after positioning the prop horizontally and letting it go, it does not move at all. Then, repeat this process for the other three props, and, if you are not terribly bored with prop balancing already, balance some spare props so that if one of your props breaks in the field, you can immediately replace it and keep flying.

can i use 5000mah 2s turnigy battery
<p>Do you have to revert the 3 pin connections for the q brain back to how they were in order to use the BESC programming card? I don't want to do this each time because I want to change the song selection for the q brain. Any easier way to do this?</p>
Here is the connectionHereh
Here is the connectionHereh
Pls I am using a flight board KK2.1 and. Hk 16A V2 6 channels receiver. I used 2 servo cables to link them, (which am not sure is correct), but when I try to arm my motors, I get a set of steady beeps. What could be the reason for that?
<p>Great instructable. Followed a lot of this when I made my Dead Cat Defibrillator. Only thing that doesn't seem to be right are the mixer settings. For motor 3 (right rear) and 4 (left rear) they seem to be the wrong way round. I based mine on the YouTube video from HobbyKing which has 3 as 100, 71, -71, 100 and 4 as 100, -71, -71, -100. Hope this helps anyone else that get some strange flight characteristics with the settings given here.</p>
<p>Thanks for the recipe, flies really well now. But there are multiple errors in the mixer editor settings you have listed.</p><p>Importantly, the signs for the rudder numbers for motor 3 and 4 are mixed up! Motor 1 and 3 should have positive numbers for rudder, motor 2 and 4 should have negative numbers. Same applies for aileron.</p><p>I have marked in <strong>Bold </strong>the places when my number have the <u>opposite sign</u> of your numbers. My numbers are also slightly different just because i measured the angles differently from my kk unit. <br>39 comes from being sin(23 degrees) which is the angle i measured to the front arms (see picture).<br>92 = sin(90-39) =&gt; 0.92 =&gt; 92<br>73 = sin(47)<br>68 = sin(90-47)</p><p>Motor 1:<br>Throttle: 100<br>Aileron: -39 <br>Elevator: 92<br>Rudder: 70</p><p>Motor 2:<br>Throttle: 100<br>Aileron: 39 <br>Elevator: 92<br>Rudder: -70</p><p>Motor 3:<br>Throttle: 81<br><strong>Aileron: 73</strong><br>Elevator: -68<br><strong>Rudder: 100</strong></p><p>Motor 4:<br>Throttle: 81<br><strong>Aileron: -73</strong><br>Elevator: -68<br><strong>Rudder: -100</strong></p>
<p>What is the length of your flight???</p>
How durable is this model compared to other copters? Do you recommend flying this if it's my first copter, or would you suggest a more crash friendly one?
<p>Ok, I'm a little confused. Your pic of the tape on the controler is clearly mode 1 but your link to the tx/rx combo is mode 2. Which one are you running?</p>
<p>This is the very best build report I have read! </p>
<p>Thanks for taking time to put together such a comprehensive build guide. Much appreciated.</p><p>I can buy all these parts in the UK. But, I have a DX6 AR7000 and an AR6000. Will these work OK with the setup given?</p>
<p>I want to build this but I just can't find a vendor who ships those parts to Germany. Can anybody help me?</p>
<p>i found when i inputed these settings my motor 1 and 2 went much <br>more forward than sideways, i found the Aileron and Elevator settings <br>for motors 1 and 2 were slightly switched around (could be a new version <br> of the software or maybe just an oversight when typing up this amazing <br>build? lol)<br><br>I found these work best for motors 1 and 2 on my KK2.1 <br></p><p><strong>Motor 1 Mixer Editor Settings</strong> </p><ul><li> Throttle: 95 <li> Aileron: -94 <li> Elevator: 34 <li> Rudder: 78 <li> Offset: 0 <li> Type: ESC <li> Rate: High</ul><p><strong>Motor 2 Mixer Editor Settings</strong> </p><blockquote> <br> <br><ul><li> Throttle: 95 <br><li> Aileron: 94 <li> Elevator: 34 <li> Rudder: -78 <li> Offset: 0 <li> Type: ESC <li> Rate: High</ul></blockquote><p>Correct me if im wrong but that gave me the correct orientation of the motors</p>
<p>i found this section to be a bit confusing at first until i relized i didnt have enough 3pin connectors...in the parts list it only says 1 CM male to male connector so thats what i bought...maybe should be revised to say 3 or 4 lol</p>
<p>1-10CM male to male**</p>
<p>I am currently in the middle of this build. But it seems my controls are all backwards. For example left is right and throttle up is throttle down ect. Anybody else having this problem??</p>
<p>Just reverse the affected channels on your transmitter</p>
<p>Very nice! I was looking for something like his. A question: Is there place to install a gimbal underneath?</p><p>Thanks</p>
Great instructable! Thank you so much, I followed all your instructions and my dead cat flew first time perfect!!! Cheers.
<p>Sounds dumb but i can't get it right!<br>I Have a Graupner MX-12, with the throttle on the right side.</p><p>In Your Instructable, it's on the left side, so how do I have to swap the connectors, so the KK Board also recognizes the right stick as a throttle?</p>
<p>Why is finding downloads for the latest KK2.1 board firmware such an elusive thing? Google always takes me to that gigantic thread on RC Groups where finding any links is like finding a needle in a haystack. Where the heck does one find KK2.1 firmware updates?</p>
very hard
<p>Hi, useful article but have one comment regarding prop balancing - don't you have the prop balancer assembled wrong? The conical elements should normally have the tips of the cones facing each other, they are designed so that they self centre on the hole in the propeller. Also there is a second step to balancing which you haven't mentioned here - to balance the hub (often referred to as vertical balancing). Doesn't make as much different as the horizontal balance but worth doing. Enjoy your flying, R</p>
<p>Hi,</p><p>Congratulations for this great Instructable. It was very useful and complete. I built my Dead Cat last week.</p><p>I was able to buy all parts from HobbyKing (USA and Europe Warehouse). I bound it to my Spektrum DX6i with a Spektrum AR610 receiver.</p><p>I found two missing things when building it:</p><p>- in step 6, &quot;Mount motors&quot;, I did not get the needed screws because they do not come with the motors. I had to look for suitable screw all over my house (and I finally used some screws from a PC). For the record, motor's package says &quot;Bolt thread: M3*4mm&quot;</p><p>- in step 9, &quot;Mount Flight Controller&quot;, I did no get the white plastic parts you are using to mount the KK board. But I bought a KK 2.1.5 since the KK 2.0 is not sold anymore. I had to used some nuts instead (3 nuts for each foot).</p><p>When I tried to fly it for the first time it completely flipped over (from right to left). I broke a prop :( I finally discovered that I had to first load a motor layout in the KK 2.1.5 menu. I chose &quot;X Quadcopter&quot; and then applied settings for the motors (step 18, mixer editors) (I used slightly different settings I found in a Youtube video).</p><p>I also add some LEDs to it, and some FPV gear, but I did not yet tried to fly it in FPV only.</p><p>FPV parts are:</p><p>- Camera: <a href="http://www.securitycamera2000.com/products/-RunCam-600TVL-Plastic-Housing-FPV-Camera-%252d-DE.html" rel="nofollow">http://www.securitycamera2000.com/products/-RunCam...</a></p><p>- Video Tx/Rx: <a href="http://www.securitycamera2000.com/products/BOSCAM-Mini-8CH-5.8G-400mW-Wireless-FPV-Transmitter-Receiver-Kit-%252d-DE.html" rel="nofollow">http://www.securitycamera2000.com/products/BOSCAM-...</a></p><p>- Goggle: <a href="http://hobbyking.com/hobbyking/store/__53706__Quanum_DIY_%3Cspan%20style=" rel="nofollow">http://hobbyking.com/hobbyking/store/__53706__Quan...</a></p><p>- Antennas: <a href="http://www.hobbyking.com/hobbyking/store/__49827__ImmersionRC_5_8GHz_Circular_Polarized_SpiroNet_Antenna_V2_RP_SMA_.html" rel="nofollow">http://www.hobbyking.com/hobbyking/store/__49827__...</a></p><p>My Quadcopter now flies quite well! I'm looking forward to fly it more but it's kind of freezing for the moment... :)</p><p>I attached a picture of it.</p><p>Thank you,</p><p>Alex</p>
<p>Hi there, I have a deadcat 450, I also just bought a Qbrain but cannot seem to get this darn thing working, please could you be more specific about the Cabling!</p>
Hi. What settings do you have in your radiocontroler??
<p>I's using an OrangeRx DSM2 reciever without numbers. How would I wire it correctly?</p>
<p>Hello I bought Qbrain and Naza.</p><p>can you post a picture to see x </p><p>how did the connection between fate and Qbrai 4x25A naza m-lite? , Thank you</p>
<p>My motors did not come with the motor mounting screws as depicted in this picture. I purchased the &quot;Turnigy Multistar 2213-980Kv 14Pole Multi-Rotor Outrunner&quot; as listed in the parts list but there are no phillips screws with them. The motors on hobby king also dont show these screws. looking at the local hobby stores and hardware stores trying to find some that will wrk but I have not had any luck.</p>
<p>Realy great instructable, but I think that yu need to charge battery at LiPo balance mode, and not at normal charge mode. In LiPo balance mode, charger will balance each of the cell separately, so is more safe, and better for battery</p><p>:)</p>
<p>Hi great instructable, how can I connect the Q-brain to the KK2.1 voltage sensor to make use of the low voltage alarm? I cant seem to figure that out. Any help is appriciated. </p>
<p>So I am in the process of scratch-building my first quadcopter, and I am trying to use a Turnigy programming card to program my Q-Brain 4-in-1 ESC. I plug the Q-Brain in to the programming hub, and that into the programming card, and then plug in the battery to an XT60 connector I soldered onto the ESC, but the programming card doesn't light up or respond. What am I doing wrong, and what could a possible solution be?</p>
<p>Never mind, I finished the build completely! Great instructable, although I noticed that some of the mixer settings were flipped, possibly because of the recent firmware update.</p>
<p>Great instructable and now I definitely want a quadcopter for my own! One question, instead of buying a SK450 Dead Cat frame for the quadcopter could I lasercut my own such as this: (http://www.thingiverse.com/thing:113497/#files)? My idea was that it would be easier to repair broken arms and what not if I could create my own frame. I plan on using the exact same parts as the list provided but change the frame. Would this theoretically work?</p>
<p>Thank you for this great instructable ! Ordered all the parts from HK ! Looking forward for the delivery ! </p>
I voted. :)
I made my first flights and crashes today (I never flew before). Yes, I swapped motors 3 &amp; 4. I need to recalibrate the motors again; since the do not start at the same time. Thanks for the instructions.
<p>Nice Work DUDE... Voted </p>
<p>A stunning instructable! Very well presented in depth. Thanks for sharing!</p>
<p>Assuming they are compatible; can anyone tell me how to connect the Q-Brain to a DJI Naza Lite (http://www.dji.com/product/naza-m-lite). Thanks!</p>
<p>Nice work! I just finish my deadcat last week;) Just a question, are you sure that the mixer editor settings are correct? I think that you switch the third and fourth motors! Let me know!</p>
<p>please please upload video step by step please :( . so that it is more easy to understand and fix it </p>
<p>This was a great instructable, infact im building it myself, the one thing that annoyed me though, as this was my first time building a quadcopter, i didnt have the parts that werent included in the parts list, which made me pay for more shipping because i needed more parts, These parts were the threadlock, the XT60 connectors and the prop balancer, For others that are/were in the same situation as me, you should add those to the parts list, will make thier life much simplier, as im stuck waiting for threadlock and a balancer now...</p>
<p>Boy what an interesting project ! Now where does that neighbour stay that skin dip on Saturday? </p>
<p>I'm going to build this but was wondering what kind of camera did you use??</p>
<p>I use a Contour ROAM Model 1600.</p>
<p>thank you for the info and quick response! :)</p>
<p>Awwww, thought this was going to be a taxidermy quadcopter made from a dead cat. Good of you to show the crashes, most people pretend they have none.. got a nice vid myself, lots of bits of desimated copter flying past the camera.</p>
<p>Nice Build and well written instructable. I plan on building a defib. deadcat soon. I found youtube videos from HobbyKing setting up the KK2.1 for the sk450 DeadCat frame. There are several other videos they do on the KK boards as well. It is ALL about the firmware on the board (I would NOT recommend you fly stock firmware) and the set-up, calibration and tuning of the board. Nice thing about the KK board is the screen and user interface. There are tons of them out there and just as many videos and guides for set-up and tuning.</p><p>Cheers! :) and Many Happy Flights</p>

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