Introduction: Aluminum Sport X Copter Frame Design for Strength, Lightwieght, and Easy.
This all-Aluminum X copter is strong, light, and easiest to repair of all the frames. Because the pieces are made of flat aluminum, even if you crash it really hard, it just gets bent, you can flatten it back out with a hammer. It reduces waste because you are not replacing major parts every time you crash. It saves you money because its the last frame you will ever need. I call it ADrone.
Here is a flight demo: http://youtu.be/p1Q24a21pxQ
It costs more than wood, but less than carbon fiber, but still high performance. You can build this from scratch with $40 worth of parts from the hardware store. If you have a drill, a saw, and a dremel, you can do it!
I care about the design details like the vibration dampening motor mounts, the space underneath for equipment, and the simplicity of the design which makes it so easy to fabricate. It has the thinnest arms possible which presents effectively NO DRAG on the air flow of the propellers. It can be scaled up or down to make a mini-quad or a huge heavy lifter. The design is open source and files are all available. Enjoy!
Specifications for this build:
6061 Aluminum 1" flat bar, 85" total.
Aluminum Square or C-tube, 5" total.
Arm length 12"
Suggested prop size 9" up to 12"
Bare frame weight: 450g = 1lb. or less.
1020kv park 480 motors x4
2200mAh 3S Li-po =+5min ( can add more up to 10Ah of lipo)
Fully assembled with electronics weight 4.4lb
Carry Capacity - ecalc says between 1.75 and 5 lb, so far have gotten 3.5lb in the air (80% its own weight)
Get ready - 30 minutes hover time, 15 minutes sport flying. If you want, you can even get 30 minutes sport flying, by lightening it up (it can carry 6 batteries)
The best part about this instructable is that you can choose the size of motors, batteries, etc. as you like. The frame is so light and strong that it can handle a wide range of configurations.
I am just showing a great frame design. You can use plywood, plastic, even CF. For big and small sizes.
The inspiration to make this this frame is configured to allow a high load to be carried so that more sensors and cameras and fun stuff can fly too. If you want a simple FPV or fun flying toy, then this is overkill strong.
I have seen some people lift some pretty high loads and they could get even higher if they used this design.
Don't take my word for it, build one.
Step 1: Materials and Tools
- Aluminum1" x 1/8" x 72" (main brackets and arms)
- Aluminum 1" C bar or 1" square tube (needed C but they only had square tube) - 4 " length (motor mounts)
- Rubber or plastic PVC tubing with ID>.15" and OD<.4"
- 18AWG or similar wire, 10 feet is good. It does not need to be insulated.
- #8-32 course machine screws, 1.5 inch long, 1.2 minimum (x8)
- #8-32 course machine screws, 2 inch long (x8)
- #8-32 nuts (x20)
- Double sided clear tape and regular clear tape
- Drill and bits, (Ryobi 23 piece black set is good)
- Dremel and a pack of cut off wheels, preferably speed controlled.
- 1/8" metal file
- Some random blocks of wood for cutting and drilling on.
- Exhaust fan or outdoor area
- Printer - print out templates
- Scratch awl or Center punch for making center punches.
- New pointed sharpie or similar felt tip marker
- Xacto or box cutter blade
Not required but helps
- Saw, hand saw or circular for mking straight cuts.
- WD-40 is good for lubricating aluminum and keeping your drills and saws sharp longer.
That is up to you! I made my own wire harness which is simple 14 or 16 guage copper with bullet connectors soldered to it. I'll show that, but wiring and electronics seem to be different for each person, so I leave it to you, but Here are some resources. Look up PDB(power distribution board), or see my video for the wiring harness (https://www.youtube.com/watch?v=-4foev6hjJk) You see the harness with the 4 corners and battery connector, one for each polarity. Twisting them helps a little with compass interference but not that important yet.
Make sure that the wires you are using can handle the current. Most PDB are less than 80A and most hobby wire harness are for around that. People can lie so u have to test critical components.
If you are new to flying be careful but enjoy it. With today's electronics, there are a lot of possibilities for RC robots, and drones. It is exciting for experts, hobbyists, and people who have never flown before with a twinkle in their eyes. If you get carried away and hurt yourself OR OTHERS you will not only set yourself up for pain, you will hurt every other expert, hobbyist, and person who was just getting started with that same twinkle in their eyes, so be careful and responsible. Don't be that guy that got killed by his quadcopter. Enough lecturing, fun time.
Step 2: Arms
Square tubes are not aerodynamic, Round ones are more expensive, and if they get dented say goodbye. I think they might be lightest, but you can see in the picture from Wikipedia that they have a good amount of drag compared to a streamlined body, so taking the flat bars and adding a thin streamlined wrapper can make it have almost 0.04 drag instead of 0.4 for circles.
Here is some reference about drag from Wikipedia http://en.wikipedia.org/wiki/Drag_(physics) note that instructables does not make links with parenthesis in them automatically and might mess it up on your viewing.
Here is another example about shape http://en.wikipedia.org/wiki/Drag_coefficient
Flat ones only bend in one direction and extremely stiff in the other. They are thinner than the round ones, and (I have not proven this yet) have less obstruction in the thrust path of the propellers.
There is a lot of open space for attachments on these arms and even room for weight reduction drilling.
To cut the arms, you can use the design and CNC them, or you can cut them by hand. I did my first ones by hand, here it is.
To do it by hand:
Print out the template and make sure that they are scaled right.
I used Paint, I found some settings that let me print out decently, If there is a better way I would like to hear it. For some reason inkscape couldn't print on target.
Paint settings: Portrait, 0.25" L &R Margins, 0.5" Up and down margins, and make the image 8"x10".
You can increase the resolution by x4 the values to get 32"x40".
And then on the print settings, select "Fit to 1 page"
You could also just use the design file and scale it yourself using a better program. Please help
Umm or you could just use the design files on a CNC. This first one was mostly by template and hand cutting.
So this is how to do it with template and hand cutting:
Line them up and tape them on to the bars and punch or scratch lightly on the corners of the metal just in case the template falls off while you are cutting, you will not want to lose the cut lines. You can also scratch the lines into the metal to help keep the cut straight as you cut.
Make the 1/8" deep cuts first on either side of each nub and then remove the remaining in the middle.
The cuts need to be very straight so take your time. Check on the back side to make sure that the cuts are straight across. The video shows a speed up of the cuts being made. Using a dremel it took about an hour and 6 cut off wheels to do the 4 arms. If you practice or get a better saw like a hack saw or something else on hand.
Then when you have successfully cut the dove tails (they are not tails they are straight cuts so not sure what to call them.) center punch, pilot, then drill the motor mount holes for the motor mounts. If you want to make an octo, then you can drill another set below.
Punch, Pilot(1/16), Drill (11/64). Then use a larger bit to chafer the edges and de-burr the holes if you like. You need 4 arms but you can make more just in case you over-cut one, but you probably wont.
see pictures above
Step 3: Main (body) Brackets
These are arranged in a square for the main body and using two plates to sandwich the arms with bolts to hold them securely. Get out your square drill bit, jk, round is ok. If you are drilling by hand, center punch on the line so that the width of the cut matches. The vice helps here, hold it in place, and use the 1/8 bit for the oval cuts. I call them oval even though they are square because it doesn't matter really and its easier to leave them round instead of squaring them.
To make these, you need a drill or drill press or mill, or even cnc. I used a drill to make some really ugly ones and they still worked.
Print out the templates, tape them onto the flat bar and then center punch the holes right in the middle. Then for the oval ones you can either drill two holes and use a dremel to cut in between, or wiggle the drill side by side until you have a slot shape. the reason for taping the templates onto the bar is so that you can see the lines and you can be more exact while you are doing it by hand. If you do it by machine, you can easily program the cuts in and just let it run. The image is included here, and you might need to resize the template to print it out the right size, I used paint and pre-sized it for you , but it might come out different depending on the type of printer you use or your margins and settings, so just resize it until it fits. Sorry
Center punch first, then use the pilot bit(1/16), then step up to (1/8), then drill the outer holes with (3/16),
Then finally use a larger bit to chamfer just enough to get rid of the burrs around the holes.
Make 6, 2 of them don't need the oval slots so if you mess up doing those, you can still use them
Step 4: Motor Mounts
Using the 1" 1/16th inch thick aluminum bar, I first cut off one side to make it a C channel. You can buy a C channel also but I could not get one.
Cut out 4 1" long cubes, and then use the motor mount supplied by the motor mfg. on the mounts and use the sharpie to mark where the holes are. Center punch them and pilot, then 7/64, then 9/64, and for the motor use a larger bit and chamfer the edges so it its flush. There is also a template for your convenience.
The center is .45 inch so step up through the bits until you get to the closest one without going over and then use a file or sander attachment to make it bigger until the motor fits without scraping when it turns. The holes are so close you might overlap a little bit, but it will work fine this metal is pretty strong.
Do the side holes that mount it to the arm. They are .4 inch apart and 11/64 wide. Try putting a 7/8" wood block inside so you don't bend it when you hammer and drill. pilot, drill, then final size. Also a vice or edge of table works.
Chamfer or deburr (countersink) the holes just a little bit on the outside and a little bit more on the inside, if you can get in there, if not, don't worry. If it is easier to work with them, you can actually cut them in half and they will work great and might have an effect on dampening vibrations.
The PVC or rubber tubes need to be exactly 3/4" long, and cut in half (kept in pairs) so actually 3/8" long
You need 4 for each mount. make extras and put them in a bag. The reason for cutting them 3/4 and then in half, is that if there are any differences between the lengths, it will keep the motors straight if you keep the pairs together on each screw.
If not using threadlocking nuts then double sided tape on the outside of the mounts where the arm screws go, so that the nuts don't shake loose. Others like to use Loctite or Locking nuts which is a good idea I didn't think of... tape is reusable and in my theory gives a little cushion when you tighten it so it might work too. We'll see.
update: tape works. i'm getting lock nuts to try out even though they cost a little more...
Step 5: Assemble
The frame is finished, now insert 2 arms into two main plates and make a sandwich. Do that twice. Once for each side. The two remaining plates go on top as you can see in the pictures or video if you watched it.
Don't over tighten the bolts, make sure they are a little loose so you can make sure everything fits correctly, and then hand tighten and then use the "star pattern" method (like you would put the wheels on your car).
The metal may bend if you don't tighten them evenly, the star pattern is not a star in this case, but same rules apply. Start with the inner nut of one corner, then the inner nut of the opposing, then the inner of across, then opposing again. Then do the same or reverse with the outer nuts. If you don't understand what I am saying I can try again, or you might figure it out as you assemble.
DO NOT put the motor mounts on yet. The motors go on the mounts first. Then the mounts go on the arms.
The plastic shoebox or whatever box or cover you want to use to house the electronics is up to you, I used a shoebox because it was $1 and I mounted it upside down using the lid as a platform. This way the top is a nice removable thing. There are other options and I would love to see what you "make fly".
It is as simple as drilling 8 holes for the screws, then then 4 more for the wires. it might vary depending on your box, but in the video and pictures you can see how its done.
The wire you see going around can be any wire or strong thread that holds the arms rigid during sideways force. It adds rigidity without much extra weight. String it around through the center holes at the end of the arms and then tie a good knot, while it has tension. If you need more tension you can add a zip tie(s) to the frame as shown in the picture, then tighten them to bring the tension to required.
The Assembly Video is here: https://www.youtube.com/watch?v=SWrHk37KZWA
Tell me if you need more info or some better explanations. have fun!
Step 6: Cameras and Accessories
The removable top is a great platform for all the things you want to add. You can even have multiple tops that you can switch depending on the type of flying you want to do.
Sport slim top,
LEDs and camera
Sensors, additional radios, more batteries.. Wifi router...
Step 7: The Future Is Unwritten
Hoping that this design gets better and better. And can get lighter and stronger.
I am asking for help too.
If you add to the project, or make your own designs, please send me a link so I can reference you in the next step.
I want to hear what you think I should do next.
Step 8: Additional Resources
I only designed the frame, But I did do a whole lot of research to get here. I am a wealth of knowledge and glad to share. If you don't need help and you just need the frame, congrats, Please build it and show me your rescue videos or stunts.
Help me make it better, join the project or just leave a comment. Anything helps!
Fully Autonomous Flight Controller with GPS. https://store.3drobotics.com/products/apm-2-6-kit-1
Also, on ebay there are ~$100 FPV kits I hope they work.
Some other controllers are kk2 or other small ones but you are really missing out without the APM which is so easy or the px4 which is super cutting edge if you are going to be programming a lot.
Motors can be the DJ or RC standard motors that are on the smaller drones. But if course if you spend a little more you can get a 90% efficient instead of 80% efficient motor that has a little more power too. Eflite is great.
If there is anything I need to clarify or questions please go ahead. Thanks.