How to design a quadcopter frame in AutoCAD

How to design a quadcopter frame in AutoCAD

How to design a quadcopter frame in AutoCAD

 

This article is written by AirBladeUAV based on his experience designing micro drones for the past 4 years. Other designers may or may not follow the same process and workflow. 

 

Are you a drone enthusiast who wants to fly your own creations? Are you an aspiring drone designer who wants to get started in the industry? If that's the case, you will find this tutorial a good starting point. 

Before diving into this tutorial, I recommend getting familiar with AutoCAD design space, basic commands, controls and navigations. There are a lot of video tutorials on YouTube on these subjects. You can download a free version of AutoCAD through their education program. Basic commands that we will be using a lot for designing drone frames are: Line, Circle, Rectangle, Trim, Offset, Fillet, Move, PEdit, Group, Ungroup, Rotate, MeasureGeom etc 

 

OK, so now that you're familiar with basic controls, and have set up your design space to your preference, LET'S DIVE IN. 

 

Step 1: Determining the general geometry of your drone

Before getting into anything fancy, you need to first determine what type of frame you're designing because the type of frame will influence the general geometry of the frame. A few popular designs that you can explore is True X frame, H frame, stretched X, stretched H, deadcat style or reversed deadcat. 

 

Step 2: Determining the max prop size your frame design supports

Next step is determining what maximum prop size your frame is going to support: 2 inch or 2.5 inch or 5 inch. Combining the decisions made after step 1 and step 2 will give you an idea of how big your frame is going to be. With experience, you will eventually have a rough idea of what sort of dimensions you can use as base line. These dimensions is what we will be using in step 3. 

 

Step 3: Sketching the motor positions

 

How to design a quadcopter frame

Knowing the general geometry of the drone (step 1), and the prop size that this frame is for (step 2), you can take the very first step in designing your frame by drawing the motor position.

In our example here, we will be making basic H frame that can accommodate 2.5 inch propellers. So how do you determine where the motor positions are? It's really a blend of art and science here, and it also requires some experience to get it right, but I'll show you the thinking process that I applied.

So 2.5 inch prop is 63.5mm. That means at the very least, you need a square with dimensions of 63.5x63.5mm. This square will ensure that the prop tips are just touching. This is provided that the electronic stack and camera are already out of the prop line. In reality, you will make the square slightly bigger with dimensions of 63.5mm + X (where X is the extra buffer).

In our case here, I plan on having the camera on the same plane as the motor and positioned a little forward, therefore the width of the rectangle will have to be 63.5mm+ 20mm (width of camera) + X. And the length of the rectangle can be as little as 65mm. I've decided to go with 80mmx100mm.

Use command RECTANGLE to draw a rectangle with dimensions of 80mmx100mm. 

Notice that I also draw 2 lines that go through horizontal and vertical midpoints. These lines are important for our Mirror command later. Because our frame is symmetrical, using the Mirror command will speed up the design process. 

Step 4: Sketching the arm profile

Next step is sketching the arm profile. Use command 'Mirror' to duplicate it for all 4 different arms. Make sure you have the mirror lines sketched out as mentioned above. 

How to design a quadcopter frame

How to design a quadcopter frame

How to design a quadcopter frame

Step 5: Test fitting your components

In this step, you want to make sure that your intended components will fit the frame. The full extend of the test depends on your design and what components you're using, but for the most basic test, you want to make sure that your props don't strike the stack or your camera. 

So first you need to draw the prop line on all 4 corners. In this case, that would be a circle with diameter of 63.5mm. Use Mirror command to replicate the same circle to all 4 corners 

How to design a quadcopter frame

How to design a quadcopter frame

Draw the intended stack configuration. In this frame, I want it to be able to take 16x16, 20x20 and 26x26 stack. Make sure you group all the different stack configuration into 1 object using command 'Group'. 

How to design a quadcopter frame

How to design a quadcopter frame

How to design a quadcopter frame

Move the stack configuration to the intended mounting place and ensure that there is enough clearance from the prop line. Please note that the square drawn in this case is the mounting dimension, you need to make sure that the edge of the board (for example, 27x27 edge to edge for a standard 20x20 board) is also clear of the prop line 

How to design a quadcopter frame

Step 6: Filling in details

Now that we know the frame fits your electronics and there is enough clearance for the props, you can start filing in the details: arm width, motor mount shape, body etc 

Remember the line you drew for the arm shape? You can use command line 'Offset' to make the desired arm width. In this case, we want our frame to be fairly light and toothpick-like, so we will give the arms 6mm width. 

How to design a quadcopter frame

How to design a quadcopter frame

Draw the motor mount and mounting holes for each motor. Use Mirror command line to replicate that for all 4 motors. Note: I forgot to add the c-clip hole in this picture, but you need to make a cutout for motor c-clip. Usually a circle of 5mm diameter. 

For micro motors, most of them use 9mm spacing and M2 screws. So what you want to do is to draw 2 lines perpendicular with each other and then draw a circle with 9mm diameter. The 4 points where the circle intersects the lines are the mounting holes. Draw circles with 2mm diameter at those intersections. 

How to design a quadcopter frame

How to design a quadcopter frame

Draw mounting holes for electronic stacks. I typically assume that they will use M3 hardware. It's simpler because M3 holes will always fit M2 hardware, but not the other way around. A trick here is that you need to draw circles with diameter just slightly larger than 3mm, so that the screws can go through effortlessly. I typically go with 3.1mm diameter. 

How to design a quadcopter frame

Step 7: Adding your own personal touch

At this stage, you just need to add your own personal touch to the design. You decide how the general shape would look. You decide how the cutouts look, how the battery strap looks. You have all the tools at your disposal. 

How to design a quadcopter frame

Use command line Fillet to soften all the corners 

Final step: Cleaning up / Finalizing the design

The final step is simple, you just need to delete any objects that are not pat of the final design. Make sure to use fillet on corners. 

Highlight all the object and group them together

Note: As mentioned above, I forgot to draw the c-clip holes for the motor mount. Usually those are circles of 5mm diameter.

Congratulations, you've designed your very first FPV frame using AutoCAD. 

Previous article AirBlade Eclair V2 Design Source Files
Next article Tips for flying long range FPV

Comments

Brendan - May 23, 2019

This is an awesome article. What is your design philosophy when it comes to micro’s? The eclair is a sick frame but it is definitely a lot larger and heavier than what is currently trending in the market it seems. It seems like the general preference is to go lightweight nowadays, but it has only gone mainstream recently with kababs toothpick. But this style has been around for a little while with the hoverbot, the pepperfish, and falconmultirotors babyshark and tiny shark and your creampuff. What are your thoughts?

Logan - May 19, 2019

Awesome Article! I have been working on a frame design for a while but have yet to transfer the designs onto CAD software… To answer the question above; Many RC companies carry sheets of high quality carbon fibre in different thicknesses. As far as manufacturing many cities have “maker spaces” now where you can pay a monthly fee to use their equipment which most often includes CNC router tables and laser cutters as well as mills, lathes, 3D printers, etc. You can also build yourself a basic CNC router table with a submerged tooling bed for fairly cheap if you want to go that route. Good luck with your designs!

jonathan hilairet - May 16, 2019

Hi,

Where do I buy the material and where to manufacture the frame ?

Thank you

Leave a comment

* Required fields