Week 02 - Computer-Aided Design (CAD)


Computer-Aided Design Tools

CAD are very powerful if it comes to actually designing 2D or 3D parts. I have worked with a lot of different tools in the past, but barely scratched the surface of their capabilities. These range from design to rendering, simulation and computer-aided manufacturing (CAM), with we'll deal in the future as well. I gained my experience with SolidEdge, CATIA, Blender and Autodesk Inventor.

Professional CAD allows so-called parametric design, whereas rather design focussed tools often don't, e. g. Rhino and Blender. For simple 2D designs, I used to use Inkscape which is also relatively easy to and for simple tasks absolutely sufficient (e. g. boxes for a laser cut design).

3D Design with Blender

Blender is also a really cool (and free) design tool, but it takes while to get used to it and it is not parametric. Especially, the rendering and compositing part is really interesting as it allows to make Hollywood-like special effects. To create of the actual video however pushes my computer to its limits and took several hours. Just to give you an idea of what is possible, here are some videos I made some time ago on simulating physics as well as compositing and animation plus a rendered image. Compositing bascially means to add computer-generated effects to a regular footage like most of the movies these days.

Compositing with Blender (animated ball)
Explosion with physics and lighting
Animation of characters
image Enterprise_Cycles Rendering with Cycles-Engine in Blender

Modelling with Fusion 360

Autodesk Fusion 360 is rather new for me, but it seems to similar Autodesk Inventor which I have used more often. With the extension into simulation, rendering and CAM it also seems extremely powerful. I highly recommend doing some tutorials before starting your project. A bunch of these can be found on Youtube, in the Fusion 360 channel.

For the time being, I will work with the "MODEL" module only. This allows 2D and 3D design of single parts as well as assemblies of interacting parts. By aligning these parts and constraining the their relationship, simulations will later on be possible as well. This helps in discovering physical collision before they occur (and cost you a lot of time fixing!).

2D design - first part

In this case, I will use Fusion 360 and Inkscape for 2D sketching. Here are some basic functionalities. Let me credit Jonathan Yen for an excellent live tutorial on this which helped understanding some basic concepts, I summarized below.


This involves basic shapes, e. g. lines, rectangles, circles and splines which can be called by a shortcut within Fusion. Typing s brings in the search function which helps finding certain things faster than via the menu. Right clicking will offer you to add dimensions to a form.

image 2D_Design_BasicShapes Basic shapes


In order to reduce repetitive tasks, patterns are a very versatile tool. In this case the a circle is copied six times in circular pattern, e. g. to create a hole for a bolt. This diameter could be given parameter in order to have a flexible design. If you were to change your design later on, only the parameter would have to be updated, the rest happens automatically.

image 2D_Design_Patterns Patterns


As most constructed product a usually a high degree of symmetry, it makes no sense to design both sides in parallel. The mirroring tool needs an object and an axis as input. The axis is represented as a line here. Press x to turn a regular line into a construction line. The so-called symmetry contraints will depict the two objects as mirrored. Contraints are in fact a very important concept in order to fix the underlying relationship between objects.

image 2D_Design_Mirror Mirror


There are a bunch of constraints to take into consideration, when designing a model. Most are pretty straight forward.

image 2D_Design_Contraints Contraints

Hello-World part

I designed a small hexagon which is slotted. I applied mirroring, as well as circular patterns, added constraints and the trim tool. It is available in the download section.

image 2D_Design_Hexagon HelloWorld file


I also used Inkscape to design a press fit kit. It is not as comfortable to design complex 2D parts accurately. You can however use a bunch of boolean operation to design a simple press fits.

image LaserPrintCut Simple press fit design

Within Inkscape, there are some import feature you should know about.

image Inkscape_Layers First, layers: layers will help you in aligning your geometric forms in order get things in the pattern you would like to design.
image 2_Inkscape_Align Second, align: once you have created your tongues and grooves, you have to align them in x and y. Furthermore, you want them equidistant. The "align" feature are very helpful in accomplishing that.
image Inkscape_Fill_Stroke Third, stroke and fill: These feature control the fill color as well as the line color of an object. Set the line width to 0.01 mm and select no fill to define a cut.
image Inkscape_Patterns Fourth, pattern: in order to repeat a given pattern, the "create tiles clone" feature turned out to be very helpful. I used it to create a bendable piece of wood. image LaserCutSettings Standard settings

The standard settings for the lasercutter have to be adapted according the material and its thickness. For 5 mm MDF material, I set the speed to 4 %, the power to 100 % and the frequency to 20 %. The outside edges were set to red line color. Inner edges will be set to green and will be cut at first.

Laser cut plywood
2D_cut_unassembled 2D cut
2D_cut_assembled 2D cut assembled

Bendable object

In order to create shapes that follow a curve, laser cutters can also be used to generate 3D shapes. A simple example is the following shape which can be bend around one axis. This is achieved by cutting away only parts of the material. The resulting radians are however hard to predict. To use this technique in product design takes some trial an error.

In order to cut plywood of 3 mm thickness, speed was turned up to 8 %. All other settings were kept the same as above.

BendableShap_HelloWorld_1 Bendable shape
BendableShap_HelloWorld_2 Flexibility demonstrated

3D design - first part

Here is the first model I did with Fusion 360. It is a box which is going to contain the camera and its gimbal later on. The final result looks like this:
Camera housing design

By the way, to find out how to embed Fusion 360 files, follow this link.

The precise design of the gimbal will come later, as there is a variety of solutions. However, here is the first draft.

image FinalProject_FirstDraft The manual sketch
image Draft_CameraGimbal First part: housing for the gimbal
image 2_InitialSketch First CAD sketch - Photobot

Let's start with the housing design. Within Fusion 360 Model, I'll start with 200 mm by 200 mm box with a height of 150 mm. This leave enough space for the electronics, the flashlight and the gimbal, it is work in progress anyhow.

image CAD_Box_1 Step 1

Camera hole draft: Draw two circle with diameter of 70 mm. Create a center line (press x to change line style). Connect the circles with a tangent and trim unneeded edges to make the design more accurate. Mirror the left side over. The oval shape will allow the camera to pitch without hitting the housing.

image CAD_Box_2 Step 2

Shell box: Before creating holes are created, the box has to be a shell. Let's create a shell with a wall thickness of 4 mm. The final box will most probably be from plywood.

image CAD_Box_3 Step 3

Camera hole: Select the "camera hole draft" and extrude inside (more than 5 mm) to create the actual hole.

image CAD_Box_4 Step 4

Fillets: select all edges to create some fillets of 6 mm radius.

image CAD_Box_5 Step 5

Stand hole: create another slot for the stand.

image CAD_Box_6 Step 6

Flashlight hole: create another hole for the flashlight to come out.

image CAD_Box_7 Step 7

Download files