2. Computer-Aided Design (CAD)#

This week we had to design a Compliant Mechanism. But what is a Compliant Mechanism 🤔? It’s a monolitics structure that transform a mechanical input into a desired mechanical output using hinges.

Compliant mechanisms are known for their simplicity, lightweight design, and applications in various fields such as robotics, aerospace, and engineering.

In this unit, we learned how to use  :

1. Inkscape

2. FreeCAD

3. OpenSCAD

Inkscape is typically used to design 2D models. It’s a vector graphic creation and manipulation program.

FreeCAD is an open-source 3D CAD software for creating and editing 3D models. It’s used in engineering, architecture, and product design, featuring parametric modeling and supporting various file formats for versatility in design.

OpenSCAD is a code-based software, on which you describe your 3D design by coding it😮.  

2.1) Openscad#

I personally used openscad to design my 3D model.

How does openscad work ?#

Transformations	Boolean operation	2D/3Dforms
mirror	union ()	polygon
translate	difference ()	cylinder
resize	intersection ()	square
rotate	hull ()	sphere
scale	Minkowski ()	circle

If you never used Openscad like me, you can visit the OpenScad cheat sheet. I also had to watch some tutorials on YouTube to understand more about this app.

2.2) Some examples#

2.3) Ideas#

In my opinion, the most difficult part was to find the idea. We searched for some inspiration on Thingiverse. It’s a website dedicated to sharing digital 3D printing files created by many different people. After thinking about it for a long time, we had the idea of creating a mouse with a flexible tail.

2.4) My design#

We had to work in groups. I had to make the body of the mouse so the non-flexible part and the other person that I am working with Louis he has to create a flexible tail for the mouse. The pieces assembled together will form a compliant mechanism.

Yes, I know it doesn’t look like a mouse, but I tried my best 🤫. Let’s hope with the tail it will be better. The main goal is to see if the pieces can be assembled together.

If you are interested, you can go visit Louis Jonas page to see the other part of the code.

Go check my module 3 if you are curious !

2.4.1) My final code for the design#

//Author : Alishba Naqi

// Date : 18/10/2023

// License : Creative Commons Attribution-ShareAlike 4.0 International [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/)

// Creation of a mouse (I tried)

// These are the different parameters 
pin_diameter=4.6;
pin_height=6.4;
trs=[0,-53,3.1];
trs1=[0,-53,-3.1];
trs2=[0,-53,0];
trs3=[0,10,0];
trs4=[0,-30,0];
rot=[100,100,12];
rot1=[90,-90,0];
rot2=[120,90,30];
pin_surface_diameter=6; 
body_size=[25,25,50];
body_radius=70;
t=40;

// Creation of a pin
module pin(){
    cylinder(h=pin_height,d=pin_diameter,$fn=100);
}

// Adding the pins to the body
union(){
    // Creating the first pin
    translate(trs)
    rotate(rot)
    pin();

    // Creating the second pin
    translate(trs1)
    rotate(rot)
    pin();

    // Creating the body
    union(){
        // Adding a surface for the pins to the body
        translate(trs2)
        rotate(rot1)
        circle(pin_surface_diameter,$fn=100);

        // Removing one of the extremities of the body to put the pin
        difference (){
            // Assembling the mouse's head and body
            union(){
                // Mouse's head
                translate(trs3)
                rotate(rot2)
                cylinder(d1=10,d2=15,h=20,$fn=40);

                // Mouse's body
                translate(trs4)
                rotate(rot2)
                resize(body_size)
                sphere(body_radius);
            }

            // Creating a cube to remove part of the body
            translate([5,-73,5]) rotate([0,90,90])
            cube(t,center=true);
        }
    }
}

As you can see at the beginning of my code, I’ve set several and different parameters to make it easier to change the values when needed.

2.5) Licenses#

Creative Commons licenses are legal tools that help you grant copyright permissions to the public.

• BY: credit must be given to the creator.

• SA: Adaptations must be shared under the same terms.

• NC: Only noncommercial uses of the work are permitted

• ND: No derivatives or adaptations of the work are permitted.

We have different form of licenses : CC BY, CC BY-SA, CC BY-NC, CC BY-NC-SA, CC BY-ND, CC BY-NC-ND

If you need more information about these licenses, you can click here.

 // File : MOUSE 3D.scad

//Author : Alishba Naqi

// Date : 18/10/2023

// License : Creative Commons Attribution-ShareAlike 4.0 International [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/)