2. Computer-Aided Design#

Two slots of two hours have been made available this week for the Computer-Aided Design and more precisely the 3D printing by digital tools.

2.1 Computer-Aided Design (CAD)#

CAD is the help given by many tools on your computer to create a design by youself quite easily. In our case, it’s modeling an object on our computer before printing it thanks to the 3D printer. In most of those tools, you can find where the issues of your design is and what type of modification you might need. This helps you to win time, increase the productivity and improve the the quality of the design. Personnaly, I find CAD goof for viewing objects created and to be aware about what will exactly be produced.

Compliants mechanisme are components that bends by their property of flexibility they have but are designed to keep enough rigidity to avoid to break. The mechanisme is able to transmit force ans someho to break other objects.
We were introduced to the compliants mechanisme and their uses mostly by this video. Thannks to the video, ideas came easily and launched me to my own compliant mechanisme. The purpose of our teachers to let us know about Compliant Mechanism is to ensure that we were aware that they exist and to give us time to think about it and eventually fall on a idea. We have also learned what a FlexLink is. A FlexLink is a component made by the 3D machine that connects different objects between them to finally be a Compliant Mechanism. Most of use choose to legos in order to make a FlexLink.

2.3 3D Softwares#

Several programmes have been proposed tu use and we were free to chose between these different softwares: * Inkscape * OpenSCAD * FreeCAD

Since my background is not at all based on coding, I decided to use OpenSCAD that works more on coding than FreeCAD that is more trivial. I’m completly new to this world and I had some issues to unerstand everything by myself very quickly.

2.4 OpenSCAD#

I installed OpenSCAD through this link. Nothing difficult, just need to follow the instructions.

OpenSCAD is a open source 3D software really usefull for the designers to create 2D and 3D objects. The creation of these objects are made by the designer through a programme/code very specific to the software. It anables you to know the dimentions,curve,etc. A memory aid can be found on this cheat sheet or by following these steps on the software: Aide -> Aide-mémoire Don’t hesistate to use this memory aid, he will be your closest fried or to watch youtube tutorial, I learned everything like this.

This is how OpenSCAD looks. On the right hand side of the desk you can find the editor where you can type the code that will post the object wanted seen in the middle of your screen. Eventually bellow the screen, a console helping you to know where there is an error in your code od there is. how it looks

At first, I tried to design a proper Flexlink compatible with legos but I encountered some issues making it. I designed one as best as I could and I ended up with this:

first flexlink

The code for my FlexLink can be found below:

//variables
side=4;
$fn=30;
radius=1;
//forme
module base(){
    difference(){
        cube([side,side,side/4]);
        translate([2,2,0]){
            cylinder(h=side,r=radius,center=true);
        }
    }
}

//multiplication du module base
module palette(){
    for(y=[0 : 4 :12]){
        translate([0,y,0]){
            base();
        }
    }
}


//lien entre les deux palette
module lien(){
    cube([side*3,side,side/4]);
}


//deuxième palette
palette();
translate([15,0,0]){
    palette();
}

//deuxieme lien 
translate([4,2,0])lien();
translate([4,10,0]){
    lien();
}

When the FlexLink was completed by the 3D machine, I realised that the dimension of it was way to small but I’m pretty sure you can retake my code and modify the variables to obtain an object with the right dimensions. Because of my mistake I decided to switch to a simple Compliant Mechanism and not modify to right dimensions and to print it a second time.

2.6 Design a Compliant Mechanism#

Once I have learned from my mistakes about my FlexLink I have started to design a Compliant Mechanism. I decided to make a bag clamp and why not use it in the future. As you saw for the FlexLink, I always take action for my code in the same way (Thibault said me to do so): * Create Variables * Create Modules * Call the different modules and assemble them to sep up the object

I also decided to writte my own code in OpenSCAD contrary to other students that copy and paste a ready-made code. I tried my best but I’m quite sure the code can be written in an other way or more compact but it works like I did so why should I change?

my compliant

The code for my Compliant Mechanism can be found below:

//Author: Antoine Depré

//Last modified: 29/10/2024

//License: Creative Commons CC BY 4.0


//Variables
height=10;
radius=30;
$fn=50;

//Modules

module arc(){
    difference(){
        difference(){
            cylinder(height,d=radius,center=false);
            cylinder(height,d=radius-5,center=false);
        }
        translate([0,-radius/2,0])cube([radius,radius,height]);
    }
}

module base(){
    translate([0,-10,12.5])cube([height*3,height,2.5]);
}

module base_deux(){
    translate([0,-10,-15])cube([height*3,height,2.5]);
}

module triangle(){
    triangle_points= [[0,0], [30,0], [30,20]];
    linear_extrude(height=height){
        polygon(points=triangle_points);
    }
}

module triangle_bien(){
    rotate(a=90, v=[-1,0,0])translate([0,-12.5,-10])triangle();
}







union(){
rotate(a=90, v=[1,0,0]) arc();



base();
triangle_bien();
base_deux();
}
*/

Despite a fairly simple object, I made a few mistakes that cost me a lot of time, such as not writing ; after a command or forget to write union at the end of my code. I played a bit with FreeCAD to smooth the corners of my Compliant Mechanism but eventually found it useless by the fact that the 3D printer will do it by “himself”.

License#

I chose to add a license to my work because it was recommended to but also because it’s the first time that I get in touch with this subject. I did some reseach about it and I would define it as A license is like an agreement that tells you what you can and can’t do with something, like software or a song. For example, it might say you can use the software but not sell it, or that you can share the song but not change it. It’s kind of like the rules of the game for using something legally. Creative Commons License is the website that helped me to understand what it is and to create my license. It is super easy ans clear! Final result from the website: `FlexLink_FabLab © 2024 by Antoine Depré is licensed under CC BY 4.0