Computer-Aided Design

model (raster, vector, 2D, 3D, render, animate, simulate, …)

I did alot of raster graphics and vector graphics before using Photoshop and Illustrator. But this is a great opportunity for me to explore new tools that are free and open. Since I’m a school teacher free and open tools provide freedom to teach across the globe and especially in Armenia where GDP per capita is 3,936 $ (World Bank 2017) for comparison Israel’s GDP per capita is 40,270 $ (World Bank 2017) and world average GDP per capita is 10,721 $ (World Bank 2017).

Krita (raster graphics) Version 4.1.7

Krita is free and open source painting program very much like photoshop and you can do advanced raster editing after some learning. If you are a photoshop. I tried to open RGB colored and CMYK colored .psd files which is Adobe Photoshop file extension and Krita easily opened it. If you are a photoshop user, some tools and their shortcut keys might be little bit confusing for example:
T that is Text tool in photoshop brings up Move tool in Krita.

Gimp (raster graphics) Version 2.8.22

Gimp is another free and open source painting program very much like photoshop too and it’s more or less easier to navigate in my estimation. I tried to open RGB colored and CMYK colored .psd files which is Adobe Photoshop file extension and unfortunately Gimp failed to open CMYK colored .psd file. One nice thing it has special plugin for saving for web which is one of my favorite parts.
After installing Gimp:
sudo apt install gimp
To get that plugin you just have to type:
sudo apt install gimp-save-for-web
after this you will have this wonderful option in your File menu.

I tried to add one of my favorite quotes to my headshot, and I have to say that it’s rather easy to work with Gimp. Text tool is very intuitive and easy to use, but after I tried to scale it by dragging it’s corners it lost it’s editability and In my estimation it would be nice if editability stays unless you choose to change it manually.

Inkscape (vector graphics) Version 0.92.3

This is a free and open source vector graphics editor. The first thing I've noticed is it supports .ai and .eps files these are Adobe Illustrator file formats and there are huge collections (freepik, vecteezy) of shapes, logos and other vector based graphics in this file format.

The next thing I did was to explore the main tools that I usually use. The first ones were fill and stroke settings that are essential. The fill option is used to determine the properties of the area inside a geometrical objects boundaries. For example you can have a colored rectangle or a rectangle with transparent area or no fill.
The next tool is stroke propertie tool that determines what options should the borders of a geometrical object have. For example the thickness, color or the style of the borders. Here is an simple step by step image I made with Gimp.

Since I'm not yet sure about my final project, I thought maybe drawing something interesting in terms of educating myself and enriching our community might be a good idea.
Radio-frequency identification (RFID) is very popular nowedays and you can find them almost in every store on every product they are embedded in many corporate ID cards and passports but the technology behind it is not so obvious particulary for me. After surfing the net I found an interesting instructable on how to make RFID Reader Detector using pieces of copper and cardboard. I thought maybe drawing the RFID antenna with Inkscape and describing further how to cut it on vinyl cutter might make it easier for creative communities and for me as part of it to explore RFID technology.

How to draw RFID antenna

I found a ready vector file examples of RFID antennas you can use them too if you want to make a specific rfid reder. The one we'll be drawing is for 13.56 mhz reader. The first thing is to change the document size to match our needs. In our case we need 100x70mm (that's the cardboard size our antennna sticks to). Next let's draw a rectangle and set it's with to 1.5mm manually from the upper right part of the interface. Then copy and paste the rectangle simply hitting Ctrl+C and Ctrl+V. Rotate the new rectangle by 90 degrees and place it according the image below. One nice feature of Inkscape is that this obects will snap with their edges. Repeat those steps until you get a square. Now select the last rectangle and reduce it's height by 3mm from the upper right part of the interface. Then repeat copy and pasteing the new resized rectangle until you get to second smaller square inside the big one (see the picture below). Again change the last rectangle's height by 3mm and repeat copying and placing the rectangles. Do this until you get desired amount of turns. We need 4 turns but in order to save material and reduce the waste I decided to have smaller antenna inside the big one. In order to separate this two antennas we need to shorten one of the rectangles. Then select all rectangles that make the small antenna and join them by selecting Path>>Union or hit Ctrl++ do the same with big antenna you you will get two antennas like in the last frame of the image below. Here is the final file:
rfid antenna.svg

FreeCAD (3D)

FreeCAD is an opensource free Parametric Modeler software. in order to install FreeCAD on linux open terminal and enter:
sudo add-apt-repository ppa:freecad-maintainers/freecad-stable
sudo apt-get update
sudo apt-get install freecad

Here I will explain how to make parametric snap fit kit using FreeCAD. FreeCAD uses spreadsheet to store parameters. In order to create one go to Start select Spreadsheet and create a new spreadsheet. Add parameters name them as you wish. In this case we need "Material Thickness" as a parameter to define joint width, "Top Diameter" for defining the main diameter, "Top joint deepness" will define the joint height, "# of segments" will define how many joints there will be on one piece.

Parameters

Now change Spreadsheet to Part Design workbench and click on the small blue shape that creates new body. Then click on the create scketch icon and draw using the tools of scketcher. Assign constraints using the constraints tools. Assigning sizes with parameters are also done with constraints.

After finishing the sketching close the sketcher by hitting "OK" on the left side. Now select the sketch we just drawn and find the "Tab" button (image below) this will extrude the sketch. The lenght setting defines by how much the sketch will be extruded. I assigned a parametric value to this too.

After finishing with the settings hit "OK" then we need to propagate this segment using "Polar array" tool.

Now to see how parametric settings work go to spreadsheet and change number of segments from 3 to 10 and see what happens. To remove the segmentation find the "Refine" setting in polar array's options and change from "false" to "true".

Here is the FreeCAD file:
fit_kit.fcstd