3. Computer Aided Design¶
Description: CAD stands for Computer Aided Design, there are different software solutions for different industries, like AutoCAD specialized in the mechanical and architecture industry, CATIA for the aircraft, marine and automobile industry, or Blender specialized in digital art.
There are also differences in licensing, for example proprietary, and open-source. Software like CATIA is proprietary and then you have to buy a license to use it, but there are also Open Sourced solutions like Blender, FreeCAD and OpenScad, that are driven by their communities, and also are free of charge.
For this week the goal is to learn and use Raster or Vector drafting software, CAD and render or simulate.
As a personal note, it’s my first time using 100% Fedora for all this process and I had some difficulties configuring my GPU drivers, something that’s really common under this operative system if not used carefully. Normally my workflow needed a dual boot system on my personal computer to use Solidworks on Linux and programming under Linux. For the first time I’ve only used Linux thanks to XDesign and Blender.
The first thing I’ve made was this sort of ideation process to define the parts of my final project an this is the result:
As my Photo is a bit Pixelated, I’ve used InkScape to make a vectorized version and then compressed it again as a JPG image:
I gave myself the challenge to draw one of the earrings used for Cow identification in the experimental farm of unilasalle:
Image compression and improvement with Gimp:¶
I took some photos and screen captures for this and sometimes I had too use Gimp to crop, scale and compress all images shown for this assignment page.
To crop the images I used the Selection tool and then the crop to selection tool under the Image menu in the toolbar.
To improve contrast and color of images, you just need to use options under the Filters menu in the toolbar.
InkScape Draft process¶
Shape sketching with simple forms.
Using difference and union path tools I got the shape, next added the text, codebar and color.
- First create this simple shapes with the circle and rectangle tools. The rounded corners were made with the bezier editor.
- Then look for the “Align and distribute” palette in the Object menu”
- Select all the shapes and use “Center on vertical axis“
- Then manually adjust the shapes to make the shape as is shown here.
- Select all the shapes again and use the “Union” boolean operation on the “Path” Menu.
- This is the result and the first part of the body for the cow earring.
- Then make a rectangle an a Oval using the rectangle and circle tools. Try to make the Oval tangent to the first body of the earring as is shown.
- Select the rectangle first and then the oval, go to the “Path” menu in the toolbar and use the “Difference” boolean operation.
- Make the same process por the right side.
- Now we have two shapes that resemble the earring.
- To complete the shape of the earring merge both shapes using the “Union” operation again.
- This is the basic shape of the earring.
- Next use the circle tool and the line bezier tool to match the image shown bellow.
- Then select the earring shape first and the lines right after. Use the “Cut Path” tool to divide the shape in 3 parts. This is needed to have 3 different colors in the next step and try to make a 3D effect.
- Then select the parts to paint it.
I’ve used this colors:
- Using the “Text box tool” I’ve wrote the numbers and codes as shown those are similar to the earring, but I didn’t found the same font.
Then I’ve painted the “plug” circles in the top:
I’ve learned Xdesign and I found it very complicated at first even as a Solidworks user. My main OS is Fedora Linux.
I’ve tried to use XDeisgn under Linux using Firefox, and Chromium web navigators.
- Chromium works better than Firefox.
- Activate Hardware acceleration.
- Force hardware GPU use.*
*For Nvidia Nouveau drivers use:
*For Nvidia propietary drivers, use Bumblebee:
There are some basic operations for 3D modeling:
- 2D Drafting for sketching.
- Linear region extrusion.
- Linear region extraction.
- One axis profile revolution.
- Parametric scaling.
The whole process can be divided into three important steps:
- 3D solids modeling
- Part Modeling
The sketch is the 2D representation of a section or projection and its the base of a 3D model.
The modeling process starts when we transform a 2D shape from a sketch into a 3D entity, there are multiple operations like extrusion, revolution, subtraction and other boolean operations to shape a 3D entity.
An ensemble it’s the combination of multiple 3D entities or parts, like in the real life process it requires constrains, joining mechanisms, but here you can restrict the displacement, rotation and collision with a “restriction or relationship” indicator.
Start a new XDesign File¶
We received an account as part of our Fab Academy course to access Xdesign:
- This is the first screen after login, but I’ve already made a week03 Dashboard:
- Then I’ve created a new component:
- I’ve named the component rfid_tag:
- This is the XDesign workspace:
This is the sketch toolbar, and I’m going to use:
- Convert entities.
This is a 2D process where I’ve made the section of a RFID TAG used for cows and it’s based on this model that I’ve available at FabLab Agrilab.
The process its as follows:
- Create a new sketch, select the plane XY and draw a rectangle:
- Redefine the dimensions of each side of the rectangle by using the dimension tool:
- I’ve measured the tag using the caliper the results are: 79 mm height and 57 mm width.
- The I’ve converted the lines to contruction lines using right click and selecting the option in the menu:
- Then I’ve made two construction middle lines.
- The circle is the holder of the RFID it has a diameter of 20 mm, I’ve made it tangent to the top line. And I’ve made a new bottom tangent line for the lower part.
- Results so far:
- The 3 points arc tool, works by selecting first the center, start and end.
- Then I’ve joined the arc and the circle with tangent lines.
- I’ve used the rounding tool to make round corners with a 4 mm radius.
- Then I’ve trimmed the lines to left the sillouete that I’m goint to extrude:
- So far I’ve been finish a half of the tag and used the Mirror tool, selecting the vertical middle line and selecting the half siloutte:
- This is the final sketch:
- The final step its to add a inner circle of 14 mm diameter, concentric to the top curve.
- I’ve used the extrusion tool and used it on my latest sketch. Left click on the sketch and on the extrude contextual menu select the thickness 3mm. This is the measurement I got from the RFID Tag using the caliper.
- Resulting 3D shape:
- Then I’ve to make a cut through the material using the sketch tool in the thickness or lateral face of the 3D model.
- I’ve used the convert entity tool to make a projection square on the current sketch:
- Then I’ve draft the lines based on the measurements of the RFID Tag:
- Then I’ve created areas to use the extrude cut tool:
- Final sketch so far:
- To extrude the cut, use the extrude tool and select cut:
- I’ve choose the “up to next” option:
- First result of the cut: And I’ve missed to define the ramp dimension:
- Defining the ramp dimension:
- Then I’ve extruded over the shown surface to create a ring using, sketch and extrusion tool:
- Then on the bottom of the tag I’ve made another ring shape, following again, sketch, extrude process:
- The RFIG TAG has two visible components, so I’ve made an assembly with the assembly tools.
- I’ve named the assembly “Physical Product 2”:
- Then I’ve created a new component named “Rfid inner”:
- I’ve used the top face of the ring shown as base for the inner tag component:
- Using the sketch, extrude tool I’ve made the 3 parts of the body:
- First part:
- Second part:
- Third part:
- Final shape:
- Then I’ve used the apply material tool:
- Selected “Black low gloss plastic”:
- Then I’ve selected the first component I’ve modeled and applied using the “Apply material tool”:
- And selected “Plastic, low glow, yellow”:
- To make this assembly video I’ve captured the screen on my computer using simple screen recorder
- Selecting a rectangular region of my screen framing my model under XDesign and then pulsing the relationship constrain “coincident surface”.
XDesign then makes and animation where the two selected surfaces move until fund each other.
This is the configuration I’ve used on simplescreenrecorder.
- This is the video result:
- And then this is a the ffmpeg command I’ve used. More info in my project management page.
This process its similar to the past processes, but instead of using the Lines and arcs tools I’ve used the text tool:
First I’ve created a new sketch on the fron surface, following the same proportions of the RFID tag:
- The number 8207 its 25 mm height, -5% spacing and 78% ratio scaled:
- The 27 0808 test its 5mm height -5% Spaced and 90% ratio scaled:
- After finishing the sketch I’ve extruded it by 0.1mm:
Finally I’ve made the same for the FR text:
And Applied “Plastic, low gloss Black” Material with the “Apply material tool”:
- I’ve captured this view from the photo view tool in XDesign: