Week 02: Computer Aided Design

Assignments:

• Design and print something that can only be made using a additive design.
• Compare and contrast different CAD software you haven’t used before.

Brief:

Since I am familiar with using Fusion360 and my final project uses tetrahedrons as the basis of my design this will form the basis of my test. I will design my additive manufacturing assignment based on a tetrahedron in Fusion 360 and then I will go in blind on the other CAD softwares and see how difficult they are to figure out how to build a simple tetrahedron based on the fusion 360 work flow and If I fail I will use the internet to figure it out.

The CAD software I selected is:

• Solidworks xDesign
• Onshape
• FreeCAD
• Openscad

Fusion 360 (Control)

STEP 1:

Make a component and then create a sketch

Choose your plane/origin that you would like to sketch on and select “polygon” under create. Click and drag to make you polygon and then press tab to change the number of sides to 3 which will make an equilateral triangle

once you have the desired triangle right click and select move copy. This will open a menu and make sure you have “Create a copy” selected. Ensure you have selected both the triangle and the center point. Then move the copy up on the Z axis to the desired height. Now you should have two triangles on top of each other

Under create select the Loft function and select the outline of the bottom triangle and the center point of the above triangle

To make it hollow select the shell function and either Type or adjust the slider to select the desired wall thickness

Then Under construct select mid plane and select the two triangle sketches (you can make this easier by hiding the bodies on the left menu. Once this is done use his mid-lane to plot the bodies then hide the top one.

You can then use your loft tool to loft the inner triangle you made by splitting the hollow body with the center of the original bottom triangle which you can then shell to make hollow as well. And there you go a Tetrahedron inside a tetrahedron. Unhide the top section and hey presto!

SolidWorks xDesign

Overview:

• Navigation: The online experience is confusing. The navigation cube is lame as you can't easily use it to select isometric views or rotate.
• Sketching: Sketching base geometry is simple and intuitive.
• Lofting: Lofting especially the way I do to make tetrahedrons in Fusion is too difficult. cannot move sketches in planes they werent drown on and it refuses to loft to a point on a different palne
• Drafting: Drafting was the solution but like I said not intuitive and slow on web browser
• History: non existant.

Workflow:

I tried lofting in the way that I did in Fusion and failed. it refused to loft to the point I created so I had to find a new method

Make A sketch: Sketching is easy and intuitive for the polygon especially when it comes to adjusting the sides.

Extruding: Very simple just drag the up arrow and done.

Drafting: kind of like the fillet function in fusion select the faces you want to “draft” then select the plane you want to stay the same and adjust the slider as needed.

Finished product: Easy one you know the correct workflow

Verdict: Yuck!

Onshape

Style & Experience Notes:

• UI: User interface is simple and uncluttered
• Dimensions: Adjusting dimensions was trickier than the others.
• Speed: Overall the easiest and fastest program.

Workflow:

Base: Sketch an inscribed polygon, adjust the sides to 3 by moving your mouse. Adjust the side length by clicking the dimension button then clicking one of the sides and dragging it so the dimension parameter pops up.

Apex: Create a sketch on the Front or Right plane and place a single point at the desired height above the base.

Loft: Use the Loft tool to connect the triangle to the point.

Verdict: Pretty good!

FreeCAD

Overview:

• Comparison: Only program that can SKETCH A TRIANGLE without adjusting a polygon.
• Lofting: A bit tricky You must click "Add Section" before selecting the next sketch for a loft to work. and its hard to find the point.
• Add ons: Optional polygon add on if you want.

Workflow:

Sketch: Click sketch select your plane from the left hand menu and select triangle the dimension pops up immediately and the angle snaps nicely to 90 what a pleasure!

Loft: select the loft tool and make sure you click add section before you select the sketch for it to work.

Verdict: Fantastic!

OpenSCAD

Overview:

• Precision: Best for geometric things because you can use direct equations instead of guessing.
• Units: Numbers are unitless in the code but treated as millimeters in slicer software like PrusaSlicer.
• Method: You "abuse" the fragment number ($fn) variable to force a cylinder to have only three sides.
• Code: If you like coding you will enjoy learning to design in this way.
• Don’t use chat gpt for this… very bad

Workflow:

Base radius: Define the dimension of your base with:

base_radius = 30;

Number of sides: set the number of sides to 3 with.

number_of_sides = 3;

Create a Cylinder with one base: make the base radius and height the same and the to radius 0:

cylinder(h=base_radius, r1=base_radius, r2=0,

Set the number of sides to 3: use the fragment number ($fn) to change the number of sides to 3 creating a tetrahedron:

$fn=number_of_sides);

Verdict: Tricky but cool