Model a possible final project, and post it on your class page.
Draftsight is a CAD design tool, I will use it draw an eye made of complex geometric shapes.
Draftsight has a layering manager built-in, it can be very useful for keeping the dimensions separate of the main design.
In order to draw, I start with a circle; draftsight allows to specify the diameter in the command window.
I then use draw an inscribed circle and a right triangle as follows:
I wanted to try the offset tool; it wasn't as intuitive to use. First you must specify the distance in the command window and then the direction of the offset. In this case, the diagonal line is offset.
I then use the trim tool to get rid of some lines. First select the cutting lines and trim as necessary.
Draftsight allows to repeat a pattern circularly with the command ar . In the pop-up window I specify the entities as the lines inscribed in the circle with lower radius. It is also necessary to specify the axis point, in my case is the center.
After selecting 10 repetitions, the drawing looked as follows:
I then draw another circle inside and repeat the ar command with 12 repetitions.
Draftsight was very smooth but occasionally crashed on my computer, perhaps the Linux-compatible version needs more work.
Pros: Excellent tool for drafting 2D designs; the amount of tools will take some time to master.
Cons: The user interface is tricky to learn but once getting used to, is very efficient.
A range of 3D design softwares will be tested.
I needed to make a hook for a tool hanger, so I decided to use freecad to design it. Freecad's constrain design tools are very handy.
The sketcher workbench is used to design any 2D model. For the hook design, I traced lines are traced using the 'line tool'. The constraints were later set for horizontal, vertical and diagonal directions in the design.
The 'parts workbench' is selected to extrude the 2D design by 5mm.
Pros: Work-benches provide a great set of tools and versatility.
Cons: The learning curve is relatively steep for beginners.
Tinkercad is a webgpl based software with an easy-to-use interface and tools. It can be run on a webgpl compatible browser. Basic solids can be created from a set of pre-defined shapes. I experimented creating an opened cube, 2 rectangles and cilinders for a tank tread.
The cilinder is aligned with the rectangular cubes and resized.
Tinkercad has an union feature and can create duplicates. Those two features are used to combine all treads.
I wanted to experiment creating a threaded gear. Tinkercad does not have advanced tools to create such a design, so in order to circumvent design limitations, the duplicate function is used. When two smaller cilinders on the opposite sides are selected, Tinkercad automatically assumes that the center of simmetry is the bigger cilinder.
Control+d hotkey is pressed to create a duplicate. The duplicate is then selected and moved 10 degrees clockwise. Once this step is done, control+d can be pressed again and again; until the whole set of symmetrically placed cilinders are placed in the sketch.
Once all the symmetrically placed cilinders are placed, they can all be selected and changed from solid to 'hole' in the settings.
The union button is clicked and the threaded design is complete.
Pros: Easy to use interface, webgl format works great on low-end systems.
Cons: Limited set of tools makes it harder to design complex tools. It only supports exporting file as STL or OBJ.
Fusion 360 is a versatile 3D tool with design, engineering and simulation features.
Fusion 360's user interface is very easy to navigate; I set up my preferences with reverse-zoom direction and modeling orientation with the Z-Axis up, as having the Y-axis as the up direction felt a bit unnatural to me.
I also liked the feature to snap the cursor to grid.
I used Fusion's sketch function and I found hotkey d very useful to dimension designs.
Looking online, I found various inspirations for the design of tank treads. A sketch can be created to design the outline of the figure.
The line and trim tools are useful for creating the desired shape.
Dimensioning is done by pressing the d hotkey and selecting the right limits.
Figure below illustrates the final dimensioned piece.
Fillets are drawn on edges.
A new component is created and extruded using the e hotkey.Also, a circle is extruded inwards to create a hole in the piece. The hole was also dimensioned accordingly, with a 2.99mm diameter.
A symmetrical hole was created on the other side of the piece too.
After the first component was created, I made a copy and pasted as a new component.
I used the join feature of Fusion360 to test the design, I also inserted a 3mm cilinder in between the pieces.
I created several copies of the design to see how it fits together. I also change the height of the pieces to 10mm.
Pros: Fusion360 is a very easy to use design program, the user interface is intuitive and powerful.
Cons: Assembly joining can be a bit frustrating but nevertheless, an excellent feature.
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