3. Computer Aided design¶
Please reference the Principles and Practices page under assignments to see an illustration and description of my final project. Below describes my attempts at drawing this initial design in CAD.
2D:¶
See week 4 under the assignments tab for work in CorelDraw - a 2D application.
3D:¶
Since I have a Mac, I use Fusion360. I have absolutely no previous experience with CAD so I first watched this tutorial.
Funnel¶
First Attempt¶
At first, I drew two circles in Fusion (via c keyboard command) and one offset from another. In order to make one offset from the other, I needed to use an Offset Plane and then draw the circle on that plane.
Then, I used the Loft function to connect the two circles.
Then, I used the projection tool to draw a line parallel to the funnel’s boundary (because we want a hollow funnel). I also drew curved lines to draw the curved top of the funnel as shown below:
I added constraits to make sure the outer and inner line drawn on the projection above are parallel. I used the revolve cut feature for the base of the funnel (made up by two circles + Loft) to make the hollow funnel 2D drawing 3D. For the curved top of the funnel, I chose the New Body option. It is important to choose the origin as the axis to revolve around. The funnel made after these steps is shown below:
However, this was just for practice so I did not worry about the dimensions at first - I made it just 3 inches tall, which I don’t believe would fit a football in it haha. When I tried to make the funnel bigger I found that I had to go back and change the dimensions of multiple steps in my “History”. I wanted to start over and use a method that would make it easier to change the size.
Second Attempt¶
I decided to not use the loft function with two offset circles for my second attempt at drawing a 3D funnel. I wanted to minimize how many steps would go into my history and I thought I could hit the majority of steps required to make the funnel through the Revolve function. So, first step was to draw half of the funnel shape, though I was not going to worry about the funnel opening for now. The first attempt at a 2D drawing of the funnel is shown below:
Since the main reason for starting over the funnel design was to make the dimensions easily adjustable, I decided to make my funnel the wrong shape at first and then see what would happen if I made it bigger. This design did not pass the test. It was overly constrained so everytime I moved a dot, the entire shape of the funnel would shift - I think it became overly constrained when I was trying to ensure that the thickness was uniform and used numerous “Equal” constraints. Instead of overusing the Equal constraint I used the concentric constraint for the circles used to create the two arcs of the circle. The final 2D drawing of the funnel used for the revolve is shown below:
Revolving this 2D drawing resulted in the funnel shown below:
Conveyor Belt¶
Next it was time to make the opening of the funnel where the football falls onto the conveyor belt. This was when I learned extrude cut was my best friend. I again used the project tool to outline the body of the funnel and then drew an ellipse. where I wanted the opening to be and preceeded to use Extrude Cut with the settings shown below:
Now it was time to draw the conveyor belt holder that the football will fall onto. This is when I learned about the sweep function. I drew the path for the conveyor belt and drew lines to make the sweep’s profile be the bottom half of the opening:
Below shows the result after the sweep:
The wheels of the thrower need to be at the end of the conveyor belt. So, the walls of the conveyor belt need to get shorter to fit the wheels. So, I performed another extrude cut on the shape shown below:
Again, I wanted the conveyor to be easily adjustable so I tried lengthening this shape and decided I just needed to change one thing (lengthen the extrude cut shape as well) to do this, which passes the test in my mind. There is probably a way I don’t know to make sure they adjust together.
Wheels Holder¶
Next, I drew the bar to hold the wheels. A requirement for my first prototype was for almost everything to be adjustable (spacing, angle, etc.). A bar to hold the wheels made sense because I could make clamps to allow the wheels to move closer/further, adjust angle (why a circular bar is necessary), and also allow the wheels to move up and down (see clamp section for how this is possible). To make the structure shown below I used the box function, used extrude cut to make the bottom and sides, drew a circle on a side, and then used the pipe function to make the bar:
Clamps¶
I wanted to model my clamps similarly to the clamps on my drumset:
I like these clamps because they are adjustable for every degree of freedom (angle, left/right, up/down). I drew this 2D side-view drawing of the clamp projected onto the side of the “wheels holder”:
Note: I don’t believe you can extrude off of a curved surface (or at least I was having trouble with it) so I had to draw a flat profile coming off the side of the circle so that we can extrude cut a slot opening. After using my best friend extrude, I got the following structure:
Now, I wanted to make the ends triangular like the picture of my drumset’s clamps. So I again used the projection function and drew the shapes I wanted:
For some reason - and I still don’t know why - Fusion wouldn’t let me extrude cut both sides at once. It forced me to do two different extrudes and two different sketches. Nonetheless, the following drawing lead to the following shape of clamp:
I copied and pasted another clamp and then used the “Move” function to slide the clamps down the bar. Then, using the cylinder function, I made simple (i.e. placeholder) wheels. The final drawing is shown below:
This design will be iterated on the find the right size, shape, angles, lengths, etc. of objects. The real prototype will have a net to catch the football and bring it to the funnel. I plan to use a physics engine and simulate much of my designs before I build them.
The STEP file can be downloaded here