CAD

When I started this project, I knew absolutely nothing about CAD. I also did not have context for what projects would be reasonable for a complete beginner. Therefore, I started my CAD journey by reading blogs about projects for beginners. I found two major themes: furniture, and accessories. A few projects piqued my interest: a phone stand, a coffee mug, and a student desk. I hope to try all three of these at some point.

I chose to model the office desk because it could be built with regular shapes and would allow me to learn how to fit pieces together across different dimensions. I then examined my desk to estimate the dimensions of an ideal desk, and to identify ways I could improve my current desk. I estimated that my desk is 4′ by 2′. I wished my desk was a bit wider so I would have more room to work. I also wished it had more storage space because it is always messy. Additionally, I wanted a pencil holding cup that is fixed to the desk so it cannot tip over.

I started my design process by roughly sketching different views of the desk I wanted to model. I included some important dimensions so I would have a place to start once I launched the CAD software.

After drawing these rough sketches, I had spent about 5 hours on this project and was ready to break for the day. I felt ready to start modeling my desk when I started working again. I chose to stick to SolidWorks because it was the software I had some familiarity with from Nilay’s presentation. I also wanted to use SolidWorks so I could get help from the TAs and other students when I got stuck.

I first drew my tabletop on the top plane because it was the dimension I was most certain about. I drew a rectangle for the tabletop and used the smart dimension tool to define its dimensions as 140 x 80cm. I knew I wanted to make this tabletop have some thickness to model a piece of wood. However, I did not know how to turn a 2D rectangle into a 3D solid. I looked up this issue and learned that there is an “extrude” tool that would allow me to add thickness to a planar shape. I used the extrude tool to create a tabletop with a thickness of 2cm. From this point forward, I used 2cm as the thickness for all faces of my object.

My next goal was to create legs for my table. I wanted to do this by attaching slabs of wood perpendicular to the table. I wanted two sets of drawers, so I needed 4 slabs of wood. This process was much more difficult than the tabletop creation. I spent a lot of time randomly clicking before I realized I could use the “bottom” view to display the bottom of the tabletop. Once I discovered this, I flipped the table upside down and created rectangles spaced 30cm apart. I planned to extrude these rectangles to make table legs. I also left some room between the edge of the table and the legs so I would have space to add a back to the table. I wasn’t sure how to make a back face but wanted to leave space just in case. I manually created and defined dimensions for the first two rectangles before I found a “copy” tool to duplicate the rectangles. I defined as many parameters as possible because I could not determine which were dependent on each other. In future projects, I will clean up this issue with better planning of the dependencies between parts prior to modeling.

I then extruded the rectangles to a 90cm depth to generate legs. I clicked on one rectangle, expecting to extrude each leg separately. Conveniently, all legs extruded even though I only clicked one. This gave me the base structure for my desk.

The next step was to add a slab of wood to the back of my desk to provide backing for the drawers when the desk is not against a wall. I anticipated this to be a simple task, but it was actually one of the most challenging. I selected the “back” view of the object and used lines to generate a rectangle. I wanted there to be a gap between the bottom of the desk and the bottom of the backing so I could fit cables through the bottom of the desk. However, every time I attempted to extrude the figure to a 2cm thickness, I received an error stating that the figure could not be extruded due to incorrectly defined dimensions. I learned that the figure was being generated on the wrong face. After about two hours of struggling with this issue, I found a youtube tutorial for an office desk. They did not have this issue but they built their backing figure off of a line related to the tabletop face. While I am not entirely sure why this works, it solved my error. If this issue comes up again in my future projects, I will spend more time figuring out how it works.

Once I got the desk backing to extrude, I was exhausted and ready to break for the day. I was not sure how to save the file so I tried saving it in downloads of the virtual desktop. I closed my tab and logged back into the desktop to confirm that it was still there. I was able to load up the SolidWorks file so I assumed that the virtual desktop could save files.

Unfortunately, when I opened the desktop the next day, I realized that the file had disappeared. I emailed both Nilay and Tufts IT. Both told me that files would disappear when a session closed and there was no way to recover them. I was so upset and scared that it would take me way too long to repeat my design!

However, when I got back to work, I was pleasantly surprised by how fast I was able to catch up to my stopping point. It only took me a couple of hours! That showed me how much I learned through my struggles with this project and gave me confidence that my next CAD project would be much easier.

Once I redid my design, my next step was to add compartments I could use to fit drawers to my desk. I did this by creating 30×2 rectangles on the front face of my desk spaced 15 and 30 cm apart and extruding them 75cm to reach the back. This worked to some extent, but the compartments stuck out of the desk front and did not reach all the way backward.

I recognized that this issue had some of the same flavor as my issue with the desk backing. Therefore, I solved it by setting a relation that made the sides of the compartment rectangles collinear with the adjacent desk legs. I then used a different extrusion setting that allowed me to automatically extrude all shelves to the back surface of the object without defining the depth. This solved my issue and taught me that I need to relate figure lines to each other whenever I am working with solids that run in perpendicular dimensions.

At this point, I was pretty excited because I had built a functional desk. The next steps were to design drawers and fit them into the compartments. I designed drawers by extruding a solid rectangular prism and using the shell function to hollow the prism and remove the top face. I used the same shell method for the drawer handles. This worked without any errors. Yay!

Before I started any CAD modeling, I asked Nilay how best to make an object which required another object to be fit in. He said to make both objects separately and use the assembly tool in SolidWorks to put them together. Because I knew I would have to fit the drawers in the compartments, I designed the dimensions so they would fit exactly into the desk. This made assembly pretty easy. I just clicked “Insert Part” and dragged the drawers into the compartments of the desk. I had to rotate the object multiple times to confirm that the fit was secure in all dimensions. From watching youtube videos on part fitting, I learned that there are more elegant ways to define planes and fix part dimensions into compartments. I recognize that I will have to do this for more complex assemblies, but the manual method worked well for me here.

Finally, I added a cylinder to the desk tabletop to act as a fixed pencil holder. I used the same shell extrusion method as I did for the drawer handles, except I started with a circle instead of a rectangle. As a finishing touch, I changed the desk material to wood to match the image in my head.

I intended to parameterize my design by making a miniature “kids desk” as the final stage of my design process. However, due to the time lost when redesigning my project after the file was deleted, I was unable to do so. I still think this will be a fun test of my learning so will likely work on it over the course of the next few days. This was another reminder that design always takes longer than expected, even with good planning.

Overall, I am very proud of my product. While it may look simple, it taught me a lot about the intricacies of fitting pieces together in multiple dimensions and gave me confidence that I can independently learn a new skill and software. I am really excited to try new projects soon. I hope to do something with curves, irregular shapes, and cutouts.