Learning To CAD — Sprint 3
During this sprint, I wanted to learn both general CAD philosophy and how to CAD for various types of rapid prototyping such as laser cutting. Because the rest of my team was using Onshape, I decided hop on the bandwagon and learn to CAD in Onshape. Overall, I made 4 revisions of our system housing and learned a ton along the way.
Revision 1
I didn’t really know how to start, so I just started. As a result, I ended up with very messy CAD. Almost every dimension was assigned to a variable. All the parts were cadded at the same time in a few parts studios — meaning that modifying any part was bound to break something else. It was also impossible to dimension the parts relative to one another (which I later learned is part of Onshape’s philosophy). In addition, lots of unnecessary parts were cadded, such as screw and nuts which could have been imported from McMasterCarr. Finally, everything was done by sketching and extruding as I wasn’t aware of any faster methods.
Revision 2
I learned about Onshape’s FeatureScript right before I made revision 2. This opted me to start cadding the system with the flat base of our housing. I then made another sketch on top of this base to lay out and make all the mounts and connectors. Finally, I used the FeatureScript, “T-Slot Joint”, to make all the T-Slot Joints. I then laser cut a preliminary housing with the help of “Auto Layout”. In this revision, my biggest mistakes were not fully constraining my sketches and not defining the base, mounts, and connectors on the same sketch. As a result, it was difficult to size the base relative to the connectors and mounts.
Revision 3
At this point I began to feel more confident. After having a bunch of CAD knowledgeable friends critique my CAD, I learned what good sketches and fully constrained systems looked like. As a result, understanding and modifying important dimensions was significantly easier. However, I shortly realized that putting the base, mounts, and connectors on the same plane would allow my to dimension all the important pieces relative to one another. As a result, I cut my losses and started again from scratch.
Revision 4
With the knowledge of many hours of failure, I came into revision 4 basically knowing every step before I made the first sketch.. As a result, the finalized CAD, later allowed me to iterate laser cut designs meaningfully and rapidly to fit the team needs. One of the other significant improvements in revision 4 is the timeline and labeling of operations. All the operations are fully labeled such that any member of the team can modify the CAD without asking me what is what.
Overall, I was able to both learn general cadding philosophy and how to rapid prototype using Onshape and laser cutters. In the future, should I ever need to rapid prototype with laser cutters, I will be able to help out right from the get go.
-Nathan
