Week 10: Machine Design
Group Project: Delta Picker
For the machine design assignment, our EECS section decided to make a delta picker inspired machine, which we aptly named the "Delta Hopper". The website documenting the design process and final product as a whole is here. On this page, I document my individual contributions to the effort as the resident "Slave Driver", a member of the Arms team, and in helping with manufacturing.
Organizing the Group
A lot of my contributions involved organizing group meetings and communicating the current status of the project across all team members. I initially sent out a When2Meet Wednesday after class to plan our first group meeting to discuss what to make and how to make it. At our meeting on Thursday, I created an agenda and took meeting notes on a GitLab issue. We were able to accomplish the following on Thursday:
- Presented and voted for project ideas: We ended up voting for the delta picker idea, which Jake Read came in and presented. This sounded quirky, challenging (since it's very different than the designs given to us), and fun.
- Assigned everyone to submodule teams based on their interest and availability. Andrew, Niki, and Priya were on the Design/CAD team since they were only available Thursday/Friday. Elysa, Alex Kaspar, and I were on the Arms/Joints team. Casey, Alex Genshaft, and Xin were on the End Effector team. Vibha, Ben, and Max were on the Electronics/Programming team. (I strongly encouraged Ben to be on the electronics team due to his expertise). Robert, Nikita, and Eleanor were on the manufacturing team.
- Set up a working schedule:
- Friday and Saturday: CAD team finished all design
- Saturday afternoon: Email out files to get feedback
- Sunday: Everyone show up in lab and all-day manufacture 1:30PM-8PM
- Monday: Debugging for all teams as needed
We didn't have access to the lab Friday or Saturday, so we had to do most (if not all) of our manufacturing Sunday afternoon when the lab opened. We ended up being unable to finish on Sunday, so I sent another email and set up another When2Meet to help subteams coordinate when they could work with the group as a whole. I also set up another GitLab issue and proposed an update format to make sure communications were clear for our final day of working on Tuesday. Throughout the machine design and building process, I tried to regularly check in with all teams and keep everyone updated on how the project was progressing as a whole.
I was a member of the Arms/Joints submodule team. We had to design and build the arms ourselves based on some constraints given to us by the Design/CAD team (the length was to be 450mm, and the arms should be very rigid). Elysa, Alex K., and I brainstormed many ideas, including 3D printing joints and buying rods on the internet.
We ended up settling on the idea of laser cutting press-fit rectangular prisms and making them into rods. We first tried to use acrylic, but the smoothness and hardness of the material made it very difficult to get a press-fit joint.
We settled on using plywood to make the press-fit tubes (a huge contribution on Elysa's part in providing the material). We decided to use looping string instead of "real" joints to connect the arms to the body and rails of the machine.
However, the fishing line would get stuck on the ends of the rods, so we had to come up with a way to make that motion smooth for when the rods slid up and down and through the holes. Alex Kaspar came up with the idea of hot glueing circles to the end. This worked!
General Manufacturing Help
The manufacturing team was a bit short-staffed, so I also helped fabricate and re-design a few pieces alongside my other Arms/Joints team members. Our most notable contributions were redesigning the top plate/bottom plate to be equilateral triangles, redesigning the end effector to be the correct size, and engraving our section name/machine name on the plates. We cut the top/bottom plates and our end effector out of plywood on the laser cutter.
I also joined everyone in helping post-process the pieces that we milled out of plastic since there were a lot of unclean lines. I was the only person in the section trained on the bandsaw, so I also sawed all of the wooden pieces that needed to be resized for the laser cutter. We stayed until early in the morning to finish things up - huge shoutout to Gavin and Anish for babysitting us!