IV.) Manufacturing & Assembly (WnF)

The manufacturing processes taken for the project are described below:

Laser Cutting (Used for cutting links and cutting the holes for the positioning of the different parts)

• Laser cutting was our best option for prototyping links because of its precision and speed. These qualities helped us throughout the project because we depended on accurate cuts for tight press fits and exact positioning. Laser cutting was also a viable option because we wanted to use plywood for the links because of the wood's rigidity and strength. Acrylic was used for the reloader mechanism, but mechanical properties aren't as important in this part of the assembly. The images below show some of our part drawings and the link results of one of our prototypes.

Drawing Files for Laser Cutting

First Linkage Assembly

3D Printers (Craftbot+ for PLA Prints and Form3 for SLA Prints

• 3D Printing offered a viable way to manufacture parts that have difficult geometries to manually produce. We 3D printed our chute slider and our pushing arm, which can be seen in the image below. There were multiple iterations made of each part, and we tried testing them with different materials (SLA, Onyx, PLA). We ended up using PLA in the end since printing in Onyx and SLA was expensive and more time-consuming, and PLA was strong enough for our tension tests.

 Slider Prototype (Onyx) and Pushing Arm (PLA)

Slider Prototype (SLA)

Manual Tools (Drills, Screwdrivers, Vise, Soldering Station)

• Manual labor was done mainly for prototyping of the crank arm and for press-fitting our bearings. Press-fitting our bearings was important for reducing friction and having a more efficient load transfer. We purposely cut undersized holes in our linkages and pressed each bearing in using the vise. 
• Additionally, we had to solder a wire onto our DC motor, which required a soldering station. Simple tools like screwdrivers and wires were also needed for the circuit assembly.

Mechanism Test with Electronics

Overall Process and Takeaways:

Our manufacturing process consisted of different iterations of each part of the project. We decided to buy a sheet of perforated hardboard to test out our walking beam and modify our ground link placements. The perforated hardboard facilitated the assembly and prototyping process, and it gave us the ability to test around our parts. One major step in the manufacturing process was testing our link dimensions, which varied throughout the project. Our work depended heavily on laser cutting because we tested various thicknesses to check for link strength, and we often had to recut our links because of interfering dimensions and changes to our desired output motion. This also meant that we had to spend time press-fitting and assembling our project multiple times. Our reloading mechanism was also manufactured with laser-cut acrylic, but this part of the assembly was much simpler since the only changing dimension was the length of the lower fan that made contact with the slider and rotated the top fan. Additionally, 3D printing our chute slider was probably the most time-consuming part of the manufacturing process. 3D printer availability and long print times delayed a lot of the assembly process, and we even had some prints fail under high tension whenever we tested them out (image below for reference). In general, using PLA saved us much more time and money than using SLA or Onyx, and its mechanical properties held out well when we adjusted the CAD and printing orientations. Lastly, the final positioning of our mechanisms was done using similar dimensions from the hardboard and was laser-cut for precision. Our z-axis positioning was simplified by inserting long bolts through the base plates and securing them in place with nuts, and we also used acrylic-cut spacers to help with the walking beam z-axis alignment (image below) because using washers and nuts created a significant cantilever effect. 

Failed Slider After Applying Rubber Band Tension

Laser Cut Spacers Prototyping