For this assignment my partner and I constructed two mechanical movements from “507 Mechanical Movements”. Specifically, we built movement #222 and movement #144. I chose to focus on movement #144  is described on the website as a system of crossed levers commonly refereed to as “Lazy Tongs”. Its purpose is to turn short horizontal motion on the left into much longer horizontal motion on the right.

I began my design with 2 Dimensional sketches. To make these, the original website file was opened in adobe illustrator and I sketched the outlines of various parts on a different layer in illustrator. That way, I could hide/show my work whenever necessary in order to better sketch the model.

 

Once this was done, I moved on to low fidelity prototyping. Using a combination of cardboard, straws, and pipe cleaners I was able to create a surprisingly functional lazy tong device that extended and shrank fairly well. The low fidelity prototyping served its purpose however: I found that after I had laser cut the cardboard parts, the lever parts were asymmetrical, and one side was longer than the other. A quick visit to adobe illustrator fixed this issue. While the cardboard model worked, it was flimsy and bendable.

The next prototype went rather smoothly, although the improvements were most noticeable during this step. This prototype’s parts were cut entirely from wood. Instead of straws for connecting rods, dowel rods were used. Most different was the central box that supported the system. This was created from a file on makercase.com and then laser cut. One difficult I discovered at this step was the tendency of the arms to slide laterally along and off the rods. This was fixed by hot gluing toothpick segments to the middles of the rods. Also popsicle stick pieces were glued to the ends of the rods to act as bushings.

While close to finished, some noticeable flaws remained. Multiple burn marks remained from the laser cutter, the entire assembly was hot glued, the support box did not fit correctly, the stand was fragile. the arms moved so quickly that it was unstable. These were fixed during the final product.

My first concept of the final project included multiple painted parts including the arms and maybe even the base. Painting proved to be a dead end however; the type of spray paint combined with the humidity resulted in a stickiness that would have made the arms unhappy with sliding against each other.

 

Instead, I sanded and stained the wood to a dark, mahogany color which removed the burn marks and contributed to a classier feel. The assembly was wood glued-instead of hot glued, which added to stability. To make the structure more stable I edited the adobe files files in order to make the base twice as thick, the box a half inch taller, and as well as make the support box fit the width of material. The arms’ movement was slowed with the addition of the stain.

One unexpected change from the previous prototype replaced hot-glue and popsicle sticks with tooth picks. A 5/64’’ drill bit was used to drill holes into dowel rods that were then plugged with toothpicks, acting as bushings for each joint. This not only removed hot glue, but made the model able to be taken apart and fixed if needed.

 

 

Overall I am proud of my project- it improved with each prototype. The “Lazy Tongs” not only reinforced fabrication methods that I have already learned, but is also quite fun to use.