I enjoyed working on this project. It’s fun to have a handmade object that actually performs some function. The final product can be seen in this image.

The purpose of this design is to rotate the handle on the small gear counterclockwise to raise the bar on the left. A ratchet system prevents the system from traveling backwards unless the ratchet is raised by pushing up on it from the back. In a larger screw jack system holding up tons of material, this is a safety feature. Once the ratchet is raised, the handle can be rotated clockwise to lower the bar.

 

This project was born in 2D vector drawing software. I mostly used Autocad to make the screw jack because of my familiarity with Autocad. The course of designs can be seen in this picture.

Earlier drawings can be seen on the left, and the final drawings are seen on the right.

 

After looking at my initial drawings, I had a very good idea of what my project would look like. My main concern was the operation of the gear system itself. I decided that I could not address my gear concerns with a low fidelity prototype because they require precise shapes and cuts, so I skipped directly to a medium fidelity prototype stage. Low fidelity prototypes are excellent for communicating ideas to others at a low cost, but I was able to communicate my design to my partner with just the 2D drawings, and I could visualize the product in my head based on the images in the provided book, so the advantage of low fidelity prototypes did not manifest for me in this project.

 

In the medium fidelity prototype stage I cut many pieces using the laser cutter. This created precises shapes but they had no post processing. My first design iteration used gears with straight edge teeth. The mechanism only operated in one direction because the teeth kept on jamming into each other. Straight edge teeth can be seen here.

I did some research on gear mechanisms and produced a second prototype with curved teeth. This worked much better but the small gear still had jamming issues. After adjusting the teeth with pliers and a dremel, I solved the jamming issues, determined the new tooth size from the adjusted gear, and printed a new small gear with properly adjusted tooth size.

After I got the gears to work, I worked on the ratchet system and the axles. The ratchet system was relatively simple. I started with a teardrop shape, but I ended up with a vertically climbing oval shape to prevent over rotation issues with the teardrop.

The axles were simple too. I cut proper lengths of dowels, and drilled toothpick size holes in the side with the drill press. The toothpicks stick out and prevent the dowels from slipping out.

 

After creating a working medium fidelity prototype, I started work on the high fidelity prototype with post processing. In this project, post processing was a series of fixing problems, making it look nice, and fixing problems created from making it look nice.

First, I was inspired by others around me and I liked the idea of etching line art/shapes into the side of the my pieces. I added line art to my 2D drawings. These are the red lines in my autocad drawings.

Then, the laser cutter acted up and refused to cut cleanly. It etched the line art fine, and I cut out test circles just fine, but the same exact settings refused to cut out my final pieces. I cut on a very slow, high power setting which charred the edges of my pieces. Hopefully the lab techs have solved this problem. Pieces can be seen here.

To solve the charred edges problem, I washed my pieces in the sink, rubbed them with a sponge, and dried them off with blow dryers and heat guns. The professor brought up the issue of warping wood, so I used an oven in the soil lab to make my pieces bone dry.

After that I used linseed oil to produce a nice finish on my pieces. Then I assembled my pieces with gorilla glue and lots of clamps. The clamps were necessary to fix the warping of the pieces. I rubbed and peeled off excess glue once it had dried.

The rotating handle was interesting to make. I drilled a hole down the center of a large dowel with a drill press and inserted a smaller axle dowel. The first couple large dowels split on me, but the third try with low pressure from the drill press was successful.

I also performed post processing on the axles and handle. I attached the cut dowels to the drill press, spun them up, and used a fine file to remove ragged edges. I also used glue to firmly attach the toothpicks to the dowels so the axles will stay in place.

Overall, I like the look of my design and it has survived tests multiple times.