Process

To start this assignment, I first had to design the shape to be cut out of the metal diamond using Adobe Illustrator. I downloaded the diamond file from Canvas, and in illustrator added the shape of a hummingbird and flower that I downloaded from the thenounproject.com, which was sent to the plasma cutter for cutting out of the steel sheet. After some troubleshooting with Hayden to get the file in an appropriate format for cutting, I was able to cut the two pieces with Hayden during our training session. At this stage, I first noticed problems with the resolution of the plasma cutter being incompatible with my design as some of the finer details of my flower and bird shape were lost, but the design was clearly still a hummingbird and flower so I decided this was sufficient. One other slight problem was noted during this step, as the ‘stem’ of the flower was slightly outside the diamond, so when it was cut, a slight piece jutted out of the metal along one side by the flower. I decided to try removing this during the post-processing as it seemed sufficiently small.

One of my metal diamonds after plasma cutting, with dross visible

Next, I used the angle grinder to remove dross along the edges where the plasma cutter had cut. While the dross alongside the outer cuts was easy to remove, it proved more challenging to remove the dross along the edges of the narrower shapes cut from the center of the diamond, and the process revealed some imperfections along these edges, which I attribute to the points being too narrow for the plasma cutter to cleanly cut.

One of my metal diamonds after angle grinding

After angle grinding, I filed the edges, which was especially important in trying to remove the jutting piece from the edge by the flower. This process was effective, but the edge was still not as smooth as I was aiming for, but more filing was not proving effective.

My metal pieces after filing away edges to try and smooth them

Next, I sand blasted the piece, which yielded very smooth pieces, but I could really see the imperfections in the inner cuts at this point.

Both pieces after sand-blasting (left), with imperfections clearly visible (right)

I decided to powder coat my piece to finish, which went mostly well, and although some texture could be seen in the pieces, I liked the aesthetic of this look and decided to keep the pieces like this.

Pieces post-powder coating (left), and after drying (final pieces, right)

I then cleaned up the powder coating area, which is the last location I worked in.

Clean workspace

The main lesson I learned during this project was to be mindful of the limitations of the machines I am working with when deciding what designs to create using them, as I attribute the imperfections in my project to this initial design error. While the post-processing was done correctly and able to mostly recover the intended design, this process would not have been as arduous if I had been more mindful of the limitations in the plasma cutter in the first place. The correct application of post-processing techniques I think is evident by how similar both of my pieces look.

Cost Model

Materials:

• Metal sheet, 12″ x 12″ sheet (use about 1/3), OnlineMetals.com: $24.2/3 = $8.07
• Powder coat, 1 lb (use 1/4 – unsure quantity so overestimate), PrismaticPowders.com: $14.64/4 = $3.66

Labor:

• Metal machine worker, US Bureau of Labor Statistics, estimated 2 hours@ $21.6/hr: $43.2
• Prototyping Engineer, Indeed.com: $36.5/hr, estimated 1 hour: $36.5

Overhead

• Machine time, The Maker Barn: $40/month, individual use 1 month: $40
• Adobe illustrator license, $22.99/month, 1 month use: $22.99

Design

• Engineering and Development, ZipRecruiter: $90/hr, 1 hour consult: $90

Total: $244.42 / 2 diamonds = $122.21 per diamond

Similar to the past few assignments, material costs remained rather low and would be decreased even further with wholesale supplying. The labor costs per item produced would go down with increased production, as fewer hours from the prototyping engineer per item would be needed, and also the metal working steps can be done separately allowing for parts to be produced in parallel assembly line-style, which would allow for the process to occur far more quickly with only a slight increase in workers (dependent on production scale). This same principle also applies for the engineering and development consultant. The machine use costs would be expected to go up with increased production, especially if the facility requires personal use or has limited access hours, so at certain scales purchasing facility space and equipment may work out to be cheaper. Since Illustrator is on a monthly subscription model, with increased use the price per item would be expected to decrease.