For this final homework assignment, our task was to cut a metal diamond with the water jet cutter, add our own cut-outs/designs to the diamond, and post-process using 3 methods. To begin this assignment, I decided to cut out a shape from the interior as my addition to the diamond structure. I went to the noun project website and debated between cutting a snowflake or tree. I ultimately decided on this tree, based on the recommendations in the homework guidelines of complex shapes that can be quite difficult to cut. I added the tree to the diamond shape in Adobe Illustrator and then with the help of a OEDK lab assistant proceeded to the water jet cutter.

Using the water jet cutter was more straightforward than I had anticipated. I selected a thin piece of stainless steel to create the diamond shape. With the help of a lab assistant, I setup the file for cutting on the nearby computer and ensured that the water jet cutter was setup appropriately to move forward (assessing water levels in the main compartment and remaining abrasive).

One procedure I would change in the future when setting up the file would be to ensure to export the .ai file as an .svg before importing into the water jet software. Directly importing the .ai file resulted in an outlined box in the water jet software, which required some trial and error to remove in order to prevent the cutting of the outlined box and conserve metal resources. We also ensured that the settings were adjusted correctly for the thickness and material properties of the stainless steel. The total cut time was approximately 2 minutes, and the steel cut through successfully on the first try. I was surprised by the speed of the water jet cutter with how quickly it was able to cut through the steel piece.

Following, I wiped off some of the sand residue. I had planned to sandblast the diamonds but learned from a lab assistant that the sandblaster was currently out of commission. Therefore, I proceeded to manually sand the surfaces and file the edges as the first post-processing method. I used 80 grit then 320 grit sandpaper to sand the surfaces of the diamonds. When filing, I made sure to file both the outside and inside edges to smooth all exterior edges of the piece. One insight I gained from this process was that aluminum may have been a superior material selection for some post-processing procedures, as I remembered how much easier it was to file aluminum vs. steel in the post-processing lecture/workshop.

After sanding and filing, the corners of the piece were still quite sharp. I therefore decided to use a grinder to further soften the corners and edges as the second post-processing method. I initially intended to use the angle grinder, but the lab assistant indicated that the angle grinder might not work well for how thin the piece of metal was. For this reason, we went into the machine shop to use an alternating current grinder to carefully soften the edges.  I first practiced with a scrap piece of stainless steel to ensure that I understood the appropriate amount of force required to achieve the desired result. After using the grinder, I still felt that the edges and corners could use a bit of additional softening. Therefore, I went back to filing and sanding before the final post-processing step.

For the final method of post-processing, I spray painted and then clear-coated the pieces. I used a dark green colored spray paint to match the tree aesthetic, let it dry, and the finished the diamonds with a clear coat enamel. One issue I ran into was picking up the spray painted pieces with a paper towel before clear-coating, which appeared to have left a minimal amount of residue/indentation on the diamonds. Overall, I was pleased with the outcome of the diamonds and the final product!

Cost Analysis

• Materials Cost – $6 (12x12in Metal sheet used to construct diamonds)
• Machine Use Cost – $40 ($20/hr for 1 hour of water jet machine setup and use time, $20 to purchase a low-cost grinder tool)
• Labor Cost – $20 (2 hours @ $10/hr, primarily post-processing time)
• Post-Processing Materials – $8 ($4/ each can of paint/clear-coat used, sand paper and filing tools assumed to be available)

Total cost: $6 + $40 + $20 + $8 = $74.