Process:

The journey to creating my plasma cut dinos was one of grit, determination, and adaptation (slight exaggeration), but after some strategic decision making and compromise, I was able to create a product that I was proud of. I wanted my piece to be the diamond with a dinosaur cut out of the center of it, so I gathered an SVG file from “the noun project” and then edited it in illustrator to achieve the following files.

SVG dino files

I created four different cutouts to have two backups in case I made any errors in the post-processing phase. I went to the OEDK with Leticia and we plasma cut our files on a sheet of steel by following the directions in the plasma cutter directions packet. The lab assistant in the machine shop suggested that we use the speed and power settings that had already been set as they assured that it had worked for previous projects, and said that it would save time and material to stick with those settings. The machine ran as anticipated, but not all four of the resulting objects were high-quality. Two of them had some excess metal that I had to pull off, leaving unappealing dents and cuts in the metal, so I decided to take only the other two into the post-processing phase. Those backups came in handy. The issue was likely because the files were too close together, so the cuts from some pieces interfered with those of other pieces. After plasma cutting, the raw pieces had a significant amount of slag on the bottom edges, so my first step was to get rid of that.

The dinos after plasma cutting with resulting slag on the bottom of the pieces.

I used the magnetic clamp and the angle grinder to remove the slag from the edges where the piece was cut, resulting in clean edges around the entire piece. The process felt pretty smooth, and I was confident using the angle grinder after the brief demo in class.

Dinos after removing slag with an angle grinder.

As can be seen in the photo, the angle grinder revealed a new, cleaner layer of steel on the edges that give the classic, shiny look of metal. The edges and corners remained sharp and rugged, so I decided to smoothen them out using a file. After a good amount of elbow grease, I was able to get the metal to the point where it was smooth to the touch around any edge and corner, making sure that there would be no risk of someone cutting themselves when handling it for reasonable purposes (meaning anything but not trying to intentionally poke someone with it).

Using the file to make the edges nice and smooth.

At this point, it was Thursday evening. I would leave for home on Friday morning, so I knew I would not have a significant amount of time to work on my project when I got back on Tuesday. I really liked the shiny look of the second layer of steel, so I wanted to sandblast the whole item and complete it with a clear finish to maintain that look, but the sandblaster was broken according to multiple accounts, and the lab assistants were busy with other students when I was in the OEDK. With limited time and the uncertainty with the sandblaster, I decided that I would finish it with spray paint in order to give it a clean, consistent look that would still be appealing and be achievable within my time constraints. The first step to doing this was to apply primer to both objects. I first applied two layers, one side at a time, letting each side dry for 10 minutes after each layer.

Applying the primer

I waited two hours, per directions on the can, before sanding the primer with 1500-grit sandpaper to clean up any inconsistencies with the coverage, and the result was two clean, primed pieces of steel ready to be spray painted.

The primed pieces of steel.

The primer covered the pieces well and the feel of the object was very smooth at this point, so I could have stopped, but I thought it was missing the “pop” that a different color would have added, so I continued with my plan to spray paint. I chose a purple color, and took the same strategy of spray painting one side at a time. The spray paint needed a little more time in between applying layers, so I waited about 20 minutes for each side and layer. When I was finally done my two layers of spray paint, it was 2 AM on Thursday evening, and I was to leave for the airport at 3:45 AM. I was very satisfied that I was able to get the spray paint on so that it could dry over the weekend and be ready when I got back. I left my pieces on the rack and then got into the uber for my flight.

Finished Spray Painted Pieces (as of Thursday)

Fast-forward to Tuesday. Great midterm recess, but came back to a surprise. The first thing I did when I got back to Rice was check my projects to see how they dried, and I was shocked to see that one of my projects was gone. I figured that it must’ve fell down or something, but I couldn’t find it anywhere on the floor. After looking for a while, I finally located it on the spray painting table, with a single layer of metallic gold spray paint applied unevenly on one side of the missing piece. Clearly, it was applied straight over the purple layer I’d applied the previous Thursday, as can be seen in the following picture.

My pieces as of Tuesday morning

I was frustrated to have come back to this, as I was excited to see how my pieces turned out when dried. But, with the deadline approaching, I needed to find another solution to create two consistent pieces. It was 9:00 am, and ideally the spray paint has 24 hours to dry before sanding, but with the time constraints I was in given that I have early classes on Wednesday, waking up early was not a feasible option. I used 200-grit sandpaper to sand down the spray paint on both pieces back to almost nothing, and decided I would reapply spray paint with a new color. I did not have the time to do one side at a time, so I hung my pieces up with pipe cleaner and then did one layer at a time, leaving 20 minutes between layer applications. I chose Texas Orange after testing multiple colors because it provided the most reliable coverage with each spray.

My rig for spray painting both sides at a time

I left the pieces to dry until the evening. When I picked them up, the paint looked better than I anticipated, but was still uneven either because I was too close to the object when spray painting, but I also noticed that the aerosol in the can must have been low because even after shaking the bottle thoroughly, it did not spray in a consistent manner, but was slightly splotchy. If I had given myself more time, I would have applied more layers and sprayed further back than I did initially, to ensure that the paint did not become too wet on the object. Finally, I applied the tape to the back which outlined the post-processing steps I took, and I was done!

Finished dinos

Steps taken:

1. Plasma Cut
2. Angle Grinder
3. File
4. Primer
5. Spray Paint

Reflection:

Overall, with the last minute adjustments I had to make due to my initial project being messed with, I was satisfied with how it turned out, and feel confident using the plasma cutter and post-processing methods for steel in the future. However, there are a few things I would change if I were to do a similar project.

1. On my illustrator file, I would be sure to leave adequate space between edges on the plasma cutter so that the cuts do not interfere with each other at all. This is why I had to throw out two of my initial cuts.
2. When applying primer or spray paint, I would hang it up like I did in the last round of spray paint so that one side would not have to lie flat on a surface when it was not completely dry.
3. When applying spray paint, I will be sure to use newer aerosol cans and leave an appropriate amount of time to apply more careful layers to the object while letting it dry completely.

Cost Estimate:

Steel: 1x sheet of 1/8″ steel – $20.00

Labor: 5 hours @ $25/hr – $125.00

Spray Paint: small portion of 1x bottle – $1.00

Primer: small portion of 1x bottle – $1.00

Overhead Estimate (OEDK electricity, plasma cutter use, Use of OEDK tools): $40.00

Total: $187.00