This week, our task was to plasma cut an item from steel. I was really looking forward to this assignment, since I haven’t had the opportunity to work with metal before. Over this experience, I had to iterate a few times to get a product, but I’m pretty happy with the results. Here’s how I did it!

Design the piece

For this assignment, we were given the freedom to cut anything from the metal, as long as it fit into a specific diamond shape. I decided that for whatever I created, I wanted to make it into a keychain that I could actually use. With that in mind, I decided to make a keychain of the Rice Owl (I thought about doing a female cut of Maryland, but MD is too small and detailed 🙁 ). Here’s the first concept I decided on:

I’ll talk a little more about this later, but the design was a little difficult to figure out on the laser since it had both male and female cuts. I ended up making a much simpler design, forgoing the hole and outer circle:

Cut the design

Kaira and I cut our pieces together! We came in with our designs ready, and set to work setting up the machine. For cut settings, we based it off the samples that were present in the machine shop along with the reference documents given, and ended with a 50 inches/min feed setting. Kaira cut hers first with pretty minimal difficulty – the hardest part was figuring out the software and orienting the beam. Next, it was my turn! At this point, we were nearing the hour mark, but fortunately, there was no team in the hour after so we were able to finish both our pieces.

As mentioned earlier, my design was a little too complicated, but we were focused on figuring it out. However, when we uploaded the design to the software, the cuts were not connected at all. After some troubleshooting with Douglas, we decided to change the design slightly to accommodate, and ended up with the final design (as shown above). At this point, we were closing in on our second hour and therefore we wanted to get the cuts in quickly. Fortunately this part was smooth sailing! However, because my cuts were so small, my owls (all four of them!) fell into the murky, rusty plasma cutter water. There was also no tools to help us get the cuts out, so we had to dip our hands in and fish them out.

 

Post-processing

Once we finished cutting, we needed to angle grind the slag off. Joe from the machine shop showed us a heavy duty angle grinder that helped get the thickest pieces of slag off quickly. Then we followed up with the lighter angle grinder to smooth everything down and remove the rusty surface from the cuts.

 

The surface was shiny, but not as much as I had hoped! The heavy duty angle grinder also left some deep cuts in my metal because I was pressing a little too hard. The was some general roughness on the edges of my owls. Dr. Wettergreen showed Kaira (who showed me) how to buff the edges with the buffer in the machine shop. This helped smooth the edges out.

 

After this step, I noticed a little bit of slag left over on the corners of the owls. Therefore, I used the metal filer to remove those pieces. I think I may have clamped the pieces too hard here (the clamp had ridges) which probably also contributed to the deep scratches.

I followed up with a 2000 grit sandpaper to smooth the surface and edges.

At this point, I was thinking of taping the entire owl except for the wing and sandblasting that part only. However, Kaira used the vinyl cutter to make a sticker of her name before sandblasting and ended up with a really cool dual texture finish. I really liked that so instead of just doing the wing, I vinyl cut the sketch of the Rice owl. I actually had to cut the vinyl stickers twice, since the initial one was too large to fit on my metal piece (maybe the dimensions changed slightly when loading the AI file to the vinyl cutter software, or perhaps I went to hard in the angle grinding and sanding).

Unfortunately, the sandblaster was broken by this point, so I had to pivot in order to get a similar effect. Because I had all four of my pieces post-processed, I was able to play around with the finishes.

First, I considered leaving the vinyl stickers on because they looked pretty good. However, the sticker didn’t fit the owls perfectly and stuck out on the edges a little bit. I tried heat gunning the vinyl sticker to the metal to see if it would shrink-wrap around, but it didn’t really work. It just crumpled the part sticking out. I didn’t love the finish, so I decided to just spray paint the negative space and remove the sticker. My first try, I didn’t use primer so when I tried to peel the sticker off after spray painting, the paint came off with the sticker.

The next time, I wiped the pieces with alcohol to remove any oils, and then primed before spray painting. This is how they turned out:

It looked good, but a little messy because the paint smeared as I was removing the sticker.

The blue spray can was actually completely empty by the time I was able to get to the samples I was going to submit, so I used black instead. I actually love the finish! I used a sealer at the end to seal in the colors:

It was a little messy when removing the vinyl sticker. There were also some fibers stuck to my bird from cleaning it before painting which got stuck in the paint as well. But overall, I actually love how it turned out! There is a really nice contrast, and I like being able to see the metal. After this assignment is over, I might ask Joe how to drill a hole into steel so I can actually make it into a keychain (or a fridge magnet if that doesn’t work).

Some lessons:

1. Each step is really important in preparing a sample for the final stage. Messing up on one stage will mess up the future ones
2. It’s ok if it’s not perfect! I was really trying to make this look awesome and still ended up with some imperfections. But the amount of learning I got through this experience, the number of new things I was able to try, and the creativity I was able to explore makes me proud of what I was able to complete.

Cost breakdown:

• Steel Solid Sheet Metal = $14.48
• Vinyl sticker = $6.99
• Primer = $4.68
• Black gloss enamel = $6.98
• Clear top coat = $5.98
• Machine use = $40/hour x 4 hours = $160
• Labor = 10 h0urs x $7.50/hour x 1 person = $75

Total = $274.11