For this assignment, I used the plasma cutter to cut out two diamonds made of metal and with a modified pattern, with the hopes that they are identical. Then, I used four post-processing methods to improve the aesthetic appeal of the diamonds. Therefore, this falls under the intermediate assignment.
I was able to plasma cut both of my diamonds during the plasma cutting tutorial, during which I asked a lot of questions and got a good understanding of how the machine works as well as how to position the torch so that it both saves cutting space and doesn’t overlap other cuts. The process was relatively straightforward, and the instructions were clear except for a few steps, which the TA helped clarify. Here are my two plasma cut diamonds, right out of the plasma cutter:
As you can see there is a lot of dross on the edges
It was clear that there was a lot of dross on the edges, so I first filed the edges, which was quite effective at removing it:
This type of file was particularly good for getting the inside edges as it was the perfect shape
At first, I used a file with a flat edge, which was effective at removing dross from the outside edges, but did not fit well inside the inner diamond shape. I fortunately found a file with a triangular shape which fit exactly inside and was very effective. The filing process was relatively quick and straightforward.
Next, it was time to angle grind the diamonds to achieve a smooth surface. I immediately noticed that the angle grinder was a lot louder than I thought, so I went to get some ear plugs, which worked very well. I angle grinded the diamonds for a while, which made my left arm really sore and shaky afterwards. I may have made the mistake of angle grinding too much, since I accidentally chipped off some of the metal in one of the edges, likely also as a result of the disc catching on to the edge. One of the things about angle grinding for the first time is that you don’t really know when to stop. After this experience, I came up with the heuristic to stop after the surface looks shiny everywhere when you look at it at an angle outside, exposed to the sun. With this ‘rule’ in mind, I angle grinded the corners more, since they tended to look more dull. Angle grinding the corners was difficult if you try to go backwards; the disc got caught a lot more than when I pushed forwards. Therefore, I reoriented the piece so that it would be easier to push forward. Sometimes smoothing would occur at a point more inside the disk than I thought, so I had to push the disc forward a little more. Perhaps attempting to change the angle could fix this; however, my arm was getting very tired and shaky, and it became increasingly difficult to control the angle grinder precisely. Here are the finished angle grinded parts:
Smooth surfaces with some residual color from the previous coating of the metal. Sand blasting would fix this, at least theoretically.
The next step was to sand blast. This part was very easy, but very boring. It took a very long time for the entire part to lose its previous coating. Most of the time, the change in color of the surface was so slow that you almost cannot notice it happening in real time, and it is only when you look carefully you can see it happening. I did my best to ensure the surface was uniform while also not staying there forever. Here are the sand blasted parts:
Sand-blasted finish on the diamonds
Last but certainly not least, is powder coating. This was by far the most challenging part of this project. First of all, access to the wet lab and wood shop is restricted, which gives you far less control over the time you can complete this project. It depends on whether there is either a lab assistant or technician around. I had to wait for a lab assistant to begin their shift to begin powder coating, and I had to heavily rely on their access to the wet lab and wood shop. I started by getting the compressor out of the wood shop, which should have been in the wet lab, after gaining access. I had never used a compressor before, so I should have probably learned some things about it before doing this. However, I was able to learn a lot on the spot. There conveniently was a document on how to powder coat at the powder coating station, and I made great use of it in setting up the powder coating. Getting access to the wet lab, I got the powder coating gun and some blue powder which I thought would look nice. I then followed the steps on the document, setting up the voltage box, connecting the powder coating gun to the compressor, which had kind of an insecure connection. For some reason, finding a paperclip was also difficult. With the help of a lab assistant and a fellow student, I was able to find some in the laser cutter room. I was concerned that one paper clip would not be long enough to hang my diamond, but it ended up working, although of course there was a lot of the part that was covered by the paper clip. I finally was ready to powder coat. I immediately noticed another issue; the pressure kept getting lower on the compressor so that after just one spray, it would go down to zero. After a lot of trial and error, I figured out that if I let the compressor run for a bit, with the pressure available to tool low, and then increase the pressure available to tool, to about 20 psi, then I would have a substatial ‘charge’ of pressure on the gun. About the pressure available to tool: at first I didn’t know the knob controlled this, so I had it at the max while the compressor was running, which of course now in hindsight it is obvious that the increasing pressure to the tool will cause the tubing to come out, which is exactly what happened a couple times. I learned a lot and was able to powder coat with less interruptions at this point. Using gloves proved to be very troublesome because grabbing the paper clips with gloves results in the gloves getting stuck on the wire mesh, so I took them off, and suddenly things were so much easier. I finally powder coated a full coat, and I realized it was difficult to get the part behind the paper clip holding it up. It certainly didn’t help that the powder coating gun, when the button is pressed, attracts the part due to the electrostatic attraction between the positively charged powder coated gun and the negatively charged, grounded, metal. So, in hopes of getting this area as good as the others, I took a somewhat dangerous risk and tried to get close, but very carefully, as the part kept spinning towards me and blocking my access to the area. Anyways, I did my best to get these areas to look the same as the rest. Also, I learned I couldn’t reorient the part upside down and powder coat because in doing so I would remove some of the coating and have to redo it. So I suppose once you hang the part, it is easiest to do the entire job in that orientation. I only had 10 minutes to get into the wet lab before the lab assistant’s shift was over, but I was able to get in and put the part in the oven. I set the temperature to 400 F and the time to 35 minutes to combine preheating time (15 min) and actual curing time (20 min). Here are images of this process:
Powder coated diamonds in the oven
The final finish
Here is a photo of my clean workspace:
Eastwood powder coat – $13.99
