Using the plasma cutter was very similar to the laser cutter, but presented a few unique challenges. The biggest of these is that post-processing parts from the plasma cutter is not merely optional, but necessary, at least to a degree. The plasma cutter leaves rough edges and slag around the tool path that make the part very unpleasant to look at and hold, and could interfere with smooth operation of a device made with these parts. To remedy this, we finish the parts after they are cut to make them look and work better.

Directly out of the plasma cutter, my part didn’t have a huge slag problem, but I used a file around the edges, keeping it parallel with the face of the part to preserve detail, I knocked off the first of the slag, leaving this:

Next, I used 60 grit sandpaper across the whole surface to remove the contamination from the production, packaging, shipping, and cutting that this metal had gone through before being cut:

This step revealed a few pits in the surface, but they were too deep to do anything about without removing so much surface material that it would be uneven, so I elected to leave them.

I then further refined the surface with 240 grit sandpaper to further smooth the surface and soften the pitting a bit

The edges were still untreated and rough so I went around them with a series of files, mainly using the round file on concave curves (as in the picture below), the triangular file in sharp corners, and the flat file on the flatter sections.

I then sandblasted the entire part to get it completely even and smooth for the finish I had in mind. I wanted to replicate this type of circular brushed pattern, which is normally done with a circular wire brush:

Since the OEDK doesn’t have that type of brush, I used 240 grit sanding disks on the Dremel, held at an angle so I could get at least half circles. This meant I had to decrease the gap between the rows of circles, but the overall effect was maintained. Starting on the back, I found the biggest issues to be keeping consistent spacing between the circles and rows, especially on a non-uniform shape like this, as well as keeping the Dremel moving at a consistent rate across the piece so as not to cause any discoloration from exessive heat.

Learning from the back, I made another attempt on the front and achieved much more consistent spacing. It may not be as precise as the finish achieved by a robot with a brush, but it still is very interesting to look at and makes for a very smooth surface.