This week, we were assigned to make two diamond tiles to form an isometric cube.  We were given the drawing file, and were responsible for plasma cutting and post-processing the tiles.

In the process of cutting out the tiles, we started by looking at the test cuts with our material and estimating which setting will produce the cleanest lines with the least slag.  We picked the settings accordingly, but Joe helped us by increasing the air pressure to produce even cleaner lines.  After cutting, there wasn’t much slag on the parts.

After talking about post-processing, we knew that filing metal parts took relatively little material off, we decided to pursue this option first due to the low amount of slag.  However, we quickly figured out that filing was going to take way too long to smooth out the edges, so we opted to use the angle grinder instead.  The angle grinder made quick work of the remaining slag and also dulled our sharp edges a little.

The angle grinder allowed us to remove more material at a time as well, as it was most effective when held near parallel to the ground for wide-area applications and more angled for areas with smaller geometry.

After using the angle grinder, we went back to the files.  As an experiment, we tried using sandpaper, and it actually proved more effective at smoothing out the edges than the file. This was most likely because of the finer grit of sandpaper compared to the file, as the file was creating small divots and ridges in the metal. Sanding took considerably longer than angle grinding, but that was expected.

After all of our edges were smoothed out, we masked off certain sections of our parts and took them to the sandblaster to put a finish onto the tiles.  We masked off areas of the tiles to prevent the sandblasting from surface finishing those areas, as we wanted a rust finish to show on the middle to emphasize the “J”.  While sandblasting, we learned that when it doesn’t seem to be abrading the surface, the sand has either clogged or accumulated in another area beside the intake.

After sandblasting, I put a “frosted glass” clear coat on the whole part to emphasize the sandblasting, but it actually did the opposite.  I assumed that it would be more transparent than it was, and it ended up covering up most of the rust (some showed through) and made the part look more monochromatic than I had planned.  I learned that you probably need one or the other (if you want a clear coat, go for a transparent clear coat).

I also tried to sand the clear coat to get a smoother finish, but the grit was too rough, and since I was putting it straight on the metal, some of the clear coat came right off. I ended up having to re-paint the part.  I learned that there are a lot of steps in post processing the parts that are time-consuming and important to achieve a high-quality finished product.