  Engraved plate.
I found a listing for a one inch thick magnesium plate on eBay. It was just a fraction of an inch bigger in each direction than the cover tiles in the periodic table (4.5" by 4.75"). When it arrived, I decided to see if I could machine it into an extra-thick replica of the magnesium cover tile. The edges were easily trimmed to the exact 4" x 4" dimensions of the tile using my compound miter saw (see the construction history page for more about this saw), and I used my tabletop belt sander to give all six faces a nice brushed satin finish.
Then came the moment of truth: Could my engraving machine (see history page) handle engraving magnesium? The answer is yes, with effort. The machine is meant to engrave plastic, and it works great with wood, but magnesium is pushing it in terms of the amount of force needed to move the cutter through the metal. The cutter itself is tungsten carbide and easily able to handle cutting non-ferrous metals. It's more a question of the strength of the pantograph arm. I think it could probably do aluminum and maybe copper, but not much more than that. Harder metals can be engraved using the diamond scratch engraving machine I keep in my office, but it just makes delicate lines, not deep grooves like these.
I applied a coat of clear acrylic varnish, because the metal tarnished almost immediately as I was working it. In fact, I had to put on gloves and go over all the surfaces with the belt sander one last time, because any place I touched it with bare fingers I left tarnish fingerprints. I polished the surfaces and then immediately varnished them to preserve the shine.
Source: eBay seller covers_machining
Contributor: Theodore Gray
Acquired: 29 May, 2002
Price: $8
Size: 4"
Purity: >99%
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