So, I've had this block of titanium sitting around for a few years, after buying it on eBay with my PayPal signup bonus. It's kind of cool and elemental, but a bit rough around the edges. I did some research and found that titanium polishes up nice, but because of the hardness it takes some work. It keeps a nice finish because a thin layer of titanium oxide forms on the surface, which resists corrosion. I got some fine grit sandpaper and quickly found that it was going nowhere fast. At some point I got the idea to automate the process.



This was my first setup. From the left, there is a motor harvested from a printer or fax machine, a rubber band drive belt, a CD sandwich with a thick cardboard disk on a big screw axle, and a dowel arm connected to a wood block taped to the titanium, which is sitting on a piece of sandpaper.

Problems with this design:
1. The motor gets too hot and the rubber band breaks.
2. The Ti block bucks up on its edge on the return stroke.
3. The CD wheel, held up with an alligator clip, comes loose and slides down the screw. The brad holding the arm to the CD then slips loose.