I found a cog buried in the ground beneath my garage when I was about 17. I always wanted to do something with it, but it was so rusty and dirty that it got left for years. Until...
Date Made: July 2012
Approx Cost: £7.50
Approx Time: 1 hour (not including getting it acid dipped)
Step 1: Clean Cog
You can do this with some elbow grease or you can get it media blasted. I got this done at the same time as a load of other stuff (see my V8 table Instructable), but it didnt come out great because it was so rusty.
I decided to get it acid dipped instead. This made it pitted but clean!