Find an area that is free of clutter to grind your piece of metal. Grinding metal can produce a lot of sparks so it is important to do it in a well ventilated and spacious area. If you are using a metal grinder, you will need to find a place to clamp your metal down since a metal grinder is hand-held. If you are using a belt sander, make sure your metal can be lifted easily. If you are planning on grinding a very small piece of metal -- for example, a piece of metal smaller than your hand -- it is advisable to use a metal grinder so you won't need to hold the metal.
Apply oil over the section you are grinding.
Turn the metal grinder or the belt sander on and begin to grind the metal. If you are using a metal grinder, angle it so that the sparks will be directed away from you. Move the grinder in circular motions over the metal you are grinding down. For the belt sander, hold the metal perpendicular to the sander and only angle it slightly if you need to. If you angle the metal too much, it can snag on the sand paper and tear it.
Turn off the grinder or belt sander periodically to check on your progress. Be sure not to touch your newly ground metal right away since it will still be hot.
Choose how you want to buffer your metal. You can attach a buffing pad to your belt sander or if you have a buffing wheel, you can use that.
Select which buffing compound you need to use. The type of compound you need is dependent on several factors including what type of buffing wheel you have, the effect on the metal and the type of metal you're using. Some buffing compounds will be more effective in removing scratches, while some will make the metal shiny.
Turn on the sander with the buffing pad or the buffing wheel and hold the compound up to it. The friction will create heat and start to melt the buffing compound on to the buffing pad creating a thin layer of it.
Hold the metal up to the buffing pad and start to buffer it. Move the metal against the direction of the wheel using a low amount of pressure for a more polished surface.