To begin, you need a basic buff motor. I got mine at the local home improvement store on sale to avoid hefty shipping charges by buying one over the Internet. It's made in China and likely not the best quality, but buff motors are pretty basic items and most run for a long time. Mine is a ½ hp single-speed motor (3450rpm) that takes six inch wheels, but you can get more hp, longer shafts and accommodate up to 10-inch wheels in a more deluxe motor, as well as potentially a dual speed motor. If you are doing whole lot of buffing, that might be the way to go, especially if you can find a motor that's built in the USA. The motor needs to be securely mounted to a bench or standalone on a stand. You need enough room to maneuver your parts when buffing without interference from the motor or the bench.
You also need the proper size buff wheels for your motor, a selection of different compounds, and proper safety gear. I ordered a buffing kit from The Eastwood Company that includes everything needed. Buff motors spin fast, throw lots of debris, and the parts get hot when you're buffing. Here is a picture of the safety gear including a face shield, dust mask and leather gloves. You also need safety goggles or wear impact resistant glasses under the face shield, as the shield may not be sufficient to provide protection from flying debris or parts. Buffing parts is actually quite dangerous. If you happen to catch an edge on your part (especially door sill plates which are very lightweight and have crisp edges), a buff wheel turning at over 3,000 rpm can rip the part right out of your hands. The speed of a part ejected by the buffer can be as much as 80 mph. Don't have any humans or pets in the vicinity of the buffer while you are working. This is one job where you don't want to short change yourself on safety gear.
Before you begin buffing, you'll want to clean your part and check for dents or deep scratches. Aluminum door sill plates are made of very soft metal that is easily scratched and dented. You can pound out dents with a trim hammer and anvil, and file and sand any remaining bumps smooth. However, remember the metal is rather thin. In my opinion, "less is more" when is comes to filing a door sill plate. In my situation, my objective was to clean up the door sills so that they would look presentable but not go overboard. I simply used 600 grit sandpaper followed by 1000 grit as needed to remove minor scratches and I sanded with light pressure. The metal is so soft that it is very easy to gouge the sill plate with sandpaper. Obviously, this won't remove and deep imperfections. You can start sanding with a coarser grit, but it will be more work to buff out the sanding scratches. You can also buy expander wheels or use greaseless compounds and use the buffer to do the sanding.
to work and have a plan of attack rather than have the part ripped out of your hands by the spinning wheel. Make sure that you are alert and sober. This is not something you want to do after hoisting a few down at the neighborhood pub! You'll want to hold the part firmly and use minimum pressure against the wheel (about two pounds of force). Excess pressure will load the motor down and can heat the part excessively causing warping or irreversible discoloration. You must be particularly careful with edges on the part. Always buff such that wheel runs off the edge of the part. In addition, you need to apply compound and hold the part against the wheel below the centerline of the wheel. Buffing below the centerline ensures that debris will fly away from your body and not into your face. Apply compound sparingly but fairly often. Too much compound will leave deposits on the part and is difficult to remove. I've found that oxidized aluminum sill plates will load up the buff wheel rather quickly. You need to use a buff rake to clean the buff wheel during the buffing process. You can make a buff rake from an old saw blade by attaching handles to both ends of the blade. If you get the Eastwood buff kit, a buff rake is included.
