Keeping lathe tools sharp not only makes wood turning easier, it makes the process much safer. Dull tools, nicked edges and excessive burrs can grab spinning wood and flip the tool out of your hand, leaving unsightly scarring that takes some effort to remove. Blades that are not sharp will also cut more slowly and require more effort on the part of the operator.
Set the tool rest for a 30 to 45 degree bevel and hold the lathe tool on the rest. Determine if the tool rest angle matches the bevel on the lathe tool and adjust the tool rest if necessary. It is not absolutely critical to keep the exact bevel but it is a good idea to get a close approximation. Tighten the tool rest in place.
Don a pair of safety glasses and turn on the grinder. If the lathe tool is very dull, the edge is damaged or you are uncertain how good the edge is, use the 36-grit grinding wheel.
Grip the lathe tool handle firmly and use the thumb on your opposite hand to guide the tool while holding it against the tool rest. Bring the lathe tool up to the grinding wheel very gently so that it just makes contact with the wheel. A very light touch works best because it will grind the edge well while keeping the steel running cool. After several minutes of grinding, you should be able to hold the tool in your fingers, ¾ inch behind the edge, for at least five seconds. If the tool is too warm to touch or you see a discoloration of the edge beginning to form, dip the tool into a can of water to cool it and resume grinding with a lighter touch.
Bring parting tool and skew chisel edges square to the grinding wheel. Use a rolling motion for gouges and scrapers because it will allow you to match the shape of the bevel on these tools.
Once sparks begin to fly up over the top of the tool, the edge is sharp.
Follow the same technique with the lathe tool on the 80-grit grinding wheel. This wheel works best on tools that already have an edge and simply need polishing.
Remove the burr that develops on the back side of the edge you ground. On skew chisels and parting tools, do this by lightly working the edge across a honing stone. On gouges, which are deeply fluted, use a dowel wrapped in 120-grit sandpaper to remove the burr.