How to Sharpen with Stones
Start the Process by Shaping the Bevel
Sharpening consists of two steps: shaping and honing. During shaping you create the primary bevel angle on the cutting edge—usually 25° or 30°—with either a flat grind or hollow grind. You can use stones (120–325-grit) to create a flat grind, shown far right, by sharpening until the full depth of the cutting edge (front to back) is flat.
Even quicker, you can form a hollow grind at the bench grinder using a 100- or 120-grit aluminum-oxide wheel. Then shape the tool further on a coarse stone to create a narrow flat (about 1/16") across the full width on the front and back of the bevel. The middle remains hollow, leaving less material to abrade away in subsequent honings. Return to this step as the bevel flattens.
A Few Points:
▪ Diamond stones cut aggressively, leaving deeper scratches than waterstones and ceramics. This makes initial shaping faster, but adds a little more time to remove those scratches when you move on to finer-grit synthetic stones.
▪ When shaping a tool on a bench grinder, avoid overheating the tool, which can negatively affect the steel's temper. Have a cup of water nearby to quench the tool often.
Now Hone to a Keen Edge
With the primary bevel established, move on to honing at the same bevel angle. On a 1,000- or 1,200-grit stone, stroke the blade as needed to remove the scratches left from the coarse stone. Repeat the process with 4,000 and 8,000 stones until the bevel has amirror finish.
Some woodworkers prefer to add a microbevel, which is a very thin bevel at a 3–5° steeper angle along the cutting edge, as shown at left. A microbevel doesn't make the edge sharper than a flat bevel. It does, just like a hollow grind, leave a smaller area to hone, making subsequent honings faster.
A few points:
▪ You can usually hone a blade multiple times before you need to return to the coarse stones to reshape the bevel.
▪ If a manufacturer doesn't offer a 4,000- or 8,000-grit stone, there's a good chance they make 6,000 and 10,000, and these will substitute nicely.
▪ Fine-grit stones tend to be softer than coarse stones, so treat them gently to avoid tool gouges or chipped edges.
▪ Manufacturers use the designations "coarse" and "fine" differently when referring to their own products, so be sure to look for the grit rating to know what you're actually buying.
