How to Sharpen Japanese Woodworking & Marking KnivesComments (0)
How to Sharpen Japanese Woodworking & Marking Knives
This Information Applies to All Single Bevel Woodworking Tools.
Because most Japanese woodworking knives are ground with a single bevel, they are relatively easy to sharpen. WARNING: under no circumstances should the blade be ground on an un-lubricated grinder. To do so will destroy the temper of the blade.
While oilstones can be used for sharpening Japanese knives, much better results will be obtained using Japanese water lubricated sharpening stones. Generally speaking, Japanese waterstones can be divided into two classes: Coarse Stones for initial sharpening and Finish Stones for final polishing to a razor-sharp edge.
First, check to be sure the surface of your sharpening stone is flat. Otherwise, it will be difficult, if not impossible, to obtain a well sharpened edge.If you are using Japanese waterstones, please follow our instructions for flattening your waterstones.
Now inspect the edge of the blade for any nicks or other defects.If there are any defects, rub the edge of the blade at a go• angle on a Coarse Stone until they are completely removed. While doing this, be careful not to change the profile of the edge.
The back of the blade should be sharpened first. To do this, place the blade perpendicular to the length of a Coarse Stone with finger pressure applied directly on the bevel. Rub the blade back and forth across the stone until the area directly behind the edge is honed the full length of the edge.Be careful not to over-sharpen the back. It is not necessary or desirable to completely fill in the hollowed area. This will be obvious by inspection. Now transfer the blade to a Finish Stone, and hone the back of the blade until a mirror finish is obtained.
To complete the sharpening, rub the bevel across a Coarse Stone until a burr is obtained along the full length of the edge. The presence of a burr is easily felt by drawing a finger at a goo angle across the back of the edge of the blade. As soon as the burr is detected, transfer the blade to the Finish Stone, and alternately hone the bevel and back side until the burr disappears. Best practice is to hone at a ratio of five strokes on the bevel for each stroke on the back side.
Should the edge seem somewhat brittle and not hold up well in hardwoods, it may be necessary to add a "micro bevel." This is done after initial polishing by increasing the angle of the bevel to the finish stone about four to five degrees and honing 10 to 15 strokes. A brittle edge in a new tool is usually considered to be a sign of a superior tool. As the tool is sharpened and the surface metal formed at the time of manufacture is removed, tougher, more durable metal underneath is exposed. Additionally, the honing process itself is thought to increase the edge holding properties of the blade.
The tips of Japanese knives are very thin and hard and will occasionally break during use. This is a normal condition, and many Japanese woodworkers regrind the tip even before using the knife. The best way to deal with a broken tip is to turn the knife on its back edge and rub at an angle of 60° to 75° on a very Coarse Stone. Continue in this fashion until the broken portion has been ground away and a sharp point reestablished.
Carefully dry the blade and apply a light coating of camellia oil or mineral oil. If you have any questions or problems regarding sharpening, please feel free to contact us.
This Information Applies to All Double Bevel Woodworking Tools.
Hold the tool's blade against the sharpening stone. The most important consideration when sharpening a blade to a perfect edge is to hold it properly against the stone. Improper positioning can result in a misshapen bevel. Begin by pressing the bevel - the angled part of the blade- flat against the stone's surface.Use two fingers on your non-dominant hand to press down on the back of the blade and hold it in this position.
Wrap your dominant hand around the tool's handle.You will use this hand to rub the tool along the stone, while using your other hand to keep the blade angled correctly.
Your non-dominant hand should be pressing firmly down on the back of the blade. Your dominant hand should maintain a loose grip; this will help prevent you from rocking the tool at different angles as you sharpen it.
Rub the woodworking tool along the sharpening stone. Rubbing the blade across the stone's surface is the process that will actually sharpen it. Proper technique is important to produce a perfect blade. Maintaining the grip outlined above, begin sliding the blade back and forth across the stone in a "W" shape. This shape will help you cover each part of the stone evenly, which will prevent uneven wear and uneven sharpening.
Avoid moving your arms while you work; sway your body instead. Moving your arms is much more likely to cause you to alter your grip, resulting in an uneven blade.
Holding the woodworking tool at about a 45a angle to the sharpening stone tends to be more stable than lining the tool directly up with the stone.
Remove the burr from the woodworking tool. Once the blade has been sharpened, the metal that has been shaved away will still be connected to the blade in a thin, rough "burr" that can be felt on the back of the cutting edge. You will need to remove this burr. Turn the tool over so that the back of the blade (where the burr is) is positioned against the stone. Rub it in a circular motion about 20 times.
Turn the tool over again, and position the bevel against the stone as before. Repeat the circular motion, continually turning the tool over and rubbing. The burr should eventually fall off.
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