Movement 1:Lengthwise Strokes
I start by laying the blade across the stone, so that the edge of the blade is hanging about 1/2″ off the edge of the stone. Using considerable downward pressure on the handle, I move the blade steadily up and down the length of the stone. I call this the long stroke.
While making the long strokes I allow the edge of the blade to drift onto the stone and move just one third of the way across the width. This might take 10 to-and-fro long strokes. During the next 10 strokes, the edge of the blade is allowed to drift back to the starting position, 1/2″ off the edge of the stone. The cutting edge of the tool spends half the honing time off the edge of the stone.
After about 50 strokes the surface of the stone will no longer be flat. The stone can be rotated 180° so that the other edge can be used for another 50 strokes.
It’s now time to flatten the stone and notice the wear that has taken place. By drawing a pencil grid on the surface of the stone and rubbing it a few strokes on the diamond stone, you can see that the long edges of the stone have become hollow and that the width has developed a bump. This bump is infinitely preferable to the usual hollow created on waterstones. A bump promotes a slight hollowing in the length of the flat side of the tool. By keeping the edge of the tool off the edge of the stone for 50 percent of the working time, a hollow stone can be avoided.
However, the slight hollowing of the length of the stone could be causing a slight belly or bump in the width of the plane blade. To check for and eliminate this problem, I change to a second movement on the freshly flattened stone.
Movement 2: Crosswise Strokes
The blade is laid across the stone, at one end, with the edge of the blade about 1/2″ off the edge of the stone. The stroke is crosswise, bringing the edge of the tool one-third of the way across the stone before returning to the start position. Considerable pressure is exerted on the center of the handle. During about 40 to-and-fro strokes the blade is allowed to drift up the length of the stone, and then back down to the starting position.
The stone is then rotated 180° as before, so that the other edge of the stone may be used. The stone should now be flattened again before doing any more work.
Observe the scratch patterns on the back of the blade. The scratches from movement one will lie across the width of the blade. You will have done enough of movement two when all those crosswise scratches have been replaced by lengthwise scratches. If a slight bump has been formed after movement one, you will see lengthwise scratches in the center of the b
lade only. This would be a signal to do more of movement two on a freshly flattened stone.
The objective is to remove all trace of the deep manufacturer’s grinding scratches just behind the cutting edge of the blade. The two types of movement may have to be repeated several times. I don’t worry about getting a band of lengthwise scratches more than about a 1/4″ wide behind the cutting edge. With A2 blades and careful sharpening technique this will last a long time, and you can do more back flattening in the future when necessary.
That’s it for now. And thanks to the ruler trick, a few seconds work later on will be all that is needed to complete work on the back side ? none of the mirror polishing of the whole surface, which is so time consuming.
Prepare The Cutting Bevel
For speed of resharpening I like to use three bevels. I first grind the blade at about 23°. I then create a wire edge on the #800-grit stone at 33°. Final bevel polishing is done on the #8,000-grit stone at 35°. This is my recipe for bench planes used on hardwoods. By honing at 35° the clearance angle under the polished bevel has been reduced to 10° (down from 15°), but I have found no problems with this arrangement. The 35° final polish seems to make blades last slightly longer between sharpenings. By keeping the grinding angle significantly lower than the honing angles, I can resharpen at least seven times between grindings. If you have a new blade ground at 25° there is no need to change to 23° yet. I am lucky to have a water-cooled grinder, so there is no danger of overheating the blade when grinding.
Honing a Straight Blade
I have a strong preference for the Eclipse-type honing guide with the narrow roller. It only takes a few seconds to clamp to the blade in the guide and ensures accuracy, repeatability and speed.
I determine my honing angles by squinting against a simple card, which has lines drawn with the aid of a child’s math protractor. After setting the blade at the proper angle, I measure how far it projects from the jig. I then scribe these measurements on the top of the flat side of the blade. This prevents me from having to work the angles out every time I sharpen.
With the blade at 33°, I freshen up the surface of the #800-grit waterstone by rubbing it with a similar grade stone. This makes the stone cut fast. Worn wet-and-dry sandpaper can glaze the surface of a stone so that it will not cut fast after the first few minutes.
It should take only two or three firm pull strokes to raise a wire edge on the flat side of the blade. I have a bench light set up so that I can see light reflected from the finest of wire edges. You can feel for a wire edge by gliding a fingertip off the flat side surface. It feels like a tiny hook.
The blade projection is then reset in the guide, i.e. shortened a little, to give us 35°. Now clean the wheel of the guide and the edge of the blade to avoid contaminating the superfine #8,000-grit waterstone. That surface is prepared by spraying with a plant mister, and then rubbing a Nagura over the stone to create a little slurry on its surface. A Nagura is a smaller stone that creates a mud on a polishing stone that speeds polishing and cleans the surface of the stone. Three or four pull strokes with gentle finger pressure on the blade are all we need to polish the front end of the narrow bevel created on the #800-grit stone. The #8,000-grit stone is a polishing stone and I caress its surface with the blade.
The Ruler Trick
This is the radical part! I freshen the slurry on the #8,000-grit stone with the Nagura. It’s important that the slurry isn’t too sloppy and wet. If it is wet, I sweep the water away with a finger. I then stick a 6″ inexpensive steel ruler, (about 0.5 mm thick) to the stone by sliding it to and fro a few times down one long edge of the stone.
The blade is placed in position on the stone for movement two with its edge off the stone. The middle of the blade is resting on the steel ruler. Using four fingertips, placed just behind the top of the bevel, I draw the blade’s cutting edge onto the stone. You may feel a slight catch as the wire edge meets the edge of the stone. The blade edge is only allowed to come about 5/8″ onto the stone before going back off the edge of the stone. This short stroke is repeated about 25 times for a new blade and about 12 times when re-sharpening.
Because the flat side of the blade has been raised up by a degree or so on the ruler, you will see a narrow band of mirror polish across the tip. This need be no wider than 1/16″, and will not get much wider with subsequent resharpenings. If examined closely, you should see that the mirror polish has replaced the #800-grit scratches at the edge.
I wipe the blade on a sponge cloth, dry it and apply a thin coat of Camellia oil. The job should be complete and the wire edge should have floated off on the stone, or sometimes on the sponge cloth. It should shave hairs from your hand without difficulty. PW