FAQ

You at least need one medium grit stone e.g. #1000 and #1500, and one fine stone. You also need a medium grit diamond plate for the flattening process. 

While the entire back of the chisel blades is to be flattened, only a few millimeters from the cutting edge of the plane blade is flattened.

You should grind off more at the tip of the blade than the neck of it. This means that the back side will be flattened at a slight angle. 

Uradashi is a process pushing the middle of the cutting edge of plane blades outwards. This will help you to flatten only the minimum necessary portion.

Chisel blades should be sharpened so that the cutting edge is straight or slightly concave. This is to make sure that the corners of the mortise and groove are cut cleanly. On the contrary, the corners of a plane blade must be more gently curved. This is because if the corners of a plane blade are as sharp as a chisel blade, those sharp corners will leave streaks on the surface when you plane a wide timber board. 

For both chisels and planes, it is generally said that the optimum angle is 26 to 28 degrees for relatively softwoods and 28 to 30 degrees for hardwoods. Technically, for planes, these angles vary depending on the angle at which the blade is set in the body. For a normal blade set angle (8/10 slope), the above angles will work.

Some people purposefully sharpen the bevel side of their chisels slightly round. By doing so, the sharpness lasts longer and prevents the blade from chipping.

This is the same logic as when sharpening a skinny chisel. By applying more force when you push, the bevel will become stable and flatter. As a result, burrs will be generated more quickly. 

Sharpening a small chisel like a 3mm chisel is extremely challenging because the bevel is prone to rounding. One trick is to push the chisel forwards only, as you sharpen it. No pulling action will be involved, because, in most cases, the bevel tends to be rounded when the blade is pulled.

Nagura is the name of a natural stone. Natural nagura has been used as a dressing stone but it’s got expensive due to production cuts. Then an artificial dressing stone came out. This artificial one was named “nagura” as well, because the function is the same. So, in short, my nagura is a natural stone, and your nagura is an artificial stone. 

I just checked and realised that we have many artificial nagura in different grits today! For the purpose of generating slurry, #6000-8000 is presumed to be optimal.