The mirror edge - is it necessary?

[Chris Fournier]

The sharper the better. I don't take my blades past 8000 but I do make sure that the blades are done well at 8000. It is far easier to get a blade to this state and then maintain it as required than it is to run a blade ragged and then have to start fresh. You may get away with "not to polished" blades but as soon as you are working very hard or cranky wood you will regret it. Sharpening does not take much time at all if you get your process tuned and efficient.

[Bob Strawn]

I use a hard surface leather strop with 0.25-0 micron diamond grit. I use soft, even pressure with the flat or bevel flat against the strop. I do not angle the blade. This means that the dubbing is kept at a minimum. The diamond grit makes a misty finish.

As I was evolving my methods, I made the critical decision to try and keep my plane blades with one bevel, so I could use the bevel as a reference. I also decided to go with constant sharpness. For a chisel this means I lightly stroke the chisel a few passes every couple of dovetails. No biggie, and overall less time spent sharpening and less wear on the chisel. For planes this meant that I had to remove the plane blade the moment I noticed a change in performance. As a result, I got a lot of practice tapping the blade into position on a woody. Once I got that down, planes with adjusters became way too much work to put up with. Planes with adjusters, at least in my hands, take longer to adjust and much more time to remove the blade and then return the blade to position.

Over time I have noticed that a good plane blade, kept sharp, seems to get better and better at staying sharp. My theory is that the surface work hardens. When you grind or even hone away the surface, you lose the packed steel surface and loosen the carbides. When you use a strop regularly, even though you are being ever so gentle on your strokes, you are pressing in the fine edge, refining it and making it denser. The micro dubbing that is caused by gentle flat stropping, also makes for a stronger edge.

A mirror polish, does seem to be better on some of my blades. I prefer a mirror polish on M2. For O1, misty might have the edge.

Bob