Thread: Japanese waterstones

Disagreeing with someone in writing is difficult at times as it can be harder to express tone and easier to offend. I am in no way offended here, just wanted to say that so my post is taken in the tone of friendly discussion with the aim of sharing knowledge and ideas and not as a rebuke of what others have said.

I would certainly bnot class myself as an expert, in fact i have really just regurgitated what someone else has said. I do regard that someone else as an expert tho'. David Finck simply suggests that with the speed of metal removal with water stones, the intermediate steps are redundant. Once an edge has been shaped to the desired straight or slightly arced profile, sharpeing aims to refine the scratches in the metal to as small as possible within practical limitations. Someone asked where to stop, theoretically i would guess that the finest possible edge would be that obtained when the sharpening device used had a grit size as small as the smallest possible particle that could be mechanically removed. Certainly, very sharp edges still look quite rough when viewed with very powerful magnification.
From a "macroscopic" point of view a plane iron/chisel, surface ground at the factory will have quite deep scratches. When sharpeing commences, the ridges of these scratches whould form the riding surface of the iron and be in contact with the sharp points of the sharpening surface be it a stone, diamond plate or sandpaper. The effect of the sharpeing medium is to erode these deeper scratches until the depth of the scratch is equal to the average height that the sharpening particles protrude above the surface of the stone. The speed that the metal is removed is likely to be reliant on a number of factors. The sharpness and size of the particles, the pressure generated between the edge/surface and the stone, the speed at which the tool is moved in relation to the stone or vice-versa and the rate at which the particle become blunt and/or are replaced with fresh, sharp particles.
The friable bond of Japanese water stones and the high pressure genrated between a very fine edge and the stone mean that water stones are capable of removing steel very quickly.
As one moves through the grit sizes, the scratches become progressively finer until they are so fine that the light hitting them is no longer reflected all over the place within the "valleys" but of the scratches but reflected uniformly back producing a mirror effect. Moving from an 800 grit stone to a 1200 grit stone means that the depth of the scratches is reduced to the depth of the smaller 1200 grit particle size, moving to the 400 grit stone likewise further reduces the depth of the scratches until the 6000/8000/honing compound leaves the surface with very very fine scratches and the mirror surface desired.
All of these stages remove steel, they have to in order to refine the edge/surface further and produce progressively finer scratch patterns. Veritas boast and actually warn that their green compound removes metal very quickly and to be careful if using it to polish softer metals like brass. The amount of metal removed at the polishing stage may be small but it is the most important as it produces the finest scratch pattern and what we term a sharp tool.
Finck simply proposes that because of the fast cutting action of water stones and the benefits of a hollow ground bevel, one can move directly from the 800 stone to the 8000 stone as the 8000 stone cuts quickly enough to lessen the depth of the 800 grit scratches to the very fine 8000 grit scratches in very little time. Whether one has used intermediate stones is therfore irrelevant as the finer grit stones should remove all traces of the deeper scratches left by the earlier stones.
One can not skip through the grades when sanding wood because the grit particles bonded to the paper dull relatively quickly and also fall off not to be replaced. 400 sandpaper would start to erode the scratches left by 80 grit paper but would quickly clog and become blunt. If the sandpaper however had grit that was replaced as it fell off or blunted i would argue that one could jump the stages for the reaons mentioned above. Sanding wood is also a little different as the difference in abrasive particle size between the grits is much greater, it would therefore take a lot longer to erode the very deep 80 or 100 grit ridges with finer grit paper.
Finck also proposes that the lesser time spent at the stones decreases the likelihood of errors creeping into the sharpeing process, ie the bevel becoming rounded. Interestingly enough, Toshio Odate describes finishing japanese plane blades with feathering strokes which involve rolling the bevel on the finish stone to create the slightest degree of rounding!! This he states increases the strength of the final edge, perhpas an important step when dealing with the very brittle steel forming the edge of Japanese plane blades.
This dichotomy strikes me as perhaps arising from the fact that japanese water stones have been used out of their normal context in the west. I heard westerners complain that dozuki's and ryoba's are difficult to use but japanese shokunin rarely work at a bench, preferring low horses and a seated position. Likewise japanese planes are normally used on planing beams which angle downwards quite sharply. Japanese shokunin sharpen their blades with a flat bevel and view the hollow grind very undesireable. It is only recently too that the average Japanese has bcome interested in home woodworking if i am to believe what i read. Prior to this only very skilled craftsmen used these tools and they had gone through a very arduous and long apprenticship.
The Japanese shokunin also have a very unique relationship with thier tools. Not many westerners have written about the "spirit" of woodworking tools and it is considered very rude to just look into another shokunin's tool box let alone handle one of his tools. The wide range of grits available in waterstones perhaps is not a reflection of the process necessary to sharpen a blade well but a refelection on the culture and attitudes Japanese craftsmen have towards their lives and professions.

I think this has become quite a long post, but thats what happens with a little bit of encouragement!!

Happy sharpening, whatever your methods

Tim

Derek,

Thanks for the info, I was going to try a kidney stone to save a bit of money, but looks like it's off to the shop one more time! (sigh!)

Cheers,

P

Hi Tim

Thanks for continuing the debate. From my side there is absolutely no need to feel concerned that you may offend because you disagree. The only thing that is offensive is that we aren't doing this over a couple of beers. I love these discussions, which can only take place because we have differing views about some points. Frankly, most of the points you raise are my view as well. Such as the "spirit" of woodworking tools. For myself (and I know that I speak for others with similar feelings) woodworking with handtools is not just about creating objects; it is about connecting with history and revisiting and sustaining the values of a bygone era. In this regard it has a semi-spiritual nature.

I really have not read Finck, and he may have forgotten more about woodworking than I will ever learn, But there are fundamental issues here that logically I cannot accept. For example, that a 8000 waterstone can both cut aggressively and do so by minute steps. If this was so, then why do we even bother with a 1200 stone? Likewise about the Veritas green rouge. I use this a lot. Have you ever tried to sharpen a blade using it exclusively? I guess you could if you had enough time, but I really don't want to make my life's work sharpening just one blade! Polishing is different from grinding, although both involve a degree of cutting.

I guess that it is possible to go from a 800 to a 8000 waterstone if the surface area for sharpening is very small. This would necessitate that you are sharpening blades that are hollow ground. Still, you would have to do a whole lot of unnecessary sharpening with the 8000 to remove the grinds of the 800 grits. Certainly, this is not an option on Japanese blades, which must be ground flat.

I must stop at this point. Time for my medication.

Regards from Perth

Derek

Tim,

Your cogent description of the process and philosophy of sharpening coincides pretty much with my own, which is that we need only be concerned with producing a mirror finish on the flat back of the blade within a few millimetres of the edge, and on a narrow (less than 1.5 mm wide) micro-bevel. The primary bevel does not come in contact with the workpiece, so its surface can be relatively rough, and it can be produced by any method that will remove metal quickly, so long as it does not adversely affect the temper of the blade.

I find that, so long as the micro-bevel is kept narrow, its honing to a mirror finish on fine (600) and very fine (1200) diamond stones and finally on MDF charged with Veritas green honing compound is very rapid - probably not more than two or three minutes in all.

I like to keep the process of sharpening quick and simple, so I avoid Japanese waterstones, with their need to be repeatedly flattened. I confess also to lacking any spiritual affinity with my tools. Although I am in awe of the fine results that craftsmen of previous eras were able to produce with primitive tools and methods, I do not feel any obligation to keep those tools and methods alive, if more efficient modern ones exist.

Rocker

Rocker

I hope that I am not misunderstanding you, but when you say "we need only be concerned with producing a mirror finish on the flat back of the blade within a few millimetres of the edge" am I to take you literally? Are you saying that it is unnecessary to flatten the back of an entire blade, or just only flatten a tiny section, and are you referring to a chisel or are you referring to a plane blade, or both?

Butt chisels (the common work chisel) must have flat backs. They simply will not pare accurately without a flat back. This area is equivalent to the fence of a tablesaw.

While the backs of Japanese chisels have a hollow, they are still flat.

While all chisels require a flat back, not all require a flat primary bevel. Unfortunately Japanese chisels do, and the necessity of sharpening through the various grits is more of an issue here. For non-laminated blades one can reduce surface area with a hollow grind. But I don't think that this is what you are referring to.

I think that you are referring to sharpening a secondary bevel on a flat grind and treating this as if it were the main area for sharpening. In theory I do not have an issue here, but it is important to decide beforehand at what angle the primary and secondary bevels will be ground. As I'm sure you are aware, there is a difference in the slicing action produced by a steep vs shallow bevel.

I am curious what angles you use, or whether you see this to be relevant at all?

Regards from Perth

Derek

Derek,
As per rockers post above I flatten the entire back of my bevel edge chisels through to about a 2000 waterstone (Norton) and then polish the first inch of the back of the blade only – I see no point in polishing the whole back. Sure material is being removed and perhaps under a microscope the back of the blade would no longer be ‘flat’, but I find no difference in use and no one looks at my work under a microscope. As for the primary bevel I go for 25 degrees on my sandvik chisels and 30 on my ugly ones – again I only go through to the 4000 waterstone. For a polished micro bevel I use a 8000 waterstone @ 26 degrees for the sandvik’s and 31 for the others. The most important thing is I find this works for me

Best wishes,
Mark

Mark

I meant to say what I do, but forgot. With all my chisels, Japanese and Western, I flatten the backs completely. 4000 is enough. And as you do, I only maximum polish the area around the bevel, probably about 2"/50mm worth. This does not take extra effort since it is being done each time I remove the wire edge. So gradually the polished area creeps up the blade.

Sharpening a bevel is dependent on the type of blade. My run-of-the mill chisels are hollow ground at 25 degrees, my Japanese are flat ground at 30 degrees, and my Witherbys are flatground at 25 degrees. They all have a different use.

Regards from Perth

Derek

Derek,

I agree that the back of a chisel needs to be reasonably flat, but, like Eastie, I only attempt to polish the few millimetres of the back of the blade nearest to the edge. I am afraid I only have a set of six Marples blue chisels. They need fairly frequent sharpening, but they work for me.

I sharpen the blade of my Veritas #5 1/4W plane with the angles shown in the attached diagam (the back-bevel angle is exaggerated for clarity). I contend that the only parts of the blade that needs to be polished to a mirror finish are those within the critical zone. The remainder of the blade's back will be covered by the chip breaker, and the primary bevel will not come into contact with the wood being planed. The Veritas instruction book suggests that the back-bevel angle can be increased to as much as 15 degrees, but I have not done this with my blade.

Rocker

Rocker

Great graphic. I have no argument with your shapening of plane blades like this. I think that we may have been discussing things a little at cross purposes, viz plane vs chisel blades, which caused some confusion for me. I see you use a 5 degree back bevel on your Veritas. This should be a more suitable set up for hardwood than softwood. Have you used the plane on both, and what is your finding?

Regards from Perth

Derek

Derek,

No; my back-bevel is only 0.5 degrees, so I do get some tear-out when planing curly jarrah. Probably I should get a spare blade and give it a 15-degree back bevel, for use on difficult grain. The Veritas instruction book says that you can increase the back-bevel to as much as 20 degrees, which yields a cutting angle of 65 degrees; apparently this should virtually eliminate tear-out, but it significantly increases the amount of force that you need to apply to drive the plane forward.

By the way, the graphic in my previous post was done using AutoSketch, which you can get from Amazon for US$95.

Rocker

Rocker

A second blade, one back beveled, is a good idea. But I would not go greater than 10 degrees (which would give you a cutting angle of 55 degrees). A couple of years ago I built an infill plane and used a 1/8" LN blade (which would be similar to your Veritas blade) plus a thick chipbreaker and set it at 55 degrees. It has a very small mouth (.002") and produces the best finish of all my planes, including the HNT Gordons, on wild Jarrah grain. I don't use it for much else as it is only a finish smoother (and slow).

Regards from Perth

Derek

If this was so, then why do we even bother with a 1200 stone?

Hi derek,
The answer to your above question is you don't (if you're a Finckite!). I would contend that because the veritas green rouge doesn't have the unique nature of the water stones, that is, their ability to constanly expose new, sharp particles, it will not cut as fast as the 8000 grit stone and not be suitable for the final sharpening from the 800 stone.

Are the scratches left from a 800 grit stone really that deep? I guesss that's the real issue. Finck would maintain that they are not and therefore able to be refined with a 8000 grit stone immediately. Even if one were to use a 1200 grit stone, how much more does this refine the scratch pattern? The step between 800-8000 compared with 1200-8000 surely can't be too dramatically different (I guess this is why you use a 4000 stone in between!!!).

Hi Rocker, how do you produce your back bevel? David Charlseworth has described a method of using a very thin steel ruler attached to a 8000 grit stone with "suction/surface tension" which acts as a "tool rest" to enable a small flat to be mirror polished on the back of a blade. He contends that this method produces a back bevel literally too small to measure but allows him to produce the all important mirror shine where it is needed, without the difficulty of overcoming the friction/suction of polishing the entire back of a plane iron on a water stone. He never uses this methods on chisels though, describing instead a minute hollow grind lengthwise along the chisel whcih allows only the tip and base of the chisel to be polished at the 8000 grit stage (he is talking about Japanese chisels too).
I have tried the "ruler trick" as Charlseworth calls it but he maintains that it does not alter the planing action of his planes at all, as opposed to a purposeful back bevel aimed at dealing with curly grained woods.

I'm finding this discussion very interesting and quite enjoyable. If i'm ever in Pertch Derek, we will take it up over a beer!!

Cheers
Tim

Tim,

I use the same method as you for the 0.5-degree back-bevel; like you, I got it from David Charlesworth's book.

Derek,

I will take your advice and use a 10-degree back-bevel on my spare plane blade, when I get one for use on curly grain.

Rocker

Are the scratches left from a 800 grit stone really that deep? Finck would maintain that they are not ...

Tim

I cannot stop myself from responding to this question/comment, so do take my reply as one from a Devil's Advocate, just a little provocative shall we say.

It is my understanding that coarse grits are larger in diameter than fine grits. This means that they extend further in three dimensions. What you (or Finck) are suggesting is that an 800 grit (and other grits for that matter) is (are) two-dimensional, that is, it extends in the horizontal and not the vertical! This is the only way in which you cannot get a deep scratch. If so, how on Earth does the waterstone sharpen?

Of course my logic may be way out.

Regards from Perth

Derek