Replacement Plane Irons.

[Jacob]

That convexity is so small compared to a flat bevel it probably makes very little difference strenght wise, imho.

It's a lot better than hollow ground (weakest) and depending on how convex it is, it approaches flat (strongest).

 

[David C]

The joiners are at it again.

Ludicrous miss information.

Toshio Odates book "The surface from the cutting edge to the top of the bevel must be perfectly flat. (This is particularly important for chisels.....)".
This is a direct quote from a man who did a traditional apprenticeship in Japan.

Why dont you guys stick to what you know about instead of misleading the greater public?

David Charlesworth

 

[Jacob]

The joiners are at it again.

Ludicrous miss information.

Toshio Odates book "The surface from the cutting edge to the top of the bevel must be perfectly flat. (This is particularly important for chisels.....)".
This is a direct quote from a man who did a traditional apprenticeship in Japan.

......

Does he say why? If he (or anybody else) can't come up with a good reason then it has to be dismissed as one of those funny little woodwork myths.
Also it seems to be widely accepted in the west that chisels should have two bevels. Can't both be right?
Another lot say hollow ground plus micro bevel. Are they right too?
I'm quite happy with the compromise position i.e. a convex bevel. Neatly in between, and also makes sharpening easier.

If you google "japanese convex bevels" or variations thereon, all sorts of interesting stuff comes up. You may be surprised!

 

[GazPal]

The joiners are at it again.

Ludicrous miss information.

Toshio Odates book "The surface from the cutting edge to the top of the bevel must be perfectly flat. (This is particularly important for chisels.....)".
This is a direct quote from a man who did a traditional apprenticeship in Japan.

Why dont you guys stick to what you know about instead of misleading the greater public?

David Charlesworth

Joiner? You're sadly miss-informed on that score David, as I'm a cabinetmaker by trade, although there's certainly no shame in being a joiner/carpenter and I was more than capable of shifting between cabinetmaking, carpentry, joinery and luthiery before retirement following the onset of Rheumatoid Arthritis. I happen to know more than a little about Japanese smithing and - although I don't profess expert status - I do know enough to hopefully pass on and help others. The source of my information is via Japanese craftsmen such as Takaiwa Setsuo, Shinozaki Masanori, Ogawa Kanekuni and Fujishiro Okisato, among others and primarily following quite a number of years communication with the above artisans. Although primarily Togi and smiths many old timers carried precisely the same skills across to tool manufacture during the post WWII ban on gendai-to ownership and manufacture between 1945 - 1953.

The surface between hardened edge (yakiba) of hard steel (kawagane) and rear of ground bevel (shinogi) in the soft - low carbon - steel (shingane) can be flat or possess a slightly convex cross-sectional radius, but the additonal mass afforded by a curved surface helps reinforce the cutting edge - as mentioned in an earlier post. It's a method also employed in the crafting of Japanese knives which are sharpened using a single bevel.

 

[woodbrains]

The surface between hardened edge (yakiba) of hard steel (kawagane) and rear of ground bevel (shinogi) in the soft - low carbon - steel (shingane) can be flat or possess a slightly convex cross-sectional radius, but the additonal mass afforded by a curved surface helps reinforce the cutting edge - as mentioned in an earlier post. It's a method also employed in the crafting of Japanese knives which are sharpened using a single bevel.

Hi,

There it is again; additional mass afforded by a curved surface? Is there heck! A curved surface has less metal behind the cutting edge than a flat surface, where the honing angle is the same. think about it!

Also, Japanese smiths did not fully finish their tools. they do not dictate how the craftsman fettles it, fitting the handle, mushrooming on the hoop, flattening the back or honing. This is down to the craftsmen themselves.You might as well ask farriers how to race a horse at the Grand National. Spurious, bringing smiths into it. All the info i have ever read, training I have had, has all stated that Japanese chisels and plane irons are sharpened with a flat bevel, giving maximum strength to the hard steel edge. There is an almost religious discipline involved in doing so, the stiving of perfection.

Odate is one of the few living Craftsmen, who was apprenticed in the traditional Japanese way. I really think we should pay him the repect he deserves.

People who 'round under' their bevels don't do it because it gives a better result, let us face it, I'm rather sick of them saying it does. They do it because it is easier than trying to hone a flat. It requires less skill. It is that simple. It may work for them, I don't know, but it cannot be said to be better. It does not provide a stronger edge as steel must be removed in the area that would be flat, if the bevel was kept flat, so it is weaker. It is also slower to do, as metal is only removed at the point of tangency that is in contact with the stone at any one time. A flat is always in contact with the stone, so metal is continuously being removed during each stroke. There is no advantage of curved bevels, only expediency and any that offer advice to others as this being the way to do it should qualify their statement to this effect.


There are certain contributers here who, in recent posts, have alluded that Alan Peters, James Krenov and Toshio Odate do not know what they are talking about. In this thread, even David Charlesworth's comments have been dismissed as incorrect. I suggest these people stop railling against the wealth of hard earned wisdom that has generously been shown them and, frankly, get real.

Mike.

 

[Jacob]

.........
People who 'round under' their bevels don't do it because it gives a better result, let us face it,

True. Not "better" but quicker and easier.

I'm rather sick of them saying it does.

They don't. I think you have read something into it which isn't there

They do it because it is easier than trying to hone a flat. It requires less skill. It is that simple.

Exactly. It's easier. You've got it. Glad you pointed that out - this is why it's good for beginners especially. IMHO of course!

It may work for them, I don't know, but it cannot be said to be better.

It does work (we aren't insane) . Nobody says it produces a better edge. It produces a good as any other freehand method edge, but the main argument is, as you say, that it is easier

It does not provide a stronger edge as steel must be removed in the area that would be flat, if the bevel was kept flat, so it is weaker. It is also slower to do, as metal is only removed at the point of tangency that is in contact with the stone at any one time.A flat is always in contact with the stone, so metal is continuously being removed during each stroke.

No that's a bit specious. It's quicker because you can put more effort into it as after the intitial 30º start you dip the handle and there is no need to be careful and/or accurate

There is no advantage of curved bevels, only expediency

Expediency, yes - you've got it!

and any that offer advice to others as this being the way to do it should qualify their statement to this effect.

I think I have done so over the years. No claims that it produces a better edge - just that it is expedient, quick, easy etc. "Practical", in a word.

are certain contributers here who, in recent posts, have alluded that Alan Peters, James Krenov and Toshio Odate do not know what they are talking about. In this thread, even David Charlesworth's comments have been dismissed as incorrect. I suggest these people stop railling against the wealth of hard earned wisdom that has generously been shown them and, frankly, get real.

Mike.

Generously? I had to buy the books! It's not free you know!
I am sure they certainly do know what they are talking about but there is a regrettable tendency to treat many of these "authorities" as infallible gurus. Even Krenov himself was anxious to distance himself from that - if you read that long interview on the net wherever it is. They are all fallible human beings, just like me and you.

 

[jorgoz]

Jacob, I googled japanese convex bevels as you suggested and first thing that i noticed was that there are more threads from foodies (knife enthusiasts) than there are from woodworkers. The results from woodworkers where more guessing at the flat/convex issue.

With knives it's a kind of a given that they would sharpen with convex bevels as it is nion impossible to sharpen with a flat bevel due to the thinness of the material and the length of those thin blades. We woodworkers have thicker material to work with. Chisels or thick plane irons jig themselves out, but it takes more concentration and muscle control to sharpen to a flat bevel. This for me is a valid reason to sharpen to a flat bevel, which i do, as it tilts the woodworking experience into another level. Muscle memory, the training of the muscles to act in a particular way and over time it becomes natural, which is an experience you loose in the convex bevel sharpening way.

Flat or convex are both valid ways to have your bevels. Concave is a general no-no in the knife world, except for boning knives. Concave is an easier way to sharpen chisels/plane blades that's for sure, and if that's how a lot of people want to sharpen, then so be it. The results are very sharp edges that might be a bit more fragile, but we are talking a couple of percent imo and in a practical sense for me this becomes a non-issue. We're working wood, not putting space rockets together. It's starting to get to academic for me.

David C, do you think if Toshio Odate apprenticed with a master craftsman who would have sharpened with to a convex bevel, we would be talking differently when it comes to Japanese woodworking tools ? It's only one man, a major figure who brought Japanese woodworking tools to the West certainly, but still only one man, who by the way i have a lot of respect for. Mesirow/Herman in "the care and use of japanese woodworking tools" even talk about power grinding japanese kanna blades which is probably a good way to weaken a japanese blade. To little good English literature about japanese ww tools imo.

The convex bevel in some instances gives to many variables, less control over the mater in hand. For example. You own a BU plane, right ? When trying to tame gnarly crossgrained wood, i think it would be better to know what angle your actual cutting angle is. With flat or concave bevels it's easily controllable and you can continue to increase the angle until you get a clean cut with the least amount of tear-out. With the convex not so, you're more guessing what your actual cutting angle is and every time you resharpen, this angle will vary. Not by a large amount but still it will vary and you loose an amount of control.

I've got some wood to work so i'll be signing of here.

 

[GazPal]

Hi,

There it is again; additional mass afforded by a curved surface? Is there heck! A curved surface has less metal behind the cutting edge than a flat surface, where the honing angle is the same. think about it!

Also, Japanese smiths did not fully finish their tools. they do not dictate how the craftsman fettles it, fitting the handle, mushrooming on the hoop, flattening the back or honing. This is down to the craftsmen themselves.You might as well ask farriers how to race a horse at the Grand National. Spurious, bringing smiths into it. All the info i have ever read, training I have had, has all stated that Japanese chisels and plane irons are sharpened with a flat bevel, giving maximum strength to the hard steel edge. There is an almost religious discipline involved in doing so, the stiving of perfection.

Odate is one of the few living Craftsmen, who was apprenticed in the traditional Japanese way. I really think we should pay him the repect he deserves.

People who 'round under' their bevels don't do it because it gives a better result, let us face it, I'm rather sick of them saying it does. They do it because it is easier than trying to hone a flat. It requires less skill. It is that simple. It may work for them, I don't know, but it cannot be said to be better. It does not provide a stronger edge as steel must be removed in the area that would be flat, if the bevel was kept flat, so it is weaker. It is also slower to do, as metal is only removed at the point of tangency that is in contact with the stone at any one time. A flat is always in contact with the stone, so metal is continuously being removed during each stroke. There is no advantage of curved bevels, only expediency and any that offer advice to others as this being the way to do it should qualify their statement to this effect.


There are certain contributers here who, in recent posts, have alluded that Alan Peters, James Krenov and Toshio Odate do not know what they are talking about. In this thread, even David Charlesworth's comments have been dismissed as incorrect. I suggest these people stop railling against the wealth of hard earned wisdom that has generously been shown them and, frankly, get real.

Mike.

I suggest you re-assess your comments assuming a supposed lack of informed knowledge on the basis that someone has not written/had a book published, nor sought public recognition for what has been a life long vocation as a craftsman. As far as I am aware, all of the Japanese craftsmen I referenced are still alive and kicking, but let's not try and delude ourselves that certain Japanese smiths solely produce swords, knives, or chisel and plane blades/irons. Some do, but this is not the case with the majority.

Concerning your assertion regarding lack of mass within a convex bevel. Grind angle is typically flat and mass behind the cutting edge would certainly be lost if it were made convex whilst maintaining the same primary and secondary bevel angles, BUT this differs to a convex edge geometry where the entire grind is convex by nature and singular/without the use of primary and secondary bevels. The convex arc itself reinforces the edge and mass can be reduced without loss of strength/resilience. Think in terms of mortise chisels and how their normal convex grind provides a stronger/longer lasting edge than if a flat grind were adopted and a secondary bevel employed. Yes, honing angles differ to those used with paring and normal bench chisels (Bevel edged & firmer), but the same convex bevel approach can be taken with all types to effectively create similar strengthening results.

One point of fact omitted previously is that I - and those I've trained over the past 30 plus years - typically employ a flat grind on all blades barring mortise chisels. I do on occasion employ hollow grind if the mood takes me and prefer this approach in terms of paring chisels. Such sharpening preferences don't prevent me from employing convex grinds, nor do they lead me to rubbish the preferences of others. To each his/her own and if it works well, use it, but let's try not to get tied up in my dad's bigger than your dad types of debate. There's no true right or wrong answer.

 

[David C]

Gaz Pal,

Apologies for the error. I have great respect for all the skilled trades.

Your views on the bevel shape of Japanese chisels are most interesting. I have never seen a convex bevel referred to in the little literature I have been able to find. The craftsmen I have encountered all use a flat bevel.

Can you suggest any documentary support for the convex bevel in Japanese tradition?

(It might be worth mentioning that all the "flat" bevels I have seen, are in fact minutely convex, but this is due to the difficulty of maintaining an exact angle by hand).

David Charlesworth

 

[Jacob]

......
(It might be worth mentioning that all the "flat" bevels I have seen, are in fact minutely convex, but this is due to the difficulty of maintaining an exact angle by hand).

David Charlesworth

Exactly.

Apparently (I wasn't there) there was a Japanese demo at a show last year where you were in attendance too David, you may recall.
Several people noted the convex bevels on his chisels! (I am told)
Did you go over to him and point out the error of his ways, by any chance!

I think it's time this argument ceased and everybody accepted that convex bevels are perfectly OK if done properly.

 

[GazPal]

Gaz Pal,

Apologies for the error. I have great respect for all the skilled trades.

Your views on the bevel shape of Japanese chisels are most interesting. I have never seen a convex bevel referred to in the little literature I have been able to find. The craftsmen I have encountered all use a flat bevel.

Can you suggest any documentary support for the convex bevel in Japanese tradition?

(It might be worth mentioning that all the "flat" bevels I have seen, are in fact minutely convex, but this is due to the difficulty of maintaining an exact angle by hand).

David Charlesworth

Never a problem David. By the way my first name's Gary. There is a genuine dearth of translated literature on Japanese smithing and tool sharpening technique (Crafts in general) in spite of quite a diverse quantity in existence, but yet to be translated and published for our benefit. I'll have a rummage around for the literature I do have containing information on the use of convex bevels behind cutting edges and should be able to provide ISBN numbers, etc., but much of what is available is subject to the translation skills employed via the publishers.

The most common and readily sourced information can be found in literature concerning the traditional crafting of Japanese weaponry, i.e., "The Craft of the Japanese Sword" Leon & Hiroko Kapp & Yoshindo Yoshihara, ISBN 0-87011-798-X

The nature of the convexity mentioned is minute, bordering upon flat/a level plain and Japanese craftsmen tend to say it is flat, but the nature of the lamination process (Eastern, Middle Eastern and Western methods) tends to benefit from a little additional support directly behind an open leading/cutting edge. Another example of how convex support for the edge metal can be found if studying other forms of laminated cutting tools, the most common being tools such as scythe and masonry chisels. I've a few examples among my father's selection of masonry carving chisels and there may even be an old laminated scythe blade in one of the old outbuildings.

 

[cutting42]

I think it's time this argument ceased and everybody accepted that convex bevels are perfectly OK if done properly.

Oh, please!!!!!!

How about you accepting that flat bevels and secondary bevels are perfectly OK if done properly?

 

[Jacob]

I think it's time this argument ceased and everybody accepted that convex bevels are perfectly OK if done properly.

Oh, please!!!!!!

How about you accepting that flat bevels and secondary bevels are perfectly OK if done properly?

Oo pleese!!!!
I always have. Take my post only yesterday (7 up from here): "No one claims that it produces a better edge - just that it is expedient, quick, easy etc. "Practical", in a word."

 

[cutting42]

I think it's time this argument ceased and everybody accepted that convex bevels are perfectly OK if done properly.

Oh, please!!!!!!

How about you accepting that flat bevels and secondary bevels are perfectly OK if done properly?

Oo pleese!!!!
I always have. Take my post only yesterday (7 up from here): "No one claims that it produces a better edge - just that it is expedient, quick, easy etc. "Practical", in a word."

But it has to be said you are very keen on reducing anyone who does it a different way to the status of time waster, silly person or just wrong. As I have mentioned before.................
.............
..
actually I can't be bothered any more, I give up, go ahead on your mission to convert the world and good luck to you.