# should i avoid using a grinding wheel on Japanese chisels



## tobytools (9 Dec 2014)

as stated i was wondering can i sharpen japanese chisels using a grinder like a record power? i ask as i have one or two that are in a bad way, to sharpen using stones or papers put me off, i know that its soft steel laminated to white paper steel (the good stuff) but even so im curious to know has anyone used a grinding when??

ive found this.. basically say NO
http://www.fine-tools.com/G10007.htm

because of the face being hollow ground, making the bevel would seriously weaken it... 

so how would one get a perfect straight bevel on the darn thing? i have a mortice jap chisel that is to big to fit in a jig so thats out of the question so would have to be free hand if not ground on wheel..,. any advice or help would be appreciated,

ill hold off on any grinding until some sound advice is thrown my way.

thanks.
TT


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## Phil Pascoe (9 Dec 2014)

Belt sander or alox stuck on a flat disc on a lathe would do it. If badly damaged, take the worst off carefully on a wheel first.


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## David C (9 Dec 2014)

I have (carefully) ground my Japanese chisels for about 30 years. Not right to the edge.

David Charlesworth


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## tobytools (9 Dec 2014)

thanks for the alternatives phil. 
and thanks also david, i use your sharpening method currently and ill take your advice now. so i should grind almost to the edge and then use flat stones?
i have to say the bevel angles on the chisels i have are all completely different and no way near 25 0r 30.

maby the belt sander would be my best choose or would grinding new 30 degree angles on all of them be my best option. i want to get these working so i can tryout before i decide to either sell on or keep, 
ive begun to sell off the tools i don't use ect

TT


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## Vann (10 Dec 2014)

Hi Toby. I don't have any Japaneese chisels, so this is not the voice of experience...

I grind my non-Japanese chisels on an 8" bench grinder (hand powered - puff, puff), so the hollow is not as great as with a 6" wheel. Anyways, I sometimes find I completely eliminate the hollow at the next stage, on my 1200g waterstone. I don't do this on purpose, and it usually only happens on finer (less thick) chisels. But even if you heavily reduce the hollow (without eliminating it completely) you should end up with enough metal behind the cutting edge to give it enough strength.

My 2d worth...

Cheers, Vann.


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## Corneel (10 Dec 2014)

I hollow grind on 6" high speed grinder being carefull not to overheat them. They don't seem to mind at all.


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## matthewwh (10 Dec 2014)

Tempering is the process of warming hardened steel to draw out some of the hardness. On a western chisel the aim is to get it right on the balance point between hard and tough, so you get both qualities simultaneously. Once tempered, the steel can be heated to anything less than the tempering temperature without changing anything. When done intentionally, the blade is soaked at a given temperature for an hour or more to allow the changes time to occur throughout. 

The danger with grinding is causing localised damage to the heat treatment by momentarily cooking the tip of the blade. 

Japanese chisels use laminated construction to give them strength - therefore the hagane (edge steel) layer can be left harder, so logically the heat treatment may begin to be affected at a lower temperature than a western chisel - which may be the root of the advice against grinding them. 

As long as you avoid getting them warm you should be fine, the part that forms the cutting edge is directly under your fingertips, which have a much lower tolerance for heat than the steel, so if you can't feel any warmth you won't be doing any damage.

As DC suggests staying well back from the very thin section at the edge would be prudent. If the edge is very badly damaged it is safer to square it off, then take the bevel back.


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## bugbear (10 Dec 2014)

tobytools":1xyvivsx said:


> I know that its soft steel laminated to white paper steel (the good stuff)



Unless you know the particular maker's technique, all you can really say is that it's soft steel laminated to hard steel.

"White" is a particular type, but there are many others used.

BugBear


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## David C (10 Dec 2014)

For hardwoods, I would grind them all at 25 degrees and then vary the honing according to use.

Paring, coarse stone 800, 0r 1,000 grit to get a wire edge at 30 degrees, and then polish at 32 degrees. This is done by shortening Eclipse type guide projection by a couple of mm.

Chopping, coarse 33 degrees, polish 35 degrees.

There is no point in grinding right up to the edge, unless you have big chip. It just shortens the life of the tool and probably loses the squareness of the edge.

Just leave a small sliver of previous honing.

My 3 stage sharpening does not reflect Japanese tradition, but has always worked for me.

David


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## Jacob (10 Dec 2014)

belt sander (or a Sorby Proedge) runs cooler than typical bench grinder and also gives a nice flat bevel (for stronger edge) or even a rounded bevel if you want to emulate the common Japanese way if done by hand power only.


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## Phil Pascoe (10 Dec 2014)

Here we go again. I've seen loads of Japanese chisels, but I've yet to see one with a round bevel. I've not been to Japan to observe the common way, though.


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## matthewwh (10 Dec 2014)

In fairness (and before we all get carried away) if you are freehanding anything on a larger surface you have to be moving the shape of it towards convexity. 

The broad bevel of a Japanese chisel registers well on the stone, so it's reasonably easy to keep it reasonably flat, but there isn't a single variable that could lead to concavity and absolute flatness doesn't exist - so it has to be convex.


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## bugbear (10 Dec 2014)

matthewwh":3j8y2yrr said:


> In fairness (and before we all get carried away) if you are freehanding anything on a larger surface you have to be moving the shape of it towards convexity.
> 
> The broad bevel of a Japanese chisel registers well on the stone, so it's reasonably easy to keep it reasonably flat, but there isn't a single variable that could lead to concavity and absolute flatness doesn't exist - so it has to be convex.



Last time this came up, I posted, from multiple blogs, videos, websites etc, Japanese craftsman showing their very flat bevels holding the entire tool fixed to the stone by suction/capilliary attraction.

The bevel may not be "absolutely" flat, but they're flat enough 

BugBear


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## CStanford (10 Dec 2014)

I suppose one can hollow grind them but the more interesting question is why Japanese craftsmen do not. It's my understanding that most are quite adamant about a flat bevel and of course a flat back which the hollow greatly facilitates.

Are we somehow loosing some essence of these tools by hollow grinding fronts and introducing microbevels of all ilks all around?

Matthew wrote above:

"In fairness (and before we all get carried away) if you are freehanding anything on a larger surface you have to be moving the shape of it towards convexity. The broad bevel of a Japanese chisel registers well on the stone, so it's reasonably easy to keep it reasonably flat, but there isn't a single variable that could lead to concavity and absolute flatness doesn't exist - so it has to be convex.."

This is absolutely true and absolutely why "Jacob's method" works as well as any and maybe even better -- at the cutting edge the tool is no different than one honed by a master Japanese craftsman.


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## bugbear (10 Dec 2014)

CStanford":vzktncvz said:


> This is absolutely true and absolutely why "Jacob's method" works as well as any and maybe even better -- at the cutting edge the tool is no different than one honed by a master Japanese craftsman.



The Japanese craftsman's edge would be polished with circa 1 micron abrasive (8000 JIS polishing stone); Jacob's edge is 43 micron (Norton India fine), so I'm fairly sure they'd be a substantial difference. Further, the Japanese tool is harder steel, so the effect of the abrasive is reduced, leading to an even better finish for a given abrasive.

The Japanese tool also has (as you pointed out) a flat back, which Jacob doesn't really bother with.

BugBear


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## Jacob (10 Dec 2014)

phil.p":r7sxi5w6 said:


> Here we go again. I've seen loads of Japanese chisels, but I've yet to see one with a round bevel. I've not been to Japan to observe the common way, though.


I've sen a few on here and other forums with rounded bevels usually with the owner crowing on about someone having sharpened them really badly. But I've also seen videos of japs sharpening a la P Sellers (and me) i.e. with a dip.
Basically there's no reason why not. A lot of old tools are done that way - it's easier.


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## Jacob (10 Dec 2014)

bugbear":rhr187ps said:


> .......
> The Japanese tool also has (as you pointed out) a flat back, which Jacob doesn't really bother with.
> 
> BugBear


A lot of Japs don't bother either.


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## bugbear (10 Dec 2014)

Jacob":2s1lso44 said:


> But I've also seen videos of Japanese craftsmen sharpening a la P Sellers (and me) i.e. with a dip.



Link to one or two of these please?

Preferably with captions or subtitles, but whatever you've got.

BugBear


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## CStanford (10 Dec 2014)

bugbear":3cpxyzt6 said:


> CStanford":3cpxyzt6 said:
> 
> 
> > This is absolutely true and absolutely why "Jacob's method" works as well as any and maybe even better -- at the cutting edge the tool is no different than one honed by a master Japanese craftsman.
> ...



One micron, that's quaint. .05 micron polishing is where it's at. :lol: 

I think the only craftsmen honing _on one plane _ (same as 'flat?') are those who hollow grind and then hone directly on the grind polishing heel and toe with no microbevels added.


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## bugbear (10 Dec 2014)

CStanford":1sohieer said:


> I think the only craftsmen honing _on one plane _ (same as 'flat?') are those who hollow grind and then hone directly on the grind polishing heel and toe with no microbevels added.



Not so in Japan;

from a previous thread on this topic:

post788026.html?hilit=%20flat%20bevels%20stick#p788026

BugBear


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## CStanford (10 Dec 2014)

I'm with Matthew on the essential impossibility of honing flat, freehand (on a cutter not hollow ground).

I'm with Jacob in that there is a difference in 'rounding under' and everything else. I'm positive that Japanese craftsman would err on the side of rounding under, be it ever so slight, the effect at the cutting edge is entirely and exactly the same as Jacob's method. I am practically positive that the Japanese do not hone a hump into the cutter right behind the edge, nor does Jacob's method. Again, if anything, they remove an extra bit of steel right behind the edge which can only be achieved by a slight lowering of the cutter during its movement on the stone. It starts at the desired angle (which of course is the 'flat' grind in the first place) and never moves higher. There is not an attempt, conscious or otherwise, to raise the angle above that of the flat grind. Otherwise, then, they would simply be introducing a higher microbevel which they do not do. Accordingly, there are really only two options - hold it PERFECTLY at the starting angle or DIP IT - little or a lot, doesn't matter one whit at the cutting edge though the attempt is to hold it on the 'grind' angle. 

This all could easily be tested by holding a straight edge against a traditional Japanese plane iron, honed by an experienced Japanese craftsman, and viewing under relatively small magnification. The angle will be seen as highest at the edge and going lower behind it. You might find 1 out of every Xth cutter that might be considered 'perfectly' flat at that particular low magnification. The 'error' (it's really not an error just not perfectly flat which they consider the ideal) on the rest would go the other way - lower behind the edge.


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## bugbear (10 Dec 2014)

Flat stone, Flat bevel; this can't happen any other way.







(except hot glue I suppose :roll: )

BugBear

PS; There's more in the thread I linked to before.


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## Phil Pascoe (10 Dec 2014)

Jacob":mbvv3ips said:


> bugbear":mbvv3ips said:
> 
> 
> > .......
> ...



Normal sharpening would flatten it -if it isn't flattened, the cutting edge would encroach into the hollow/s and make the chisel useless.


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## matthewwh (10 Dec 2014)

I can see what you're driving at BB, but the requirement is for the two surfaces to mate perfectly - not necessarily both be flat. 

The same effect is at work with the morse taper in a drill press or lathe.

It does however demonstrate that their strokes are consistent - remarkably consistent!


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## Phil Pascoe (10 Dec 2014)

I think given the angle that iron is at across the stone it would be one almighty coincidence if they weren't flat.


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## CStanford (10 Dec 2014)

bugbear":3vngbumn said:


> Flat stone, Flat bevel; this can't happen any other way.
> 
> 
> 
> ...



This photo is not close enough nor sharp enough to prove that the bevel is being kept flat. Only a photo of a quality straight edge registered to the bevel and both under a bit of magnification would. I could take a photo of a distinctly rounded bevel on a honing stone at the same distance from camera and with the cutter positioned the same way and all would look flat.


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## CStanford (10 Dec 2014)

They either stay at the "grind" angle or a little lower, never higher. Perfection is achieved, or Jacob's method. Take your pick. There are no other possibilities for what the Japanese would consider an adequately honed plane iron. Errors are under the grind angle, not higher, and this is only an error in theory since it produces a perfectly functional cutter.

A hollow ground iron with a higher microbevel is exactly equivalent to a flat ground iron ground at the microbevel angle. The one and only error to avoid in working with a flat ground cutter is producing a hump behind the edge at a higher angle than the edge. Any errors, again, by a skilled craftsman would ALWAYS be to the low side. They have to be.


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## bugbear (10 Dec 2014)

CStanford":1owp4l8m said:


> bugbear":1owp4l8m said:
> 
> 
> > Flat stone, Flat bevel; this can't happen any other way.
> ...



The entire blade is being supported, off balance, by the capillary attraction (casually "suction") of the honing fluid.

This needs a very narrow uniform gap to work, and the gap is defined by the surfaces of the stone and bevel.

It's the fact that the blade is standing up that means the bevel is flat, not any attempted photogrammetry of the (hidden!!) bevel.

BugBear


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## Phil Pascoe (10 Dec 2014)

CStanford":3saaeg9u said:


> bugbear":3saaeg9u said:
> 
> 
> > Flat stone, Flat bevel; this can't happen any other way.
> ...



If the bevel was rounded, to "stick" to the stone it would have to be sitting in a perfectly corresponding concave across the stone at an angle, which I would have thought so unlikely as to be impossible. It's nothing to do with the accuracy of the photo.


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## CStanford (10 Dec 2014)

Matthew's example of a Morse taper applies here. 

I absolutely agree that the bevel has taken on the shape of the stone at that particular spot and that the surface tension tension or other physical property of the water is assisting the whole phenomenon and that, in the main, it's flat. For all intents and purposes that's probably as perfectly a flat cutter as can be produced in a workshop on a day in and day out basis. Were the cutter longer it probably wouldn't stand but what would we deduce from that? That it wasn't flat? I'm pretty sure that cutter would stand even if the bevel were slightly rounded under assuming the stone was of a corresponding shape (likely with a waterstone!). It's sitting in a pool of water.

I'm also positive that I have to tap pretty hard on a Morse taper drive center to get it out of the headstock. 

It's as much a matter of complimentary shapes as anything else, especially where a rapidly eroding stone is in play.


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## tobytools (10 Dec 2014)

thanks for the advice, i was just curious as no where can i find a video of a jap chisel being hollow ground but if it been done and the chisel works then ill give it a shot.
my thanks again.

cheers
TT


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## CStanford (10 Dec 2014)

To answer your question I think the concern is the uneven movement of heat through laminated steel and the changing of the physical properties of the softer steel through high-speed grinding. The Japanese put great stock in laminated steel. Western manufacturers made perfectly lovely laminated irons but quit doing so when it became cost-effective simply to make them entirely out of the 'hard stuff' in the first place. If you think that the softer steel adds something to the equation, then it might be best not to use power grinding equipment. 

IMO, there is a barely rebuttable presumption that fine Japanese tools should be used (sharpened, etc.) as they are by fine Japanese craftsmen. I don't understand the point of owning Japanese tools and then insinuating Western shop practices on tools from an entirely different tradition. Buy the whole hog, not just its squeal. You'll be happier in the long run. Pick a tradition and work in that tradition.


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## bugbear (10 Dec 2014)

CStanford":3amrwr2k said:


> Were the cutter longer it probably wouldn't stand but what would we deduce from that? That it wasn't flat? .



No; if the cutter doesn't stand, we can't infer anything. But if it _does_ stand we can infer a very close match between the shapes of the bevel and stone.

Now, even if we were to assume a hollowed stone, the craftsman would still have to seat the bevel perfectly during the whole stroke; any variation would result in the curve of the bevel being different to the curve of the stone.and the blade wouldn't stand.

So we can infer no "dipping" or "raising" has taken place.

In practise, since the Japanese are careful to flatten their stones, the only hollow will be by the amount of stone worn away during the current sharpening, which will be minimal, so the "curve" will be flat to good tolerance.

BugBear


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## CStanford (10 Dec 2014)

We'll never know for sure but I'd bet there are at least a dozen other locations on that stone where the cutter would not stand. And a long cutter wouldn't stand anywhere and it could dead flat to the last angstrom. It's meaningless, perhaps as meaningless as it standing on the spot it is. Might be flat, might not be flat.

Again, the only relevant and objective test would be registering a straight edge against the bevel and enhancing the view with a small bit of magnification, maybe a light behind the cutter, etc.

Find a photo of this and then you'd have something. All extraneous items are out of the analysis - capillary action/surface tension of water, the condition of the stone, whether or not the shop fan was running in a certain direction, the length of the cutter, etc. Too many variables!

In the end, it's all moot because it implies a level of perfection, precision, and utterly consistent workshop practice achieved by a country's entire population of craftsmen and this almost by definition cannot be the case. What is entirely relevant is that the error or 'intentional miss' as I would refer to it is rounded under. Unless you *pull the cutter exclusively* during honing (which the Japanese do not do), polishing all the way up the bevel almost guarantees that the miss will be a rounded under one anyway. You can prove it to yourself in your own shop. The 'rounded under' intentional miss is essentially baked into the process of honing the entire bevel. It's inextricable except for what otherwise on occasion amounts to a Friday afternoon diversion or parlour trick (I always wanted to spell parlor like that!). And it's doubtful such a coddled cutter works any better than a workaday cutter slightly rounded under - one that likely wouldn't stand on a freshly maintained waterstone.

Trust me, Jacob's method is more right than you think, and again something you can prove to yourself in your own shop.


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## G S Haydon (10 Dec 2014)

Getting Sharp https://www.youtube.com/watch?v=HXWkuVgiRvk

I wonder if the flattening stone will be stocked by all good tool retailers soon  

In Use https://www.youtube.com/watch?v=oYQKTUKvZ4k

In Use https://www.youtube.com/watch?v=9h4t5TMwvbo

Moral of the story, be more like the honey badger https://www.youtube.com/watch?v=4r7wHMg5Yjg


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## CStanford (10 Dec 2014)

I love his adjusting hammer...my kind of guy.....

Titemark brass plane hammer it is not. 

And I'm sure that the cinder block was poured and trued to a tool-room standard. :mrgreen:

Not to mention you can clearly see him rounding the bevel under as he moves it on the stone. =D>

As I'm sure he was taught to do!


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## G S Haydon (10 Dec 2014)

They only pick the finest cinder block but it must be followed by a rub on the pavement/sidewalk too 

I like to see a hammer used with control and skill, just 'cos it's not a nice hammer don't mean it's not going to work.


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## Jacob (10 Dec 2014)

CStanford":2nkmuhng said:


> ...
> Not to mention you can clearly see him rounding the bevel under as he moves it on the stone. =D>


You have to ask - why would anybody _not_ do a rounded (under) bevel? I've never heard a good answer to this. There isn't one.


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## Vann (10 Dec 2014)

CStanford":12zn4uze said:


> We'll never know for sure but I'd bet there are at least a dozen other locations on that stone where the cutter would not stand. And a long cutter wouldn't stand anywhere and it could dead flat to the last angstrom. It's meaningless, perhaps as meaningless as it standing on the spot it is. Might be flat, might not be flat.
> 
> Again, the only relevant and objective test would be registering a straight edge against the bevel and enhancing the view with a small bit of magnification, maybe a light behind the cutter, etc.
> 
> Find a photo of this and then you'd have something. All extraneous items are out of the analysis - capillary action/surface tension of water, the condition of the stone, whether or not the shop fan was running in a certain direction, the length of the cutter, etc. Too many variables!


I think you're just having a problem admitting that you were wrong Charles... (hammer) 

Cheers, Vann.


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## tobytools (10 Dec 2014)

wow, he is ruff with his gear, 180 plane flips and throwing his planes about no wonder he has to keep adjusting it lol.
and the hammer......

TT


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## CStanford (10 Dec 2014)

Vann":1mi3bwmm said:


> CStanford":1mi3bwmm said:
> 
> 
> > We'll never know for sure but I'd bet there are at least a dozen other locations on that stone where the cutter would not stand. And a long cutter wouldn't stand anywhere and it could dead flat to the last angstrom. It's meaningless, perhaps as meaningless as it standing on the spot it is. Might be flat, might not be flat.
> ...



I absolutely think that the photo of BugBear's shows a cutter as flat as one can get it. That said, I'd like to see a straightedge applied to one. 

Why not? What's to lose?


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## G S Haydon (10 Dec 2014)

Honey Badger don't give a s%4t! Now you know how to reduce the tools Toby, all you need is a claw hammer for everything!


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## CStanford (10 Dec 2014)

Jacob":tj0s6phv said:


> CStanford":tj0s6phv said:
> 
> 
> > ...
> ...



Agree.

There isn't a good answer because anybody doing freehand honing at all to anything other than a hollow ground tool (and maybe then, too) is rounding under to some degree.


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## CStanford (10 Dec 2014)

G S Haydon":2j40xlik said:


> They only pick the finest cinder block but it must be followed by a rub on the pavement/sidewalk too
> 
> I like to see a hammer used with control and skill, just 'cos it's not a nice hammer don't mean it's not going to work.



Funny, and words of wisdom, too.


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## James-1986 (11 Dec 2014)

I'e never experienced any problems hollow grinding chisels, I use an 8" dry grinder and used to have a 6". Grinding is a skill and it takes practice to gdo accurately without overheating the steel.

Square block cutters for spindles, moulders tenoners etc are the same setup as one of those Japanese chisels, HSS laminated on the back of soft steel. Wadkin often specified that they needed to be hollow ground, the grinding machines ran dry.


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## woodbrains (11 Dec 2014)

James-1986":2sbmf72y said:


> I'e never experienced any problems hollow grinding chisels, I use an 8" dry grinder and used to have a 6". Grinding is a skill and it takes practice to gdo accurately without overheating the steel.
> 
> Square block cutters for spindles, moulders tenoners etc are the same setup as one of those Japanese chisels, HSS laminated on the back of soft steel. Wadkin often specified that they needed to be hollow ground, the grinding machines ran dry.



Hello,

Japanese chisels and plane irons are not HSS (there are a few modern and not particularly good exceptions) and the steel is much harder and more brittle than spindle knives etc. so the comparison does not hold up. The softer back of Japanese tools is meant to support the very hard steel cutting edge and should be honed with a flat single bevel to maximise strength. Purposely making a convex edge removes too much soft steel back so is not done. A little inadvertent convexity probably won't be worth worrying about. Hollow grinding on a large diameter wheel, and a secondary honed bevel that incorporates a certain amount of supporting steel should be fine also. It is widely documented that Japanese tools are honed with single flat bevels. Discussing anything else is Western expediency, or just plain nonsense.

Mike.


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## Jacob (11 Dec 2014)

woodbrains":my69bzsn said:


> .... Purposely making a convex edge removes too much soft steel back so is not done.


Nobody suggests "purposely making a convex bevel"


> A little inadvertent convexity probably won't be worth worrying about.


Exactly - you've got it! It also makes sharpening easier and faster as you can relax and put more effort into it. 
This is why so many old (inc jap) tools have a convex bevel - old users hadn't picked up on the new sharpening obsession with flatness, which is mainly a byproduct of using jigs, and a misunderstanding of the the universal advice to avoid rounding over (rounding _under_ is fine).


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## Phil Pascoe (11 Dec 2014)

I think Mike meant "concave" and "concavity".


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## Jacob (11 Dec 2014)

I think he means convex.


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## Phil Pascoe (11 Dec 2014)

You don't remove too much steel by making it convex, you leave it there.


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## Jacob (11 Dec 2014)

phil.p":2gjo8goy said:


> You don't remove too much steel by making it convex, you leave it there.


You remove more than you would if you left it as one flat bevel, assuming the same edge angle.


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## bugbear (11 Dec 2014)

Jacob":3402pseh said:


> This is why so many old (*inc jap*) tools have a convex bevel



A repeated assertion, which I continue to believe to be false.

The Japanese, (as discussed, with evidence, in this very thread, as well as previously) want flat bevels, and
go to some lengths to achieve them. Plenty of website, blogs, videos in support. 

So I'll repeat my request for any evidence at all for your assertion that the Japanese have tools with convex bevels.

BugBear (expecting more assertions, sweeping generalisations, ad homs, and no evidence, as usual, but ever optimistic)


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## Jacob (11 Dec 2014)

bugbear":26z2dh8p said:


> ....
> So I'll repeat my request for any evidence at all for your assertion that the Japanese have tools with convex bevels.
> 
> BugBear


Have seen them, live and on forums - ISTR it was woodbloke complaining about the awful way the previous owner (jap?) had sharpened his jap chisel, some years ago. There are lots of references on the net. Do your own research!
The weird thing about this endless discussion is that no one has ever given a reason for a convex bevel being disadvantageous, likewise a reason for sticking so religiously to flat (and or hollow ground). Until they do, they have nothing interesting to say on the matter. They are just arbitrarily sticking to a rule which someone made up from thin air. I think they like rules for their own sake!

PS there was a Jap demo at one of the shows a few years back. All his chisels and planes had convex bevels. This was drawn to my attention on this forum. You should be able to find it BB!
I'm not saying they all do it - no doubt some of them take pleasure in arbitrary rules and procedures, as you do yourself BB. Others take the easy way.


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## bugbear (11 Dec 2014)

Jacob":39bba4v0 said:


> bugbear":39bba4v0 said:
> 
> 
> > ....
> ...



A Link? Book citation? Photograph? Since they're so common (*) you should easily be able to find one or two examples.

I've already shown flat ones, and the pride taken in same, and we have Odate's clear statement on the subject.

Evidence thus far presented says flat.

BugBear

(*) I don't think so


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## Phil Pascoe (11 Dec 2014)

Jacob":tcmcmvyp said:


> phil.p":tcmcmvyp said:
> 
> 
> > You don't remove too much steel by making it convex, you leave it there.
> ...


Precisely - making it concave, not convex. The OP's question was whether the concavity left from grinding on a wheel caused a problem.


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## Corneel (11 Dec 2014)

Well, I will probably go to tool hell and all that. But I tested it thourougly for you all. My Japanese chisels (Koyamachi's) don't self destruct after being ground on a high speed 6" grinder. I use them for all chopping jobs I can think of, except mortising. I keep a close watch on the temperature while grinding because these chisels are tempered at a low temperature. 

The hollow from a grinder is so small that it is very hard to imagine a negative effect.


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## Sgian Dubh (11 Dec 2014)

Over the decades I've had to regrind and sharpen quite a number of Japanese chisels, usually a tool a learner or inexperienced woodworker had damaged in some way - dropped on the floor, or being a bit hairy chested excavating a mortice, or some other such carelessness.

I've never thought too much about the method for fixing them, and sharpening. I just take (or took) the chisel and use(d) whatever is or was to hand for grinding and sharpening. I've reground on standard vertical running high speed grindstones, hand held belt sanders, linishers, coarse oilstones, a horizontal running grindstone with an oil drip, diamond plates, and so on. This is, or was, followed by honing on, again, whatever was to hand - oilstone, ceramic stone, a bit of abrasive paper, diamond stone, etc, always freehand in my case because I'm not a fan of jigs and guides. The honing angle is a touch steeper than the grinding angle. 

The result has always been a tool that cuts satisfactorily. That's all that seems to matter. It may be that over time and successive honing the honing angle merges into the grinding angle, and may even develop a convexity. It seems to me that on the whole it isn't particularly important how a keen edge is achieved. I don't think the metal in a Japanese chisel cares much one way or another any more than a western style chisel how it's sharpened. Freehand the job, jig the job, use whatever suits you, the user: in the end, sharp is sharp, although I suppose we could debate 'appropriate' sharpness. Sharp enough to do the job in hand has always been sharp enough for me. Slainte.


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## Jacob (11 Dec 2014)

phil.p":3trbjsvw said:


> Jacob":3trbjsvw said:
> 
> 
> > phil.p":3trbjsvw said:
> ...


Er, no. Could be either - leave the edge untouched but grind the bevel concave on a wheel, or ditto but grind the heel of the bevel flattish or rounded to make it a double or a convex bevel


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## Phil Pascoe (11 Dec 2014)

Struggling a bit?


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## Jacob (11 Dec 2014)

phil.p":2kke8k8v said:


> Struggling a bit


Are you? I'm not sure which bit you don't get.


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## Phil Pascoe (11 Dec 2014)

Down to misquotes now?


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## woodbrains (11 Dec 2014)

Hello,

For the same effective cutting angle, convexity must remove steel behind the cutting tip, exactly where it is required in a Japanese tool. If we are being true to the nature of the tools. Jacob's rounding under method relies on the fact, otherwise the cutting angle would increase; a condition that he denies happens in his tools. The soft backing steel is there for a purpose, so removing it defeats the object.

Hollow grinding, if one measures the angle the tool makes with the stone, also removes steel in the supporting area, though it should be noted that this will produce an angle on the tool somewhat lower than measured at the tool rest. A bit of experimentation will correct the tool angle and results in more steel in the tools bevel.

Mike


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## James-1986 (11 Dec 2014)

woodbrains":2dtup4aj said:


> Hello,
> 
> Japanese chisels and plane irons are not HSS (there are a few modern and not particularly good exceptions) and the steel is much harder and more brittle than spindle knives etc. so the comparison does not hold up. The softer back of Japanese tools is meant to support the very hard steel cutting edge and should be honed with a flat single bevel to maximise strength.
> 
> Mike.



Seems like a good comparison to me, hard metal laminated onto soft metal! Decent HSS is 60 to 65 on the rockwell scale so hardly soft, and you know when you have a hard bit as glue lines etc don't chip it. How much hardness increases as the numbers go up on that scale I don't know. I also have a big pair of blank moulder knives which are TCT laminated to tool steel which are hollow ground, harder than white steel. Its hard to say which is more brittle unless you know the exact blend.

As the tool has a bevel on the end, the softer steel is no where near the cutting edge to support it anyway. Unless we're talking about a big chunk snapping off?!


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## richarnold (11 Dec 2014)

Hi Toby.
If this helps I have been using Japanese chisels on a daily basis for over 30 years, and have always ground them (carefully) on a 6" bench grinder, and have never had any problems. I do grind all the way to the edge. One important thing for me is to be constantly dressing the grind stone. This is a great help in keeping the heat down.
Cheers, Richard.


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## woodbrains (11 Dec 2014)

James-1986":2o7az9ue said:


> Seems like a good comparison to me, hard metal laminated onto soft metal! Decent HSS is 60 to 65 on the rockwell scale so hardly soft, and you know when you have a hard bit as glue lines etc don't chip it. How much hardness increases as the numbers go up on that scale I don't know. I also have a big pair of blank moulder knives which are TCT laminated to tool steel which are hollow ground, harder than white steel. Its hard to say which is more brittle unless you know the exact blend.
> 
> As the tool has a bevel on the end, the softer steel is no where near the cutting edge to support it anyway. Unless we're talking about a big chunk snapping off?!



Hello,

There is a difference between hardness, brittleness, toughness, wear resistance etc, etc. also, HSS is resistant to losing its temper during grinding; high carbon, low alloy steels are not. There is little in common with machine knives and handtools, even grinding angles are different. Planer knives might be 35 degrees, japanese tools less than 25 . The comparison is really non existent.

Regarding the backing steel being nowhere near the edge in Japanese tools, we have to consider the ura, which makes the hard steel much thinner and needs the support of the softer backing, and the shock absorbing effect of the whole mass of the thing, which damps vibration at the tool tip preventing micro fractures that lead to edge failure. It is a complex system, that, if we choose to deviate from prescribed methods of use, can lead to disappointment, or at least a compromise should be expected. Frankly, it is no hardship,just following tradition, and preparing the bevels flat, or as close to flat as humanly possible and enjoying the tools and methods for what they are.

Mike.


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## Jacob (11 Dec 2014)

woodbrains":1tzcv456 said:


> Hello,
> 
> For the same effective cutting angle, convexity must remove steel behind the cutting tip, exactly where it is required in a Japanese tool. If we are being true to the nature of the tools. Jacob's rounding under method relies on the fact, otherwise the cutting angle would increase; a condition that he denies happens in his tools. The soft backing steel is there for a purpose, so removing it defeats the object.
> 
> ...


You don't seem to understand what I'm saying Mike. Steel is required behind the edge in any tool, not just the Japs. The slightly convex bevel which is the accidental result of my lazy but quick sharpening will remove steel from the heel of the bevel to some extent. Better than hollow ground where the tool is thinned nearer to the edge..


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## David C (11 Dec 2014)

I have never found a problem with hollow grind, Though Tormek has 10" wheel so hollow not very great.

I can't remember a faliure in use in the last 35 years

David


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## G S Haydon (11 Dec 2014)

"Hello,

There is a difference between hardness, brittleness, toughness, wear resistance etc, etc. also, HSS is resistant to losing its temper during grinding; high carbon, low alloy steels are not. There is little in common with machine knives and handtools, even grinding angles are different. Planer knives might be 35 degrees, japanese tools less than 25 . The comparison is really non existent."

but not so long ago we were discussing where we were discussing edges we said

"I still don't see why a spindle cutter will dull any differently than anything else. Perhaps a variation in degree, but a completely different mechanism altogether is not likely. Micro fractures in the grain structure of metals exist, the wood is the same, the colossal forces at the cutter tip are of similar order. Why do we feel that hand tools will behave differently? And if so, someone else prove it, I have read what I have read."

I hate to be a "tool" and mention the above but sometimes we all make this a heap more confusing than it needs to be (or quite possibly I'm to dim to keep up  ). Mike, I like your posts a lot so forgive me if this seems personal, it was just an example.

I think Richard Jones has good take on the situation and I don't think Jacob has any issue with maining angles with a rounded bevel. I'll hold my hands up and say I was less than convinced his was the most legit way but that's the problem. Thinking something has to be "legit" and relying _only_ on the text and not on experience at the coal face. Equally Mike your approach is proven and works. The only evidence required is how skilled folks get results. What we can take from this thread is that Japanese Chisels can be hollow ground, flat ground, secondary bevelled or convexed and still turn out great work!


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## CStanford (11 Dec 2014)

The more interesting question is why Japanese craftsmen are so utterly opposed to hollow grinding.

"I've done it and I don't think I broke anything...," far less interesting.

It may be that there is no *real* reason, but that in itself conveys a lot and might inform how we interpret other 'edicts' (codswallop?) from the Asian traditions.

Is it possible to demonstrate 1) a perfectly flat bevel 2) and whether it cuts better than any other kind of bevel.

I personally doubt it but have no dog in the fight, per se, since I don't own or plan to own Japanese tools in the future.


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## woodbrains (11 Dec 2014)

G S Haydon":2106l24t said:


> "Hello,
> 
> There is a difference between hardness, brittleness, toughness, wear resistance etc, etc. also, HSS is resistant to losing its temper during grinding; high carbon, low alloy steels are not. There is little in common with machine knives and handtools, even grinding angles are different. Planer knives might be 35 degrees, japanese tools less than 25 . The comparison is really non existent."
> 
> ...



Hello,

We were talking about abrasion in this instance though. And if I recall, I did not introduce the comparison between edge tools and machine knives, here, either. If I recall it was the contention someone had that machine tools somehow remove more material in a single pass (3mm is often quoted as max material removed) whereas I was proposing tht machines remove similar thickness chips to hand tools, to a thickness of 3 mm. It was also about power required to push tools compared to the power of machines. There is little context between these 2 threads, and it would get too complicated explaining the differences here. 

So now Jacob is not intentionally arm flapping to get a convex bevel anymore, but accidentally doing it whilst trying to hone a flat? His bitchin all these years about rounding under has just disappeared into the ether then! Is it because he cannot find all those rounded bevels on Japanese tools he keeps promising us exist. 

Mike.


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## G S Haydon (11 Dec 2014)

Hi Mike, you are of course right, there was an epic amount of context here and on the other thread  

I do agree with you that from what little I know it is a tradition that Japanese tools have a "flat bevel" and again with what little I know the tradition with Western is pretty much Primary & Secondary. However it's clear that a bunch of other methods work and work well including a bit of convex and they will work on both Japanese & Western tools. Folks can split hairs on best if they feel so inclined but as long as he edge is good enough for the task at hand why worry?


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## Jacob (11 Dec 2014)

woodbrains":1p67s01g said:


> ....
> So now Jacob is not intentionally arm flapping to get a convex bevel anymore, but accidentally doing it whilst trying to hone a flat? His bitchin all these years about rounding under has just disappeared into the ether then! ....


You just don't pay attention Mike. 
I've been saying over and over again right from the beginning that there is no value in a rounded bevel as such - it's just that if you don't struggle for perfect flatness you can do a relaxed and speedy form of hand sharpening which incidentally results in a rounded bevel but can be repeated indefinitely without having to reshape the bevel with grinding. Happy Christmas!


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## gwr (11 Dec 2014)

http://www.oobject.com/12-knife-bikes/a ... nder/4444/ 

Anyone of these will do the job and some even on your way to work ccasion5:


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## Derek Cohen (Perth Oz) (11 Dec 2014)

David C":2z5x8tyz said:


> I have never found a problem with hollow grind, Though Tormek has 10" wheel so hollow not very great.
> 
> I can't remember a faliure in use in the last 35 years
> 
> David



Absolutely.

The OP asks whether a Japanese laminated blade can be hollow ground ..... and we get a bunch of responses that go off on a hobby horse .... what's new?! :lol: 

The fact is that a Tormek is perfect for hollow grinding laminated blades as the hollow is shallow and the steel does not overheat. I have done this for years. As David notes, there is no weakening of the edge due to the removal of "backing" iron. I cannot recall a Japanese chisel chipping or breaking as a result of a hollow grind (which I do to the very edge of the blade). 

Keep in mind that Japanese chisels are, by the nature of use with a gennou, constantly testing the durability of a hollow grind. What they have proved for me without a shadow of doubt is the effectiveness and reliability of a hollow grind. I am not saying this to convince others that hollow is the best way to sharpen - what ever floats your boat - but it is the way for me.

Regards from Perth

Derek

Edit: Here's link to another David ... http://www.finefurnituremaker.com/news/ ... s-year-49/


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## sdjp (12 Dec 2014)

CStanford":35tt6pxj said:


> The more interesting question is why Japanese craftsmen are so utterly opposed to hollow grinding.



I don't know, but I have a theory; and it's (partly) the same reason they use waterstones, not oilstones.

Firstly, I note that the Japanese have a much stronger history of deferring to tradition then any other cultural groups. Therefore, it requires something to be 'better', to some standard, to effect a noticeable shift - and without that, there will be a strong pointer to keep doing the same. I therefore submit that a historical answer would suffice.

Japan was a metal poor country - in addition to there not being much ore, it was what would have been called 'poor quality' in other places, needing a lot of work to get a good steel. So there was a lot more labour involved in making the tools, hence expensive. Thus using a sharpening process that's slower, but less likely to damage the tool (through overheating) fits with that. Also, the tradition of using them was a bit more 'respectful' of the tools - you were really really not supposed ding the cutting edge; hence less grinding needed to keep them good.

In a counterpart to that; consider the materials that were used for sharpening. Most of the good naturally occurring stones in Japan were softer than western ones, and this leads to two separate effects. Firstly, they are faster cutting - so the point at which you'd want more mechanical assistance is larger. Secondly, these softer stones are not quite as strong - meaning that for a naturally occurring stone, you face two issues. Getting a large enough piece to make a wheel is more difficult; and they are more likely to shatter. Not necessarily a lot more likely, but I submit that it would be enough to discourage this process, relative to other places.

Therefore I would answer the question by a mixture of: More expensive tools, favouring labour over mechanical assistance; and sharpening equipment more suited to flat grinding than hollow.


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## DTR (12 Dec 2014)

sdjp":3sjadh17 said:


> ....consider the materials that were used for sharpening. Most of the good naturally occurring stones in Japan were softer than western ones, and this leads to two separate effects. *Firstly, they are faster cutting - so the point at which you'd want more mechanical assistance is larger*. Secondly, these softer stones are not quite as strong - meaning that for a naturally occurring stone, you face two issues. Getting a large enough piece to make a wheel is more difficult; and they are more likely to shatter. Not necessarily a lot more likely, but I submit that it would be enough to discourage this process, relative to other places.



I was thinking along the same lines.


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## Derek Cohen (Perth Oz) (12 Dec 2014)

I would offer another reason why a Japanese chisel is not hollow ground.

First of all it is incorrect to state that these blades are not hollow ground by the Japanese blade maker. They are ... just look at the back of the blade. In other words, the Japanese blade maker believes very strongly in hollow grinding! It is the bevel that they choose not to hollow, and probably for two reasons.

The first is that the softer backing is also intended to speed up sharpening. 

The second is that there is a value system in the way the hard cutting layer is applied, with good, better and best chisels being determined by the excellence of the steel layer. Honing a flat bevel will show this off to it best.

Regards from Perth

Derek


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## Jacob (12 Dec 2014)

The main reason for _not_ hollow grinding _thick_ blades is that it makes them effectively thinner. Whatever advantage there is in thickness is thereby reduced.
The main reason for _not_ hollow grinding _thin_ blades is that it could make them too thin with a higher risk of overheating.

The main reason _for_ hollow grinding is that it's quicker than doing it by hand, but no faster than a belt sander, which is a much better option IMHO.


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## CStanford (12 Dec 2014)

Is anybody aware of a book or article, in translation or otherwise, where a professional Japanese craftsman (not a Western hobbyist) states the case for a flat grind? This isn't to say all of you aren't probably right, but do we have anything from a horse's mouth?


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## bugbear (12 Dec 2014)

CStanford":r3c3synb said:


> Is anybody aware of a book or article, in translation or otherwise, where a professional Japanese craftsman (not a Western hobbyist) states the case for a flat grind? This isn't to say all of you aren't probably right, but do we have anything from a horse's mouth?



"Japanese Woodworking Tools: Their Tradition, Spirit and Use" Toshio Odate, already cited.

The problem is finding a Japanese Craftsman who uses English and publishes.

I've been learning directly from Japanese web pages, but Google translate
(and make my own guesses from pictures) is not a Royal Road.

BugBear


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## Jacob (12 Dec 2014)

He recommends it but doesn't really "make a case" for it as such. 
The only case to be made for it is that it's good advice for a beginner (doing it hand only), without going into complicated details.


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## woodbrains (12 Dec 2014)

Hello,

Wood craftsmen in Japan were largely things like temple builders, shoji screen makers and that ilk. All working on site with no access to mechanical grindstones. They sharpened there tools only with waterstones so hollow grinding was never going to be something done. 

Mike.


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## G S Haydon (12 Dec 2014)

I guess now we have access to grinders then it's ok to use them. A few highly experienced and skilled people use them with success anyway.


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## CStanford (12 Dec 2014)

I'm attempting to give the benefit of the doubt that there could be some actual and tangible advantage during use. All of the explanations are perfectly plausible and I tend to agree with them. Yet, I still wonder...

Otherwise one wonders, too, why wheels gave them so much heartburn. If you're building a temple by hand, you have time to transport a grinding wheel to the jobsite. The time to build a lot of those things was measured in decades I'm sure. Erecting shop fixtures, shelter for the building materials, etc. would be but a speck of time in the total time to build a Japanese temple (have you seen some of these things? they didn't go up overnight). In other words, "we don't have time, energy, manpower, etc. to move a wheel to the site" *makes virtually no sense at all*. I imagine some craftsmen lived out their entire working lives on no more than one or two projects. Think about it.

They probably built shelters in order to live at the worksite, and certainly other structures, shelters, shanties, and shacks to service the project and its materials, but no time to install a wheel? Frankly, a half dozen or more of them were probably in order.

Sump'n don't gee-haw boys and girls.

Could it be that the rotating grindstone simply never occurred to them? I'm pretty sure there's sandstone in Japan.


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## Kodama (30 Dec 2014)

Trying to add a modest point of view as it was thought to me by my teacher Kaneko-san. 
"..your stone and _bevel_ should be perfectly flat..." (I might add that perfect would be within a visible tolerance which you can see with the naked eye).

It is not always considered 'good practice' but daiku do use grinders. Being very careful not to heat up your tool a hollow is ground in the middle of the bevel. Thereby easing and speeding up the sharpening process which is done freehand. The grind marks are almost completely gone after one or two sharpening sessions.

Since freehand sharpening without a grinder is really fast and efficient a grinder is not that commonly used amongst daiku.


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## tobytools (30 Dec 2014)

I sold the chisels in question  
Im sticking to western style tools from now on apart from saws 

TT


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## CStanford (1 Jan 2015)

tobytools":4vgf3lv9 said:


> I sold the chisels in question
> Im sticking to western style tools from now on apart from saws
> 
> TT



You must not have had to sharpen (or pay to have sharpened) one of your Japanese crosscut or joinery saws yet.


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## tobytools (2 Jan 2015)

CStanford":3bh2okaz said:


> tobytools":3bh2okaz said:
> 
> 
> > I sold the chisels in question
> ...



nope 

TT


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## lurcher (2 Jan 2015)

i wonder if the japan members of there workshop forum go on about the best way to sharpen a western chisel .
myself i dont hollow grind i just use diamond stones start at the back and as i push forward [ no bevel guide] i lower my hand as i go to far end this works finr for me with chisels and planes then a good strop


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## tobytools (4 Jan 2015)

More than likely

TT


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## CStanford (4 Jan 2015)

tobytools":33a2ewra said:


> CStanford":33a2ewra said:
> 
> 
> > tobytools":33a2ewra said:
> ...



We'll be here to welcome you back into the fold when you do.


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