Hollow grinding japanese chisels

[Edwin Santos]

It has been my workflow to hollow grind western chisels and then freehand hone them. Freehand honing a hollow bevel is fast, accurate and easy.

I recently acquired some japanese chisels and have been advised not to hollow grind them. Any other opinions on this? What are the reasons for the advice, and what am I risking by hollow grinding?

Does the no-hollow grind advice apply even if the grinder is a Tormek, which is a large diameter wheel (thus a shallower hollow)? Plus the Tormek is as gentle as a grinder can be due to the slow speed and the water.

If I must stay with a flat bevel, I just see it taking more time than my usual routine, and possibly more reliance on a honing jig.

Thanks,
Edwin

[Howard Pollack]

My understanding is that Krenov used to hollow grind his Japanese chisels. I've tried it on occasion and have found no bad results, but people do warn against it.
-Howard

[brian zawatsky]

Hollow grinding isn't necessary on a japanese chisel because of the laminated construction. The majority of the steel in the tool is very soft and abrades quickly. Only the bottom lamination (~2mm thick or so) is hardened, so honing a flat bevel is not a time consuming process. In fact, the jigane (japanese name for the soft iron or steel backing) is so soft that you need to be careful not to lay the angle of the bevel back too far when setting up the chisels. Keep your finger pressure right at the cutting edge, but be sure the whole bevel is touching the stone. One of the really nice things about Japanese chisels is that microbevels are totally unnecessary so the honing jig stays in the drawer where it belongs lol

Since these are your first nomi, I would recommend using your jig to do the initial flattening and trueing of the bevels, and then work on your freehand honing once you know you have a flat true bevel to use as a reference point. This cut the learning curve way down for me.

Here is a good video for your reference: https://youtu.be/MhgzGI4vlkY

In the video, he flattens the back using a kanaban (steel plate) but I use a 1k grit synthetic stone. The Shapton pro stones are hard enough to use for flattening since they don't wear hollow as fast as some of the softer synthetics. Hope this helped

Oh yeah, almost forgot. As far as the time factor, once the chisels are set up properly sharpening is quick. It takes me 3 or 4 minutes to go from 1k (if needed) to a final polish that you can shave with.

[Robert Hazelwood]

I suspect you will be ok to hollow grind. None of the die hard J-tool aficionados seem to recommend it, but there are several western woodworkers I can think of who do it. The biggest danger in grinding would be overheating, they are more sensitive than the typical western blade in this respect, but you should be fine with the water cooled tormek.

However, you may just be creating extra work. If the edge geometry on your chisels is good and does not need major correction, just sharpen them (freehand). Keep the pressure on the cutting edge, just on the verge of tipping it, to avoid removing more steel from the soft part and lowering the angle over time (eventually causing the steel to chip in use). They do not take long to sharpen if there is no major damage to remove. If you need to change the bevel angle or remove a chip, then work it over on the tormek and then return to freehand maintenance. That's what I'd do anyways.

[david charlesworth]

I have used Tormek hollow grind for many years with no ill effects.

Best wishes,
David

[brian zawatsky]

While I’m sure a Tormek would do no harm to a Japanese chisel, I just don’t see the value in it. Allow me to elucidate.

I like Japanese nomi for 3 main reasons: 1 - The steel. Well-tempered white steel is super hard and fine grained so it is capable of taking and holding a very keen edge, which brings me to, 2 - The cut quality. That very hard, very keen edge is a joy to use, they will leave end grain glassy and do it for quite some time between sharpenings. 3 - Aesthetics. I find a high quality, well executed nomi to be a thing of beauty. The appearance of a fine polish on a laminated blade is a magnificent thing that will surely be misunderstood by the uninitiated. On a more practical note, I feel that a highly polished flat bevel reduces resistance while the edge is engaged in the cut.
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You wont get a polish like that with a hollow grind off of a tormek ;)

[Andrew Hughes]

That’s looks great Brian. I also don’t hollow grind my Japanese chisels. They sharpen so fast it just seems like a waste of expensive steel.

[Brian Holcombe]

Neatly done, Brian!

Edwin, don’t grind them. Develop a reliance upon yourself to set the angle and maintain it, it’s a worthwhile pursuit.

[Patrick McCarthy]

Brian Z, you have done well on your trip down that rabbit hole. Very nicely done.

Patrick, just starting to go down the rabbit hole. . . . . .

[Warren Mickley]

"On a more practical note, I feel that a highly polished flat bevel reduces resistance while the edge is engaged in the cut."

A chisel is not just a cutting edge, it is also a wedge. It pushes material aside as it penetrates. Both concave and convex bevels make for poor wedging action. One who has never used this type of chisel might not notice this.

[brian zawatsky]

Brian Z, you have done well on your trip down that rabbit hole. Very nicely done.

Patrick, just starting to go down the rabbit hole. . . . . .

It’s deep, VERY deep. And I keep wandering further in. Just ordered my first kanna yesterday...

[Derek Cohen]

As David notes, one can hollow grind (some) laminated blades (only on a Tormek, however). I have done this on Iyoroi, which are beaters for me ...

http://www.inthewoodshop.com/Furniture/FittingTheLidHinges_html_2c4e8a78.jpg

.. as is a Fujikawa, which is PM HSS (really, really hard and tough!). The reason for this is that the hollow simply speeds up honing. Removing the soft cast iron supporting steel does not weaken the edge in any way. I have never experienced any chipping. It is just faster since balancing the bevel is easier than keeping it flat.

https://i.postimg.cc/7Y3fMDh4/Fujikawa.jpg

On the other hand, my Kiyohesa and Koyomaichi chisels are all honed on the flat. I take the time to do this, and I respect the traditional honing methods here.

https://i.postimg.cc/pTwv9w7J/8.jpg

Regards from Perth

Derek

[Nicholas Lawrence]

What do people use to sharpen Japanese chisels? Not the HSS stuff, but the regular white or blue steel versions. Will an Arkansas stone work, or do you need something fancier?

[Robert Hazelwood]

What do people use to sharpen Japanese chisels? Not the HSS stuff, but the regular white or blue steel versions. Will an Arkansas stone work, or do you need something fancier?

People will generally say you cannot use arkansas stones, but I have been using them on J-tools for a couple of years and I think they work fine. I have shaptons, but without a sink in the shop it's more of a hassle to use them than the oilstones.

My tools are mostly white #2. I use a fine india to raise a burr, then soft ark, and finally a translucent. I get a good hazy mirror polish with a nice distinction between hard and soft steel, and the process goes quickly. Edge quality and edge retention seem very good.

I don't have experience sharpening the extremely hard white #1 tools, so can't say about those. I imagine they will go a little slower but produce an even better polish.

The blue steels have more wear resistance so should be tougher to sharpen, but I have a blue #2 gyuto (chef's knife) that comes up very nicely on the arks. Blue #1 or Super Blue might be pushing it, but I can't say.

[Brian Holcombe]

.. as is a Fujikawa, which is PM HSS (really, really hard and tough!). The reason for this is that the hollow simply speeds up honing. Removing the soft cast iron supporting steel does not weaken the edge in any way. I have never experienced any chipping. It is just faster since balancing the bevel is easier than keeping it flat.


There is absolutely a risk that you will damage the chisel with the higher hardness white and swedish steels.

[Edwin Santos]

There is absolutely a risk that you will damage the chisel with the higher hardness white and swedish steels.

Hi Brian, could you be more specific? What kind of damage could occur by doing this on a Tormek wet grinder?

The various expert opinions here have convinced me to hone my japanese chisels by hand with a flat bevel, but I ask the question anyway out of sheer curiosity.
I believe my chisels are made from white#1 steel and I also have some made from blue steel. Thanks

[Brian Holcombe]

Basically one need separate the possibilities of damage in preparation from those of damage in use caused by the type of preparation. Super hard steels need support, if you take away their support than they run the risk of damage by absolute failure.

Damage in preparation can be mitigated by a wet grinder.

Damage in use cannot, the edge needs support as intended so that it won't be destroyed when you use it to the fullest capability of the chisel.

[Charles Guest]

Presumably one is missing the point when hollow grinding a tool that has traditionally been flat ground. If you want to use Western methods of tool preparation, then buy Western tools in the first place.

[Derek Cohen]

I will say again that one can hollow grind a Japanese chisel. I have done this for many years, and David Charlesworth has done this for a lot longer. Jim Krenov was another, by the way. However - and this is relevant - David and I have only ever used a water-cooled Tormek, Jim used a hand driven grinder, and in my case I have named the brand (Iyoroi), which is not one of the extremely hard steels mentioned by Brian. These chisels have not shown any edge weakness as a result of being hollow ground.

I am also not recommending that others should hollow grind their Japanese blades. I have a few Iyoroi, which I consider to be my beater chisels. Being “beaters” does not mean that they are abused, just that they are used outside the workshop, such as carpentry type tasks. They are hollow ground out of expediency. My good Japanese chisels are treated with reverence, and honed on the flat. I love the way this looks.

Regards from Perth

Derek

[Warren Mickley]

I will say again that one can hollow grind a Japanese chisel. I have done this for many years, and David Charlesworth has done this for a lot longer. .

Derek, it seems like just earlier this year you and David Charlesworth were singing the praises of A2 chisels. Was I fooled into thinking that what you actually use are A2 or PM VII chisels? Was David's A2 post just some sort of infomercial? Do you really use Japanese chisels in some significant way?

https://sawmillcreek.org/showthread.php?272154-There-s-nothing-wrong-with-A2&p=2900678&highlight=#post2900678

[Derek Cohen]

Warren, you add a little ... I would not say that I "sang the praise of A2" - I said that I did not find them the bogey man that many claim them to be. They sharpen up and work well enough for most users. In terms of steel and edge-holding, I have demonstrated (http://www.inthewoodshop.com/ToolReviews/FourChiselSteelsCompared.html) that they are better than O1 but far behind White Steel and PM-V11.

Do I use Japanese chisels? How rude you are. Do you actually do woodwork? I can show that I have been using Koyamaichi chisels for nearly 2 decades. I think that I have had my Kiyohisa slicks for about a decade. My builds show their use over the years. Can you say the same?


Regards from Perth

Derek

[Charles Guest]

To the extent that hollow grinding a laminated chisel thins the softer steel behind the cutting edge then have not the desired characteristics of the chisel been compromised? It may make no difference in light paring, but certainly might if using a mallet or even the heel of one's hand.

[Derek Cohen]

Charles, I assume that you are speculating.


This was from an article on my website on morticing a hinge ...


http://www.inthewoodshop.com/Furniture/FittingTheLidHinges_html_4a16ab6.jpg


Start by chopping 45-degree kerfs into the mortice. These kerfs will extend about half the depth, and stop about 2-3mm from the inside boundary line.


http://www.inthewoodshop.com/Furniture/FittingTheLidHinges_html_m566623e0.jpg


Use the wide chisel to pare away the waste. Stop short of the inside boundary.


http://www.inthewoodshop.com/Furniture/FittingTheLidHinges_html_m538653e7.jpg

Link: http://www.inthewoodshop.com/Furniture/FittingTheLidHinges.html

I have used these Iyoroi this way for many years.


Regards from Perth

Derek

[Charles Guest]

Though I own none, if I did, I'd rather defer to how expert Japanese craftsmen set up their meticulously crafted chisels. I think they deserve the benefit of the doubt, your very fine photos notwithstanding.

A flat ground Western chisel, un-laminated, is certainly nothing to sneeze at either especially with a grind of no more than 25* and hopefully a little less. Hollow grinding is a lovely expedient, but certainly not an absolute necessity, regardless of what tradition one chooses to follow.

[Doug Dawson]

Though I own none, if I did, I'd rather defer to how expert Japanese craftsmen set up their meticulously crafted chisels. I think they deserve the benefit of the doubt, your very fine photos notwithstanding.

A flat ground Western chisel, un-laminated, is certainly nothing to sneeze at either especially with a grind of no more than 25* and hopefully a little less. Hollow grinding is a lovely expedient, but certainly not an absolute necessity, regardless of what tradition one chooses to follow.

If a chisel can't handle the _very_ slight hollow grind from a Tormek T8, then it's not a very good chisel.

Too delicate to live, etc.

[Edwin Santos]

Presumably one is missing the point when hollow grinding a tool that has traditionally been flat ground. If you want to use Western methods of tool preparation, then buy Western tools in the first place.

Snarky response from one who admittedly owns no Japanese chisels.

[Edwin Santos]

Thanks for the responses and valuable perspective from several experienced Japanese tool users!

Looking forward to putting the new chisels to work and getting familiar with them. Cheers
Edwin

[Stewie Simpson]

Snarky response from one who admittedly owns no Japanese chisels.

Edwin; I also don't own any Japanese Chisels, but that doesn't impede my ability to read advise that warns against the use of hollow grinds on Japanese Chisels.

regards Stewie;

https://www.hidatool.com/image/data/pdf/Sharpening%20Japanese%20Chisels.pdf

[Derek Cohen]

Stewie, you and some others are reading what you want to see ... not what is actually written. The Hida article clearly states that one should not grind on a dry grinder because of the heat. And I would agree with this.

To repeat, my comment, along with that of Doug (above), made reference to the hollow created on a wet Tormek (with a 10” wheel), which is both cool and shallow. All this hollow does is remove enough cast iron to jig the bevel and reduce this area. It does not affect the hard cutting edge. I do not recommend dry grinding. Read that article again.

Regards from Perth

Derek

[Stewie Simpson]

Stewie, you and some others are reading what you want to see ... not what is actually written. The Hida article clearly states that one should not grind on a dry grinder because of the heat. And I would agree with this.

To repeat, my comment, along with that of Doug (above), made reference to the hollow created on a wet Tormek (with a 10” wheel), which is both cool and shallow. All this hollow does is remove enough cast iron to jig the bevel and reduce this area. It does not affect the hard cutting edge. I do not recommend dry grinding. Read that article again.

Regards from Perth

Derek

Derek; you warn "against reading what we want to see" and yet you chose to ignore the fact that the article by Hilda also covers the use of wet grinders,.

regards;

[Pete Taran]

I think Doug Nailed it. To show how preposterous the notion that any chisel is too fragile to tolerate a hollow grind from a 10" wheel, check out the drawing I just made in Aspire. 10" diameter wheel with a 25 degree chisel placed so the heel and cutting edge of the chisel just touch the wheel. The measured distance of the crescent shape which represents the hollow grind? .009"! If a chisel is so fragile that it can't handle a .009" divot, it best be relegated to opening paint cans and scraping dandelions from between the sidewalk cracks.

I don't own any Japanese Chisels, but as fate would have it, I am talking to Stan the Man Covington, now in permanent SMC exile, about getting some. I only intend to use my Tormek for sharpening them. When all this comes to pass, I will report back on the deleterious effects of the .009" hollow grind on their ability to stay in one piece through normal use.

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[Edwin Santos]

Presumably one is missing the point when hollow grinding a tool that has traditionally been flat ground. If you want to use Western methods of tool preparation, then buy Western tools in the first place.


Edwin; I also don't own any Japanese Chisels, but that doesn't impede my ability to read advise that warns against the use of hollow grinds on Japanese Chisels.

regards Stewie;

https://www.hidatool.com/image/data/pdf/Sharpening%20Japanese%20Chisels.pdf

Stewie,
I took issue with the second part of his comment which I thought was uncalled for. Read my original post. It's not that I want to use "Western methods of tool preparation". I simply wanted someone to explain to me why a Tormek hollow grind would be ill advised.

I can understand and appreciate tradition, and tools as art. But at the same time, we all find ourselves fighting the clock some days. The Tormek is fast and safe and I own one, so if I'm under time pressure, I wanted to know why I can't turn to it. I have a set of Shapton water stones and a Japanese polishing stone. Setting aside honoring the blacksmith and tradition for tradition's sake, I have not found a faster way than a hollow bevel to hone an edge and get back to work. This said, I'm not insisting on using it on the Japanese chisels, and this is why I don't need to be admonished that I should have bought western chisels in the first place. For some of us, learning involves asking questions.

Edwin

[Brian Holcombe]

My first concern is to honor the maker. The person making my chisels has honed his craft for over fifty years, I want to show that I respect that by preparing them in a way befitting the product of his experience to the best of my abilities. These makers are not simply working off tradition, they’re scientific in their approach to creating their end product and they want a flat bevel so I respect that. Who am I to dismiss the care they have taken to ensure I have a professional quality tool?

Second, it is a weaker edge so why would I chose to use it for a tool which will be stressed? I don’t know what normal use is, but I know well when I’m approaching the extremes as I have taken lesser chisels to failure.

I’ve shared my experience and expressed my opinion and concerns.

[Edwin Santos]

I think Doug Nailed it. To show how preposterous the notion that any chisel is too fragile to tolerate a hollow grind from a 10" wheel, check out the drawing I just made in Aspire. 10" diameter wheel with a 25 degree chisel placed so the heel and cutting edge of the chisel just touch the wheel. The measured distance of the crescent shape which represents the hollow grind? .009"! If a chisel is so fragile that it can't handle a .009" divot, it best be relegated to opening paint cans and scraping dandelions from between the sidewalk cracks.

I don't own any Japanese Chisels, but as fate would have it, I am talking to Stan the Man Covington, now in permanent SMC exile, about getting some. I only intend to use my Tormek for sharpening them. When all this comes to pass, I will report back on the deleterious effects of the .009" hollow grind on their ability to stay in one piece through normal use.

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I could make a case that the hollow is even less significant that your excellent illustration. Most would come off the Tormek and finish hone on finer stones. This process will create a very small flat bevel at the cutting edge and the heel both. This will change the geometry such that the hollow bevel would become even less significant. Maybe .008 or .007?

And of course, re-honing the small flat bevel is very fast, and with successive honings, it will become larger and larger until the hollow is gone and the chisel is effectively back to a flat bevel. When I was trained (admittedly not on Japanese chisels), this would be the point where we would go back to the grinder and create a fresh hollow and start the cycle again.

[Jim Koepke]

This has been an interesting discussion which has very little connection to my way of keeping my chisels sharp.

It is clearly true about being easier to freehand sharpen a hollow ground blade. Though to do so it requires one to have a grinding wheel to create a hollow grind.

One of my favorite chisels, a Karpenter 1" socket chisel came to me with a hollow grind. It hasn't required any power grinding since it arrived. After years of use, any remnants of the hollow grinding have been honed away.

It just seems funny of the contrast between a chisel from the land of hollow grind has a flat bevel and there is a discussion of the merits or sacrilege of a hollow grind on a chisel from the land of flat bevels.

Sharpening discussions are the political discussions of woodworking.

jtk

[Graham Haydon]

Slightly off on a tangent. I personally don't find a hollow gring "jigs" itself very well. I find it easier to give a slight lift and create a secondary bevel. Unless the edge to be worked is thick and or wide, maintaining a full bevel does not take very long.

[Jim Koepke]

Slightly off on a tangent. I personally don't find a hollow gring "jigs" itself very well. I find it easier to give a slight lift and create a secondary bevel. Unless the edge to be worked is thick and or wide, maintaining a full bevel does not take very long.

In my experience, without using a secondary bevel, maintaining a full flat bevel doesn't take very long.

jtk

[Mel Fulks]

Brian, you do great work with wood. But you would have not been successful in slapstick movies. " These pies were made
for eating, not for throwing in faces to get a laugh", would have quickly branded you as "difficult "

[Graham Haydon]

Agree, Jim. Not sure I did a good job of explaining it. For 25mm wide chisels and narrower along with bailey irons I do the whole bevel. On wider chisels and traditional western irons I tend to go for a secondary. I do not own or use Japanese chisels so can't comment. I would defer to the traditional approach if using them.

[Brian Holcombe]

Brian, you do great work with wood. But you would have not been successful in slapstick movies. " These pies were made
for eating, not for throwing in faces to get a laugh", would have quickly branded you as "difficult "

Guilty, :D.

[Charles Guest]

I am admittedly a poor spokesman for the few thousand year old tradition of Japanese tool set up. But do I, or anybody else for that matter, need to be a spokesman for it or simply an observer of it to be convinced there's something to it? That one has yet to personally run across the "there's something to it" part is essentially meaningless is it not? Maybe when some utterly stupendous Japanese master craftsman comes out and says it's all essentially a bunch of hooey, then maybe that would be an answer.

Food for thought perhaps.

I went through my "Japanese Period" and did so probably before a lot of you were born. I've owned Japanese chisels. I just honed them on the flat, like they arrived. No big deal. I never gave doing anything else a moment's thought.