Chisel sharpening - difficulties

[James Pallas]

This is my experiment over the years. Jigs in general register off of the flat side of a chisel. This includes the eclipse, which is shown, and the Veritas mk2 that I also own. In doing so that is where registration is obtained. If there is a discrepancy in thickness fro the front to the back of the blade there will be a difference in how the bevel is formed. When the blade is placed on the stone and the wheel is kept tight against the stone than the bevel will be formed coplaner to the registered back. If pressure is placed at the bevel and rocked to meet the stone you have a 4 point unstable arrangement with one side of the wheel raised up. Now the bevel will not be coplaner with the back. If you now try to form a secondary bevel and press lighter, which we tend to do, the secondary will not look equal to the main bevel. It does not take much. I would have used a chisel for the demo but all of mine are freehand and would be slightly off from a jig. I hope the photos explain it some. And yes that is an original eclipse. Looks new doesn't it. It rarely gets use.
Jim

[ken hatch]

This is my experiment over the years. Jigs in general register off of the flat side of a chisel. This includes the eclipse, which is shown, and the Veritas mk2 that I also own. In doing so that is where registration is obtained. If there is a discrepancy in thickness fro the front to the back of the blade there will be a difference in how the bevel is formed. When the blade is placed on the stone and the wheel is kept tight against the stone than the bevel will be formed coplaner to the registered back. If pressure is placed at the bevel and rocked to meet the stone you have a 4 point unstable arrangement with one side of the wheel raised up. Now the bevel will not be coplaner with the back. If you now try to form a secondary bevel and press lighter, which we tend to do, the secondary will not look equal to the main bevel. It does not take much. I would have used a chisel for the demo but all of mine are freehand and would be slightly off from a jig. I hope the photos explain it some. And yes that is an original eclipse. Looks new doesn't it. It rarely gets use.
Jim

Jim,

I have one of those as well and like yours it gets little use. I keep it for nostalgia reasons but if I were to want to use a jig it would be the first I'd try. BTW, I tried the new LN Eclipse rip off and while well made (as are most things sold by LN) it was still a jig. I gave it to a friend to put in his grandson's tool chest.

ken

[Jessica de Boer]

I have been hollow grinding cheapish Iyoroi chisels for 20 years without ill effects.

I think it's fair to assume their not as hard as my oire and atsu-nomis. When you have a thin layer of steel with a hardness of 66HRc the strength is seriously compromised by hollow grinding. A large piece can even break off from one wrong blow with a mallet.

[Derek Cohen]

Jessica and Brian

Here is a photo of two hollow ground nomi ..



I've used these a decade or more and they get struck with a gennou, sometimes one that is 375gm. I have never experienced an edge chipping.

There was a time when I hollow ground Koyamaichi chisels, which were used to dovetail hard Australian timbers. They never chipped either. The only reason I stopped doing so on these chisels was to follow tradition, and not because I was concerned about the steel.

To be clear, the grinding is only done on a 10" (closer to 8 1/2" these days) wheel on a Tormek, which runs wet and cool.

Others I know who follow this method include Jim Krenov and David Charlesworth. Now I am not suggesting that everyone throw caution to the winds and hollow grind their nomi. I am suggesting that it does not look that black and white to me.

Regards from Perth

Derek

[Mike Henderson]

I grind my Japanese chisels with a 25 degree primary bevel on a WorkSharp and then put a higher angle secondary bevel. I use those chisels for a variety of tasks, including chopping waste for dovetails. No problem with the edges. They will eventually get dull but they don't dull quickly and the type of dulling is essentially the same as when I used to sharpen them with a high angle flat bevel.

Mike

[Jessica de Boer]

The only reason I stopped doing so on these chisels was to follow tradition, and not because I was concerned about the steel.

My reason is tradition as well I guess. My father was taught how to sharpen his Japanese tools by old timers in Japan. He passed it on to me and it has always worked well for me.

How hard are your chisels by the way? A lower hardness makes for a tougher chisel so that might be the reason they tolerate a hollow grind. I know from experience that a maximum hardness white steel #1 doesn't like it. I seriously damaged one of my dad's Ichihiro oire-nomis with a hollow grind when I was young and inexperienced. Your tools have no problem with it but I'm not taking any chances with mine as they are also made with maximum hardness white steel #1.

[Robert Engel]

Re: the comment about hollow grinding. No, it is not "necessary". But it helps (registers angle/decreases wedge effect/speeds up honing) "Necessary" qualified: personally I can't imagine a shop without one. What if you chip out an edge? Or want to grind a chisel or iron to a different angle?

I started out with the jigs and after trying freehand sharpening just once, I, like the others realized the learning curve is pretty low and the whole process is much quicker for me. Plus for me its quite satisfying.

[Jessica de Boer]

Re: the comment about hollow grinding. personally I can't imagine a shop without one. What if you chip out an edge? Or want to grind a chisel or iron to a different angle?

I do have Tormek but it's just for some old Stanley chisels that get used for very rough work and sometimes one of my plane blades.

[John Schtrumpf]

Re: the comment about hollow grinding. No, it is not "necessary". But it helps (registers angle/decreases wedge effect/speeds up honing) "Necessary" qualified: personally I can't imagine a shop without one. What if you chip out an edge? Or want to grind a chisel or iron to a different angle?
...

I don't have a grinder, but I do have a coarse/fine crystolon stone, as well as my water stones going down to 80 grit. For chipped edges I usually just freehand on an appropriately coarse stone. For changing bevel angles or a major camber, I usually start on the 80 grit water stone with the MkII honing guide (I have both heads and bases).

[Brian Holcombe]

Jessica and Brian

Here is a photo of two hollow ground nomi ..



I've used these a decade or more and they get struck with a gennou, sometimes one that is 375gm. I have never experienced an edge chipping.

There was a time when I hollow ground Koyamaichi chisels, which were used to dovetail hard Australian timbers. They never chipped either. The only reason I stopped doing so on these chisels was to follow tradition, and not because I was concerned about the steel.

To be clear, the grinding is only done on a 10" (closer to 8 1/2" these days) wheel on a Tormek, which runs wet and cool.

Others I know who follow this method include Jim Krenov and David Charlesworth. Now I am not suggesting that everyone throw caution to the winds and hollow grind their nomi. I am suggesting that it does not look that black and white to me.

Regards from Perth

Derek

If it works for you and the work you do, great.

I don’t do it because my chisels are general purpose and I’m sometimes cutting very fine work, other times I’m cutting light timber joints in soft and hard woods. They get a workout because deep pocket joinery pushes them much closer to the limit.

If you’re chopping out joints with those and they’re holding up, that’s impressive but if you’re using them for lighter duty work that is fine but you may want to change the bevel shape if you get into something requiring heavy chopping.

[Derek Cohen]

Brian, you may recall a review I did back in 2013 comparing 4 chisel steels (Koyamaichi white steel, Veritas PM-V11, Blue Spruce A2, and Stanley O1). There was a fifth chisel that was also in play (used to clean up when a chisel failed), a Funmatsu-Nezumi-Haisu (which is PM-HSS).

All these 1/4" and 3/4" chisels were used with a hollow grind.

The task involved chopping into the sockets of dovetails that made up the panels for a chest. The wood here was 3/4" thick Curly Marri, from Western Australia. This stuff is incredibly hard. At the time I called it "beautiful firewood". The article is here: http://www.inthewoodshop.com/ToolRev...sCompared.html

Here is the Koyamaichi ...



Here is the Funmatsu-Nezumi-Haisu ...



Here are the boards at the end of time ...




The relevant factor for this thread was that the Japanese chisels, with their laminated blades, did not show an inkling of chipping at the end of time (or at any stage of my ownership). To this day, the Funmatsu-Nezumi-Haisu continues with a hollow grind because the steel is soooo hard, that trying to sharpen a full bevel is very frustrating.

Regards from Perth

Derek

[Warren Mickley]

I wonder how one would know that a Japanese chisel that was ground on a grinder had not had its temper compromised. I believe that the tempering heat for such chisels is low enough that it does not show oxidation colors. Over heating on the grinder would cause the chisel to become tougher and less brittle.

I also wonder how much you actually use Japanese chisels. Probably not nearly as much as some other respondents to this thread. I would have guessed you used A2 or Pmv11 chisels, based on previous comments.

Marri is "incredibly hard"? I had he impression it is not even as hard as jarrah.

[Derek Cohen]

Gee Warren, compliments always.

I wonder how one would know that a Japanese chisel that was ground on a grinder had not had its temper compromised.

Did you read the part where I mentioned "use a Tormek". I very much doubt a wet grinder could affect temper.

I also wonder how much you actually use Japanese chisels. Probably not nearly as much as some other respondents to this thread. I would have guessed you used A2 or Pmv11 chisels, based on previous comments.

Warren, how about posting some of your work here? I have never seen a piece you have built. Blow us away ..

Marri is "incredibly hard"? I had he impression it is not even as hard as jarrah.

That's Jarrah with a capital.

Jarrah's Janka is 8.5Kn.

Marri's Janka is 9.0Kn

for comparison - American Oak is 6.0Kn

see: http://www.borthwick.com.au/species/hardness-rating

Regards from Perth

Derek

[Warren Mickley]

We don't actually have a species called "American Oak". I don't know what you are referring to. Just here in Pennsylvania we have 16 species of oak which vary considerably in hardness. And even within a species there is a wide range of hardness depending on environmental factors.

We do have timbers that are harder than 9.0Kn in Pennsylvania.

[Derek Cohen]

Warren, we have timbers in Oz that go to 15.0, but that is not the point. The point is that you never reply to anything I post without it being a criticism or negation. There is nothing constructive either in your comments.

Regards from Perth

Derek