Just a wondering about chisels

[Ethan Liou]

Most Japanese chisels come with hollows on their back, to ease the flattening I suppose. I wonder if there has been any western style chisel that has hollows on their back, for the same purpose.

Some western handplanes have a corrugated sole. Why not "corrugated" chisels?

[Jessica Pierce-LaRose]

I've never come across one with the pronounced hollow of a Japanese chisel, (not that my experience is all encompassing by any means) although I have seen drawknives that seem to have a bit of an intentional hollow. I've certainly purposely ground out the backs of tools where it doesn't matter to performance (although again, not as pronounced as a Japanese tool) to make treating the back go quicker. Saves a lot of time, especially when you've start with a convex back. I've had a couple of old vintage chisels (marples and witherby, I believe) with the blade stamped on both sides, which has made me wonder if the chisel was heat treated before the bevel was ground, and the concave side chosen for the back after treating, but nuts if I know.

[Jim Matthews]

Are the backs of Japanese blades made this way in forging, or is it an additional machining step?

[Sam Takeuchi]

Good quality ones are scraped hollow by hand post forging.

[Aaron Rappaport]

I once corrugated the back of a beater chisel to ease the flattening of it. I used a 6" grinding wheel to make 1/4" wide grooves, which I calculated would be less than 0.0026" deep. After that, the flattening went quickly and most, but not all, of the grooves disappeared in the process, in the same way that the hollow in the back of a Japanese chisel recedes in the course of flattening it.

My grooves were probably considerably less than 0.0026" deep, because that number came from assuming that the back would be dragged straight across the rim of the grinding wheel, while I dragged the blade across the corner of the wheel, closer to parallel to the side of the wheel. I *did not* put the blade against the side of the wheel, since there are all kinds of warnings against doing that.

I'd be interested to know about others' experience with this. One question I have is whether the post-grinding flattening on a stationary abrasive brings the back's surface enough below the bottom of the grooves made by the high speed grinder to avoid any local fracturing that it causes. If you have to take an extra 0.0015" off *below* the grooves just to get to intact steel then grinding the grooves probably won't save you any time.

[Joe Bailey]

At least one manufacturer of Western style chisels has attempted to address this design aspect:

http://www.toolsforworkingwood.com/store/dept/TBBC/item/IL-100-40.XX/Mk2_Beveled_Edge_Bench_Chisels_by_Ashley_Iles

[Mike Henderson]

I was always told that the reason Japanese chisels had hollow backs was that the hard layer of steel was more difficult to work on a water stone. By putting the hollow in, you don't have to grind so much metal away to flatten the back. On Western chisels, the steel is not as hard so it's not as difficult to flatten the back of the chisel.

I've had old Western chisels that had a belly on the back and I ground a slight hollow on the back with a grinding wheel to make the back easier to flatten. Like Aaron, I found that the hollow eventually disappeared after the chisel was sharpened enough times.

Mike

[Mel Fulks]

Possible. But some things just have traditional elements that are hard to understand. Why do they use two types of planes inside the through mortises used in the temples ? Will never forget that documentary on tv about rebuilding those temples just to preserve the trade.

[Sam Takeuchi]

Possible. But some things just have traditional elements that are hard to understand. Why do they use two types of planes inside the through mortises used in the temples ? Will never forget that documentary on tv about rebuilding those temples just to preserve the trade.

Rebuild just to preserve the trade? Where did you hear that?

[Mel Fulks]

Documentary on tv,many years ago. They said they tore down the temples every 400 years rebuilt on same spot so that these tradesmen would all have a chance to work on one.The strangeness of it is why I remember it. I just watch em,I don't research them.

[Sam Takeuchi]

It's not so much about keeping the trade alive, but that's about the life span of the buildings themselves. Aside from normal wear and tear over the years, buildings go through thousands of small to large earthquakes and it becomes necessary for repair and/or rebuild in order to withstand future earthquakes and aging. There are thousands of Shinto shrines and Buddhist temples that there are always needing to be repaired and/or rebuilt. Some places go through quicker repair and rebuild cycle than others, but like I said, it's not for the sake of keeping the trade alive. Some places haven't gone through any rebuilt at all, but gone through a number of repair and reinforcement work, in some cases, contemporary temple builders are working to reverse the botchy repair and reinforcement works done a couple hundred years earlier as well.

As for keeping the trade, there are even school(s) to train temple builders, but traditional apprenticeship is still in place for this type of work. Even when people graduate from temple carpentry school, they are not going to be starting wielding a plane, chisel and saw, start like everyone else from the bottom. They may not spend 3 years scraping the bottom, but they aren't going to be automatically accepted as capable hand either.

[Mel Fulks]

Sam ,thanks for the clarification.I was reporting accurately what the documentary said,guess it won't be the first or last cultural misrepresentation .We have a Japanese neighbor who has commented to me that tv coverage of Japanese news often misses the fine points.

[Jack Curtis]

Sam ,thanks for the clarification.I was reporting accurately what the documentary said,guess it won't be the first or last cultural misrepresentation .We have a Japanese neighbor who has commented to me that tv coverage of Japanese news often misses the fine points.

And you think our tv coverage ever gets the finer points of an event here? I don't think so.

[David Barbee]

I'm not sure how to even approach this question. You can't think of japanese chisels and western chisels as being in the same classification. They may do the same job but they are a different beast all together. One is not better than the other, just very different. The only reason that japanese chisels can have the hollows in the backs is because they the bulk of the chisel is made out of a soft malleable steel. As you sharpen the chisel over and over and the chisel gets shorter, your cutting edge will get closer and closer to the hollow. At this point you must do maintenance on your chisel with a technique knows as "tapping out" the chisel. In this process you put the chisel on an anvil and "tap out" the hollow that is near the edge. Basically you remove the hollow from the back of the chisel a little at a time. If you can't remove the hollow, as would be the case in a western chisel, you would effectively ruin the chisel because you could only use a small part of the chisel for a cutting edge.

That being said some manufacturers will introduce a very tiny hollow to the back of their western chisels. This tiny hollow will be removed by lapping the back of the blade during sharpening. This greatly reduces the amount of lapping you have to do.

David B.

[Jim Koepke]

At this point you must do maintenance on your chisel with a technique knows as "tapping out" the chisel. In this process you put the chisel on an anvil and "tap out" the hollow that is near the edge.

To me, this seems confusing. How do you "tap out" hardened steel without it cracking?

jtk

[Christian Castillo]

Hi Jim, I don't know where you got that quote, but chisels aren't tapped out, you just put a bit more pressure at the edge of the tool and with a few swipes on some 220 grit paper, the land comes back in less than 1 minute, and you're fine again for another half decade. I have heard of some people tap out chisels, but this is normally done on chisels that are 1 1/2" to 2" or larger in size. Tapping out is done on plane blades because for a japanese plane, the blade is the wedge itself, and lapping the back would ruin the fine fit, so you avoid lapping the back again. You bend the edge of the blade downard by striking the soft layer of laminated iron, which distributes the force of your blows to the point where they can bend the hardened steel slightly. I've done this on a vintage laminated western tapered plane blade and it worked the same way, you never strike the hardened steel itself.

I'd like to add to what Mike Henderson said about the purpose for the hollow, when I took a class from Jay Van Arsdale, that was part of the reason, the other reason being that with such a small amount of land at the edge, honing off a burr is much quicker since in essence, you are only really honing the edge of the tool. Japanese carpenters purposely only tap out their plane blades to restore the most minimal amount of land rather than bring back a lot and be done with it for a while. When one has but a glimmer of steel land, its like working with a back bevel in the speed to hone a burr off.

[Stuart Tierney]

Hi Ethan,

The back hollow in Japanese chisels is to ease sharpening, and by extension flattening of the blade's back.

Traditionally forged chisels out of 'the West' would often be made to a general shape and the fellow on the grinder doing the final shaping would see where the natural 'bow' of the blade was, and make the concave side the back, the convex side they'd grind the bevel edges on to. It was inevitable that the chisel would take a curve of some kind during the process, so they simply went with the flow to make sure that the side that was going to make up the cutting edge would be able to be sharpened right up to that edge, to heck with the rest of the back.

Over time, the back should become flat but it's not that essential.

That's as I heard it anyway.

Regarding Japanese chisels, the hollow in the back is usually ground in between laminating/forging to shape and heat treat. It may well be that some are actually scraped in by hand, but I've never heard of it or seen it done. I have seen and heard that most chisels (and plane blades) have the hollow ground into them, and I hear that information from the folks who make the tools. Usually it's a quick job done when the rest of the chisel is being ground to it's overall shape, and after heat treat it's 'buffed' in the case of a bright finish hollow, left as is when a black back hollow is desired. The black finish is a combination of forging scale, burned oil and residue from the miso/mud mixture used when the chisels are hardened. This mixture the blades are coated with minimizes de-carburization and I believe thermal shock, and occasionally you'll see little specks of 'brown stuff' in the tight corners of chisels, and that's what it is.

Not every chisel goes through all of that though.

In other matters, I've never tapped out a chisel, and never expect to need to. If I did need to and some folks I know heard about it, I'd be in trouble. As in 'hand in the cookie jar' trouble, not 'cuffed and thrown in a car with party lights blazing' trouble.

Building temples and shrines is, as Sam rightly says, a continuing process. They're built to 'ride out' an earthquake, not be a solid mass and tough it out. As such, they need maintenance and they get it as often as they need it. There is one shrine, Ise shrine in Mie prefecture, is completely rebuilt every 20 years whether it needs it or not. It's a very important and sacred shrine, so it gets the rebuild every 20 years so it's never in a state of disrepair, it's always in very good condition. There may be others that get frequent, scheduled repair and rebuild, but Ise is the most famous and is always rebuilt every 20 years. Most other shrines and temples get done as they need it, usually repair and replacing damaged timbers, but occasionally a complete rebuild and usually to the same specifications/design as the original, only getting larger or smaller as the times of the day decide is appropriate.

A true 'temple builder' is a rare fellow. They are not a 'Jack of all trades' they are a 'Master of all trades', and not everyone who takes up the profession can be a master at everything. Someone may be the most amazing craftsman imaginable, but if they can't also read drawings, draw plans, get the whole building in their head and make it all work together, organize a working crew and a bunch of other details all by themselves, they'll often be a helping hand, not the boss. Age has little bearing on who is top dog, ability is everything and occasionally familial ties will also decide who gets the label 'temple builder' or not. I've met several builders ranging from late 20's who've just started to late 60's and 70's, and some of them have only just recently graduated to running their own crew as well. Often, the best jobs will be gifted to those who earned their stripes young and have several years of experience, just so the job is guaranteed to be done right, but often it'll be the 'next in line' that actually does these jobs, with the boss overseeing. Often that 'next in line' will earn their own stripes on such a job as the bigger, more difficult jobs are a real test of how well someone gets the job done. If they pass, they can do anything. If they fail, they may never get another chance.

I don't claim to know everything about Japanese tools, temple building or anything like that, but I do live here in Japan, I do talk to tool makers quite often and pretty much all of them know me by sight, even if they've never met me. I also ask the questions that very few folks actually ask of them, simply because while I might already know the correct answer, I need to hear it from them directly for those times where 'the truth' comes into question. It often takes more time and trouble to explain why I need to hear the answer to a simple, silly question than to ask the simple, silly question and get an answer to it.

(And some of the questions I ask, let's just say few folks ask them because they've never thought to ask them...)

I hope that helps,

Stu.

[David Barbee]

To me, this seems confusing. How do you "tap out" hardened steel without it cracking?

jtk

Perhaps a video would help? I'm no expert on this process but I have seen it demonstrated.

http://www.youtube.com/watch?v=-NG8Wz6Wk54

David B.

[Stuart Tierney]

Perhaps a video would help? I'm no expert on this process but I have seen it demonstrated.

http://www.youtube.com/watch?v=-NG8Wz6Wk54

David B.


Oh.

My.

God.



Stu.

[Steve Friedman]

The only thing I know about tapping out Japanese blades is from watching Wilbur Pan's video on it

http://giantcypress.net/tagged/sharpening/page/2

Compared to the guy in the you tube video, Wilbur seems to be using a might lighter touch. Just my observation.

Steve

[Jack Curtis]

... As you sharpen the chisel over and over and the chisel gets shorter, your cutting edge will get closer and closer to the hollow. At this point you must do maintenance on your chisel with a technique knows as "tapping out" the chisel. In this process you put the chisel on an anvil and "tap out" the hollow that is near the edge. Basically you remove the hollow from the back of the chisel a little at a time. If you can't remove the hollow, as would be the case in a western chisel, you would effectively ruin the chisel because you could only use a small part of the chisel for a cutting edge....

Tapping out is seldom done on chisels, only the huge ones now and then. What I do is lap the back lightly every time I sharpen. What this does is make the chisel just a bit less thick from the back, which in turn reveals more of the hard steel that makes up the slope of the hollow. Thus the steel edges are maintained.

[Jim Koepke]

Christian,

Thanks for the explanation. My chisels seem to be doing what I ask of them when I keep them sharp. Most likely will not try others unless they are at a garage sale.

jtk

[David Weaver]

Oh.

My.

God.



Stu.


Oh my! Notice that tapping out on that chisel has created another problem - the edge of the chisel is not touching the flat stone, and now the whole operation needs to be lapped anyway so that the black marks on the stone extend to the edge.

Will give the guy props for one thing - he's just about consumed an entire stone. That'll never happen to me.

The tutorials I've seen about tapping out blades say stuff like "5000 light taps". Fortunately, I haven't ever had to even lap a chisel, just the initial metal should last a long time unless someone is abusive with work or overzealous about how far down they go in grits to start.

[Andrew Pitonyak]

Sam ,thanks for the clarification.I was reporting accurately what the documentary said,guess it won't be the first or last cultural misrepresentation .We have a Japanese neighbor who has commented to me that tv coverage of Japanese news often misses the fine points.

I would say that the News in general usually misses the fine points :D

[David Weaver]

I would say that the News in general usually misses the fine points :D

We're lucky if all they do is make up the fine points (but leave the general news story at the core), or tweak them a little to make them sound more interesting.