should new chisel edges be square?

[Paul D]

I have just received a set of 5 new Kumagoro Oire Nomi chisels which look good quality except that the edges are not perpendicular to the sides - typically they are 1 - 2 degrees off square. the suppliers promptly sent me a new set which are the same as the ones I sent back - they are unable to tell me if this is normal for Japanese chisels so the question is should I crack on and get them honed and polished or is this degree of 'skew' unacceptable?

any advice before the 10 day deadline for returning them much appreciated

Paul (Lancaster UK)

[wilburpan]

If you are talking about the angle of the side wall relative to the back of the chisel, typically they are tipped in by a degree or two. This prevents binding if you are using the chisel to lever out a chip.

If you are talking about the angle of the cutting edge relative to the sides, that should be square, but that's something I would just take care of myself, as I would sharpen a new chisel myself before using.

[yojimbo]

I agree completely. I sometimes find new nomi to be off, and just square them up on the first polish and honing.

[Paul D]

I'm talking about the angle of the cutting edge in relation to the sides

thanks both for the quick replies twill get the waterstones out!

Paul

[Sheets]

Believe it or not - you should be at least thankful that they come with an edge (although these days, most tools do. But I found some of mine to be a little off as well). Sometimes, you get brand new tools without a sharp edge, just the initial bevel angle established. Imagine having to remove about 1 mm of depth just to make a rough-ground edge and then have to complete each tool with medium and fine stones (times the number of tools in the set). Same for new kanna (its no fun having to remove the same 1 mm of depth across a 65 or 70 mm edge, believe me):(. You may have read previous threads lamenting the slow progress when trying to remove lots of metal.
If you ever chip an edge (my guess is you probably will - no reflection on your skills or abilities, its just inevitable) you will have the pleasure of removing enough metal (maybe a lot) to make the chip disappear.:oo: It will make straightening a crooked edge seem not so bad.
Anyway, welcome to the forum.

Steve

p.s., you can gradually even out the edges over a couple or more sharpening sessions with larger chisels. It can be tiring doing a lot of sharpening at one time when there are lots of stones to go through or much metal to be removed. Sharpening when tired is not recommended:no: as inattention can be both dangerous and provide inferior results.

[Paul D]

Hi Steve

thanks for the advice

these are my first new chisels since I started out with a couple of Stanley 5002s 15 years ago. Everything else has been second hand and has generally been put to a 240grit waterstone to get a rough straight edge before working up through honing and polishing stones. I bought these on recommendation as I'm doing more woodwork now so I think I'll do one at at time starting with the small ones! Having sorted the backs out would you start with a 1200 grit or take off the edge with a 240 first to straighten out the edges?

thanks

Paul

[Sheets]

Paul,

As far as a starting grit goes, its up to you. Certainly, with small chisels 1.5,3, 6 mm), 1200 will be fine as there isn't that much metal to remove. You would save a step not starting with a coarser stone, but you can. With the larger sizes, its a trade-off between more work on the 1200 and skip the coarse, vice a bit faster starting with the coarse and having to add in the medium (although it doesn't take much time on a 1200 to remove the 240 marks). You could try starting on the 1200 and see how its going speed-wise and go back to the 240 if it seems too slow.

Or - you could do like I do - use the chisels as they are and then deal with straightening the edges at the same time you're removing the chips:D

Steve

[yojimbo]

Hi, Paul (and you other reprobates),

Welcome aboard (I forgot to say last time).

I know it's considered sacrilege, but when I receive a tool with blunt edges, I use a Jet waterstone sharpening wheel. Clearly, you don't want a hollow grind, so I use the side of the wheel, which is quite flat, or otherwise can be trued with little trouble.

This is especially helpful when you have to sharpen a whole new set.

The key is to be really careful of your angle: it's (to me, at least) a little weird to work on the vertical, and finding whether you have to skew the blade this way or that to get the smoothest finish possible.

As a rule, I'm a purist. Would much rather do it by hand. But I also often just don't have time or energy to put in so many hours of work starting on a kanna or nomi blade -- or worse, a whole set of them -- that have arrived blunt.

You should definitely hear what the others have to say on this, too -- they may well blast me off the forum for suggesting such a callous approach...:o

I'm not saying it's the ideal approach, Paul, just that in a jam, you can get good enough quick results to move on to the medium grit stone with a fair edge.

Good luck!
Becky

[Sheets]

Hi Becky,

Well, why not? So long as you are careful not to overheat the edge, I suppose any method is valid. Me, I'm too cheap (maybe stubborn, too, but not a purist thing) to spend money on a machine when I have the stones and the time. Certainly, for those of you who need to make a living using your craftspersonship, saving time is usually a higher priority.

Also, I (we) know there are some out there who have no qualms at all about hollow grinding and micro/secondary, etc. bevels, so whatever works is up to them. (although, I object when I hear somebody - I recently read an article - who uses Japanese tools and sharpens them with Arkansas oil stones - talk about wasted potential:()

I believe (just my opinion - no proof or basis in fact) that tools that come with a skewed edge are done on a machine anyway. I can't imagine a living human spending the time to sharpen edges by hand and accepting (or the boss who's paying them) anything but perfectly square. Machines save time and labour, and if a side effect is a slightly off square edge, well the end result is a more economical price. I doubt that expensive tools would ever be sold this way, as one of the reasons they are expensive is they are sharpened by human hand (which is costly). Tools which are sold with dull edges (the purchaser is expected to sharpen them) are slightly less expensive because of this fact. Again, this is all conjecture on my part.

Steve

Freedom to create
Is impossible for those
Who slave to the way

[NeilS]

Clearly, you don't want a hollow grind....

Becky - do you say that for aesthetic or technical reasons?

Neil

[yojimbo]

Hi, Steve and Neil,

First:
So long as you are careful not to overheat the edge, I suppose any method is valid. That's why I like the Jet -- it's cheaper than Tormek, and is also water-cooled.

Neil -- I shouldn't have said "clearly" -- that was pedantic of me. While I'll sometimes use a hollow grind, and always a micro-bevel, on Western tools, I much prefer to keep J tools flat. I find that if you take the time to sharpen and hone with waterstones, they'll hold an edge pretty much forever. As I noted in another thread recently, I worked not too long ago with a timber nomi, carving a large piece of Matsu. That nomi held its edge for two solid days of pounding, with barely any honing (on a strop with green rouge) needed. It was amazing. So I don't see the need to use either a hollow grind or a micro-bevel.

Just me, y'know. My "clearly" was totally out of place.

I've read some posts by woodworkers (possibly here, but maybe elsewhere -- can't remember) who complain that they have to resharpen too often, and so they use coarse stones or grinders to restore a good edge. I generally find that if you take the time to work the metal on a kanna or nomi thoroughly through medium and fine grits, working out all the scratch marks at each stage, and doing so long enough that the (natural) stone material compresses itself into a finer and finer grit, the time spent is far less than doing a quick sharpen and then having to resharpen often.

This, then, is the main reason I prefer the flat bevel.

Hope I've been lucid -- a little short on sleep...

Becky

[Studley 2436]

There is no problem grinding Japanese Tools on a bench grinder. Just don't overheat them or you can muck up the temper of the steel. With Plane Blades they have a hollow in the back you will have noticed if you have one.

Guess how they put that in there? They use a really big grinding wheel and just grind it out. It is all productivity and if you can't belt the work through your shop you are in trouble.

I did notice references to micro bevels. This is a popular technique with Western Blades. The Western Blades are made from different steel to the Japanese ones. When you sharpen a big problem due in large part to the blade being hard all the way across is that you get a bit of rolling as you sharpen and so put a shoulder on the blade. Effectively a blunt blade. So to get around this raise it up and put a tiny micro bevel on it. This means the bevel goes all the way to the edge.

Back on Japanese blades the back is soft. If you just keep the weight of your hand on the edge you are trying to sharpen the soft stuff on the back will look after itself. Of course holding the lot on the stone while just trying to keep the weight on the sharp edge makes it very easy to sharpen by hand.

Hollow grinding is no issue. Grind the blade ready for the stone and stone it off sharp. If there is a good edge and some hollow left it is no issue. As you sharpen the hollow will disappear.

If your blades are chipping consider the angle of your bevel. A really small sharp angle will expose a lot of the hard brittle steel without the support of the soft steel. This makes it very easy to chip. Remember that Western Blades include stuff like Chrome and Nickel that gives them good toughness. Angles that might seem just fine based on western blades may not be very good on Japanese Blades.

Studley

[NeilS]

Becky, Steve, Studley, et al

OK, we are on the same page on this one. Power grind if you need to remove large quantities of metal but do so carefully to avoid de-tempering and de-laminating the blade... another recent thread on this board (What do you use for removing a lot of metal? (http://www.woodworkforums.ubeaut.com.au/showthread.php?t=78512)) also covered that topic. Also worth mentioning, while on the topic, the slower surface speed of a belt sander is less inclined to 'burn' the cutting steel and maintains a relatively flat bevel.

Otherwise, the combined thin hard cutting edge layer + soft backing layer(s) of Japanese blades don't need hollow grinding and micro bevels for regular sharpening the way solid steel Western blades do. Although, I have read that master sharpeners in Japan will give a top class kanna finishing blade a one stroke 'micro-micro' bevel.

Having said that, an aesthetic has developed around the Japanese blade due, in part, to its flat bevel, with high class blades giving some attention to the soft layer/s which is/are polished as part of the sharpening process. Such things as the Jihada (http://www.nihontoantiques.com/jigane_and_jihada.htm)/Jigane (http://www.nihontocraft.com/japanese_sword_terms.html)grain in the soft layer/s and mokume-gane (http://en.wikipedia.org/wiki/Mokume-gane)(damascus style lamination) are admired and appreciated. Hollow grinding would obliterate some/much of that detail.

Anyway, that is why I asked Becky if it was for technical or aesthetic reasons that you wouldn't hollow grind Japanese blades.

Neil

[yojimbo]

All well said, Neil. Though I've never tried the sander... kinda makes my teeth hurt to think about it...

Also might mention the beautiful haze created by natural waterstones, which I believe is called kasumi. Man-made stones will give you a spectacular mirror finish, but I have to say, I prefer the cloud-like haze from natural stones.

Anyone want to discuss uradashi as a footnote to Studley's post? Anyone with more experience than mine? (Uradashi, for the uninitiated, is the method of hammering down the back hollow so that it again meets the blade, once the blade has been sharpened past the first border of the ura/back hollow of the blade.)

And -- slightly off-thread here -- anyone have a technique for cutting down large waterstones that won't kill either the stone or every saw blade you own? Bought a gigantic zebra stone, and need to cut it into more economical pieces so I'm not always removing more stone than I need to in order to flatten it. Wore one saw (a fairly solid but inexpensive one) down to little bitty nubby teeth...

Sorry for the tangential query, but... well, I'm here, so I thought I'd ask...

Thanks, folks.
Becky

[Sheets]

Hi Neil,

I won't hollow grind a laminated blade because I feel you weaken the tool (there is less metal behind the edge) and its ugly and it does obscure the hada (I do like to "see" the ji-gane - and its not so much a function of a "high class" tool, its just the steels used by the blacksmith to make up the ji-gane, sometimes there is a contrast which is visible, other times not). Again, I know people do it and don't seem to have a problem. Its not so much about right and wrong ways to do things, just different strokes for different folks.

I wonder when the "masters" add there one-stroke micro bevel? I doubt it is when the blade comes off the finishing stone (but I don't know that), but rather at some point after using the blade awhile when they are able to sense the change in cutting ability and know such a technique will be of benefit vice going back to the stones. I know Odate, for one, is opposed to the concept of a micro bevel.

Steve

I just read Beck's reply, so will add some comments in here.

Uradashi - I'm no pro, but have done it against a block of wood with good results. Others preach using a metal backing, but again - more than one way to hammer your back (or shoulder?). Key point is to be accurate with your hammer taps.

As to the big stone, my suggestion would be to use a tile/ceramic type blade (one which can be used dry - less complicated unless you have the proper watering system with the saw) in a table saw or skill saw. Failing that, maybe a hacksaw with a supply of cheap blades.

[Studley 2436]

Becky if you want to cut up a stone I would use an abrasive cutter like a Brick Saw.

Best idea might be to find a stone mason who does stuff like headstones and ask them to do it for you.

As far as beating the blades out get a decent hammer and a heavy block of wood if you don't have an anvil and beat away. Be really carefull to keep the hammer on the soft steel. Tough the hard stuff and it will chip straight off. That is pretty much it. I do mine with the edge of the blade over the side so it is unsupported and start back from the bevel and really hook into it. If you have a decent blade that isn't far from where you want it skip this bit. Because I got a big bundle of blades from Japan that were much loved and unloved by the tradies that had them there were blades I have had to be really agricultural on.

When the blade is close-ish then go to work beating on the bevel behind the hard steel. Start in the middle and work your way out. You can work in just one spot if it needs more than the rest.

Something I do to help me see where I am is just give it a lick on a rough stone. I have a silicone carbide stone (oil stone) that I use for this. The box it came in said oil stone but I just use water with it. This rough stone is valueable to get the blade around abouts when you sharpen before going onto the finer stones.

Something that wasn't mentioned is about grinders. There are many wheels available. They all have an operating speed. A grain size, grain hardness, bond, and bond hardness too. The wrong wheel will burn your chisels straight away. The right one will just grind and grind with no problem. Grinder wheels are often sold with the presumption that people are going to cut mild steel and then grind the ends off as weld prep or other rip it off quick and dirty sort of jobs. You need something better if you are going to sharpen tools with your grinder.

The wheel I use is sold for grinding carbide and works decently well on Japanese tools. There was a grinder at one place I worked and it had a 600 mm diameter wheel. Just tore tons off drills we sharpened there and no burning at all. Was great just rip it back on the big one and then dolly it up on the small grinder to get a nice edge.

Studley

[yojimbo]

Thanks, Steve --

Do you use a gennou (or genno, depending on where you're from), or a narrow-tipped hammer? I generally like the control I have with a small tap hammer (really narrow tip -- but not so narrow it punctures the metal). But would welcome knowing what you use.

Ceramic blade's a great suggestion, as is the hacksaw/cheap blade method. Will try to find someone with a grown-up size table saw (I'm not big on machines, and only have a puny 4" (yeah, that's what I said -- you got a problem with that?) table saw. All I really need. Well, there's also an adult-size chopsaw, but I wouldn't trust it not to blast the stone into powder. Otherwise, it's the hacksaw for me!

Thanks, Steve. You are, as has always been the case, a peach.

Becky

[Studley 2436]

You know Becky hammer size and so on is personal.

I would recommend though getting one that is big enough for the job. A little one you have to really swing to do anything so you have less control than a bigger hammer. Of course a really big one will be too heavy to use the way you want to.

Just a thought but a Ball Pene hammer should be just the shot. Using the round end of the hammer.

Studley

[yojimbo]

Hey, Studley,

Sorry to get so personal about size...:B

Thanks for the information. The few times I've set myself to uradashi (have done more on nomi than kanna, as I use them more), I've worked with the smallish hammer I described -- actually, mis-described (un-described?!), since it's got a horizontally flat tip, about 1/2 inch (1.27 cm, by my desktop converter -- can that be right?) and is nicely balanced. Will certainly try with a larger head.

Never have chipped the top of the blade -- and am horrified to hear I could! What I did with caution but no terror will now become a Hitchcockian nightmare... Ah, never mind. I'll get over it. The ball peen's an interesting idea, though I'd worry about seeing as well, since the ball will, of necessity, occasionally obscure my view of the blade. I'll give it a try on a really shot old kanna I've got. No great loss if I screw up, and I may find it works great.

I have a small flat metal anvil that sits on my larger one (which is fairly small, itself -- a bit of old rail). Never even thought to use wood. Are there advantages to wood, do you think?

Since my skills are still being developed, I'm very cautious: takes a long time. I've seen footage of Japanese carpenters doing it, and they work with lightning speed -- of course, they've been doing it for far longer than I. Perhaps a medium gennou will help.

Thanks much, Studley.
Becky

[Studley 2436]

*L* nothing personal. I use a bit of hardwood because I don't have an anvil. An anvil would be great if I had one.

Studley

[Sheets]

Becky, Studley,

I use a fairly small (300 g) hammer with a cross peen on one end (22 mm or 7/8". I won't call it a genno because its Chinese - Flying Swallow Brand:D). I have a steel anvil (also a piece of old railway track - picked it up myself some years ago when they were repairing a line nearby), but I prefer wood as it's feedback is more to my liking. I've only corrected kanna that have been sharpened up to the hollow through use, so nothing radical required in terms of correction. Hence, only a little bit of tapping needed and my hammer is perfect (I hit with the cross peen at an angle so only a corner hits and makes a small indentation - very easy to be accurate). As Studley described, start at the top of the bevel (as much to ensure first taps are not going to go errant towards the edge steel) and work across the bevel with more hits in the middle. I never go past midway on the bevel (very little steel in terms of depth there and as you near the edge so you risk making the hard steel move too much and crack).

Becky, if you've been able to do uradashi on nomi successfully, I think you won't have trouble with kanna.

Steve

[yojimbo]

Perhaps I'll start feeling a little more confident now. Interesting what you say about the feedback from wood, Steve. I'll have to try that. Can't say I feel, er, uninformed by the anvil -- to me it's the sound of the hammer strike that lets me know how I'm doing (but then, I gather a lot of information by sound) -- but the wood might give it quite a different feel. Next time, I'll hit the scrap pile and find a good bit to use.

Thanks, fellas.

[wilburpan]

For tapping out, I've used a ball peen hammer and the pointy end of a Japanese hammer, and did my tapping on the end grain of a piece of scrap white oak. I haven't found much difference between the two hammers, but then again I'm not so sure about my overall technique. The times I've tried to tap out a plane blade or wide chisel, I tended to go back and forth between tapping and flattening the back, and I was never sure as to how much the tapping contributed to the process.

To go back to hollow grinds, I've used a Tormek when reestablishing the bevel angle on a plane blade or chisel, and you do get a hollow from that. But because the wheel on the Tormek has such a large diameter (mine's currently at 240 mm), the hollow is really shallow, and goes away fairly quickly as you work on the bevel side.

I wouldn't use a dry wheel grinder on a Japanese tool. My understanding is that since they use high carbon steel, the range of temperatures for tempering is fairly narrow, which is one of the reasons that it takes a lot of skill to make these tools. Likewise, there's not much of a safety margin if you overheat the tool while dry grinding it. But maybe I'm just paranoid.

[Studley 2436]

Gunna Check Machinery's Handbook tomorrow on that one.

Basically Steel is Iron with Carbon in it. I don't think the carbon in the Japanese steels, that is hand smithed tool steels, is out of the ordinary.

I can say though that one of the major reason for the grain and other features of japanese tools is due to the smithing/forging process.

Studley

if you want to get an idea of steel check machinery's handbook. There are as many flavours of steel as you care to name.

[wilburpan]

When you check, see if they say what the carbon content of the steel is. The term "high carbon steel" seems to refer to any steel with a carbon content of 0.5% and up, but the carbon content of the steels used in Japanese tools is higher - 1% minimum, more often in the 1.2-1.4% range, and that seems to be the difference.

I do agree that the hand forging process is a big component in how these tools behave.

[Sheets]

Its not only the carbon content, but the size (very small - microscopic level) of the carbide particles and their distribution within the steel matrix (very evenly distributed as opposed to clumped together in clusters) which makes Japanese steels so fine and capable of taking an extremely sharp edge. Most of the Japanese tool edge steels come from companies like Hitachi and other than the laminating/hardening/tempering, are relatively unchanged by the blacksmith (certainly an incredible amount of skill and knowledge required to put it all into a hand-forged tool).

Steve

[Paul D]

I don't have a Tormek/equivalent; the 240 grit stone has always done the job unless really badly chipped in which case I've carefully used the cheapo 6" grinder with a white stone. I think when I get a minute to myself (in middle of bathroom refit) I'll try the 1200 grit and then a 240 if things are too slow to straighten the edge up. I've heard Becky's idea before and have also seen horizontal waterstones before but have always wondered about the ease of keeping the surface level as my 240 stone has needed dressing a couple of times.

On further examination the hollows on the chisels I've just bought are really close to the edge so the backs should be pretty easy to lap.

Thanks again all am amazed at the responses really helpful!

On a different note anyone got any pictures that explain the 'laminated' structure of Japanese chisels?

thanks

Paul

[Sheets]

Paul,

Have you looked at the thread "How to Sharpen a Plane Blade Part 1"? There are drawings of a kanna (but the same is for nomi - just imagine a skinny tang attached. Although with nomi, the hard steel wraps up the side whereas with kanna, it is just laid flat accross) with colours to denote hard and soft steel.

When you look at your own nomi, you can see the difference in the two steels by the colour (generally, hard is shiny whitish and soft is dull grayish). Look closely and you can see where the two steels meet up the sides and at the tang.

As for tools that have a laminated structure within the soft steel, this can be seen best at the bevel although sometimes the effect is carried out to all the surfaces of the tool (except the hard steel) for cosmetic appeal. Because of the forging of this type of steel, layers are created (due to mixing of different steels or the manipulation/modification of the soft steel - not for cosmetic reasons) before the hard steel is welded to it, and these layers become visible as a colour contrast (shades of gray - sometimes obvious, sometimes subtle) when the bevel is sharpened with natural stone (it may be visible with man-made stone, but is most visible with natural stone - "Play Kasumi For Me" :D).

If you look at pictures of Japanese swords, for example:
http://www.aoi-art.com/sword/katana/08367.html,
you can see one example of the "grain" in the steel and the change in colour between hard and soft steel (although here, the process is different than in tool construction. You can study the making of traditional swords if you wish to know more about them - a whole new world of study if you get into it).

Perhaps a pic is worth 1000 words: not the best example and my polish is lacking, but you can see some layers within the bevel. Often, the soft steel is as prized as the edge steel.

Hope this helps,

Steve

[Studley 2436]

When you check, see if they say what the carbon content of the steel is. The term "high carbon steel" seems to refer to any steel with a carbon content of 0.5% and up, but the carbon content of the steels used in Japanese tools is higher - 1% minimum, more often in the 1.2-1.4% range, and that seems to be the difference.

I do agree that the hand forging process is a big component in how these tools behave.

This is one where things can be confused. Machinery's Handbook says, "Steel is the generic term for a large family of iron carbon alloys, which are malleable within some temperature range".

Later it says:

Carbon Steel: A steel qualifies as a carbon steel when its manganese content is limited to 1.65% (max), silicone to 0.60% (max), and copper to 0.60% (max).

Anyway looking a bit further if you look at what a basic mild steel is compared to better stuff. I am pulling out a few grades here because I am familiar with them. 1012 or basic mild, 1040 nice steel you can machine well and heat treat also often used for hubs and bearing shafts, 4140 steel can be hardened to about Rc60 though it is typically left around Rc35-40. It is popular for Hydraulic Shafts.

1012 has 0.1 to 0.15% Carbon
1040 has 0.37 to 0.44% Carbon
4140 has 0.38 to 0.43% Carbon

Checking further Machinery's (aka The Bible) says that, "The Maximum attainable hardness of any steel depends solely on carbon content". When I was an apprentice they used to say you have to have carbon to make it hard, means the same thing.

When you get to tool steels one you might all know is A2. Plane blades are often made of this. It is called A2 because it is the second one in the Air Cooling series. Used for cold work which lets face it is what planing is.

Anyway to the point A2 has 1% Carbon 1% Molybdenum and 5% Chrome. You do see it up around Rc60 and as high as Rc62.

So A2 hardness is very similar to that of Japanese blades but they are quiet different. Either way I think it is safe to assume the Japanese blades have a similar carbon content to A2.

The crucial thing I think in Japanese blades is the formation of Austenite under the forging process. It is important to remember that the hard steel the Japanese Smiths use is very brittle. To overcome this they laminate it to a piece of soft steel. I don't know enough about this but I think they use a very low carbon steel such as 1012 or even iron so that the whole blade can be heat treated in it's laminated state without hardening the back of the blade. Western steels they tried to produce steel that was able to do everything by itself. Of if you like they got the qualities they needed by adding things to it such as Chrome and by heat treatment also. The Japanese answered the same question by joining two different bits of steel.

Studley

[yojimbo]

Just an amusing interjection, since Studley's brought up molybdenum:

During WWII, the cork that comprised the center of baseballs was needed for the war effort. So they decided to replace it with molybdenum. The results were disastrous: hard-hit balls fell like dead birds a couple of feet from home plate. If Babe Ruth had been playing (he used a 52-ounce bat, compared with the +/- 30-32 ounce bats used today), maybe, just maybe, he could've hit one just over the pitcher's head.

Totally useless information, brought to you for no apparent reason.

Cheers,
Becky

[Sheets]

Hi Studley,

A couple of points of clarification vis a-vis Japanese steel and Western steel.

As I mentioned earlier, it is not just carbon content. Japanese steel superior to Western steel in the size and distribution of the carbide particles (and carbon content on average - as Wilburpan noted, Japanese steels tend to run in the 1.+ish range - capable of being hardened to RC 62-66 - substantially harder than Western A's and O's on the high end and hence the need for lamination to a tough, softer steel backing, as you mention. Otherwise, much too brittle. Western steel can be hardened to a higher value than it is, but would also be too brittle at that value, so must be tempered and the hardness reduced to increase toughness and the addition of alloys to provide abrasion resistance to be useable).

"White" steel* is essentially high carbon steel with little added and impurities carefully eliminated. "Blue" steel is high carbon steel with the addition of alloys to increase abrasion resistance (wears more slowly than white steel, but is harder to sharpen.
*1.15wt% carbon
others %
Si 0.10-0.20 Mn 0.20-0.30 P less than 0.025 S less than 0.004

Japanese tool steel is produced to much tighter standards with respect to carbide formation. Smaller, evenly distributed carbide particles can be sharpened to a finer degree because the structure of the steel can be abraded into smaller bits by smaller grit. Western steels reach a point where the carbide particles are larger than the grit being used (even at the same level of hardness) and come out of the steel leaving a relatively rough surface (we're still talking microns here, and the resulting edge will still cut wood quite cleanly - just not as cleanly as the Japanese tool).

You are quite correct in that the soft steel used in the Japanese tool must be of sufficiently low carbon content so as not to reach a hard state when heated and quenched. An additional benefit to forging steel (as opposed to machining it) is the crystal structure or "grain" is preserved and oriented to provide maximum strength. Doing all this at the proper temperature is where the skill of the blacksmith is vital and why some are more skilled and sought after than others.

If there wasn't a difference in the steels (providing some sort of superior capability), then there would be little point in the Japanese tool maker using his steels (modern) and his methods.

Steve

[Studley 2436]

Sheeze and If you hit the batter with one of those he would be done and dusted.

Actually impressive that anyone especially a girl read all of that.

Studley

[yojimbo]

Oi, Studs, give a girl some credit, eh?:wink:
Becky

[Studley 2436]

Loads of credit Becks loads.

Studley

[Studley 2436]

Hi Studley,

A couple of points of clarification vis a-vis Japanese steel and Western steel.

As I mentioned earlier, it is not just carbon content. Japanese steel superior to Western steel in the size and distribution of the carbide particles (and carbon content on average - as Wilburpan noted,
If there wasn't a difference in the steels (providing some sort of superior capability), then there would be little point in the Japanese tool maker using his steels (modern) and his methods.

Steve

Yeah Steve. I am a really big fan of Japanese tools I have many. JAP PLANES I MADE (http://www.woodworkforums.com/showthread.php?p=808307#post808307) you can see the pic at post 65.

On our Aussie Hardwood the western tools are not as good. I have stanley chisels which I tried to chisel mortices with and the end just bent over. Japanese chisel went through a treat. Actually I have several Japanese Kitchen Knives and they are wonderful also. I much prefer them to Western Blades. I think the Western Blades are made out of 17-4 PH Stainless which is the same as the SAE/AINSI standard 304. So don't get me wrong I will have a Japanese tool everytime and my admiration for the men who make this stuff and the high standards and consistency they achieve time after time is boundless.

Talking Steel though I don't believe it is the steel that really makes the big difference between the Japanese and Western Blades. It is the way it is worked. I am making assumptions here because I haven't spent the time to dig into it. I think the Hard Steel Japanese Smiths produce is basically Iron and Carbon. I don't think you will find other elements in there such as chrome nickel Molybdenum manganese sulphur or lead that you will find in various steels.

This Iron Carbon blend is great for producing a hard piece of steel, however it will lack other qualities such as toughness, it will be a brittle piece of steel. That is OK every piece of steel ever made has been a compromise of various qualities. With the hardening process Austenite is formed. This is the thing that gives steel it's hardness. Hardening will go deeper and deeper the longer a piece of steel is left at a high temperature. The Smith however has a high temperature and folds the steel back on itself. The purpose is to remove impurities but I think that at the same time he changes the grain structure of the steel. You are right about the fineness of the steel in Japanese tools. They can be sharpened to a much sharper edge than any piece of A2. Personally I am baffled why anyone even makes an O2 plane blade as A2 does not hold up that long on the timber we have here. This is most of the reason I have a stack of Japanese planes. They go and go and then really only need a light dust up to get them back to screaming sharp.

So far as steels go there are hundreds of types of steel for hundreds of uses. Saying Japanese Steel is better is a bit like saying Japanese women are better cooks. It all depends which one you are talking about and if you are comparing apples and apples.

Studley

[yojimbo]

Loads of credit Becks loads.

Studley

Thanks, Studley. You're a gent and a scholar.

I'm actually enjoying this discussion quite a bit. Always had a clear concept about Japanese metalwork, but never knew the specifics. I'm loving it.

Becky

[Studley 2436]

Something I found at http://www.watanabeblade.com/english/pro/pro.htm

The Steel Used In Japanese Knives
When people talk about traditional Japanese knives, you may hear them say that the knives were made from "white (Shiro in Japanese)" steel or "blue (Ao)" steel. Alternatively, they might say "white paper (Shiro Kami)" steel or "blue paper (Ao Kami)" steel. These are not technical standards but refer to the color of the labels that Hitachi uses for some of their commercial grade steels. Among Japanese manufacturers, these become "Blue Label #1," "White Label #2," and so on. Both types are high-carbon steels in the 1.0% to 1.2% carbon range alloyed with silica (0.1% to 0.2%) and manganese (0.2% to 0.3%). The "blue paper" steels also have chromium (0.2% to 0.5%) and Tungsten (1.0% to 1.5%) added for toughness. Japanese manufacturers routinely produce knives from these steels in the Rc62 to Rc65 range, substantially harder than any Western-style blades.


For the soft-steel back, they use a very low carbon steel (0.06%) with a bit of silica and manganese (both at 0.2%). The highest-quality tools still use wrought iron from old anchors or anchor chain as the backing material.

[NeilS]

http://www.watanabeblade.com/english/pro/pro.htm

...snip...

The highest-quality tools still use wrought iron from old anchors or anchor chain as the backing material.

Good site that one Studley and its very nice steel in those Watanabe blades. We have a couple of his blue steel Santoku knives and they seem to keep their keen edge for ages... well beyond our Global and Shun knives.

And, the first image on that website page is highly relevant to this topic. Have a look at the size of that (wet) 'grinding' wheel...it must be about 30" across. That one is not going to leave much of a hollow before going onto the flat stones...:)

On those old iron anchor chains... I understand it was all off English ships back in the 19thC.

Neil

[Sheets]

All in the name of education.

I think we're both trying to say something similar. I'm not a metallurgist/engineer/40 lb head guy, so I'm just passing on what I've learned from reading. I suppose I shouldn't add my own opinion as to superior/better (at least it is only opinion - not fact). I'll leave it up to others to reach any conclusion as to why Japanese tools (and kitchen knives/swords) perform differently than Western tools. A large part is due to the type of steel, and how it is handled by the blacksmith. Its like two cultures - different, not necessarily better or worse.

Austenite (the name applied to the phase or crystalline structure carbon steel becomes when heated above a certain temp) exists only at that temperature (too long at this temp is not good - again, the smith needs to know what he is doing). When cooled quickly (quenched), the steel changes to martensite (hard steel with carbide particles - cooled too slowly, the steel reverts to ferrite and pearlite - soft steel, no carbides).
With modern tool steel to work with, there is no need for the smith to fold the edge steel and remove impurities (for tamahagane - the traditional hand smelted sword/tool steel - this is a necessity to make the steel homogenous, remove impurities and create/orient the grain structure).

The lamination process is a compromise so one steel can pushed to a higher limit (hardness/sharpness) with the other steel providing the toughness as opposed to making one steel which trades off hardness for toughness. Even at that, the Japanese tool undergoes some degree of "tempering" so is not as hard (nor brittle) as is possible.

I was rereading some of my sources and I was wrong to say that Western steels in general are not as fine grained as Japanese steel. Some are as good - also Swedish and British steel has a reputation for being very fine grained, but if the quality control is not as good, there is more variation in the final composition of the steel which can affect both performance and quality as a tool - a fact which, I think, widens the performance difference compared to Japanese tools.

As a synopsis:
Japanese tools: sharper and stay sharp longer. May have alloys added to further improve wear resistance.
Non-Japanese tools: less sharp and dull more quickly (carbon steels). Alloys added to improve wear resistance.
HSS: even less sharp but dulls very slowly (not really a good choice for hand tools).

Point of clarification: toughness means structural integrity, not resistance to wear.

Steve

p.s., thought the expression "a real corker" might have applied to baseballs, but apparently to the bat (illegal practice of plugging the centre with cork - a form of lamination? - supposedly to make the ball go farther). Apparently, Babe Ruth (among others) partook of such a form of cheating. Perhaps to compensate for the molybdenum in his balls?

[NeilS]

Becky if you want to cut up a stone I would use an abrasive cutter like a Brick Saw.

Best idea might be to find a stone mason who does stuff like headstones and ask them to do it for you.

Or maybe look around your area for a buiIding site where they are cutting bricks with a diamond saw. A diamond saw will cut through a natural waterstone like butter.

Neil

[Studley 2436]

High Speed Steel is another interesting alloy. Rc65 and holds up well at high temperature. There is another known as super HSS which is Rc70. To get us really off topic Sandvik have made a disposable tip tool from Cubic Boron Nitride that cuts HSS at 200 metres/minute. HSS cuts steel like 1020 at 30m/min. There is an even flasher tip they make called Poly Chrystaline Diamond. None of this means anything as on a hand tool it is impossible to generate the pressure required to make CBN or PCD work. They are actually quiet blunt. Compared to steel that is.

HSS has really good toughness compared to almost any steel. It has great strength as well as being hard. I think it could be sharpened to a brilliant edge but nobody has really tried. No need for the high temp situations it is used in. Get it sharp on a grinder and that is good enough. Of course being such tough and hard steel it would take a lot of effort to polish it up.

Sheets you'll have to explain it to me a bit more as I am not getting your description of the hardening process. Consider the Stainless Steel series which is divided into Austenitic Ferritic and Martensitic types.

Studley

[yojimbo]

p.s., thought the expression "a real corker" might have applied to baseballs, but apparently to the bat (illegal practice of plugging the centre with cork - a form of lamination? - supposedly to make the ball go farther). Apparently, Babe Ruth (among others) partook of such a form of cheating. Perhaps to compensate for the molybdenum in his balls?

Babe Ruth had molybdenum -- ?! Oh... oh, I see.

Actually, the term (which dates to the 1880s) most likely applies to a champagne cork popping.

But corking the bat (done by carefully drilling a hole down the hitting end of the bat, filling it with cork, then replacing the very top of the wood to conceal the crime ) [I]is (was?) a long-time practice. No one's actually been caught at it since Graig Nettles in the mid-seventies ('74? '75?) -- he loaded the bat with "SuperBalls" -- heavy-for-their-size, unpredictably-bouncing things (maybe 25, 30 mm across?) that had amazing rebound. Trouble was, when he hit the ball, the force of all those SuperBalls (I think he used five) slamming into each other as he made contact with the ball cause the end of the bat to shatter, and the illegal augementments to scatter on the ground. Busted.

Good connection, though, Steve. Might've been, but for the fact that "corker" is generally a positive phrase. And originated at a time when baseball was just beginning to become a national game (spread from the Northeast, via Civil War POWs) -- and its use was too broad to apply to such a (at that time) locally popular game.

Great stories of attempted (and successful) cheating in baseball: great innovation, almost always detected. But there are pitchers, for example, who scuffed or loaded the ball for most of their careers: everyone knew they were cheating, but no one ever caught them.

Keep talking metal, guys. I'm having a great time!
Becky

[Studley 2436]

It is too late here Beck to do that. There is some crucial detail on Austenite and Martensite that I have to look up.

A lot of the deal with Steel getting hard has to do with heat treatment and quenching it, typically in oil or water. It then becomes really hard and brittle so has to be tempered. This is done by heating to a relatively low temp and quenching again.

By the tempering treatment steel can gain all sorts of qualities, tough, hard springy you can even if you wish heat it right up and let it slowly return to room temp and normalise it.

If you want to get a head spin go to a steel company and get their fact sheets. They will all do hundreds of different flavours of steel. There are standards about what is what and each nation has it's own standard. We get some rubbish here trying to work out the Japanese Standard and where it all sits in relation to the SAE/AINSI standard.

Studley

[yojimbo]

Some great films of Japanese blacksmith at work
here: http://web.mac.com/nami_aru/Daiku/Noko.html
here: http://web.mac.com/nami_aru/Daiku/NokoGiri.html
here: http://web.mac.com/nami_aru/Daiku/NokoGiri.html
and here: http://web.mac.com/nami_aru/Daiku/Genno.html

Enjoy (now or when you wake up).
Becky

[Sheets]

Studley,

As I understand it (again, I'm not an expert in this field so quite subject to erroneous thinking), the steel produced at the factory has all the needed elements (carbon, alloys, etc.) when it gets shipped out to the customer. The structure of the steel has a certain arrangement amongst all these different things (crystal lattice, grain formation and distribution of the atoms/molecules, etc.) and it stays that way as long as it stays below (very hot) temperatures. During forging, the steel obviously is subjected to high enough temps to change to austenite and is plastic enough to be shaped by hammering. During this stage, there can be some modification to the carbon content (loss due to oxidation or added if using charcoal as fuel), but is always under the smith's control. It is at this stage where the low carbon backing steel is welded (laminated) to the hard edge steel. But since the temperature of forging is never dropped rapidly (I shouldn't say never, sometimes it is dropped into water to cool it, but not for the purpose of creating martensite, just to cool it quickly enough to handle without tongs or be a fire hazard when unattended), the steel always reverts to a pearlite (soft) state. In fact, the smith usually fully anneals (a slow process of cooling from a high temp.) the tool prior to hardening to ensure the steel is fully pearlite.
When heated sufficiently, the structure and properties of the steel change (hence the different names used to denote the various phases). Steel with enough carbon in it will change to austenite (this temperature is the one the Japanese blacksmith is concerned with and is fairly narrow in range - it varies with the carbon content of the steel) where the carbon atoms are somewhat free to move about and combine with the iron atoms. If the temperature is held too long or raised too much above the "critical" temp. (around 750 deg C), the carbon begins to form clumps and the carbide particles grow larger. When cooled quickly below the "critical" temp., the steel changes to martensite where the carbon/iron combination is locked and the steel is hard (and brittle) plus there are all kinds of internal stresses present (much like reaction wood). To relieve these stresses and reduce the brittleness of the steel, it is heated again, but to a much lower temp. (170-200 deg C) and cooled again. So long as the steel is not ever again heated too much, it will maintain this crystal arrangement and hardness/toughness combination. This is why you can't risk heating a tool tool during grinding or machining, unless it is a HSS made to stay hard at higher temperatures.
There is this site:
http://www.threeplanes.net/toolsteel.html
which has a useful description (more complete than mine) of the process. Of course, further reading is always advisable to really know more about it.

Again, hope that helps. I would certainly welcome any clarification if my meagre understanding has resulted in a real corker.

Steve

I presumed a "real corker" applied to the ball being well hit - certainly (usually) a positive thing.

[NeilS]

I can't add anything much further to the discussion so far on traditional Japanese blacksmithing process other than to mention two points that seem to be mentioned frequently as important by the 'experts' from whom I have bought Japanese blades. Both of these points have been raised already by others in the discussions, but I thought I would highlight them:

1. Using Pine wood charcoal (although more expensive) as the furnace fuel helps maintain the high carbon content in the cutting steel during the forging process.

2. Extensive hammering during the cooling down process helps to compact and align the crystal structure to give a harder, finer, and longer lasting cutting edge.

Of course, all the other critical factors such as starting with a high carbon steel to begin the process and maintaining the small size and even distribution of the carbon/iron metallurgy with careful temperature management are needed to benefit from the above two points.

Probably someone has already mentioned this, but I have read that traditional Japanese blacksmiths waited until dusk to do their final temper quenching so that they could more accurately judge the colour of the metal as a temperature guide before plunging the blade into the quenching vat. As I child I spent many hours in the gloom of our local blacksmith's workshop watching him forge the everyday farm items used around our district. Perhaps he wasn't just stingy on the lighting!

Another point that might be worth mentioning. Japanese blades (not sure if it's all of their steels ) can get harder with time. The crystalline structure continues to change in the cold state. So an old blade can become harder than when it was first made. Makes me think of them more like a natural living material like wood than an inert metal.

Neil

[Studley 2436]

You don't realise what a big can of worms you have opened up here Steve.

Just going through Machinery's Handbook and giving you all a quick once over.

Hardness is determined by the carbon content.

Hardenability is determined by alloying elements. Hardenability is the ability to harden a piece of steel to a greater depth. The way Japanese Smiths make cutting tools it isn't really such an important feature. The way Western Forges make blades it is, mostly because the hard bit of the steel is much thicker.

Alloy refers to a metal made of various elements. Brass is a good example being largely copper with whatever else added to it. There are many Brass Alloys. Alloy Steel is Steel with elements such as chrome Nickel Molybdenum Manganese and so on added. 4140 is a good example or A2 for that matter.

I think you are going to have to read the book so that you can get a good grip on the structure of steel and its changes due to heating. It is complicated stuff at that level. Basically when a steel has more that 0.85% carbon it has an excess of cementite above that required to mix with the to
ferrite to form pearlite.

At the lower critical point which is in the range 1335 to 1355ºF the alternate bands of ferrite and cementite that make up the pearlite begin to merge with each other. This process continues until the pearlite is thoroughly dissolved forming Austenite.

Effects of cooling on carbon steel: As the cooling rate is increased the layers of pearlite formed by the transformation to austenite become finer adn finer until they can not be detected under a high power microscope, while the steel increases in hardness and tensile strength. As the cooling rate is increased still further to beyond the critical cooling rate a new structure is formed. The Austenite is transformed into Martensite, which is characterised by an angular needle like structure and high hardness.

Just my impression but Japanese Smiths doing their quenching in water are very likely gaining this Martensite structure.

Back when I was an apprentice and the best steel they would give us was 1040 and they called it tool steel we used to make tools out of it and harden them with an oxy torch. Heat it up cherry red drop it in a bucket of oil then go and polish it up back to the oxy set and give it a gentle heat until the polished surface started to show straw and blonde colours, next you get up to the blues so we let that happen in the middle of the punch and tried to drop it in the oil when the straw colour was just at the tip of the tool. That might be all you need to know about hardening.

Anyway heat treatment is a huge area it is a discussion that could go on for years and still not be at the end.

Studley

[Sheets]

Studley,

You are correct in that this subject is complex. My knowledge comes from reading various sources (just as yours). Obviously, my sources are limited and don't delve very far into the complexities (meant as a quick synopsis for the lay person). Realistically, when reading something out of a book or magazine that attempts to describe (in this case) the methods used by Japanese blacksmiths to make tools, knives and swords (methods which take years to master and understand), obviously the articles can't even approach being complete (for instance, there is no mention of age hardening, at least the chemistry of it, which seems to result from the existence of retained austenite amongst, no doubt, many other things going on) and often tend to put a bias of superiority over other methods (which I admit to adopting).
So I'm learning much more than I knew thanks to you illuminating the subject (and I mean that sincerely).
What we really need is a more complete pairing up of what's going on chemically in the steel with the various stages it goes through on its way to a tool. Its probably all ready out there in the various posts of this thread leading up to here.
Anyway, I'm happy to close the can unless others want to keep it open.

What I believe is, even though today's Japanese blacksmiths use modern steel, there is something in the traditional method of forging tools that results in a definite difference in the finished product, not merely a different path to the same end.

Steve

p.s., my use of the term alloy, was used erroneously. You are right (again) in that other elements are added to the steel to create an alloy.

Also, blacksmiths of any age and nation prefer(ed) to keep there forges dark so that they can see the colour of the steel and know its temperature.

[Studley 2436]

Age hardening is when there you harden to a Martensite condition but there is left over Austenite. Over time the Austenite converts itself to Martensite. This can produce growth in the steel.

The Japanese method is important to the stuff they produce, I feel sure. To learn more I might have a dig around to see what I can learn about forging.

I did sell one of my planes once on eBay (actually I still have a heap so if anyone wants one email me, my PM box is full) and the guy who bought it was BlackSmith. We he came around to pick it up which was neat as I didn't have to pack and ship it and we got to talk for a while about it. he was quiet clear we had a laugh about unbreakable samurai swords. Because of course anything can be broken if you hit it hard enough. He told me a bit too about the "layering" of Japanese blades and how it was nothing more than a way of removing impurities from the steel. Of course steel being steel you fold it back on itself red hot beat it out and it is once again one layer of steel. That said there is very likely some interesting stuff going on at the microscopic level.

I think the real genius of the Japanese Smith was to laminate a hard piece to a soft piece. That way the hard steel gets the toughness of the soft steel and you gain qualities that were hundreds of years ahead of their time. Modern alloy steels can almost certainly match the hardness and toughness combo. Can they be sharpened to as fine an edge as a Japanese Blade? My experience with A2 is that it can be made pretty sharp but not much point going beyond a 1200 stone. Doesn't seem to give it much if any more. I do have a 4000 grit that I use on them a bit but while they get sharper it isn't much sharper so usually I save myself the effort. Japanese blades on the other hand it is good to go to 8000 grit and finer as you will be rewarded with an amazing sharp edge. These edges hold very well too.

Could Western steel be as good? Don't know. I have thought that even though H7 is a hot work steel used for dies and punches and so on that it would make a very good blade. The big hang up would be keeping it sharp. So lamination would be a really good answer to this. Laminate it on to a bit of 1010 or whatever (I think they would more likely go for 1040 because 1010 machines up like rubbish) and just use a thin bit of H7 on the front of it.

More bleatings

Studley

[NeilS]

...Japanese blades on the other hand it is good to go to 8000 grit and finer as you will be rewarded with an amazing sharp edge. ...

Studley....it's nice to go above #8000 but there are limited options available. In synthetic waterstones Naniwa go to #12000 and Shapton have #16000 and #30000 and they start getting to be quite expensive, the last costing over $500 for the professional series.

The other option is to go with natural finishing waterstones above #4000 or #6000, but it's a tricky road to go down. I have noticed a few members of this forum have and use them. I have a few and I'm still finding my way with them. There are many pros and cons for going with this option. Is there enough interest from members to start a new 'elementary' discussion on natural Japanese waterstones?

Neil

[Studley 2436]

Those are the stones I have Neil. They weren't shockingly highly priced as they are Japanese but man made stones. I do have to get another 1200 or thereabouts as I have worn mine out *LOL*

Studley

[Sheets]

Well swords I know something about.
When you fold steel over on itself and weld the two "layers" together, you do in fact now have two layers of steel within one solid piece. In order to get the two layers to weld together, you need a flux and this causes a distinct division between the two (or four, eight, sixteen, etc., depending on how many times the steel is split and welded together again). The steel doesn't get melted, so things stay separate (chemically). You probably can't see this division when the steel is polished as the whole thing is still the same type of steel. In order to make the layers visible after polishing, more than one piece of steel (each different slightly than the other) is used, so that as the folding continues, the layers alternate. So long as the layers don't become so thin as to be invisible (seven folds would produce 128 layers, each thick enough to be discernable in the finished blade, whereas 20 folds would produce over a million layers, so much too thin to be visible to the naked eye. Also would not be necessary to fold that many times).
The number of folds depends on how much refining of the steel is required to remove impurities (slag and voids usually left over from smelting), to more evenly distribute the carbon content throughout the billet (essentially, ending up with a homogenous piece of steel without melting it all together. After smelting, the raw steel or "kera" will be steel, but will not have a uniform composition throughout) and, since some carbon is lost with each "heat", to arrive at the carbon content the smith requires (it needs to start out with a higher content to compensate for the loss). A direct benefit of the folding and forging is the creation of all the layers which enhances the strength of the blade (think plywood).
This steel (high carbon) will become the edge and sides of the blade. Within the centre of the blade is a piece of low carbon steel to provide the same function as the low carbon steel used in a laminated tool (toughness).
Hardening differs from that used in tools, in that you don't want the whole blade to have the same harness as the edge. Because the entire outside steel jacket is the same carbon content, it has to be heated to different temperatures (hotter at the edge and cooler at the sides and back. The center doesn't matter because it is low carbon and will not harden). This is accomplished using a clay coating applied prior to the hardening heat. The clay is thin at the blade edge and thick elsewhere. Naturally, when hot, the heat differential due to the clay is minimal (eventually, the whole blade gets to be about the same temp.). But with the last seconds in the fire, the smith ensures the edge is in the hottest part of the fire, so t will gain temp. on the rest of the blade. He judges the temp. by the colour, and when right, plunges the blade into a trough of water. Where the clay coating is thinnest (at the edge), the steel cools very rapidly and forms martensite. The rest of the blade cools more slowly due to the thickness of the clay (sheesh, I'm writing a whole book here) and does not cool rapidly enough to become martensite, but changes back to pearlite.
Now, a couple of interesting things happen here. As the back of the blade cools, it contracts and imparts a curve to the blade shape (hence the usual shape of a Japanese sword). This curving away from the edge is resisted by the cold, hard edge martensite which tries to remain strait (it actually curves in reverse when the blade is first plunged in the water as the edge cools and contracts faster than the back). The resulting tension within the blade creates a tremendous force which enhances (I know Studley, you're going to roll your eyes at this one) the ability of the edge to cut. Honest, that's what they say (and they've actually proved it using strain gauges).
There is, just like the study of steels in general, a lot more to it. I won't go on, so if anyone is really interested, I encourage you to read up on the subject.

Steve

[Studley 2436]

The resulting tension within the blade creates a tremendous force which enhances (I know Studley, you're going to roll your eyes at this one) the ability of the edge to cut. Honest, that's what they say (and they've actually proved it using strain gauges).
There is, just like the study of steels in general, a lot more to it. I won't go on, so if anyone is really interested, I encourage you to read up on the subject.

Steve

Nah Steve tension introduced to steel by the hardening process is pretty standard knowledge. There are sometimes large forces contained in a piece of hardened steel.

The way the Japanese do their blades think kitchen knives is to have the bevel on the right and keep the blade flat (well it isn't flat there is a hollow as Steve describes) on the back. This is really good in the kitchen as you can slice things very thin. It gives you really good control, first rate stuff.

I do want to have a think about this idea of layers of steel. I am skeptical. I know for instance that Fitters have been "marrying" steel together for ages. Good way to do it put a steel pin in the chuck of a drill press and start the drill. Then press the pin into an undersized hole. Gets all bright and red hot press it in and hit the stop button before anything really lets go. No flux nothing melted but it is welded in there. It would be possible to see the difference between the join and the two metals but within the weld could the point of joining be seen? I don't know.

Another point is that for the so called million layer blade you end up with layers that are smaller than an atom. It would be really interesting to find a metalurgist and see what they had to say about all this.

Studley

[yojimbo]

Is there enough interest from members to start a new 'elementary' discussion on natural Japanese waterstones?



I use natural waterstones in most cases. Am getting more proficient.

Would be delighted to get involved with that discussion. (Not tonight: you guys are just up; I'm about to fall down.)

What d'you say?
Becky

[Sheets]

Creating a millions layers, while possible, is not practicable (and certainly not common practice). For one thing, as the steel is heated each time, some is lost due to oxidation and the formation of scale (which just flakes off and falls away. It becomes an impurity, so you don't want any of it in your steel - so couldn't add it back in) and the carbon content is being reduced as well, so you either run out of sufficient steel to continue, or the carbon content goes too low, or both. Now I suppose you could combine say ten pieces of steel (all previously folded a number of times) and fold all that lot a few more times to reach your million layers (you'd only need 500,000 layers here, because the final fold occurs when the high carbon steel is wrapped around the low carbon core, doubling its own layer count and incorporating how ever many layers are in the core steel). But, the cost in time, labour, raw material and fuel (charcoal) involved makes it almost totally impractical and there is in any case, not likely any advantage (quite likely some disadvantages and the law of diminishing returns) over stopping the folding as soon as the steel has reached the state desired (in terms of purity and carbon content).
When you're trying to make a living, being efficient as well as skillful means you just can't afford to spend time and resources beyond what is reasonably necessary (unless you have customers willing to pay enough - but they need to know (believe) they are getting something worth more).

Karaziguru's Weapons Emporium

This week's special - anti shuriken shirts - 5 pieces of gold (free with the purchase of a new sword)

For sale (special order*): new samurai sword made with over one million layers of steel - can cut through fifty bodies in one stroke. Cost: 1000 pieces of gold**. *Please allow 6 months for delivery. **Testing charges may apply.
For sale (in stock): new samurai sword with a beautiful pattern in the steel - can easily cut a man in half in one stroke. Cost: 100 pieces of gold. (talk to us about discounts for quantity orders). Testing included.
We also have used swords in stock - many to choose from - all sharp, sharp sharp. No name from 20 pieces of gold. Famous makers (Masamune, Muramasa, Suzuki, Honda, etc.) from 75 pieces of gold.
So come on down and get that "armed and dangerous" feeling (impress the ladies, scare the ninja). Don't trust your life to a flea market special (you never know where it came from). Never feel insecure again.
Showdowns every friday at noon.

Its one of those days,
Steve

[yojimbo]

This week's special - anti shuriken shirts - 5 pieces of gold (free with the purchase of a new sword)



Good to see you back in form, Steve. 'Bout time. Cripes, haven't seen a truly howl-worthy pun from you in ages.

Becky

[Sheets]

Hey thanks. Last week's special was "Elevator Geta (sold out)". Not only will you cut an imposing figure, but very useful in the rain.

Steve

"When one has nothing to say, it is better to remain silent".
- Kwai Chang Caine

[yojimbo]

Get help. Now.

Really.



:U

[Pam]

...The ball peen's an interesting idea, though I'd worry about seeing as well, since the ball will, of necessity, occasionally obscure my view of the blade. I'll give it a try on a really shot old kanna I've got. No great loss if I screw up, and I may find it works great....

Becky, a narrow cross peen might be a better idea than ball peen.

Also, do you know what type of lacquer Tomonori-san sells for stone integrity? It's water based, which begs several questions about using it in water. But my main concern is whether it's urushi, since I recently read that urushi is a close relative of poison ivy/oak/sumac, to which I'm very allergic.

Pam

[Pam]

For stone cutting, use a stone cutter. I wouldn't think of applying my table/band/mitre saw blades to stone, they're too expensive and don't work. I used a stone cutter (circular saw with special blades and a water bath) saw when learning masonry in a survey course on bldg tech. These saws are pretty cheap, but someone advised hiring a stone cutter for this, I agree, good advice.

Or perhaps you want to learn the score and tap method like brick layers and stone fence builders? Using cold/stone chisels? I haven't a clue how to do this, but I've seen it done.

Pam

[yojimbo]

Hi, Pam -- long time no... whatever this is.

The hammer I've been using is a lot like a cross pean, so I'm thinking I'll probably stick with that... But I'll try out all the suggestions here on that beat-to-hell old kanna. Really nothing to lose.

I got my lacquer from Nakaoka-san (Mifuqwai) on eBay. I've used it quite a bit: dries absolutely impervious to water. And it's quite mild -- no signs of irritation, though I've gotten plenty on my hands. I'm positive it's not related to urushi, from everything I've read about it (and yes, it is dreadful: was considering learning the process, but after discussing it with some Japanese friends and reading up on it on line... no way).

Nakaoka-san has a video of his very young daughter (five or six?) using the water-based lacquer with no protection, which also gives me confidence. (Sorry -- I have no idea where that film was: probably on Fujibato...?)

This stuff is quite impressive. Nakaoka-san recommended mixing it about 1:4 with water (lacquer/water) -- if I'm remembering correctly -- and painting it on. I find that ratio a bit thin, and have cut back to about 1:2 1/2, or 1:3.

On my low grit (zebra) stone, it soaks in pretty fast, and needs many coats to build up adequate protection (though it's been holding against a bad crack in the stone). On higher grit stones, it goes on beautifully. I use around three or four coats on these, just to be sure (overkll, no doubt, but that's just me).

I just bought a couple of ceramic blades for my hacksaw to try on the waterstone, but -- haven't checked -- am thinking the frame won't allow me a deep enough cut into the stone (it's quite round). And I wouldn't want to lose so much stone as trying to meet the cut from the other side would probably cost me.

However, just called some friends with a tile-cutter: they say it'll work (one of them watched me wear my saw down to nubs on the hand-cutting attempt). Will let you know how it goes.

Great idea, Pam -- when I asked these friends about it, my colleague (wife in the couple) said "Why didn't I think of that?"

So you get major points for innovative thinking. Thanks much.

[Studley 2436]

Ball Peen really works a treat for flattening out blades. Makes it easy to work on the bevel. I have found it really quick and easy to use.

Studley

[Pam]

Thanks for the lacquer info, Becky, I'll have to get some the next time I order from Tomonori-san (shoot, just received a stone from him, looks like it will be a while, though).

I take it you think it's better than epoxy, which was recommended to me for leveling stones on the bottom. I've thought about trying it on the sides, too.

Pam

[Studley 2436]

Seems you guys know some stuff I don't. Mind you all my stones are man made so it isn't the same as natural stones. I did dig around for the guy you talked about and he has some good prices on his stones. Some of the prices I have seen have been huge. Hundreds for a single stone.

Interested to hear more about laquering the stones up to get them sitting flat.

Studley

[Pam]

Tomonori-san has some very expensive stones, too, prices that take my breath away.

As to lacquer, my impression is that it's more to protect the integrity of the sides and bottom, not level the bottom, which would be the job of epoxy or something similar.

Pam

[yojimbo]

Pam's right, Studley: the lacquer will do absolutely nothing to level the back of your stone: too thin. All it does is help protect against chipping and splitting.

Have been trying myself to find a way of leveling the back of one stone... I just haven't trusted anything but what Nakaoka -- let's stop confusing things here -- Tomonori-san recommends: am too afraid of contaminating the stone. But I would guess, if I had to, that anything fairly neutral and water-based wouldn't be too bad.

Pam: have you dealt much with Tomonori personally? Does he know you're a woman?

I had a wonderful exchange with him (yes, communication can be an effort, as I don't speak Japanese, either) when, after about eight months, I got tired of him addressing me as "Sir." I responded to an e-mail of his by saying not all woodworkers were "Sir." He wrote back with this shocked response:

"You are women?????!!!!"

(I so wanted to write back and say, no, I am not "women." Only one. But I was worried about being a smart-ass through e-mail: too hard to make clear you're joking, even without the language barrier.)

At first I was worried my dealings with him would suffer -- so few women carpenters in Japan. But to my delight, he went on to say exactly that: that there are none he knows of, though he's teaching his daughter a bit, right alongside his son, and that I must be very strong. He said he was impressed. I blushed. Now I address all e-mail to him as "Sensei," and he writes back to "Highness" -- which makes me uneasy, but which I take in the good-natured manner it's meant, rather than the more uncomfortable American take on it -- that it's a haughty person. Haughty, I ain't.

So, Pam, have you had any such exchanges with him? Does he know your work and your gender?

Studley -- it just occurs to me that, with the lacquer on the back and sides of the stone to protect it (many layers), you could probably use anything you want -- epoxy, etc. -- to give it a level base, as the lacquer will seal out any contaminants. (That took a long time -- sorry, it's early.)

Tomonori-san/Nakaoka-san also says this lacquer makes an excellent protective finish for furniture, though I haven't had the time or nerve to try it out yet... not much time to diddle around with anything but the commissions... Anyone ever used it as a finish?

Once or twice, back when I wasn't going broke building a workshop, I splurged on a few of his really high-priced stones. Can't say whether it's worth it or not: the feel of a stone is such a personal thing. Some of them I love, others (like the super-hard ones) I'm not so taken with -- though they really are only for a super finish, and used only briefly, so I suppose they're economical: at the rate I use them, they'll last more or less forever. More than half the time, I don't bother with that final finish: only if I have to be imparting a final, smooth finish with the cuts I make, either nomi or kanna.

Becky

[wilburpan]

I'm not sure that Tomonori-san's command of English is the greatest.

I asked him a question about how much softer one of his 4++ stones was compared to a 5+++ stone. This was his reply:


Sir.
some softer.

Having said that, he's doing a much better job of running a business in English than I could in Japanese.

[yojimbo]

Classic answer. And I agree: he does a fine job, and except for a few questions I've had a hard time figuring out the answers to, the language is virtually never a problem.

[Pam]

He hasn't a clue about my gender, although I tried several times to tell him, never made a dent.

Pam

[NeilS]

Or perhaps you want to learn the score and tap method like brick layers and stone fence builders? Using cold/stone chisels? I haven't a clue how to do this, but I've seen it done.

Pam/Becky - a bit of lateral thinking there, but having cut and/or cracked a few thousand stones in my time (viz - pic of sample attached), I would suggest cutting with a suitable circular saw blade (ideally diamond) to avoid ending up with nothing but a pile of small shards and, if you avoid that tragedy, the crack rarely follows the score line in stone which has its own internal structure which it wants to follow.. :C. Your friends with the tile cutter sounds like the way to go to me.

Neil

[NeilS]

Pam's right, Studley: the lacquer will do absolutely nothing to level the back of your stone: too thin. All it does is help protect against chipping and splitting.

Have been trying myself to find a way of leveling the back of one stone... I just haven't trusted anything but what Nakaoka -- let's stop confusing things here -- Tomonori-san recommends: am too afraid of contaminating the stone. But I would guess, if I had to, that anything fairly neutral and water-based wouldn't be too bad.

...snip...

Studley -- it just occurs to me that, with the lacquer on the back and sides of the stone to protect it (many layers), you could probably use anything you want -- epoxy, etc. -- to give it a level base, as the lacquer will seal out any contaminants. (That took a long time -- sorry, it's early.)



Becky/Studley - on advice from So-san, I just glued mine down to a base with water resistant caulk that I picked up from the local hardware shop (M10), the sort of glue-gun stuff used to bed down sinks to benchtops... just avoid getting any on the working surface...pic attached.

Neil