Kanna Help You?

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Chris Hall
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Kanna Help You?

Tue Nov 18, 2014 10:04 am

Here in Massachusetts, the seasonal swing in relative humidity is fairly extreme, typically ranging from 34% (comfortable) to 98% (very humid) over the course of the year, rarely dropping below 16% (dry) and reaching as high as 100% (very humid):
MA humidity swing.jpg
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The blue line indicates average daytime high relative humidity, the blue line the night time relative low humidity.

Wood and wooden tool parts, like plane bodies, are continually adapting to the changes in humidity. This can make hammer and chisel handles loose when the wood shrinks, and a wooden plane body can also shrink to the point where it runs into the blade, and the result can be a stuck blade, or worse, a crack in the plane body. The way the dai (the Japanese term for the wooden part of the hand plane, , which, strictly translated, means 'platform') shrinks, I might add, associates to the way the grain in the block is oriented. Dai with the most movement across the width are flatsawn.

I try to set up a new plane when the relative humidity is somewhere around 'average', a sweet spot between the driest and most humid times of the year. This way, when the dai swells or shrinks to its maximum extent, the fit of the blade should still - hopefully - be reasonable. If one set up a new plane when the dai was its most swollen or most shrunken, then the fit at the time of year when humidity is at the opposite end of the range may result in the blade either being swimmingly loose, or too tight to be capable of adjustment. The looseness can be rectified somewhat by shimming under the blade with paper, however the tight fit scenario means either you are opening up the fit to accommodate the blade, a cycle which, over time, is likely to eventuate a poor blade fit most of the time. Or, the tool gets put on the shelf for a while and you use another tool which has a blade you can adjust properly. An overly-tight blade fit, combined with a metal hammer used to adjust the iron, combines to result in a mushroomed over or deformed blade head after a while.

The rational answer, for those that can afford it and who live in a place with large seasonal fluctuations in relative humidity, and who wish to have the best fitting blades throughout the year, would be to buy two of each plane you use, setting one up at the humid time of year and one at the dry time of year - what might be called 'summer' or 'winter' planes, though it is not always the case that high/low humidity levels correspond perfectly to those seasons. East and west coast of North America, for example, are reversed to one another in terms of which season is the most humid.

It's not a bad idea, when you obtain a new Japanese plane, to let it sit on the shelf for a full year or more, blade backed well out and protected from rust, to allow the dai to get a run through the highs and lows of your local relative humidity. That's not always practicable, but is an ideal. I have a number of planes which I have purchased in the past while, one of which has been on the shelf untouched for 3 years, the others anywhere from a year down to 8 months. As we climb into May, I have decided to set up some of these planes. My patience has evaporated - I want to try some of these delectable works by various smiths, see how the cutting 'tastes'.

It might be presumptuous on my part, but I thought that some out there who have a new Japanese plane, or who are contemplating getting one at some point, might be interested in seeing how I go about setting up a plane. I would hardly call myself a 'plane guru' by any stretch, but I have picked up the odd useful bit of information here and there over the years -- and I'm sure I've done it wrong in every conceivable way as well, mistakes being the greatest of teachers.

I view each new plane as a chance to set the works up as perfectly as I can, and believe me, 'perfect' is a vanishing horizon that moves away as fast as you can move towards it. I may never attain it, because it is probably impossible, but I enjoy trying for some perverse reason.

Japanese planes remain, it seems, the poor stepchild of the Japanese tool family, as least insofar as being accepted into the arsenal of tools by woodworkers across the globe. Japanese saws and chisels are part of many craftpeople's sets outside of Japan, but the plane remains somehow forbidding, remote, and there are few who delve in. Many who do so emerge frustrated. Yet, the plane, kanna, is the central tool in the Japanese woodworking tradition, even today. Why nibble at the side dishes when you can experience the delights of the kanna?

Well, the reasons that the kanna hasn't been more widely adopted are apparent enough, at least to me. First off, few woodworkers use handplanes of any type, even if they happen to own one or two. Most automatically reach for the random orbit sander when it is time to prepare wood to a finishing point. That's too bad. At any rate, the pool of people who do try to use planes in their woodworking is a minority these days.

The plane, western or eastern, remains a problem to use for many, knowingly or otherwise, because it works well only when finely set up and finely sharpened. Sharpening is something most woodworkers seem to avoid, for some reason, or do not delve into to a significant extent. A poorly set up or poorly sharpened plane can make a mess of a surface in a hurry, and for some, once bitten twice shy in this regard.

On top of this, unlike most better western planes, even the finest Japanese kanna comes to the new owner as a kit of sorts. You can't simply take it out of the box and start taking shavings after a preliminary adjustment. It is designed this way in purpose in fact, not because the smith wants to offload the labor onto the buyer.

While there is information in English available on the topic of how to turn this kit of parts into something usable, as well as DVD offerings, Youtube tutorials, etc., I would by no means describe it as complete, at least as far as what I have come across. If there was a complete source of information, there wouldn't be much point in rattling on further on that topic, now would there?

I also tip my hat to those who have put information out there in one form or another, in the effort to bring this knowledge to a wider group, and to those who have helped me along the way (knowingly or otherwise). A shout out to Mike Laine, Harrelson Stanley, Des King, Werner Weis, T. Kunimoto, the folks at Japan Tool, Kamijo sensei, to say thanks - - if I've left out a name, no offense intended.

I'll work through the procedure of setting up a brand new plane (kit), and try to be thorough, though I imagine I'll overlook a detail here and there. Please let me know if you think something could be added. There are quite a few steps, and I imagine it will take a few posts to get to the end of the list, so try and remain awake.

Here goes nothing then....

Step One: Protection

Working on a plane involves sharpening and the use of ink and/or charcoal to provide telltales during fitting, and both processes can make your hands dirty. With a nice white oak dai, it is unfortunate to get to the end of set up and have the thing looking all grubby, so I like to cover the dai in painter's tape prior to getting underway:
DSC08496-small.JPG
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Cut the tape away carefully from the mouth on both sides so you have full access for making adjustments:
DSC08497-small.JPG
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One can consider this step optional, though it seems to me that the idea, at the end of setting up a new plane, is to have a new-looking plane, clean, shiny and all ready to go. Would you deliver a piece of furniture to a client with marks and dirt on it? I hope not. This is your tool and it is your 'gift' once it is complete, so taking a few moments to protect it from grime during set up is well worthwhile.

I'm working on a few planes at the same time so please don't expect absolute consistency in the photos representing the same tool, step after step.

Step Two: Trim the mimi

Invariably the width of the new plane blade is greater than the width of the mouth and it needs to be adjusted to fit. In the following photo, note the two red circles, within each of which you can see that the blade edge's corner protrudes slightly beyond the edge of the ramps in the mouth opening:
DSC08498-small.JPG
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If the blade corners or 'ears' - mimi in Japanese - were left long, then shavings can get stuck in the corner between the blade edge and the ramp, and this throws off planing as you slightly lose registration to the wood surface. There needs to be a slight gap between the end of the blade edge and the inside corner of the ramps in the mouth opening.

There are various ways to trim the ears back, but I prefer a metalworking vertical belt sander. It has a large abrasive surface and platen which makes it quite hard to overheat the blade. A grinder can also be used, but take extra care not to overheat the blade.

I hold the blade like so, carefully aligning the bevel of the mimi to the platen:
DSC08499-small.JPG
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I opted to not try and take a photo with the machine running, holding the blade with one hand - -seemed like discretion was the better part here. By holding the blade as shown above, most of the metal is removed back away from the cutting steel surface, thus creating little or no burr. If a burr does form on the cutting steel when you trim the mimi, you will need to dress the burr(s) off on a finishing stone before proceeding further.

As you sharpen a blade, the edge recedes back little by little, and as the ears are trimmed on an angle, the blade edge gets progressively longer as the edge is taken back. This means that you'll be revisiting this step in the future, after many sharpenings have caused the blade edge to once again be wider than the space between ramps in the mouth. If you consider this problem, you can see that it is better to grind the mimi on a 30˚ angle (relative to the side of the blade) rather than a 45˚, as this prolongs the time until the ears will need trimming once again.

Here's the result after trimming, red circles now showing the clearance near the mouth opening:
DSC08502-small.JPG
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If your mimi grinding was a bit overzealous, it is not the end of the world, it just means that the blade is going to be narrower than it could be. No biggie. Ideally you want about a 0.5~0.8mm gap at each side.

Step 3: Check the main blade (kanna-mi) for twist

The process of forging a Japanese laminated blade, where a hard and brittle cutting steel, hagane, is 'glued' onto a soft iron backing, jigane, makes for a happy marriage in many respects, but like unions between opposites, certain stresses can manifest early on and need to be dealt with before they fester. As the forge weld cools, the steel and iron shrink to differing degrees, and the iron has less resistance to bending than the steel. Essentially it is a tug of war which the steel will win every time. The result, if both backing iron and cutting steel were flat to begin with, is a cupping of the blade towards the cutting steel side (the ura, or back of the blade). The removal of metal by grinding or scraping to form a hollow on the ura afterwards can also affect the finished shape of the blade in terms of the degree of cupping. It is not an uncommon outcome as well for the blade to develop a certain amount of twist during this process of accommodation between the hagane and jigane. You need to check the blade for these two conditions carefully before proceeding to do any sharpening.

With a twisted blade left uncorrected, the process of flattening the back will be screwed up, and it can mess up the fitting of the blade to the dai afterwards even if you do manage a half decent flattening of the back of the blade. Unfortunately, sometimes the person who cut the dai for the plane blade - the dai-ya san - did not notice that the blade was twisted and as a result has performed an initial set up to a deformed blade shape. Or, maybe they did notice but it is not their task to deal with this issue so they chose to only barely fit the blade into the dai.

Here's how to check for twist: start by placing the blade ura side down on a reference flat, so that only the cutting steel portion of the blade is on the flat surface:
DSC08503-small.JPG
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Start with one finger in the middle, as shown above, and then use the first finger on your other hand to tap the two corners of the blade, right where you recently trimmed the mimi. You're looking for any gata-gata - a clattering sound indicating that the ura side is not completely touching or in plane with the reference flat. If the blade contacts in the middle, but not at either corner, then the bevel area is bowed across its width and both corners will therefore need to be raised a little. If the blade contacts at both corners of the edge, it is still possible that it is raised in the mid-portion - one can check using feeler gauges.

You can also swing the blade down on the corner of the reference flat (I use a Starrett Lab grade 'A' surface plate), using the upper end of the cutting steel line as a 'hinge', until the cutting edge meets the stone surface at some point, and then tap on each corner to see if one of the corners is lifted from the reference flat:
DSC08504-small.JPG
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In the case above, I found that the blade had a fairly pronounced twist, and the high corner (i.e., the corner not contacting the reference flat) is indicated by my finger in the above photo. I say 'high corner' in regards to the above view of the blade, however if we flip the blade onto its other side, ura side facing up, then this same corner would be the 'low corner'.

Note: unless the blacksmith has totally fubar'ed the blade, one can normally expect that the blade will touch the flat somewhere along the edge portion. A bad situation would be where the edge does not contact the reference surface anywhere, and the blade is therefore meeting the surface somewhere in the middle, an indication that the blade's ura is bowed convexly. If you find this situation, it is probably best to consider returning the blade to the store you bought it from. A convex ura can be dealt with, but it's much more of a hassle.

Generally the blacksmith engineers things so that after the forging and grinding is done, the ura side (the cutting steel side) is slightly concave lengthwise. I'm not talking about the blade's hollow - the concavity I'm talking about - sori as it is termed - can be measured along the portion of the blade at the edge which is outside of the hollow. The degree of sori reflects the blacksmith's skill, his philosophical attitude as to how meticulously finished the tool 'should' be, the price point of the tool, and how much work was done to the blade after it left the blacksmith by the sharpening person, or sei-ken-ya. More on that later.

To get rid of the twist involves a bit of pounding. First make up a copper shim, about 1/16" (1~2mm) thick - I used some 5/8" (15mm) copper pipe strapping that was laying about, folding a couple of bits over one another:
DSC08505-small.JPG
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Now for the nerve-wracking fun part. Put on some ear protection and place the blade upon an anvil. I use the anvil on the back of a larger Japanese metal working vise that I have. You want to place the blade ura side up, so the blade edge is well away from the anvil, and place the low corner of the blade upon the piece of copper. You will then place a short piece of wood (or a large brass drift, or a non-hardened hammer head, etc.) against the middle of the ura and, using the piece of wood as a drift, strike it as hard as required with a hammer:

You might find it helpful to tape the copper shim down so it does not fly or fall off of the anvil.

A heavier hammer is better than a light one for this step. You can strike the blade in the center with the drift, for the most part, and you may wish to also strike it on the mid-potion of the blade side, directly below the place you have shimmed. Please do so at your own risk, and hammer judiciously. Do not hammer the drift anywhere close to the blade edge. It wouldn't hurt to put the blade in a glass of hot water before any whompin' but I haven't found it necessary to achieve results (though it may speed up the process). Patience certainly helps!

Depending upon how twisted the blade is, you may have to give a few gentle whomps, or you may have to get a bit more, shall we say, determined. It should not reach the level of red-faced Hulk Hogan-esque shirt tearing and bellowing - be clear about that. Try a test hit or two, then go over to the reference flat and re-check the blade to see if you have removed any twist yet. My blade was quite twisted, so I had to hit the drift pretty hard, and through many rounds, probably spending 20 minutes on this step until I had the twist out. You will know when you have the twist out as the blade will sit flat on the reference surface without any gata-gata at either corner.

By bringing the twist out, however, you also intensify one of the other side effects of the blades forge-welded nature, increasing the sori on one side of the blade commensurate with the amount of twist removed. Further, it makes the blade's bevel surface a bit more convex. But one thing at a time - first we get the twist out, then we deal with the other deformities. That's the order in which things have to happen.
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Chris Hall
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Re: Kanna Help You?

Tue Nov 18, 2014 10:35 am

Step 4: Dealing with a Sori Situation

As mentioned in the last post, when the cutting steel, hagane, and backing iron, jigane, are forge welded together, it is the marrying of two materials with quite different characteristics. As the forge weld cools, stresses are induced to the body of the blade. As the back of the blade is hollowed by scraping and/or grinding, further stresses are released. The usual effect on the blade after all is said and done is that the blade cups along the length of the forge weld - termed sori - and it may also twist, and may cup crosswise as well. The blacksmith can attempt to compensate for this effect by making the pieces to be laminated curved shaped slightly opposite to the direction in which they will bend, or some other such stratagem which I can only guess at, however it is extremely difficult to obtain a dead flat blade given the variables and vagaries of the process. The worst outcome would be to have a blade which is bent towards the jigane side, as it is much harder to try and flatten a convex hard steel surface. As it is preferable to err on the side of a concave surface, in the interest of facilitating the later flattening of the blade back, that is precisely what blacksmiths do - err on the side of having the blade cupped to the hagane side:
Curved blade problem a-small.jpg
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If you try to flatten a blade with sori, 'as is', you will have the following situation upon a sharpening stone, which, for purposes of illustration, is dead flat:
Curved blade problem b.jpg
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The area shown in red in the above sketch is the hollow left by the curvature of the hagane upon the commencement of the flattening process.

One could proceed to flatten the blade, and let's assume you take the process along until the cutting steel has been made dead flat, like so:
Curved blade problem c.jpg
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This works, however the process has made the cutting steel thinner than ideal at both ends. Were the curvature in the blade more pronounced, the thinning would also be more pronounced at each end.

So what's the big deal with that? Well, this problem is really one that affects both the long term life of the tool and the ease with which it can be kept flat. Consider that each time you sharpen you will be dressing the back off to remove the burr formed from grinding and polishing the bevel. And, from time to time over the years of use the blade will need to be tapped out to re-establish the 'landing' of cutting steel immediately behind the cutting edge, and this process will require the cutting steel side, or ura, to be ground to some extent again, and again re-polished. With every re-working and polishing of the cutting steel side, material is lost from the steel, just as it is when grinding the bevel to establish a fresh edge. The steel is getting thinner and thinner with each sharpening session. Ultimately, by making the uphill end of the cutting steel thinner by the strategy of simply flattening a blade with sori, you risk the eventuality that one day you will end up with apparent length left in the cutting steel but the steel is actually too thinned by this point - or all gone - thus rendering the tool dead before its time. And after all that time spent getting to know it, the triumphs, the failures, good times and bad, you have to let a dear friend go prematurely.

Many tool users, including ones in Japan, could care less about such things, and flatten a blade with sori all the same. The characteristic of a blade in which the user has tried to flatten a curved back is that the ura perimeter (ura-suki) becomes a gourd shape:
Curved blade problem d.jpg
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A new blade on the left, the 'el gordo' outcome on the right.

Another side effect of removing so much cutting steel to obtain flatness on the ura is that what is formed with the gourd shape is an ura with a lot more cutting steel present, which means that flattening and polishing the back from here on out is now a more onerous task. The main reasons for the hollow on the ura side to begin with is to decrease sharpening effort and to make it easier to obtain perfect registration of the ura on a flattening stone. If there was no hollow, given the 70mm blade width and typical steel hardness of Rockwell 62~64, you would spend quite a long time - hours if not days- trying to flatten the back of the blade. And trying to perfectly register a broad flat surface upon a stone means fighting against the tendency of the steel surface to want to ride atop the water and slurry below. It can be quite challenging to obtain a flat and even polish across a large area, especially where it is most critical - along the very edge of the blade.

The gourd shaped ura is a possibly a sign of a tool user who doesn't care much for his tools (or perhaps doesn't care about the blacksmith who may have put all his hard-won knowledge and skill into making the tool), or doesn't quite know what they are doing, or who does know and doesn't care all the same - or some combination of the above. I've done this to a plane blade myself before I learnt that it was a poor way to flatten the ura. A plane blade with a gourd-shaped ura will work fine, but its ultimate lifespan has been likely shortened, and you've made dressing the black flat more work than it needs to be from here on out. So, best avoided.

Another approach to dealing with an ura having sori would be to only work the last 1/2 or 1/3 of the hagane upon the stone, like this:
Curved blade problem d2.jpg
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This solution can work well IF the amount of sori on the blade is minimal, and IF you take a lot of care to focus all the pressure on the cutting edge of the blade, virtually 'floating' the mid section of the blade along on the stone arris. Those who are good at freehand sharpening could look at this method.

If the blade had a pronounced amount of sori however, this approach will likely not work so well, and you will simply replace the curved ura with one that now has a faceted flattened front half. The ura would likely look something like this:
Curved blade problem e.jpg
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It's at least functional - let's call it the 'mini-gourd'. The polish won't be even of course between the front half and the back half of the ura, and if you were to inadvertently move the flattening stroke on the stone further inboard, the registration off of the flat created is lost and you will create a secondary bevel right at the blade edge. This will be obvious also from the various polishing streaks you will see on the uphill side of the hagane.

Worse though, is the outcome in regards to fitting the blade to the dai: the back of the tool is still not flat, and thus as the tool is fitted further and further into the dai the likelihood of the blade digging into the support ramp down low is significant. The support ramps are supposed to be totally straight, and by cutting a curve into them, you spoil the fit. The arrow shows where the damage occurs in the following picture:
Curved blade problem f.jpg
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I'll remove the blade and zoom in so we can see the damage at the bottom of the indicating arrow:
Curved blade problem g.jpg
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You really want to take care not to cut the ramp like that.

In recent email conversations I have had with the proprietor of Japan Tool, I learned some interesting tid-bits in regard to various blacksmiths and their approach to sori. I had thought that a blade with a lot of sori was a sign that the smith was less skillful, and a blade with just a smidgeon of sori indicated good work, however it is more complicated than that.

After the blacksmith has done their work, the blade is sent to a suiken-ya (水研屋), and one of their tasks is to perform a basic sharpening of the blade, and this necessarily involves dealing with the sori issue. Some smiths are very fastidious in their work, taking extra care to stamp their makers mark cleanly, shape the blade carefully, form a shapely hollow, etc.. There are other blacksmiths who consider this fastidiousness as, well, undesirable. It's not manly. It's over-fussed. Too pretty. They prefer a bit more of a rough and ready approach, and are less interested in making something pretty than in making something that works well as a workaday tool an average craftsman can afford. I hope you see what I am getting at -they don't produce a tool with all the wrinkles worked out, partly because of cost considerations and partly because of philosophical reasons. The time of the suiken-ya costs money, so in order to keep the costs down on the tool, the labor the suiken-ya might otherwise have been asked to do is simply off-loaded to you, the consumer. And if the manly, rough-and-ready plane buyer couldn't give a fig if the ura looks like a gourd and is happy to flatten the thing as is, then all is good.

It's an interesting philosophical point of view, and while I understand it, frankly I would rather have paid the suiken-ya to do a thorough prep on the tool. They are used to working with metal - plane blades specifically - all the time, and are doubtless going to do a better job than I will. That said, perhaps the performance of the tool over time will win me over, and I'll forget about all the struggles we went through together. To borrow one comment from the Japan Tool owner, I may end up marrying this girl, though I found her ugly and obnoxious at first....

Another option now for dealing with sori - this is the method I use. The idea is to find a way to suspend or support the blade so that it can ride upon the stone with the rear portion of the sori close to parallel with the stone surface:
Curved blade problem h.jpg
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You could try free-handing this if you like. I prefer to find a means of supporting the blade, at least for as long as it takes to obtain a registration flat at the bottom end of the hagane.

Before supporting the blade though, it is important to determine exactly how much curvature you are dealing with in the first place. I do this by placing the hagane portion of the blade down upon a reference flat, and seeing how large a feeler gauge can be slipped in to the side:
DSC08509-small.JPG
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This blade has a very minimal amount of sori - 0.0015". One of my other new plane blades however had nearly 4 times that, at 0.0055".

The idea with this method is to find some tape that you can place on the uphill side of the blade, and the tape you select will have about the same thickness as there is sori.

How thick is tape? Well, it can be easily measured.

Painter's tape:
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Aluminum duct sealing tape (which I used on the blade with the worst amount of sori):
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Clear heavy duty packaging tape:
DSC08512-small.JPG
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I don't think those round numbers for tape thickness obtained above are accidental.

Note: I was just measuring some different kinds of tape for comparison purposes only. The painter's tape is not a good choice for use as it won't stand up. Preferable is the heavy packaging tape, aluminum tape, or best: UHMW plastic tape.

Once you've selected the appropriate tape, place it on the upper half of the hagane:
Curved blade problem i.jpg
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With the tape in place, you can then start to work the blade on the stone, the entire hagane zone in play over the stone:
DSC08517-small.JPG
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You can start with a finer diamond plate, like an Atoma 1200, if you are confident that the plate is flat. Or, as shown in the above photo, start with a 1000 grit stone. When using a stone to flatten the back, you must be extremely fastidious about keeping the stone flat. I would suggest taking about 10 strokes, then re-flattening the stone again. Concentrate your finger pressure only on the bevel end of the blade.

The function of the tape here is to act like a little temporary sled to support the uphill side of the hagane. You are still looking to pretty much float the blade over the stone on the taped end, applying almost no pressure there beyond the weight of the blade itself. The tape of course doesn't last long, even when taking care not to wear it, so you need to look at the condition of the tape each time you go to re-flatten the stone.

If the tape starts to wear through, replace the tape. It's only tape. It only needs to do its job long enough for you to adequately flatten the sori at the end of the blade. Once you have established a flat on the end of the cutting steel, it will begin to self-jig. Then you can spend most of your time working the hagane on the last 1/3 portion.

Again, about 10 strokes on one side:
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Then 10 strokes on the other side:
DSC08514-small.JPG
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I also use the middle strip on the stone to work the bevel. Then re-flatten the stone. My grip on the stone you see above is in compensation for holding the camera in my other hand - normally my right fingers would be pressing on the bevel.

Once the back is flattened, you can work the bevel, staying on the same 1000 grit stone (or drop down to the diamond plate if the bevel is pronouncedly convex and there is a lot of steel to remove). It is important again to concentrate on keeping the coarse stone dead flat, as a flat stone will produce a flat bevel. A check to see if you are obtaining a flat bevel can be done when you are in the middle grit stone(s) - the blade should stick to the stone on the bevel for a period of time:
DSC08540-small.JPG
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If it barely sticks, either the bevel or the stone is not flat. If it sticks for about 5 seconds, that's decent. 10 seconds is excellent with a larger blade. With a smaller (shorter and lighter) blade, like a 48mm, I have had one stick for over 30 seconds. It's not a contest, but it is satisfying to know you have obtained a decently flat bevel - even if you may later plan to make the blade edge have a slight smile (curve) to it.

You keep working the same pattern with the next stones in the sequence. I move from 3000 grit ceramic (shown above) then on to a natural stone.

Here are a couple of blades after the above ura flattening process has been completed:
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DSC08525-small.JPG (254.12 KiB) Viewed 4996 times
You can perform a check at the end similar to the start: place the hagane side down on the stone and see if you can get a feeler gauge in there. There should be no space. Both of these blades had only a modest amount of sori to begin with, so the amount of work was on the reduced side. The blade on the left is about where I want it, with a land on the back side of the edge about 1.5mm wide. The land is not perfectly straight, but acceptable. The blade on the right has a 1mm land, and I would prefer it be a little wider. I could keep flattening the entire back, starting down on the coarse stone, however the portion of land on the sides of the blade- threadlike in the above examples, would then begin to fatten. And, for as long as possible, I want to keep those lands - those legs - on the skinny side.

The blade which had the most pronounced twist and greatest degree of sori ended up like this after the above flattening process:
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DSC08548-small.JPG (328.65 KiB) Viewed 4996 times
I have had more of a battle with this one, as you can see. Here the land behind the edge is more like 4mm wide, and the left side, which had ura-a-ge performed (see the previous post) to remove the twist, has ended up with a somewhat irregular hollow. Not the prettiest, and there are a few scratches yet to be dealt with. I feel like I won the battle.

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