More thoughts on ura-dashi (tapping-out a Japanese plane blade)

A few points that I want to emphasize here. I'll step back .....



For this round of ura-dashi, these marks are all of it. What is that, like.... 20 strikes, maybe?

I am using a light hammer. My "anvil" is a lead filled can. I like that the lead is soft, because it cushions the blade. A chunk of hard metal works great, but feels..... Hard and slippery. The blade slides around more. A chunk of dense wood works well, too, but cushions a little bit TOO well. It will require more force from the hammer.

A turning point for me, was realizing that I WANT to make dents in the bevel of the blade. I want the sharp little edges of my hammer to dig in, and actually move the metal around. I am striking the blade pretty lightly, but because the hammer digs in, very little force is required.

I had read dozens of times about supporting the blade, using the face of the hammer obliquely, hit in the thicker 1/3 of the blade, don't hit the hard steel part, etc etc. My error was thinking that ura-dashi was a "bending" process. That you are hitting the end of the blade, to "bend" the edge down. You read of others having the same mis-perception, and wondering why they are having problems.

I forget where I first read about a "good" description of ura-dashi, but the essence of what you are doing is this.

• You hit the soft iron
• You create dents, that cause the surface to expand
• The expansion causes the end/edge of the blade to deflect downward.

The anvil backing is nice to have, but you could actually do this on a flat surface (in theory, although I wouldn't want to). As soon as I stopped thinking in terms of "bending" and started thinking about dents and displacement, it all came together. After that, ura-dashi became fun and relatively simple.

I think that this line of thought needs to be emphasized more. 

It is difficult to see, but there is a little bump that protrudes to the left, and right under that, a dented area on the face of the bevel. The dented area looks like a smudge, or hazy spot (among the dust specs). Hitting, way down on the bevel, caused the metal to deform all the way at the top of the blade. That's pretty cool!

The amount of distortion is made evident while grinding.

Even though I was striking in the middle of the bevel face, the effect is amplified, and spreads clear to the edge. The picture above shows that even after a fair bit of grinding, the dented area remains. Small, well directed taps can give big results.

In this case, I am only focusing on that little bit, the zone in the bottom center. I eventually hope to get the entire edge to look like a flat line.

I am trying to sculpt a straight line, only shaping a minimum amount of metal. Something like this would be ideal....

Mandara-ya has the REAL info!

And again, wrought iron makes this a LOT easier! This blade.....

...needed a lot of work to hammer out the back hollow (urasuki). This blade is made with normal, soft iron, NOT wrought, and it was MUCH more difficult to move.


MANY little hammer strikes.

I am striking at the thicker portion of the blade, trying to affect a large area and volume. This is heavy shaping, and a skilled practitioner would use a large hammer.

The result was acceptable, not perfect, but...

The upper blade, not the lower.

Why bother?

Good blades have VERY hard steel. Now that we all have access to cheap diamond sharpening stones, the question of whether ura-dashi is worth the bother, seems moot. Not so, not so.

The blade is all important. Each blade is different, and the wooden dai is cut to fit the blade perfectly. If you change the shape of the blade too much, the fit will be ruined.

A different blade.

This is a blade that has probably never had ura-dashi performed on it, ever. The lighter colored areas represent steel that has been removed, effectively changing the shape of the blade, causing it to fit poorly. This is a blade that will not work as well as it could've.

What happened with this kanna, is that the blade essentially became thinner, and therefore fit loosely. To tighten things up, the user needed to add a thick paper shim to the blade bed. This works.


A better solution would be to preserve the original shape.

Worse than a sloppy fit, a bigger problem is that if you don't do ura-dashi, you might run out of steel.

At the outer corners of the blade, the steel is getting thinner. Some blades will show the steel nearly disappearing. You see this problem on chisels, too.


Another blade. This one was owned by someone who took care of his tools.

The urasuki is getting very small, but still maintains its proper shape.


When you look to the bevel, you can see that the line of hagane is even, and of full thickness.

The longer one might not last as long as the shorter of the two.

This kanna looks old, but has seen little use.

The beautiful blade was forged by a very talented blacksmith.

 Look at how thin the steel is! The owner of this tool needs to be VERY diligent in performing ura-dashi. This is a high end kanna. Very nice!

It's not that hard to do. A little hammer with sharp edges.....

My ura-dashi hammers

I'm just looking for any excuse to not do what I should be doing, which is working on the house. We are relocating to Hilo, Hawaii in just a few short months, and there are a multitude of loose ends to tie up, before we rent out our house.


My friend tsuresuregusa wants more details of the tack hammer that I use for ura-dashi.

This is a little tack hammer that I picked up at a thrift store/junk shop for a couple of $'s. One end of the head is split, to better hold small tacks (at least I *think* that is the reasoning). The split end is the face that I use ( I would prefer that the face were NOT split, but......). The most important detail is that I filed the faces to have sharp corners. This allows the hammer to really dig in, making nice tiny divots in the metal. A smooth face will tend to slip. I want something that will grab and gouge!

173g total.

It is a small, but precise tool, and makes ura-dashi fun, rather than nerve wracking. It's so much fun, I do chisel blades, too.

I have another hammer head that has been patiently waiting for a new handle.

This little guy has forge welded inserts on both faces, and one end comes to a nice sharp wedged shape.

Looking for guidance.



This is on my wish list, maybe not this exact hammer, but something in this style.

Pro Shop Hokuto has style

A funate genno with a good sharp end. This would be just the tool, for those hard to convince kanna blades.

The process of ura-dashi is made soooooo much easier if the kanna blade is made with ren-tetsu wrought iron. The soft iron works very easily, helping you to shape the blade as you choose. Less force is required, so there is less likelihood of grievous mishap. A regular soft iron backed kanna blade seems to require at least twice as much force. Wrought iron...... It's about more than just good looks.

SK-11 diamond sharpening stone and some $store surprises

Planing away, hard at work building a deck, I am having some issues with edge retention. I don't know what it is, but there seems to be one board in this batch that has some serious abrasive qualities. It's like it's filled with sand or something (not that living at the beach has anything to do with that, or.......).

You see all of those nicks? They weren't there a few seconds ago. In any event, it's time to sharpen. Again.


First, a surprise.

The other day, I was wandering the isles, looking in some unlikely places for some diamond grit abrasives (More on this later). While I was at the $Store I found, of all things, a sharpening stone.

How bad could it be? For $1, expectations are low, but I was actually quite surprised. This thing works! I soaked it in water for a minute and used it like a waterstone. One face wasn't perfectly flat, and it is a touch soft, but....... This bugger cuts! 6"x 2"x 1" of steel eating fury! This blade is one of the hardest ones that I own, so the speed is even more impressive.


With two faces, it is ostensibly a coarse/fine combo, but I didn't see much difference, to be honest. The coarse side is softer than the fine. It is noisy. Crunchy sounding. The coarse side is soft enough to make a little bit of mud, which seems to speed the grinding action.

Did I mention that it is soft? Being soft, it will require regular attention to keep it in the realm of flatness. I need two.


There is an antique mall/ flea market kind of place here, and way in the far back corner, there is a booth that sells tools. The cheapest of the cheap, but I've found some decent stuff there. They ALSO have some sharpening stones, and they're even cheaper than the $Store.


I splurged and got the big 8"x2"x1".

$0.75 (The 6" one was only $0.60, haha!).


Like the smaller stone, one face is slightly dished, but only by  .15mm.

The cause of the dishing is a bit of a raised lip around the perimeter, a remnant of the molding process.

Bevel the edge, and it will be almost perfect.


The other face is as flat as I can measure. A 0.038mm feeler won't fit, and that's the limit of my measuring tools.

Good enough for me. It will go out of flat in use, anyway.

This stone is harder than the one from the $store, more like a traditional oilstone.

Being harder, it is also slower. It is possible that using this one with oil would improve its action. This stone wouldn't have any problem with your average western style mono-steel blade.


The fine grit side would bring the blade to a near-mirror finish, given enough patience. The softer expensive ($1!) stone has spoiled me!

I never would've thought that the $store would have sharpening stones, much less ones that work. I've been looking for a coarse grit stone that works tolerably fast, and this one is nearly as quick as using the belt sander! Now if only I could find one in a 8"x3" size......


The ura on this blade is starting to encroach on the edge. Time for a little bit of ura-dashi.

A new weapon in my fight for flatness, an SK-11 diamond grit sharpening stone, bought from eBay seller: Sakura*pink. The stone is targeted towards  the Japanese market, but is made in China.

I've bought from him before, and he has always been patient with my utter lack of Japanese language skills, helpful in finding stuff, and very good at getting the best shipping price (and refunding any extra!). A great seller!


The stone is 204x65x7mm, and VERY heavy. It's over 1/4" thick.

The embossed pattern is #400 grit one side, #1000 grit the other.

The #400 grit side is flat. The #1000 shows a bare sliver of light under the ruler, but the gap is less than I can measure (so less than 0.038mm). Both sides are absolutely flat along the short axis. This stone is light years flatter than any american made diamond stone I've ever owned.

I want to focus on just a small area. It is easier on the blade (and me) if I do a small bit frequently, rather than waiting until it becomes a large endeavor.

The ren-tetsu is nice and soft, making ura-dashi fun. Just this little bit of tapping, using my modified track hammer, displaces the soft iron and pushes the hard steel down.

Sighting along the cutting edge, you can see that the edge has been deformed, resulting in a small bulge to the left.


The bulge gets ground down. That's why I bought the SK-11 stone.

These stones have a reputation for being only a short step down from the Tsuboman Atoma stones, and at 1/2 the price (or even less. Sakura-pink sold me this one for $35! A great guy!). This is what most of the Japanese guys use, particularly for waterstone flattening.

With judicious tapping, I am gradually evening out the flat area, just back from the cutting edge. 

Each time I do ura-dashi, the shape gets a bit better.

On the bevel side, the hammer marks show how the displaced iron actually pushes the steel down. You want to do ura-dashi before grinding the bevel, sharpening the blade.

From this point, it's sharpening as usual.


Ura-dashi adds some extra work to the sharpening process, but the new diamond stone works quickly. The finish is still rough, much coarser than the grit numbers indicate, but that should mellow with use.

The quality of the SK-11 stone isn't perfect, but it's pretty darn good, MUCH better than I was expecting, and far flatter than anything made in the good 'ol USA. I plan on using this stone with the lightest touch possible, in hopes maintaining its speedy cutting action. Most important to me, though, is that it's flat. Why can't WE make good stuff?

Professional Japanese woodworking tools..... IN ENGLISH!

I haven't noticed this before, but Pro Shop Hokuto has an English language site. This store is one of my primary information sites for REALLY nice stuff. To date, I've been viewing it in the Google-ized translated gobbledygook version.

Samurai Tools Pro Shop Hokuto


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OK, I guess that it's not all that I had hoped for. I wanted everything spoon fed to me, but......

On the positive side, the site has the Japanese kanji side by side with the English (at least in some places). That helps immensely! I have been trying to parse out meaning, through example and guesstimate. This can act as a Japanese tool dictionary for the hard/unusual terms that I can't find anywhere else.

I wish that I had this resource 2 years ago!

The wonders of using a high angle Japanese plane

Being half out of my mind, suffering from my first cold of the school year (a condition that every parent well knows), I can't seem to muster much enthusiasm for house related work.


I am still working on the deck.

The skewed blade of a kiwa-ganna is effectively a very low angle plane, perfect for planing endgrain. The Port Orford cedar is so nice to work with, I just can't restrain myself. The deck surface will remain un-planed.



Another kanna that has proven very useful throughout this project has been this higher pitch kanna, a 47 1/2° bed angle vs the more common 38°.

This EXTREMELY generous gift has helped me tame some of the more unruly grained sections of this occasionally fussy wood.

POCedar is a wonderful wood to work, but the stuff that I have is of lower quality (really inexpensive, though!), and has plenty of flat grain and quilted figure. It's beautiful, but will tear-out if you look at it funny.


Dave's kanna is virtually brand new, in fact it would surprise me if it has ever been used before. It is of good quality, sakura hiromasa forged by Kouichi Kobayashi, and is currently available through Japan Woodworker . The blade is made of blue steel, forge welded to good soft wrought iron ren-tetsu. The back blade is laminated. The oil soaked dai is fine grained and straight.

This is my first new kanna. Thanks Dave, this is going to be interesting!




In the western tradition, difficult figured woods are surfaced using a special plane with a steeper bed angle. While the standard western bench plane will have a typical bed angle of 45° (common), a higher pitch plane for figured wood will have a bed angle of 50°(York), 55°( middle), 60°( half). Steeper than that, and I call them scrapers, but I'm no pro.

It would seem that the addition of a few simple degrees will make a plane perform wonders, but why don't more Japanese planes come with steeper pitches?Japanese planes are cut almost exclusively at a 38° bed angle, and even though this would be considered a "low" angle plane to western eyes (and therefore completely unsuitable for use on hardwoods), skilled users are able to get them to work incredibly well, even on the hardest of figured woods. I have some problems, particularly with this POCedar, but also with rowed wood, burls, quilted...... Jeez, most anything gives me trouble sooner or later!

High angle kanna are made, however, mostly for the american market. I have had the intention of making one for a while now, but when you haven't used something before, you naturally question it's utility. That's where Dave came to the rescue. He knew that I had been wanting one of these higher pitch planes for a while, and being the generous guy that he is..... (Actually, Dave doesn't know me from Adam, only knowing that I've obviously got some serious Japanese tool issues that I'm sorting out, haha!)


I am going to write this under the assumption that this IS a brand new kanna, and is representative of what anyone would receive, if they bought one from the same retail store. Japanese tools are seldom ready to go, and almost always need some work to prepare them for use. This is normal stuff and is all part of the fun.


 Any comments that seem to be even HINTING at anything less than absolute wonder at Dave's generosity should be written off as a lack of talented authorship skills. I love this plane, and it is a fantastic gift!






The plane came to me commendably sharp, so I was able to use it immediately. If this kanna were a car, it would have that "new-car-smell". No dents, dings..... Nothing. Did I mention that it's sharp, too?

While the blade is perfectly sharp, the fit of the blade is a little loose and uneven side-to-side. I was able to set the blade well enough to be used, but it took a LOT of fiddling, and was too loose to maintain its setting, tending to self-advance, and cut too deeply.

This is a perfect example of how a person, new to the peculiarities of what to expect from new Japanese tools, might order a plane/chisel/whatever, and be, um..... less than satisfied. As it came, this plane would be a BUGGER for a kanna novice! And, to be clear, this is about what you would get if you bought a tool "ready-to-go". A tool intended for the professional market would require even more work! I'm no pro, but I DO know that I like my kanna to be a particular way, and a factory can't provide that.

A pro will set the tool for the conditions. There is no "one-size-fits-all". This kanna was probably perfect when it left Japan, but by now the wooden body has moved a bit, the blade may have relaxed it's shape some, whatever. Believe it or not, this is part of the attraction (for me at least). It gets me more involved, more integrated, in what I am doing.


A couple of light taps with my little wooden mallet is enough to set the blade far deeper than you would ever want.

Sighting down the underside of the kanna body (upside down), you can see the blade protruding unevenly on one side.

Because the blade bed fits unevenly (and I'm in a hurry to use this plane!), I choose expedience and shim the blade using tape.

I put a small scrap of thin, house wrap tape in one corner, then a larger piece over the top.

Even these two, very thin pieces of tape prove too thick..... And too slippery.


Blue making tape to the rescue.

One piece is fine for now. It really doesn't take much. I prefer a paper shim over either tape or a thin wooden shim, but this kanna only needs a little bit of assistance (and I'm excited to try this guy out!).

A loose blade is easy to remedy. I live on the Oregon coast, but this kanna came to me from Virginia. It's very possible that the blade will fit perfectly in another month or so, and if I had taken more drastic measures........


These tools almost always come with a coating of rust inhibiting lacquer. I don't like the shiny look anymore, and the lacquer feels gummy on the stones, so.....

Lacquer thinner or acetone takes it right off. I still need to strip the chip breaker.

That's better.


The chip breaker is very tight, and will require more extreme measures to fit, so for the time being, I will use this kanna as a single blade plane.


I want to try this kanna on some wood that has been giving me fits. This is a chunk of African mahogany (khaya, perhaps?) a moderately hard wood (about like american red oak) that is often rowed and almost always tears out at least a little bit. In the past, I have had to resort to sanding :'(

The pull is significantly heavier than a traditional lower pitch kanna, but not bad. There is some tear-out, but less than I would normally expect.



Here's another little thing. When I am adjusting a blade and I just want to advance or retract one side of the blade, I often wedge my thumb against the side of the blade while tapping the head of the dau, right at that chamfered corner above my thumb.

This frequently causes the dai to crack, so I give myself a large target to hit. Here is a different kanna, to serve as counterpoint.

I like the clean, crisp look of the traditional kanna dai, but a bit of rounding (or at least a very generous chamfer) doesn't look too odd. I tend to get rather enthusiastic when customizing my kanna, though.

Even taking the lightest cut that I can, I still get a fair bit of tear-out.


 The #1 cause of poor performance is a blade that needs sharpening.

See that bright line at the very edge?

The blade dulled quickly, but remember that I had been using this for a few days on the POCedar. This African mahogany is very abrasive, too.

Another factor that would contribute to premature dulling, is the sharpening angle. Despite being fitted to a high angle body, this blade was still sharpened to the ubiquitous 25-26° angle.

I favor 28° for my normal smoothing planes, so I figured that this high angle kanna can comfortably go up to 35° or so.

I could jump right to 35° if I don't mind losing 3-4mm of blade length, and having to perform ura-dashi immediately. I could also use a guide, and only sharpen the 2-3 mm at the tip, but for now, I only do the minimum.

I favor gradually sneaking up on my target sharpening angle, so holding the blade vertical, I file the end to a flat. I am using my cheap China diamond stones that I have mentioned a time or two.

I want an even line of reflected light, and in this case, end up with a 1 mm thick, blunt edge.

Still on the diamond stones, I gradually lower the blade until the majority of the blade is in contact with the stones surface. This only requires a few minutes effort. By blunting the edge, then concentrating just on the tip, I can raise the sharpening angle by about 1° at each sharpening session. You need to be attentive, though. Gravity and the centered mass of the blade conspire against you. Dropping the angle is easy. Raising it is more difficult.

Raising the angle gradually helps me to better know the blade itself. Each blade is slightly different, and it is entirely possible that this blade might not work well at, say 35°, but be a stellar performer at 32°. If i jump to 35° right from the start, I would have no basis of comparison.

Today, because I am only doing a minimum, I jump from #220 diamond, #1000 king hyper, #5000 rika, then finish on a natural stone of around #8000-#12,000 or so.

This wrought iron likes the natural stone and polishes out nicely. This is a nice looking blade.

The polished blade gives a wonderfully smooth finish to the wood....... and NO tear-out! To get a finish this nice, on tricky wood, using no chip breaker blade? I am amazed!

The shavings show a remarkable lustre.

Shiny shavings =

The wood is glassy smooth and extremely reflective.

This plane has been a revelation for me. I know that a higher pitch plane will handle difficult wood, sure..... But that generally comes at the expense of finish quality. A steeper bed angle translates into a blade that scrapes proportionally more of the wood cells, as opposed to shearing them cleanly. I was expecting a dull surface. This is anything but dull.

The wonderful shine is partly due to the species of wood used. This "mahogany" is harder than pine, and should finish to be more shiny.

The chip breaker/back blade/secondary bladeblade/sub-blade, whatever (I need to just start using the Japanese term, osae-gane) compresses the wood shaving as it is cleaved from the surface being planed. This does effect the finished surface, and typically results in less shine. Single blade kanna are used for the "brightest" shine.

For difficult wood, the osae-gane is a necessary evil. At least that's what I thought. That this plane worked so well, just as a single blade, make me wonder how it will feel when the osae-gane is properly fitted. The pull will be heavier to be sure, but I am feeling optimistic about is capabilities on heavily figured grain. We shall soon see.

Sharpening. If nothing else, this example proves the value of a sharp tool. Dull doesn't cut it.


Thanks Dave, for the wonderful gift. I love it!