On Ura-Dashi Failure and Success

[Brian Holcombe]

Hello gents, I want to share my story of failure and success with Ura-dashi so that others may learn from my mistake and subsequent improvement of process.


Around July I acquired a Kikuhiromaru old stock 65mm kanna blade which I ear marked for a Nagadai kanna. A little while later I chopped out the block and fitted the blade to it, but left it untouched. I had a friend, who runs camera crew for PGA stop by the shop and he wanted to take a video of my doing the ura-dashi process.....well some months later he was still traveling and I wanted to put my tool to use so I decided it was time to have at it.


Anyways, during the process of normal setup I begin with straightening the blade (removing twist) then tapping out to get a nice ura and begin the blades life on the right track. However something went awry, during the process the blade was not budging at all. I would tap and get little to no movement in the iron.


The hard steel layer of this blade is quite a bit thicker than any of the other blades I own and so my failure in assumption was that I needed to continue at it and eventually the steel would move. I was correct, the steel began to move and I began to see results when working the back on the stones.....great! .....not great...so much pressure built up in the blade that it literally snapped down the center while I was holding it (not actually doing anything other than looking at it). After the shock wore off, I decided it was time to evaluate my position.


I ground back the blade and did eventually uncover two flaws in the metal, I'm uncertain if they are what led to the blade cracking or not.


I received feedback from Jim Blauvelt and my father, who is a long time metal worker. My father provided me an accessory for my anvil, which is a rounded shape (not sure what it's called) item that fits into the hardy hole. The rounded shape, judging by the amount of dings into it, is a softer steel or iron than the anvil surface. The rounded shape better supports the blade during ura-dashi than using a rounded corner of my anvil.
Jim suggested making a cross peen shape on the end of my hammer and removing the chamfered edges which were creating a cut more than moving the metal, per say, the cross been shape moves the metal better with each blow than does the squared end with chamfers.


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To restore the edge I purchased an 1800 rpm (Baldor) grinder with 36 grit and 60 grit wheels. I first ground back the edge at 90 degrees until all of the damage was gone....it was about 3/4" of material! I thought the blade was dead, but decided to keep at it and see if I couldn't bring it back to life. I dipped the blade routinely to keep it cool, and surprisingly after reading all of the warnings about Japanese tools and high speed grinders, I managed to keep the blade cool throughout the process. One trick is not to grind up to a thin edge, leave enough, maybe 1/32" thickness or slightly less to finish grind by hand.


https://brianholcombewoodworkerblog.files.wordpress.com/2016/07/img_5595.jpg


The ura, not without a land. The hollow is quite deep this far back, about 1/32" at the center by my eyeball estimate.


https://brianholcombewoodworkerblog.files.wordpress.com/2016/07/img_5596.jpg


After grinding the blade back, my next step was to begin restoring a bevel, this is fairly straightforward work, but now both the hard steel and the soft iron are starting with equal areas of contact since the bevel is hollow ground. If equal pressure is applied the iron will wear quickly and the hard steel will hardly wear at all. I made certain to apply pressure to the edge mostly and still the angle did decrease from 28 degrees to 27 degrees.

Once a rough bevel was applied I wanted to get back to ura-dashi before committing too much time to the bevel. Those who've done the process know that when you're doing it, you're moving metal, so your once flat bevel is now....not flat, instead you have a hollow in the center of the bevel. I was able to restore the back to a very thin contact.


https://brianholcombewoodworkerblog.files.wordpress.com/2016/07/img_5597.jpg

After which I finished the bevel, though leaving anything rough behind the leading edge alone. I wanted to get the blade back into the dai and see if I had a cutting edge or if I had committed some hours to a trashed blade.

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The blade cut very well, now time to get it 100% back in shape. Back to Ura-dashi. Now with the blade thinned, the metal was moving exactly as it should. Even taps across the surface were producing and an incremental increase of the land on the ura.

https://brianholcombewoodworkerblog.files.wordpress.com/2017/01/img_5601.jpg

I leave the marks, just work the blade as usual and the marks that remain will slowly disappear, in my experience it takes about 2-3 good sharpenings to completely remove the marks.

https://brianholcombewoodworkerblog.files.wordpress.com/2017/01/img_5628.jpg

In reading a similar thread a few years back Winton suggested that the edge of a hammer was not good for ura-dashi, the comment was not given much notice but stood out to me. It turns out to have quite a bit of merrit

[Stanley Covington]

Nice job Brian!

I like the rounded hardy knob.

Stan

[Brian Holcombe]

Thanks Stan! My dad's collection of metalwork tools never ceases to amaze me, lol.

[Robert Hazelwood]

Thanks for sharing this, Brian. Detailed information on this process is a little sparse (at least in English). I've had to do a bit of this recently on an old blade I got from ebay- it came with quite a skew ground into it and a way too low bevel angle, so I had to do a lot of metal removal to get it into shape. So far I've had beginner's luck with ura dashi, I guess. After reading some advice in one of Stan's old posts, I made a little anvil out of threaded iron pipes with a cap as the top surface- it is actually quite similar in shape to the anvil accessory your dad gave you. Being malleable iron (I believe) the cap is quite soft, so this seems like it could be a good alternative for someone without easy access to such sweet metalworking equipment.

Not being too familiar with a cross pien hammer's shape, it looks like you just created a subtly domed shape from top to bottom on the small end of the funate genno, eliminating the hard chamfers in the process, correct?

Also, how do you like the Nagadai kanna?

[David Wong]

I had a similar failure a few years ago...

Japanese blade "tapping out" disaster (http://www.sawmillcreek.org/showthread.php?213187-Japanese-blade-quot-tapping-out-quot-disaster&highlight=disaster)

I now use a hammer (240g) similar in shape to the one Brian shows. I also use a piece of thick vinyl or lead sheet covering the striking area of the anvil, to better support the bottom of the blade. There continue to be occasions where I have difficulty getting the metal to bend. Just need more practice...

[Patrick Chase]

Nice post, Brian!

[Patrick Chase]

I had a similar failure a few years ago...

Japanese blade "tapping out" disaster (http://www.sawmillcreek.org/showthread.php?213187-Japanese-blade-quot-tapping-out-quot-disaster&highlight=disaster)

I now use a hammer (240g) similar in shape to the one Brian shows. I also use a piece of thick vinyl or lead sheet covering the striking area of the anvil, to better support the bottom of the blade. There continue to be occasions where I have difficulty getting the metal to bend. Just need more practice...

I think George hit the blade on the head (sorry, couldn't resist) in that old thread: The business ends of Japanese blades are extremely hard, and hard steels lack toughness and are inherently prone to fracture when subjected to impact loads, as for example from tapping with a hammer. The softer top layer in the laminate can only do so much to cushion against such loads. In other news, there is no free lunch, Santa Claus, or Easter Bunny.

As an engineer I'm not entirely convinced that Brian's blade was defective. Fractures tend to propagate rapidly through brittle materials once started (stress concentrations and all that), so the fact that it extended so far back from the blade doesn't really say anything about how it came to be in the first place. It might have been defective, or it might have been a tapping-induced point failure that propagated.

[Stanley Covington]

Japanese planes are wonderful tools, but as I have said before, they can be a pain in the butt. Before I learned how to do uradashi properly, I damaged more than one blade.

The key thing to understand is that uradashi is not about using a hammer to bend the high-carbon steel layer (hagane). Nor is it about applying impact force to the hagane. As Patrick correctly pointed out, this material is too hard/brittle to endure much of a bending force or impact force if applied directly by a hammer, and the hagane can be relied on to crack or chip if such attempts are made.

Use the hammer to rather deform the soft layer of steel (jigane) with an accumulation of many tiny dents. Yes, those little dents Brian made, and seen in his pictures, caused the jigane layer to deform a tiny bit with each dent. This created stresses which created a bending moment in the jigane. Being welded to the hagane layer, the jigane transferred that bending moment to the hagane layer over a distributed area causing the hagane leayer to bend in turn without cracking. It is a clever engineering solution.

Experience leads me to believe that strange cracks, of the sort Brian experienced, sometimes develop in the hagane because the bond between the two layers is not consistent, and that stress concentrations are created in the hagane as a result.

The round knob Brian used is clever because it increases the bearing surface area on the hagane that transfers the impact forces to his anvil (equal and opposite reaction), thereby reducing the PSI (stress) of the reaction forces on the hagane, and consequently the stress concentrations that might crack the hagane layer.

As David mentioned, a cushion of sorts helps. I have never tried lead sheeting, but that sounds like a clever solution. I tape paper or thin cardboard to my anvil. I use a small sledge hammer in a vise for an anvil. It doesn't take much mass to get the job done. The paper or cardboard help to keep the blade from slipping too.

The benefit of the rounded corners on Brian's funate hammer is debatable, IMO. You want to make dents. So the hammer needs to dig into the jigane a little. A rounded face does not necessarily improve the efficiency of this task, IMO. I have done it both ways, and prefer to make sharper dents than the rounded, pretty dents Brian made. But I can't say which is more efficient.

Try to make lots of little dents with light blows. Try very hard not to hit the hagane layer (ouch!). Be patient.

Stan

[Shawn Pixley]

This is off topic of the central point of the discussion (which is very cool). That poor hardie tool (the rounded bit) has been abused. As a smith, you cringe when you see a good tool abused like this. It is akin to someone taking a hammer to the sole of one of your good planes and putting lots of dents in it. These tools are meant to work with hot steel or much softer metals. Those dents will transfer to the material that is being worked. You will chase the repair of that damage through the rest of the normal smithing work.

It might have been preferrable to do the work on the plane blade with a ball peen hammer. As you have to work cold, you could get a cheaper hammer at HF. If and / or when damaged, is is easier to repair or sacrifice to the cause than the hardie tools. I have two sets of tools. One is hot work smithing tools and anvils. The hammers and anvil are all smoothly dressed.

Periodically, we all need to bang on cold steel for some reason or another. I use the hammer block on my machinist vise (not the post vise) and some hammers that are used for general work where I don't care if the faces become damaged / dented. If I really need to prvide some force, I have a plate I will place over the anvil and go for the small sledge.

Back to your regular programming... The thread is very interesting. While I have made damasquene steel via forge welding, I have never done a simple lamination and then worked it afterwards. I can see how a little "wrong" work could cause a delamination or facture.

[Brian Holcombe]

Very interesting discussion forming! I want to note that the shape of the funate is now more like a rolling pin and less like a thumb tack. Jim recommended me to shape it like a saw straightening hammer. The goal being to move the ji front and back rather than side to side. Not sure if it helped or if I'm simply much more aware of the subtleties of what's going on in the impact zone.

Robert, the nagadai is very enjoyable to use, nice and light. It has quickly replaced my other shooting board tools.

[Brian Holcombe]

Shawn, the anvil and associated tools came out of a high school, both were beat to hell. The anvil surface needed to be ground flat. I can certainly polish the hardy tool but I don't feel the ura-dashi process further abuses the hardy tool.

In other words those dents were there long before I received the tool, or even my father for that matter.

My machinist vise is from Kurt, I wouldn't bang on that....

The hard steel does not impact the hardy accessory, it is supported while the soft iron is worked. After all I'm using a hard steel hammer to impact the soft iron to no ill-effect on the hammer.

[Shawn Pixley]

Brian,

I didn't think you did the damage. I just hate to see good tools damaged like this. The soft steel won't be good on the hardie but I doubt you'd put those sorts of dents in it. Itis just bad practice to work cold steel on these sorts of tools.

[Brian Holcombe]

Ah, I see. As a metalworker, long prior to being a woodworker, I did not take offense to thought of using this as a type of dolly bar, which is exactly what it is being used for. The backing of a Japanese plane is not steel, it is very soft iron which readily deforms. The deformation is what makes this entire process possible. I would agree with you in not working steel on the hardy accessory, but soft iron....I think that can readily deformed using the hardy as my backup.

I do not come from a blacksmithing background, but a welding/fabrication and machining background which is why I have obviously a different take on what exactly is offensive to me. I can appreciate that as a blacksmith you may see this as less than ideal use.

I had considered making my own accessory for the hardy using brass as the backup, but ditched the idea when this solution was presented to me.

[Brian Holcombe]

I had a spare moment this afternoon, and your comment about how beat up my hardy accessory was couldn't be shaken.

Repaired;

https://brianholcombewoodworkerblog.files.wordpress.com/2017/01/img_5644.jpg

....now, dont begrudge me of my use of the tool :p

[David Eisenhauer]

OK, completely off topic Brian - how in the world do you post these very large, very close up photos? Please don't tell me "Google is your best friend", but perhaps a very short explanation that can point me in the proper search direction would be possible.

[David Eisenhauer]

Follow up to anyone that can help with my above question - I believe that I am looking more for camera info rather than "how to attach" info. My older Canon does not seem to be able to get that close and stay focused. Is there some trick to it or is it just buying a better, more close up type photo suited camera.

[Brian Holcombe]

OK, completely off topic Brian - how in the world do you post these very large, very close up photos? Please don't tell me "Google is your best friend", but perhaps a very short explanation that can point me in the proper search direction would be possible.

Believe it or not those are IPhone photos. I'm very particular about lighting and it helps a weak camera tremendously. My blog is my host and they host full size but of course I have to pay for the storage.

[Patrick Chase]

Believe it or not those are IPhone photos. I'm very particular about lighting and it helps a weak camera tremendously. My blog is my host and they host full size but of course I have to pay for the storage.

Indeed.

Phones unavoidably have very small sensors, but the modern higher-end ones (and all iPhones are fairly high-end) have good optics, low-noise electronics, and very clever image-processing. If you have enough light to allow the camera to operate at or near its base ISO and if the scene contrast (difference between lightest and darkest tones) is reasonably low then they do pretty well.

Each pixel in a state of the art SLR can record something like 12 stops (a 4000:1 ratio) from saturation to the noise floor at base ISO, and they do even better than that if you look at visually relevant areas instead of individual pixels. No phone can come remotely close to that sort of performance because they simply don't scoop up enough photons, but as long as you don't ask a phone to do stuff that needs that sort of performance it can do remarkably well.

Background: I worked in image processing for a fair while in between ME and CS careers. Imaging was my bridge between the two. I've also shot quite a bit with everything from phones to 8x10" view cameras (the kind where you put a hood over your head and stare at an upside-down and backwards image on ground glass).

[Phil Mueller]

Aw..now you've made it too pretty to use. Very nice restoration though.

[Brian Holcombe]

Indeed.

Phones unavoidably have very small sensors, but the modern higher-end ones (and all iPhones are fairly high-end) have good optics, low-noise electronics, and very clever image-processing. If you have enough light to allow the camera to operate at or near its base ISO and if the scene contrast (difference between lightest and darkest tones) is reasonably low then they do pretty well.

Each pixel in a state of the art SLR can record something like 12 stops (a 4000:1 ratio) from saturation to the noise floor at base ISO, and they do even better than that if you look at visually relevant areas instead of individual pixels. No phone can come remotely close to that sort of performance because they simply don't scoop up enough photons, but as long as you don't ask a phone to do stuff that needs that sort of performance it can do remarkably well.

Background: I worked in image processing for a fair while in between ME and CS careers. Imaging was my bridge between the two. I've also shot quite a bit with everything from phones to 8x10" view cameras (the kind were you put a hood over your head and stare at an upside-down and backwards image on ground glass).

Exactly, I had a very frank conversation with an excellent photography equipment store owner who suggested do everything to make the job easy on the camera before upgrading the camera.

For instance, I have one area of my shop that I use as a sort of photography spot. I painted the walls around it super white (BM color), added lighting including spot lighting, and I can get some pretty high quality shots out of the phone.

I noticed I get the most realistic looking color range out of the wood when I'm placing it against a white background, so thats what I did. It also makes it easier on the lighting to have white walls.

If you can control your environment, then you can work around a lesser camera.

[Patrick Chase]

For instance, I have one area of my shop that I use as a sort of photography spot. I painted the walls around it super white (BM color), added lighting including spot lighting, and I can get some pretty high quality shots out of the phone.

I noticed I get the most realistic looking color range out of the wood when I'm placing it against a white background, so thats what I did. It also makes it easier on the lighting to have white walls.

White walls help you in three ways:

First, they help you avoid mixed color temperatures within an image. As an example of what you don't want, if you have a blue wall then you'll end up with fairly warm lighting on surfaces that are illuminated directly from your light source, and cold lighting in the shadows where most of the light is bounced in. There are cases where you may want that effect, but product photography usually isn't one of them. The same thing happens when you mix flash with ambient, unless you filter the flash to match (some recent phones can do that automatically).

Second, white walls make life easier for the automatic white balance (AWB) algorithm in the camera by providing a large neutral highlight reference. Most cameras only shoot JPEG, so you're more or less dependent on the camera to get AWB right the first time. If you're shooting RAW with a "real camera" (tm) then this isn't such a big deal since you can clean it up easily in post.

Third, white walls help keep the scene range within the dynamic range limits of those itsy bitsy sensors by bouncing light into the shadows. Again not as big of a deal with a "real camera".

On a quasi-related note, have you ever tried cross-polarization? It can really bring out the color in higher-gloss finishes, though at the expense of potentially deadening their appearance. You can even do it with a phone cam...

Way OT now, except that we are talking about photographing furniture :-).

[Shawn Pixley]

Beautiful dressing job Brian!

[Brian Holcombe]

White walls help you in three ways:

First, they help you avoid mixed color temperatures within an image. As an example of what you don't want, if you have a blue wall then you'll end up with fairly warm lighting on surfaces that are illuminated directly from your light source, and cold lighting in the shadows where most of the light is bounced in. There are cases where you may want that effect, but product photography usually isn't one of them. The same thing happens when you mix flash with ambient, unless you filter the flash to match (some recent phones can do that automatically).

Second, white walls make life easier for the automatic white balance (AWB) algorithm in the camera by providing a large neutral highlight reference. Most cameras only shoot JPEG, so you're more or less dependent on the camera to get AWB right the first time. If you're shooting RAW with a "real camera" (tm) then this isn't such a big deal since you can clean it up easily in post.

Third, white walls help keep the scene range within the dynamic range limits of those itsy bitsy sensors by bouncing light into the shadows. Again not as big of a deal with a "real camera".

On a quasi-related note, have you ever tried cross-polarization? It can really bring out the color in higher-gloss finishes, though at the expense of potentially deadening their appearance. You can even do it with a phone cam...

Way OT now, except that we are talking about photographing furniture :-).

Hah, indeed pretty far off topic. I've never tried cross polarization, this can be done with an iPhone?


Thanks Shawn! Fair to say I should not have abused looking tools in my shop.

[michael langman]

I had to read up on Ura Dashi because I never heard of it before, and did not understand what Brian was trying to accomplish.

It reminds me of bringing bowed pieces of tool steel, after being heat treated to straightness again by peening with a ball peen hammer. An older German Tool an Diemaker taught me this many rears ago.

I made a carbide punch with the end ground to about a 25 degree angle and rounded on the end slightly, to use, instead of the round side of the hammer.

It moved the metal more precisely for me and helped to hammer with better accuracy and control of amount of impact.

Very interesting post Brian. Thanks for posting it.

[Brian Holcombe]

Thanks, I think there are some significant similarities there. I've also straightened knives and find the process far far more unnerving than ura-dashi, but also another situation where hard steel can be worked.

Glad that you have found it to be an interesting topic!

[Patrick Chase]

Hah, indeed pretty far off topic. I've never tried cross polarization, this can be done with an iPhone?.

You can buy various solutions for mounting filters on an iphone, or you can just tape on the same film (https://www.amazon.com/gp/product/B000B78216/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1) as you would for polarizing the light source (Rosco Cinegel is sort of the gold standard for this sort of thing, there are cheaper options as well). For the most part phone cameras don't need circular polarization to function as they don't have polarization-based beam splitters like an SLR.

EDIT: The idea behind cross-polarization is that you polarize the light source[s] in one direction, and then use another polarizer set at ~90 deg to that direction on your lens. This eliminates specular reflections just like using a polarizer outdoors (in that case the atmosphere polarizes the sun). It's a very old trick in macro and document-copy photography.

[Brian Holcombe]

Thanks for the idea! I may give that a try.