How to Sharpen a Plane Blade Part1: How to Make a Beautiful Ura (Uraoshi Technique)

[soatoz]

This must be very useful for those of you who already own a new plane blade but have not adjusted it yet, or someone planning on getting one but hesitating because you are not sure if you could manage adjusting it properly.

Now you need not worry!
Kore wo yome!(Read dis!):2tsup:

How to Sharpen a Plane Blade Part1: How to Make a Beautiful Ura (Uraoshi Technique)

I would like to introduce a fail safe way I have created, for making a perfect shaped ura for a Japanese plane blade. Making a good looking ura is very difficult. Many users compromise with a ura that is deformed and ugly. But with this method, anyone can make a beautiful ura without almost any practice. I have never read or heard of this method before, so this would probably be the first time to be introduced, at least in a written form!

Pic.1 shows the equipments you need for this method.

Pic.1

http://www.geocities.com/soatoz/photos/Ura_Dashi/Pic1.jpg

a. A small size rule.
b. A kana-ban. Kana-ban is simply a bar of soft steel. If it is hardened it would be impossible to fix the surface, so it is not hardened too much. It is specially designed for uraoshi purpose. (You can substitute this with a very hard #1000 grit stone, but you would have to flatten the surface more often. Kana-ban is very heavy so it would be very expensive item, but it is far better compared to hard med grit stone so I recommend to get it.)
c. Diamond stone to fix the surface of the kana-ban.
d. Kongou-sha. Coarse grit compound that has strong cutting strength.
e. Plastic tape
f. Piece of hardwood wrapped with paper and heavy duty duct tape.
g. Coasters from your local bar for spacers. I find this certain brand’s coaster the best (please laugh).
h. And lastly of course your new plane blade.

Okay here we go!

1. Check how much the steel is bent with the small rule. If the steel is miraculously not bent at all, then you don’t need to read this. Just do uraoshi as usual. But it is usually bent because of the difference in tension between the iron and the steel. The older the blade the more bent.
2. Wrap a paper around the head of the plane blade and secure it with the plastic tape to avoid the black skin to be scraped off.
3. Set the kana-ban and the hardwood as shown in Image 1, and check the space between the steel and the kana-ban, and adjust the height.
4. Sprinkle some kongou-sha on the kana-ban. Just a little at a time would do. About the tip of a cotton swab.
5. Move the blade as shown in Image 3 in red arrows. Move back and forth in a short stroke as shown with set of fine red arrows. Don’t keep using the same part of the kana-ban, but move it as shown in blue arrows. Turn around the kana-ban and use the other half side.
6. If any part of the tip does not touch the stone, you need to perform uradashi at this stage. I will explain about uradashi in another article.
7. After a little while, going back and forth using the whole surface of the kana-ban, wash away the black water, and flatten the surface using the diamond sharpener.
8. Keep doing this until the red part of the blade shown in Image 1 is ground off.
9. Once enough flat surface has been created, then you can go on to the finer stones and polish it up. Remember to keep only the flattened part touching the stone.

http://www.geocities.com/soatoz/photos/Ura_Dashi/SHARPE1.jpg

http://www.geocities.com/soatoz/photos/Ura_Dashi/SHARPE3.jpg

Diagnose your uraoshi technique.

Image 2 shows three kinds of ura. A is the correct shape. B and C are the most frequently seen shape of ura. The red part shows where it was ground off.

- A is done by the method explained here. Only about 1/3 of the steel is touching the kana-ban.
- It will look like B if you let all surface of the steel touch the kana-ban. The most common shape of ura.
- C is when the kana-ban is not flat. You need to check with an straight edge rule and check the condition of the surface of your kana-ban. Once you are used to managing the surface you don’t need a rule to see if the kana-ban is flat or not, but until you get used to it, it is better if you constantly check with a rule. Same thing can be said with the stones you use to polish up the ura, after this kana-ban uraoshi.


http://www.geocities.com/soatoz/photos/Ura_Dashi/SHARPE2.jpg

If you have any questions, please feel free to ask.

Now you can enjoy uraoshi!

[willie]

Thanks for this Soatoz. It does seem like a fairly foolproof way of setting up a nice edge.

BUT...... do new plane blades require ura-dashi? If so, does this tecnique of yours replace ura-dashi as well or should we do ura-dashi first, provided we can do it without chipping our plane blades?

[soatoz]

Thanks for this Soatoz. It does seem like a fairly foolproof way of setting up a nice edge.

BUT...... do new plane blades require ura-dashi? If so, does this tecnique of yours replace ura-dashi as well or should we do ura-dashi first, provided we can do it without chipping our plane blades?

If you want your ura to look beautiful, unless you get a fully adjusted one from someone who can properly adjust a plane blade, or Kanzen-sugu-zukai (Fully adjusted by the store for extra charge) plane, ura-dashi is always necessary. If you don't mind the deformed look of ura, then you can simply grind until whole width of the tip of the blade touches the stone. But depending on the condition, you might need to grind a lot! So, I personally think ura-dashi is essential. You can see if your blade needs ura-dashi or not in step 6. Sometimes the tip of the blade is flat enough you don't need to do any ura-dashi.


New blades are not adjusted at all, and especially old ones are very difficult to adjust since the steel is warped more.

I personally feel that ura-dashi is very easy, and I have never chipped the blade. But I hear some terrible stories, so it is better if you tapped lightly in the beginning and see how strong you can tap. You need to hit strong enough but not as strong to chip the blade. And of course you need the right equipments. An anvil and a small hammer.

If anyone wants me to adjust and sharpen your blade, old or new (plane, chisel, etc.), you can contact me through email, or private message. If you live around Northern Beaches, you can just bring it over. If the blade is a particular one I want to try, I can do it for free, because I want to see what it's like!:wink: All Usui Kengo (except for Ken-mei), Chiyozuru Nobukuni, Tsutsumi Tomokazu planes, Ichihiro, Nishiki chisels are welcome. Anything that is made of genuine tama-hagane (you can tell me the mei and I'll know) is welcome as well. You might find out that your plane blade cuts more than you'd thought!

[Groggy]

I wonder how many of us jump on these posts when they appear? Fascinating stuff, thanks again soatoz.

[Skew ChiDAMN!!]

Can't speak for anyone else, but I'm keeping an interested eye on 'em. :)

[underused]

Yep, me too:2tsup:
Soatoz, would like to see some of what you've made using your handtools:)

[willie]

Okay, I missed Step six. I thought Ura-dashi was first but apparently this is not so.
Is Ura-dashi always before inital grinding (on stone) with new chisels or does it depend?

[JDarvall]

Looks good alright.

western planes totally different though uno. And my mind set stuck on them. And I won't be replacing them with japanese planes. So, its hard to get really involved.

But, I think its good to someone get passionate about them. :)

[dburnard]

Very useful information, So. I've been pondering a few things in this area lately, and there are a couple of things I've been wondering about...

On another forum, the subject of this extra curvature came up and it was suggested, that it was an intentional additional means for the blade to wedge/spring itself into the dai. I was skeptical, since I knew the origin for much of this curvature is the relaxation over time of the stress from yakiire (hardening). The toolmaker straightens the blade and often waits a considerable time before doing so to lessen this problem, but over time the blade continues to relax and the curvature "overcorrects" and the blade becomes slightly concave along it's length as your pictures show.

I have seen another possible reason for blades with large amounts of curvature - it means that you don't need to do ura-dashi on a "young" blade. No tapping/bending is necessary because the blade is already bent in the proper direction. Thus when the blade goes past ito-ura, you can just flatten the back a bit without tapping - ura-oshi only. Obviously this would apply to a new blade curved from the start - but I have not seen one, and only guessed at their existence from looking at web pages I can't really read. :(

While these explanations seem plausible, I don't see how such a curved blade fit's into it's dai - I would think that as a curved blade is tapped in to the dai, the blade would tend to dig out the grooves to match the curve of the blade - and in effect loosen the fit. In order to make a dai to fit such a blade it would need to have the grooves cut to match the curve of the blade - and I've never seen anything like that before.

When the dai-maker cuts the dai for a new blade, the extra curvature will not have happened yet, and so the grooves in the dai will be straight, fitted for the blade which was straight as the time the dai was made. Over time the blade may start to recurve, sometimes more sometimes less, sometimes not at all. If it sits on a shelf for many years, the dai will continue to shrink as it ages and adjusts to the local climate and the blade that may no longer be straight sided. So after several years they don't fit well together at all.

How to resolve the problem? With the blades I've fit in the past there wasn't so much curvature to worry about, but I have a couple in mind now that are fairly curved (luckily one of them has no dai yet).
If I remove too much curvature from the hagane side of the blade, then I will have changed the thickness profile of the blade and the blade will no longer fit the grooves in the dai - although fortunately the dai will have shrunk a bit and that may compensate for much of this.

Questions:
Q1: What does a dai-maker do when someone sends in an old blade (which has become curved) for a new dai - would the dai-maker flatten the blade himself first? I suppose it depends on whether one asks for the blade to be fully fitted in the dai, or not (which would leave the flattening and fitting to the customer).

Q2: So when we refit an old blade into an old dai, how much of the curvature should be removed before refitting the dai? In your drawings it only looks like you tried to remove a portion of the curvature. For some blades the curvature is small enough (only .002inch/.05mm or so) that removing it all is no problem - or it's so small that it should just be left alone. However on other blades the curvature is large enough (0.5 - 1mm) that removing all of the curvature at once would significantly alter the ura-suki, could make the hagane very thin at the edge, and noticeably change the taper of the blade so it may become loose in the dai, perhaps requiring a new dai. What would you suggest?

[soatoz]

Okay, I missed Step six. I thought Ura-dashi was first but apparently this is not so.
Is Ura-dashi always before inital grinding (on stone) with new chisels or does it depend?

You need to check if there is any need for uradashi, and if there is, you need to check "where" exactly you want to bend, so you need to rub against the stone a bit.

But you'd better not do ura-dashi for chisels unless you are very confident with the process. The mimi(ear. The steel wraped around the corner) being wrapped around makes it easier for the chisel to chip. It would be a disaster when that happens!

Give me a bit more time, and I'll work on Uradashi article!

Thanks

[soatoz]

Yep, me too:2tsup:
Soatoz, would like to see some of what you've made using your handtools:)


Really~~? Should I~~~?
Oh well, why not.

I tried to choose photos with tools in.

http://www.geocities.com/soatoz/photos/Work_of_So/Dovetail.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Chisel_case.jpg
From left 4 Tasai mortice chisels, 3 very old Tokyo mortice chisels (Yoshihiro), Very famous Sanjyo blacksmith Tsunehiro Carpenter's chisel, my grandfather's old carpenter's chisel (Katsumori).


http://www.geocities.com/soatoz/photos/Work_of_So/Mallet.jpg


http://www.geocities.com/soatoz/photos/Work_of_So/Ebony_head.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Cabinet_making_plane.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Cabinet_making_plane1.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Cabinet_making_plane2.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Cabinet_making_plane3.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Tama_hagane.jpg
100yrs old tamahagane chisels that actually cuts! From my grandfather.

http://www.geocities.com/soatoz/photos/Work_of_So/Sewing_Box.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Sewing_Box1.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/Sewing_Box2.jpg


http://www.geocities.com/soatoz/photos/Work_of_So/Inlay.jpg
The inlay was carved out of a huge (about 25cm) Japanese Shell. I broke 2 drill bits... It was so hard.

http://www.geocities.com/soatoz/photos/Work_of_So/kogatana.jpg

http://www.geocities.com/soatoz/photos/Work_of_So/tamahagane.jpg
Tamahagane kogatana. This one is a common very britle tamahagane.
It's so soft but it cuts very well. This kind of soft but keen edge is called Ama-gire.

[soatoz]

Looks good alright.

western planes totally different though uno. And my mind set stuck on them. And I won't be replacing them with japanese planes. So, its hard to get really involved.

But, I think its good to someone get passionate about them. :)

Yeah, I know! I had always assumed that not many people would be willing to try Japanese planes. I've heard many people are using J chisels and saws, and that's understandable, but planes, even Japanese are having hard time using them properly. But it seems that many people are interested! So I decided to sell them, and write an detailed introduction for the beginners to be able to try them.

One friend from the forum who has contacted me has an extensive collection of Gordon planes, and they were absolutely beautiful. I was wondering why he still wants more planes, but he said that he wants to try them out of respect for Japanese woodworking. And he's making bokuto (wooden sword for martial art) so it makes sense:)

I think for someone who already has a set of great quality western planes, tiny planes might be a good choice if you'd like to see the difference out of interest. They are cheap so easier to buy, and very light so it suits small projects. And much easier to adjust too. Do you have any tiny planes in western style planes? Like 2cm wide, 7cm long?(this is the size of the block, so the blade width is smaller.)

Thanks

[willie]

dburnard (http://www.woodworkforums.ubeaut.com.au/member.php?u=15338) vbmenu_register("postmenu_478495", true);
Apprentice (new member)
Join Date: Mar 2007 Location: Oregon (bloody American!)
Posts: 1


Welcome dburnard. And please take it from me, we know "bloody Americans!" are not all the same and I for one, have much respect for the way many Americans go about their woodwork and crafts (like car restoration) in general.

By the way, you are obviously no beginner when it comes to Japanese tools. Feel free to tell some of us (who are beginners) about your experiences.

[dburnard]

Thanks Willie, a bit of tongue in cheek in my bio.

Woodwork is a hobby for me, and I've been using japanese hand tools pretty much exclusively since about 1988. I'm a bit of a pack rat so I have a small collection of the tools, but lately I have started studying the making of the tools themselves which has opened up a whole new world of questions for me. So's posts are very interesting and informative so I thought I'd join in the fun. One of my favorite "murican" sites is Daiku Dojo, which is organized by the fellow who inspired me to jump ship and work with japanese tools. They have classes and lots of interesting pictures and projects to look at: Daiku Dojo (http://www.daikudojo.org/).

Keep up the good work So - I especially like that little spokeshave!

[underused]

Soatoz,

Theres some beautiful woodwork there mate! very impressive!
Did you use sandpaper, or was it traditionally japanese, and plane only:)
What wood is the drawer fronts made from? looks really nice.
Cheers!

[soatoz]

Hi dburnard!

Sorry it's taking me so long to get back to your email, but like I wrote I wanted to take time replying to that one, so give me a bit more time!

Let me just answer these for now.



Q1: What does a dai-maker do when someone sends in an old blade (which has become curved) for a new dai - would the dai-maker flatten the blade himself first? I suppose it depends on whether one asks for the blade to be fully fitted in the dai, or not (which would leave the flattening and fitting to the customer).

I think the answer to both questions are basically the same and YOU have given me the answer yourself, so I'm gonna cut and paste it!:D

You were saying that "I would think that as a curved blade is tapped in to the dai, the blade would tend to dig out the grooves to match the curve of the blade" and that's exactly correct. Hahaha, you have answered instead of me:)

Then you said "In order to make a dai to fit such a blade it would need to have the grooves cut to match the curve of the blade - and I've never seen anything like that before." but I think you have! Every dai should be like that because the groove is cut to match the curve by the blade itself like YOU have suggested!

It is thus very important not to touch (shave, file, cut) the upper part of the slot yourself, but let the blade do the cutting. You adjust the looseness of the slot by shaving the Omote-najimi(the surface where the front side of the blade touches. Front side is the side without the mei=brand.) I will write an detailed article on how to set the blade into the block for the first time, soon(?)



Q2: So when we refit an old blade into an old dai, how much of the curvature should be removed before refitting the dai? In your drawings it only looks like you tried to remove a portion of the curvature. For some blades the curvature is small enough (only .002inch/.05mm or so) that removing it all is no problem - or it's so small that it should just be left alone. However on other blades the curvature is large enough (0.5 - 1mm) that removing all of the curvature at once would significantly alter the ura-suki, could make the hagane very thin at the edge, and noticeably change the taper of the blade so it may become loose in the dai, perhaps requiring a new dai. What would you suggest?

Yes, this is a good "helping question" for further understanding my above article. Thank you!

The intention of uraoshi is not to make the ura flat in order to match the dai, but to gain enough flat surface so that you can maintain the flat contact between the steel and the stone. (Someone help me out with the English here!!) If there is only 5mm of flat area, it is very difficult to keep it apressed onto the stone flat, so you'd need about at least 2cm. The amount depends on how curved the steel is.

If the curve is great, and this was the case with my drawing being exagerated, you can only grind off a little, because as you have explained you'd be grinding so much and loosing the ura-suki=the hollow. And you don't want to bend it any further either, thus you need to keep the ura-dashi minimal. And as you use it you gradually grind off the blade side of the ura and try to increase the flat surface. You start off from 1 in the below drawing, and by the time you've sharpened your blade, uhhh I don't know 100 times? you'd be at the #2 line, and #3 when you have sharpened 300 time! The below drawing is super exagerated to make it easier to see.

http://www.geocities.com/soatoz/photos/Ura_Dashi/SHARPE4.jpg



You need to press the blade side harder, and try to kind of lift the other side (called kai-saki, the lamination line) a little without actually lifting it up, creating more pressure on the tip of the blade and less on the kai-saki side. By doing so you can avoid looking like B in the above article.

http://www.geocities.com/soatoz/photos/Ura_Dashi/SHARPE5.jpg



If the curvature is just a little, basically you can flatten the whole steel part. Again you need to press the blade side harder, and kai-saki side lighter.

Thanks for the question. I hope I have answered your question well enough.

Talk to you soon.:)

[JDarvall]

Do you have any tiny planes in western style planes? Like 2cm wide, 7cm long?(this is the size of the block, so the blade width is smaller.)

Thanks

no. not that small. You mean like violin makers planes ?

The smallest I've got is around the block plane size. And .....my planes arn't pretty mate like yours .... not in me to really get into that side of it unfortunetly.

But lovely work in those pictures. Great big thick blades are always appealing to me. And the hollowed backs I always thought was a good concept.

:)

[dburnard]

Thanks So, like many things in life - one often knows the answer, but doesn't realize it yet. :doh: I' have been doing the proper things - but the blade with big curvature was outside my experience and threw me a curve - so to speak. Glad to make it easy by providing my own answers.

Dead on - never mess with the top cut of the groove. Which is why they are the critical saw cuts when making a dai from scratch - they need to be straight and parallel to each other or you might as well just chuck it and start over. For the newcomer, rubbing a pencil or something similar on the "underside" of the blade while fitting will help point out the tight spots that need to be relieved. We'll all look forward to an article (or a 3 part series on DVD!) from So on dai fitting when he can find the time.

I guess I didn't look closely enough at the dai to detect any curvature - but since the residual curve in most blades is so small I would have had a hard time seeing or measuring it. I'll go measure the blades I use regularly for curvature and carefully check to see if the dai matches. Some will be old enough that the curvature will likely be gone but others are newer or not used as much.

Very good drawings and description of the balance between needing a flat part on the back so you can actually hold the plane on a stone for maintaining the back while sharpening , and the need not to remove so much that the hollow is lost unnecessarily. I don't think I've ever seen as good an explanation of this before. Just to be crystal clear for others the 1-2cm flat area So refers to is not measured in the middle of the blade - but measured at the sides. That reminds me of the name I have always heard and used for the flat part of the blade between the cutting edge and the hollow "puddle" in the back - we call it the "land" since it separates the puddle from the edge. I've wondered if that name originated in Japan?

Anyway then, for my rather curved blade I should approach the flattening over a period of time - doing just enough for now that I can sharpen effectively and do a bit of maintenance along the way until regular sharpening and periodic adjustments remove the excess curvature.

It does sound as though you (like me) don't think the hagane curvature is left/put there on purpose to aid in securing the the blade in the dai - otherwise you'd be trying to preserve the curvature as much as possible, instead of making a nice wide >1cm flat to work with. I could be wrong though and would like additional confirmation of this since it affects how the blade is actually made, I will try to confirm with a blade maker and a daimaker if I can.

An aside - some folks ask - if you can tap a blade one direction why can't you just tap it the other way and remove the unnecessary curvature. If you think about what's happening, bending the blade so that the hagane side becomes hollow puts the hagane side in compression and tapping the other way puts the hagane side in tension (stretching). Highly hardened high carbon steels can handle the compression pretty well so long as it's fairly uniform - but it does not handle tension very well and the common result is a crack.

[soatoz]

It does sound as though you (like me) don't think the hagane curvature is left/put there on purpose to aid in securing the the blade in the dai -

No, it is definitely not intentional. This is not my opinion but a fact. Many of the most expensive sugu-zukai planes have absolutely flat back. The block maker spends hours making it flat and grinding the hollow again, if it is lost too much. So you can see why kuro-ura (the back that has the oxide film intact) which is flat is so special.

Ichihiro takes extra care for his chisels not to be curved. Like you've explained he makes it convexed and expect it to be flat once he hardens.