Can someone explain how a Japanese long plane planes flat surfaces?

[george wilson]

In the latest issue of Popular Woodworking is an article that says,in diagram and extended description that the Japanese naga-dai kanna,a 15"-16" long Japanese plane,has the sole made hollow. It is about 1/64" hollow on the bottom,touching the wood only at the front and rear of the sole. There seems to be no mistake in what I have read. The sole does not touch the wood just in front of the blade as in the common configuration.

My question is,how does such a hollow sole not plane a bit more off the wood at the beginning and end of the stroke,when the iron is allowed to be in full contact with the wood,leaving the wood a little convex. What am I missing here?

Every one always wants to make their Western planes as flat as possible. This isn't article making sense to me. I have never used Japanese planes,so please educate me.

[David Weaver]

I can't resist. ....

it's made possible by spiritual magic.

I just got a mosaku, and I spent a lot of time yesterday when the power was out tuning my arsenal (er some of it) for some furniture work, so nobody call me a hater for not talking to the wood and making it a quasi religious experience!!

[John Coloccia]

Shoot, I'm not even sure how a western plane works. Always seemed to me like the area just behind the blade should be exactly the same depth as the plane iron in order to truly flatten something.

[John Coloccia]

dumb question: I've heard of this before and I always assumed that the hollow was across the width and not the length. I figured it was just done like that to make it easier to flatten. It never occurred to me that it was lengthwise!

I guess that's more of a statement than a question :)

[David Weaver]

Sounds like a statement to me.

I'll leave it up to someone else to ponder the hollow and what the reason is that it's there. For me, it makes it easier to prepare the sole and keep it true. According to odate, depth varied by craftsman. I have seen burnishing wood mentioned, too, but there isn't going to be a lot of that on woods we use here, and you plane off a lot of the burnished surface, anyway.

I let my pww subscription lapse, no interest in the article, either.

Odate's book states three points of contact for the plane george mentions. It is intended to prepare a flat surface for a smoother. Go figure it makes more sense at three points. If the article says something different, I think i'll fall back on odate's information.

[Greg Wease]

We have had a couple of Kezouro-kai planing contests at Palomar College sponsored by Hida Tool. Several Japanese temple builders (at least one designated a "national treasure") came to demonstrate the proper set-up of Japanese planes (kanna). After flattening the sole they would remove a couple thousandths with a scraper between the toe and the mouth and between the mouth and the heel to reduce drag. This way the area around the mouth was at the same level as the toe and heel despite what PW says. Full-width, full-length, micro-thin shavings were the result. More important, the surfaces were glass smooth. Should note the wood was yellow cedar rather than hard wood.

[george wilson]

This was Wilbur Pan and another author's article. No mistake,just the toe and the heel touch the wood. Diagramed and discussed at length. The mouth of the plane does not touch the wood,as in the usual configuration. Me no geed dis!!!

P.S.,if the area just behind the plane iron was exactly the same depth as the iron,it would rub the wood,and cause the cutter to soon rise out of the cut.

[Frank Drew]

In my experience working with Japanese carpenters, they used a scraping plane to hollow the soles of the planes; on what could be considered their smoothers (about the length of a Western jack plane), only a small strip at the front of the sole and another right in front of the blade mouth touched the wood you were planing, everything else was relieved, including the entire sole in back of the blade.

On the longer planes, three small strips made contact -- the toe, right in front of the blade, and the heel.

No one tuned their plane soles so that only the toe and heel touched.

[Chris Mahmood]

The article isn't correct, at least according to what I learned from classes with Jay Van Arsdale, Toshio Odate's books, and hanging around the two Japanese tool stores where I live (Japan Woodworker and Hida Tool).

There are two sole configurations I know of (there are probably 40, Japanese techniques are pretty evolved), a) roku-dai and b) another whose name I can't recall. Roku-dai is used for jointing and flattening and the sole has a very slight (1/64" would be a lot) concavities scraped between the front and cutting edge and cutting edge and back so that the sole only touches the surface at the front, cutting edge, and back. b) is used for smoothing and dimensioning and here the entire front of the sole is scraped so that the plane only touches at the back and the cutting edge. I've seen planes with long soles that have an extra contact point when setup as roku-dai between the front and cutting edge to help avoid snipe but crutches like that would probably earn you a beating by the master in the old days.

The naga-dai kanna would be roughly a jack plane and be roku-dai as far as I know. I haven't seen the article you mention but maybe the author had modified it for shooting miters or something like that?

[Tim Put]

I have not seen the article, and I am surprised by the claim that Japanese 'jointer-ish' planes do not have a contact point in front of the mouth; but I can comment on the operation of planes generally.

I'll be brief. Planes don't make flat surfaces, they make surfaces that conform to the arc of a very large circle. Three points define a circle, depending on the plane those can be either: the toe, the tip of the blade, and the heel (with the mouth only serving to limit the depth of cut); or the toe, the mouth, and the tip of the blade.

It is very important to note that, even metal bodied planes, are flexible (thus the need for a mouth to limit depth of cut, among other effects of flexibility).

[Johnny Kleso]

When you place plane on wood you place the Toe and just in front of the mouth on the board before the blade starts cutting..
The hollow makes no difference..
Coming off the wood the blade stops cutting before the back of the mouth goes to the hollow..

You just cant plane sideways with them :)

[Chris Vandiver]

I haven't seen the article George mentions but I will say that a properly set up naga-dai-ganna has contact points at the toe, at just in front of the mouth and at the heel of the plane. Sometimes a "land" is put between the toe and the mouth as well.
The idea of hollowing a sole like this is that it is much easier to keep these small lands in "plane" with each other than to do so with the whole sole.

[Pam Niedermayer]

This is fairly confusing to talk about.

First, Japanese planes are pulled, not pushed. This is key.

Second, because of this, the terminology seems backwards. The toe is the western heel and the heel is the western toe.

Third, the sole treatment is different for different types of planes.

Fourth, in what follows, I talk about front (the western toe, Japanese heel) and back.

Inomoto-san, one of the premier dai makers, taught me how to make smoothers, The smoothers I make produce read thru (literally) shavings. Smoothers have a hollow scraped between the front and the area in front of the mouth. It's very slight. I've never measured it, but examine it with a straight edge with a cut out for the blade, and stop scraping when it's more or less uniform. The very front and the area immediately in front of the mouth are coplanar. The backs of the planes, behind the mouth, are also relieved by roughly the same amount.

Other planes, such as jointers, typically in this country at least, aren't relieved at all, flat from front to back; however, often jointers have 3 or 4 contact points defining the hollows: very front, immediately in front of the mouth, immediately behind the moutn, and at the very back. I suspect this stuff varies based on the wood being planed.

I'm sure there are variations, I just haven't made them. And observation of other Japanese planes, such as rebates and skewed rebates, have no hollows. Finger planes, small Japanese planes, have no hollows.

Pam

[Pam Niedermayer]

.. I just got a mosaku, and I spent a lot of time yesterday when the power was out tuning my arsenal (er some of it) for some furniture work, so nobody call me a hater for not talking to the wood and making it a quasi religious experience!!

Congrats! How do you like it? There are no hollows scraped on mine. Yours?

Pam

[David Weaver]

Pam, haven't used it yet or looked over the dai much, just got it in the mail. Hopefully will do it this weekend, though I don't have a project to use it on yet - in the middle of building two things cherry per wife's orders, but I guess I could try it out on them. I haven't had trouble on soft/medium hardwoods with cheap white steel planes.

Still trying to figure out who puts a stamp on the dai where it looks like a snowman with a scarf - do you know which maker that is? I thought inomoto maybe did that, but I see from daiku dojo that's not his mark.

(i snarfed this picture from the auction for it, but since I bought it, I doubt the seller will mind).

[george wilson]

So,most seem to agree that at least 3 contact points,with 1 being in front of the blade,are needed. The article did assert that the long plane bottom was just hollow. That the 3 contact points were used on the shorter plane.

This isn't complicated. The 3 point contact makes sense to me. I think the article is just plain wrong,which is surprising to me. You can mis print a statement,but when you also draw a diagram,it is doubly misinformation.
Doesn't anyone here subscribe to Pop. Woodworking??? I could copy the article and post it,but I don't think it's allowed,or legal.

[Sam Takeuchi]

I don't have detailed info, but that's a dai made by Nashiya and quite well regarded dai maker. You find this stamp on a lot of Japanese planes.

I think that stamp is supposed to be calabash. Back in the old days, the Japanese made and used it as water or booze bottle.

[Orlando Gonzalez]

Here is some info from Stu's blog:

"The shita-ba, plane bottom, is not flat as might be found on other planes. The reasons for this is to reduce the effort required to pull the plane on the wood being planed and to allow the critical areas at the very front of the plane (in it's direction of travel) and the area just ahead of the mouth to be easily and quickly adjusted so they are 'in plane' with each other. Aside from these two critical areas, most kanna have the remaining area of their bottoms 'relieved' so they are not touching the wood being planed at all. There are exceptions to this rule of course, but the common dimensioning or smoothing plane only touches the wood being planed in these two relatively small areas."

[george wilson]

Another agreement that the plane must touch just ahead of the mouth.

[David Weaver]

I got an email explaining the article. The comment in the article is based on Odate's comments at an event that the plane touch at the heel and the toe, and that there is still an area in front of the mouth that isn't scraped hollow, but it is slightly proud of the heel and the toe, and the iron is set exactly in line with the heel and the toe.

Since I don't get the magazine, that's about all I can relate. I'm still a little confused. I don't really follow instructions on what you're "supposed" to do with the planes, though. I just use them, and when they work right, I don't bugger with them much - a copule of times or year to check if they're true, and I haven't yet had a good quality dai move much at all other than to shrink tight on the iron or chipbreaker, but they stay flat pretty well.

[Pam Niedermayer]

Pam, haven't used it yet or looked over the dai much, just got it in the mail. Hopefully will do it this weekend, though I don't have a project to use it on yet - in the middle of building two things cherry per wife's orders, but I guess I could try it out on them. I haven't had trouble on soft/medium hardwoods with cheap white steel planes.

Still trying to figure out who puts a stamp on the dai where it looks like a snowman with a scarf - do you know which maker that is? I thought inomoto maybe did that, but I see from daiku dojo that's not his mark.

(i snarfed this picture from the auction for it, but since I bought it, I doubt the seller will mind).

It works great on my cherry, and I love the Hon Red Oak dai, all that incredibly hard wood and I didn't have to cut the mouth. :)

I've never seen that mark before. Of course, it could be the mark of the aggregator (the guys who go around signing up producers and then resell), which is why Hiraide's mark is all over my tools.

Pam

[Pam Niedermayer]

So,most seem to agree that at least 3 contact points,with 1 being in front of the blade,are needed. The article did assert that the long plane bottom was just hollow. That the 3 contact points were used on the shorter plane.

Doesn't anyone here subscribe to Pop. Woodworking??? I could copy the article and post it,but I don't think it's allowed,or legal.

Two contacts on smoothers, none on joiners.

My copy hasn't arrived yet. When it does....

Pam

[Stuart Tierney]

Two contacts on smoothers, none on joiners.

My copy hasn't arrived yet. When it does....

Pam

I've seen the long planes done 2 ways. #1, dead flat all the way. #2 (arguably more common, for a rare as it is kanna) 4 points. Front end, mouth, tail end and a point between the front and mouth.

FWIW, the very long jointer is VERY rare, and at Tsunesaburo at least, they almost all go overseas. Nagadai are common enough, but the really long stuff, nope. Historically not used much, if at all. Just wasn't something that was needed, wanted or desired. Not needed, because folks could straighten something out with a plain old plane. Not wanted, because a big chunk of wood needed to be man carried, and who wants to do that? Not desired, because it was an extra thing that, well, see the previous two points...

By the time carpenters and furniture makers were able to stuff their gear in a car and drive it to the job, power jointers were on the scene which explains why you find the big things (usually 10" wide, 6' long just like mine!) under every rock, but wooden jointers are found at a ratio of 1:100, with the 1 being the woody, the 100 being te-oshi-kanna.

HTH, Stu.

[george wilson]

Johnny,a hollow base plane would plane a convex surface,just like a compass plane adjusted to plane a convex surface,only to a slighter degree,based on the radius of the hollow sole. On a hollow sole plane,just after the cutter enters the wood,the blade starts to rise as the corner of he wood contacts the sole. The curved sole pulls the cutter up,rounding the start of the cut. As the end of the plane's sole slides over the final corner of the board,the cutter is allowed to dip deeper into the wood,cutting a slight downwards arc. Repeat this enough times,and the entire length of the board will be the same radius as the hollow plane sole. The longer the board,the more total curve it will have.

[David Weaver]

I don't have detailed info, but that's a dai made by Nashiya and quite well regarded dai maker. You find this stamp on a lot of Japanese planes.

I think that stamp is supposed to be calabash. Back in the old days, the Japanese made and used it as water or booze bottle.

Thanks, Sam. I had figured it was a maker's mark and not a store mark. It's nice to know who it is, though I've never passed on a plane because a dai wasn't stamped.

Daiku dojo mentions that nimura dai are often found with mosaku planes, but in my case, I've had two nimura stamped dai on other makers, and when I find a mosaku for a price that catches my eye, it shows up with a different dai.

I intend to use it and make it dirty.

[David Weaver]

It works great on my cherry, and I love the Hon Red Oak dai, all that incredibly hard wood and I didn't have to cut the mouth. :)

I've never seen that mark before. Of course, it could be the mark of the aggregator (the guys who go around signing up producers and then resell), which is why Hiraide's mark is all over my tools.

Pam

I'm generally a cheapskate, and you know the old saying, beggars can't be...the way resale goes here for most makers, I don't want to buy new tools and take a hit if I decide I wants something else. The exception being the blue steel planes or the yamamoto special steel planes that are not very expensive to begin with but are good quality. I still lost $100 on the last yamamoto I decided to sell on ebay, after ebay fees, and it was unused. That was a big disappointment, and I don't get the sense that the guy who bought it understands that he got off really cheap getting a 70mm unused plane with a special cutting steel iron and a laminated sub blade. He's probably peeved that the dai has shrunk and he has to stone or sand a little off of the second iron.

Anyway, because of that experience, I buy my higher $$ planes "used but unused" from people who bought them and decided to never use them, and I don't have anything from harrelson stanley. Does he still deal tools? I went to his website a few weeks ago and it looks a little sparse.

As far as hardware store marking, I have to admit that I'm the kind of guy who takes the license plate ad off of a new car, and peels off dealer stickers, too - they can pay for their own advertising. I really wouldn't want anyone marking my tools other the maker and any dings from use. Everyone has their quirks, I guess, and IIRC, i've seen NOS planes from japan that had the hardware store mark on them, so it's not like it isn't authentic.

Outside question, when you took the the dai making class, did inomoto have you cut a dai with a ledge? I sort of have to agree with odate, I've had more trouble than help from ledges (one that wasn't cut deeply enough where the bevel of the iron, even at 26 degrees, was in contact with the ledge - just required a little tuning, but I don't like it to interfere with setting depth of cut), but I do like the way they look, and they've been on everything I've gotten. I'm 99.9% convinced they don't do anything functional for a user...well, 100% convinced. it's a nice concept, but in practice, the tolerance is too little and it's more likely that they'll just interfere.

I just don't know if I want to go to the trouble of cutting a dai with the ledge when I fit the ogata iron sometime later this spring. It will make it take a lot longer to make the dai.

[Pam Niedermayer]

Johnny,a hollow base plane would plane a convex surface,just like a compass plane adjusted to plane a convex surface,only to a slighter degree,based on the radius of the hollow sole. On a hollow sole plane,just after the cutter enters the wood,the blade starts to rise as the corner of he wood contacts the sole. The curved sole pulls the cutter up,rounding the start of the cut. As the end of the plane's sole slides over the final corner of the board,the cutter is allowed to dip deeper into the wood,cutting a slight downwards arc. Repeat this enough times,and the entire length of the board will be the same radius as the hollow plane sole. The longer the board,the more total curve it will have.

George, you pull a Japanese plane, very different geometry. All the force is toward the worker, plane is held with the dominant hand sort of wrapped around the top of the blade, and the recessive (that's a joke for all you genetics fans) hand is wrapper over the top of the front.

Pam

[David Weaver]

I don't have a plane with a dai long enough to keep me from putting my fingers on the back of the plane and on the back of the iron at the same time.

What do you do with a longer dai and you can't do that ? grip it at the back, or do you grip it at iron and not touch the end of the dai?

I just haven't found a reason for a longer dai - anything that doesn't show up on a 2 foot straight edge isn't going to cause a problem once the wood is joined. It probably flexes that much when you pick up the board.

[Pam Niedermayer]

...Outside question, when you took the the dai making class, did inomoto have you cut a dai with a ledge? I sort of have to agree with odate, I've had more trouble than help from ledges (one that wasn't cut deeply enough where the bevel of the iron, even at 26 degrees, was in contact with the ledge - just required a little tuning, but I don't like it to interfere with setting depth of cut), but I do like the way they look, and they've been on everything I've gotten. I'm 99.9% convinced they don't do anything functional for a user...well, 100% convinced. it's a nice concept, but in practice, the tolerance is too little and it's more likely that they'll just interfere. ...

The students made planes without the ledge; but the Inomoto-san made plane I won in class has a landing. I'm ambivalent.

I haven't bought anything from Hiraide for at least 5 years, IIRC, switched over to Hida (I seemed to spend much more business time in San Francisco than Boston in those days) and Iida.

Pam

[Stuart Tierney]

it's a nice concept, but in practice, the tolerance is too little and it's more likely that they'll just interfere.



You didn't hear this from me, and I didn't hear it from anyone else.

The ledge doesn't make any difference to the performance, but does mean someone cut it out by hand. Machines can't make the ledge. Now, it's almost required to have a decent kanna with a ledge in it otherwise folks will think it's a lesser grade plane.

[george wilson]

Pam,of course everyone knows you pull the plane. It would still plane the board convex anyway,without a contact surface in front of the iron. This isn't complicated.

[Frank Drew]

Hand placement depends on which side you like the work to be, and personal comfort; I'm right handed and I'm more comfortable having the work on my right, so my left hand is on the plane at the blade and my right hand at the front of the plane body. Although your hands and arms are doing some of the work, due to the pulling action your stomach muscles are getting the biggest workout!

My two "smoothing" planes are around 11" long, and my longer plane is 15" inches long. The former are tuned so that the soles have two contact areas, and the latter with three. In use, that is if you're basically doing nothing but planing all day, as could be common on house work featuring lots of exposed wood, the plane sole might have to be tuned up multiple times during the day to keep it working at maximum effectiveness.

[David Weaver]

You didn't hear this from me, and I didn't hear it from anyone else.

The ledge doesn't make any difference to the performance, but does mean someone cut it out by hand. Machines can't make the ledge. Now, it's almost required to have a decent kanna with a ledge in it otherwise folks will think it's a lesser grade plane.

I have had the same thought. I've never noticed it to be anything other than an indicator of quality for the dai, and of course, any high $$ iron is going to have it, too.

I admire the skill that it takes to make one quickly.

I understand the taiwanese used irons from japanese planes and didn't even bother with abutments, just used a rod and pressure on the second iron to hold the primary iron in place.

Many ways to skin a cat.

[David Weaver]

Frank, more specifically though on the nagadai, do is the back of the plane far enough away that you can't have your left hand both on the back of the plane (to pull) as well as the iron? If so, where do you put it - on the dai or on the iron?

As a righthander, it never occurred to me to put my right hand on the back of the plane and have the work to my left.

[Frank Drew]

Frank, more specifically though on the nagadai, do is the back of the plane far enough away that you can't have your left hand both on the back of the plane (to pull) as well as the iron? If so, where do you put it - on the dai or on the iron?



David,
I haven't used one of the very long planes, but on those I have or have used my left hand is on the iron plus plane body. Not at the back/heel of the plane body, which I think would give me less control, or less feel for how the blade is cutting. And my right hand is right at the front of the plane.

[Dale Osowski]

I think a tsutsumi is not needed but I do feel it does represent a higher quality dai. It may cause a bit of tuning issues however or may spring down if blade is set to deep.

http://i65.photobucket.com/albums/h235/Timberwerks/IMG_5223.jpg

[Pam Niedermayer]

Pam,of course everyone knows you pull the plane. It would still plane the board convex anyway,without a contact surface in front of the iron. This isn't complicated.

George, I think the difference between pulling and pushing is intuitively obvious, not that I don't use eastern and western planes both ways on occasion. My reiteration of pulling was intended to be an important reminder, not something I thought no one knew. So, it seems that my planes defy your convex contention somehow. I don't plane boards to concave unintentionally or unknowingly.

For jointers with flat soles, NOT smoothers with the front hollow, I intentionally spring long boards, whether I'm using eastern or western planes.

To Frank and David, I think it was a mistake to try to describe how the hands hold a Japanese smoother. What's more, I think in the early hours I got it wrong, or at least not right; but my point about the forces on these planes holds. All the force focuses on the front touchdown.

Pam

[george wilson]

Pam,I do not understand what you mean by "convex contention". You aren't making your plane concave throughout the sole are you? From re reading your posts,apparently you are not. Therefore,I wouldn't think your long plane would generate convex work from having a hollow sole,whether they are pulled or pushed. And,of course,to spring boards you must plane them a bit concave,which would be the opposite of what a hollow sole would want to do.

[Johnny Kleso]

Here is a link to Wilbur's Blog
I know somewhere on there is some graphics of the sole..

http://giantcypress.net/

Click on link below and at bottom of page keep clicking OLDER
http://giantcypress.net/tagged/plane/page/4

[Pam Niedermayer]

Pam,I do not understand what you mean by "convex contention". You aren't making your plane concave throughout the sole are you? From re reading your posts,apparently you are not. Therefore,I wouldn't think your long plane would generate convex work from having a hollow sole,whether they are pulled or pushed. And,of course,to spring boards you must plane them a bit concave,which would be the opposite of what a hollow sole would want to do.

Sorry, meant to say concave.

Also, I think I'm not helping anyone in this thread, too distracted or something. I now bow out.

Pam

[george wilson]

Wait for your magazine,Pam. I don't know how I got mine so quickly. I've had it for days.

[David Weaver]

George - just open the wallet and buy a few of them and experiment.

[george wilson]

I don't have the strong back to pull a plane!! Really,I'd throw it out quick. I think you need to do these things(like PULLING a plane) over the years to stay in shape to do it on any sustained basis. I can PUSH one because I'm used to that.

[Dale Osowski]

I feel Japanese planes are easier on the body and joints, it's one of the reasons I use them :-) I have carpal tunnel, and over the weekend I tore a ligament between the bicep and forearm. Thanks to the way Japanese tools are designed I'm still able to work comfortably. Besides, your not really using your back to pull ;-) Even pulling a 120mm plane is easy on the body:

http://i65.photobucket.com/albums/h235/Timberwerks/52550014.jpg

I even make my Krenov style planes to be pulled:

http://i65.photobucket.com/albums/h235/Timberwerks/75215569.jpg

[David Weaver]

Dale, they are definitely a lot easier on the elbows and shoulders, that's for certain, especially in a heavy cut.

I like your krenov design much better than the standard design - it wouldn't have such a restriction on the length of the iron, which I think is very limiting if someone uses their planes a lot - they'll only get a fraction of the iron life that current krenov irons will give someone before they'll need to have something welded to them to adjust them in the plane.

[Dale Osowski]

Thanks David

I'm actually going to make a few more Krenov-kanna for myself. The new ones will use a krenov style pin vs a dowel, touch points and a relieved outfeed vs a flat sole. I'll also cut in mimi and chamfer edges to meet blade just like a dai.

[george wilson]

Still no word from PM about correcting their article. It's been about 9 days. Wonder how long it takes? I do hope they don't tell me a hollow bottom plane isn't just a compass plane.