Japanese Dai Size Question

[thumbsucker]

I have a general interest in hand planes in particular wooden ones. In the western tradition the hand plane scales up in a very regular linear fashion, with a steady increase in the length of the plane body with the width remaining relatively stable 1 3/4" - 2 1/2".

However my general assessment is that Japanese planes tend to have less range in length but a greater range of width's way beyond that seen in Western planes.

Having seen Japanese planes that were wider then they were long (I have seen 250 mm wide dai) but never a 24" plus, how is the Japanese craftsman able to plane large flat surfaces without following the hills and valleys of the board.

This is why a western jointer due to its length will only take of the high spots over its greater length giving a flat even surface.
Or is it just a matter that Japanese craftsman is planing a wider area at once that he can level out the hills and valleys of a board.

However another example is when jointing a boards edges, how does a Japanese plane get the board edge flat with such a short plane body with the bulk of the width overhanging and no length in the dai. We in the west would never joint an edge with a smoother length plane.

I am much interested as it may over some insights into other means of constructing wooden planes.

[Clinton1]

Others will be more knowledgeable than me, however with respect to shooting an edge:
When in Japan I sought out a few cabinetry shops to take a look at.
A common feature was large low tables used to prepare timber on. Shooting boards were built into the tables.
The one Shopfitter that I saw working had brought one of the above tables to the shop for the preparation of timber.

I'll see if I have a photo of the setup. If so, I'll post it into this thread.

[Claw Hama]

Hey TS you should talk to our old mate Soatoz on the forum or check out his
web site at Japan-tool.com and email him. He has all the Japanese answers.

[thumbsucker]

Lets Hope Soatoz drops in.

[sumu]

In the meantime, check out this nice videofeed: http://www.shizutanischool.org/videos/Contest.html

Edit, found some more Ookanna fun: http://okanna.blogspot.com/2006_03_01_archive.html (the one in the end of the page :) )

A youtube link: YouTube - Kezurou-Kai 2005 - Nishiyama ookanna planing demo

"Two finger planing technique" :)). Wonder if it gives out some hint why and how come ;)

BTW, That is great how he lets that little kid try out the plane. That's how the future generation is motivated, let them try out the best there is.

kippis,

sumu

[Schtoo]

Why do you need flat surfaces? To joint two boards together to make a wider one, or for a table top or something like that, right?

That kind of thing just wasn't so important here. Straight enough was straight enough, so long as it looked right. Joining two boards together wasn't done because it just wasn't needed. Very few wide wooden surfaces were needed, and when they were they typically were not very long or they just didn't need to be that straight.

You can joint with a block plane if you have to, and for those times where a really straight surface was required, well, the good guys could probably do it with a chisel. ;)

That, and if I recall my (broken) Japanese history, all the tools would have to be lugged to the job site by hand. For quite a long time, nobody was allowed to use wheels for transportation. (Explains the big mobile shrines that are carried by a bunch of folks rather than sticking some wheels on it doesn't it?) Adding a long jointer to a toolbox adds inconvenience, especially when it usually just wasn't needed.

Nowadays, joining up boards to make wider ones is much more common, but so is the 12" wide power jointer.

There is also the probability that a prepared Japanese style jack sized plane won't follow the bumps like a Western Jack sized plane with its flat sole. Once you put only the tip of the toe and the mouth in plane, and get the rest of the sole up and out of the way, the thing will plane off a bump without trouble or riding over it. Hollows? Well, they are where you take the bumps down to, right? :)


Nothing to stop you making one up, but I have never seen one longer than 24" myself, and I have seen just a few Japanese planes...

[wilburpan]

Maybe some math can make this clearer, or maybe not. :wink:

A Japanese plane references off of the two touch points on the infeed side of the plane for the entire stroke, one at the front of the sole, the other right before the mouth of the plane, as opposed to western planes where you are transitioning the pressure from the infeed to the outfeed side over the stroke. It can be easily set up to take a shaving of 1/1000-2/1000 of an inch (25-50 microns). The distance between the touch points on a standard Japanese plane is about 6 1/4 inches (160 mm).

So theoretically with two touch points and a blade set up this way you could get a circular surface with a curvature that would match a circle in the diagram below where m would be 25-50 microns and c would be 160 mm. If you work out the math, this would be equivalent to an arc of a circle with a diameter of 128 meters.

And if you think that is too much of a curve, consider this: machinist straight edges are usually spec'ed to a flatness deviation of 1/1000" per foot (25 microns over 300 mm). The Japanese plane in our example would give you a deviation of 2-4/1000" per foot, which is pretty close.

There are Japanese jointer planes that are about 14" long (350 mm), and unlike the typical Japanese plane, these have three touch points at the front of the plane, just before the mouth, and at the back end of the plane. Because of the longer base, and with a blade set to take a 1/1000" shaving, that gives you a deviation of 1/1000" over 14 inches, which really is machinist edge territory.

But who needs this amount of precision in wood, anyway? Especially since when I joint an edge flat for a glue up, I'm going to spring the joint anyway. :wink:

[pfelps]

Sumu:

Nishiyama-san was teaching the young boy in the video. That boy brought that 120mm Funahiro plane up to him when he was checking everyone's planes out. He then showed how easy it was to pull because the plane had been sharpened so well. The small boy is my son, Cole. The opportunity to learn from these Toryo level craftsmen such as Nishiyama is a gift and one we will always cherish. He spent a good hour with us discussing sharpening and the various intricacies of preparing a plane. As many of you know, these skills are dying out in Japan and to have a chance to learn from these craftsmen is an amazing opportunity, Kezurou Kai was founded to not lose the hand crafts and skills and pass them on to the young. A truly worthy endeavor. One thing he told us was sharpen everyday, even if just for 15 minutes, it is how your hands will come to know how to sharpen and your other skills will improve at the same time.

Thank you

Paul Phelps