The blade is laminated flat.
Then a special swaging tool is used to bend the edge down.
Then it is ground on stones to an edge.
When you have sharpened it enough to get past the swaged part, you
swage it again.
That is why they laminate the really hard edge steel to a soft mild
I have a very good book on Japanese joinery that shows the whole
Looks can be deceiving after forge welding parts together. What
appears to be 1/16" thickness is probably closer to 1/8". I am not
really sure of just how thick a piece of tool steel you should begin
with. The size of the finished plane blade will dictate that. I would
guess a piece of high carbon no less than 1/8 or 5/32", laminated to a
1/4 or 5/16 piece of low carb or wrought iron (if you can find some)
should yield a average sized plane blade. A considerable amount of
metal is lost when welding and forging. I would always prefer extra
cold work instead of a blade that is to lean. There is very little real
working data on this subject most is aimed at woodworkers and NOT smiths.
I sent another email about forging a yari kanna and after looking
over my notes from 10 years ago i realized I made a mistake in
describing how the hollow is formed. Yataiki uses a mini anvil made from
a chunk of 4"x4" steel about 10" long, set on end. The corners are
rounded off. When forming the hollow the plane blade is held at an
angle against the rounded edge of the block (tool steel side down!) and
lightly hammered on the top surface at a low heat (dull red). It does
not take much to form the hollow and NO metal is lost at this point.
The "sen' is used to true up the surface and refine the hollow. Not
much metal needs to be removed, just enough to remove all the scale.
You have embarked on a project that will take time and patience.
Expect to add to your scrap pile before you get a good blade. Also, I
have never had good results welding O-1. It seems to be rather hot
short and unforgiving. I would try some W-1 or as Yataiki suggested
"old lawn mower blades"
Good luck dude,
Both. Hammering is traditional and the main method for planes.
Chisels are now a mixture - grinding for the low end ones, hammering
for the better ones or those with itame hada. When they're worn back
to the hollow, the forged ones are re-shaped by cold tapping, or the
ground ones are re-ground.
Depends on the steel you're using.
My plane irons are between just under 1/4" and just over 5/16" thick.
Their hard steel varies between about 1/6 and 1/4 of this, with the
better and thicker ones also being proportionally thicker. I also
have some Japanese irons (Samurai brand) made for Western
Bailey-pattern planes which are thinner, but maintain similar
I presume you're failiar with Japan Woodworker etc., but another
vendor worth a look is Steve Knight (I have one of his
A couple of highly recommended books are:
Toshio Odate's "Japanese Woodworking Tools"
<(Amazon.com product link shortened)>
and Leon Kapp's "The Craft of the Japanese Sword"
<(Amazon.com product link shortened)>
Thanks for the reply. My first thought of steels is to give it a try with
the steel I have on hand: some 1018 and O2. I'll check out those books -
I've looked at the titles before and passed, I'll have to take another look.
Hey Eide n'all,
Here is what and how i know about japanese wood
working tools. About 10 years ago I had the chance to work with a
Japanese toolmaker for a weekend. His professional name is Yataiki. His
specialty is saw making but he makes all sorts of edged tools as well.
Anyway, He showed me his process for making a yari kanna which is sort
of a cross between a plane and a chisel. Laminated steel, hollowed
back, spear shaped (ie yari) with integral iron handle. When it came
time to hollow the back he a wooden mallet over a wood stump. This
prevents hammer marks being left in the hollow area which are hard to
remove. In my first note to the group on this subject I mentioned the
use of a tool called a "sen" This really is a vital part of making any
japanese tool or weapon. They are extremely efficient stock removal
tools and are made in a wide variety of sizes and shapes to suit the
purpose at hand. Some are tiny, like .5" wide some even smaller for
forming grooves like in a sword blade. Other sen are several inches
wide for planing off wide surfaces like when making a saw blade. This
is the way to go on a chisel back. Don't be to concerned with the loss
of material as the hollow only needs to be .020" or so. One interesting
thing is that this is one of the few Japanese tools that is pushed
rather than pulled in use. A sen for hollowing a plane blade would be a
little narrower than the hollow itself, maybe 1.25" and about 1" from
cutting edge to back edge. The face of the tool would have a slight
radius and the face angle would be about 55?- 60?. As I have said this
thing looks like a draw knife with handles on each side. If you started
with 3/4 x1/2" stock about 14" long, welded a piece of 1095 in the
middle you would be on your way. Draw the handle material out to about
16" with pointy ends to drive on some wooden grips. Also the handles
droop slightly below the cutting plane for more better control in use.
I know a picture of these tools would be nice but I have not found
many. That sword making book others have mentioned shows it in use but
it is not talked about in detail. Really and for true this is the way
those little guys do it.
Glen G. in Pgh.
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