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Sword Shop
Basic Forging of a Katana Blade
Form
By Randal Graham
I get a number of e-mails and phone calls each month from aspiring
bladesmiths as well as other makers asking about how things are done with
regards to swords. The problem I keep facing is answering all of the
e-mails and calls; with a schedule of a sword every week or bi-weekly it
doesn't leave a lot of time for very definitive answers or explanations.
My hope for Sword Shop is that I can address these questions much more
thoroughly and with pictures depicting the processes involved. Also, it
should give the neophyte an opportunity to see how different kinds of
swords are put together, what's involved in their making.
So we'll jump right in. The sword form I am most commonly making currently
is the Japanese Katana, so for the first chapter of Sword Shop I think
it's a good idea to start with the basic forging and forming of the Katana
blade.
It starts with the steel; for the blade shown I'll be using W-1 steel from
Crucible, named "Black Diamond". I get this steel in round bar, so it
first must be broken down to suitable bar stock from which to forge the
sunobe - or blade forging blank.
1. On the left of Photo 1 is the bar of W-1 as I receive it from Crucible
Metals. This particular piece is 5/8 of an inch in diameter. On the
right is the size I will break it down to; 1/4 inch thick by 1 inch wide
nominal. For some blades the requirement will be slightly different, up to
3/8 of an inch thick, but for the standard blades a thickness of 1/4 inch
will meet most blade requirements nicely.
2. This is "Chomp" - my press in action. I use a hydraulic press built
specifically for blade-related work to break down the round bars. Doing
this by hand is extremely time-consuming and adds no benefit so the press
is the answer here, and provides a level of precision that I can't
achieve by hand - at least inside of a day or two.
After the round bar has been sized down, the next step is to forge a
sunobe - or blade-blank. What I am doing is pre-shaping the bar
with a taper in width and thickness for both the blade and tang, as it it
is easier to do this now than trying to accomplish the same after the
bevels of the blade are in place. It takes a great deal of guess-work out
of the process.
I know from experience that the blades will widen and lengthen a certain
amount as I'm forging the bevels into the blade, and this is used to
determine the size of the blank. In this sword's case, I want the blade
to be 1.25 inches wide at the notches where the handle starts, and 1 inch
or a bit less at the kissaki (tip), or the portion of the blade
just before the point starts. My blade blank will be 1 inch wide at the
notches, and a touch under .75 inch wide at the kissaki. With 1/4
inch thick bar I usually get around a 1/4 inch growth in width as I forge,
and this is as complicated as the math gets around here.
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3. Tapering the bar to form the sunobe. You'll notice here and
in following pictures that there is water running off of the anvil face.
This is the Japanese technique of wet-forging, where a layer of water is
kept on the anvil face and the hammer is dipped often to keep it wet as
well. The result is that as the hot blade is struck with the hammer steam
is generated violently, which serves to loosen and blow off a great deal
of the scale that forms on the blade during forging. This also reduces the
pitting and marks that would otherwise be pounded into the blade by the
build-up of scale throughout the process.
I start forging the sunobe to blade by starting with the point.
I'll spend some time here to forge the taper to the very tip, as well as
defining the separate angles that define the point from the body of the
blade. It's also a good warm-up for things to come, since it is fine work
it gets my arm loosened up and "zeroed-in".
4. Refining the taper, and squaring up in prep for forging the point.
5. Now I'm starting by pushing the edge-corner around to line up with the
back.
6. It starts to take shape.
7. It's just not possible to be in a hurry at all during the forging of
the point.
It must be straight, the bevels must be lined up, and on the same plane as
the rest of the bar. The rest of the blade grows from this small
beginning and I'll strike a few licks and constantly stop and examine the
point from all angles. If it's wrong at the start, it's simply miserable
to go back and refine later.
8. Rough shape is outlined and the bevels are started.
9. Now I'll go ahead and start the bevels on a short section of blade
proper, back from the point. I'll still work around this area and
alternate from tip to blade proper, so I can get it all together in
proportion and in proper relation.
10. Ok, now I can start to rock! I'll take a section of blade, about 4
or 5 inches, and get it to a high heat, in the area of
2000-2200oF - very hot, and I forge very hard and
quickly to establish the basic bevels and lines
(approximately 2750oF is the
melting point of steel,by the way.)
After the first heat, the temperatures will be much lower, more in the
1500-1700oF range, as I refine forge the surfaces and bevels to
a very smooth and defined state. The edges are forged down to a little
thicker than 1/16 of an inch, and on each section of blade I'm working on
I'm constantly checking for alignment and straightness. It takes three or
four trips to the forge to get the section where I like it, generally, and
then I'll move to a new section.
11. As I get three or four sections done, I'll start to back track and do
more straightening, as well as blending and lining it all up into a nice
evenly tapered and profiled blade.
12. Eventually I'll have the blade it's self formed and and pretty much
finished.
I'll continue past the pre-determined blade-length for about 6 inches or
so, and it's in this area I'll set the starting area of the tang by
forming the "mune-machi", or back-notch, and the "ha-machi",
or edge-notch.
These notches can be formed in a bunch of different ways, filed, cut,
ground, but for all-around integrity you just can't beat forging them in.
For this I simply turn to my Hydraulic press one more time; I bring the
blade up to heat, place it in the dies, and give the blade just a very
tiny "bump" with the dies. The reason I use the press is that the front
edges of the dies are lined up perfectly, and this makes an easy job of
the process. I've also formed these notches with tooling for the anvil
that is struck with the hammer, but this works best with another person in
the shop acting as striker, with the press I can do this in one short
operation by myself.
13. This picture is enhanced a bit where the dies make contact with the
blade and form the notches. From this point I'll forge the rest of the
tang with the opposite thickness and width taper as the blade; getting
thinner and narrower from the notches to the end of the tang.
14. Now I have the lion's share of the forging and forming complete. I'll
spend some time now "tweaking" the blade overall; making sure it is as
straight, flat, and as smooth as I can get it along it's entire length.
15. Lots of sighting along the edge and spine, and constant light taps
and gentle flexes is what it takes to get things in place.
16. Ok, just about got it!
And I end up with the basic forged W-1 katana blade. 26.75 inch blade,
with a 10.75 inch tang, both measurements a little unusual, but this
particular blade has slightly different requirements than most of the more
"standard" katana that I do, which will generally feature a tang length in
the 9 to 10 inch range. It's what the "custom" in the term "custom
bladesmith" stands for.
From here I'll normalize, do some scraping and filing to get the flats
flat and all the lines crisp and straight, and in their proper place.
In the next article of Sword Shop, I'll go through the
hand-shaping, and
the heat-treating of a katana blade, including a look at the different
equipment and techniques that can be used for the thermal cycle of the
Japanese sword. You will see the second part of this article on the
Main Menu. So come back on March 15 and click "Reload".
Randal Graham is the owner and operator of Dragon Fist
Forge. Randal specializes in high performance sword blades by employing
modern technologies to forge blades, raising performance to new heights.
His website is http://swordforum.com/randalgraham
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