Hey folks, welcome to the channel! Today we're going to be building a "cumai"
katana. "cu" means copper and "mai" means layered. The outer cladding of this sword
is going to be twisted damascus, so here we're using 1095 and 15n20
steels and stacking them up. Our starting billet looks something like
this... the black is the 1095 and the white is the 15n20 steel. After a little dip
in kerosene to help with the forge weld, in the forge it goes. We're going to heat this up
and give it a little squish to set the weld. After a few heats the forge weld is
complete. Now we're going to take the graphic in the corner and turn it more into this... The machine i'm using here is a 30
ton hydraulic press. It makes quick work of steel. If you were doing this with
a hammer, this would take a really long time! Now that we've got this forged into a square
bar it's time to change the pattern a little bit. We're going to put it in the squaring
dies and re-square it on the diagonal. It's impossible for you to see here but
I'm actually holding this on a slight angle... this way we're going to re-square it
again and get a little curve in it. Now i'm just drawing this
out into a long square bar. Here it is all done, cut in half, because we're
going to need one half for each side of the sword. The next step is to twist each of
those bars but before we do that we're going to round them out a little bit. This is to make sure that we don't have any sharp edges as we twist it. It
just makes it easier that way. Now we're doing the actual
twist. Here I've got a pipe wrench and i've just heated up the steel, locked
it in the press, and just twisted it. After this, we're going to
forge each twisted bar flat and we're going to get a
pattern something like this: Now i've got some kiss blocks set up
on my press. This allows me to get a constant thickness all the way
down the billet as i'm pressing. Now I'm taking each bar to the rolling
mill and getting a perfectly even thickness all the way down the bar. Now we're just straightening any curves
the rolling mill might have introduced. We're ready to take this to the next step. Here we are with the finished twisted bars.
They came out at about 3/16 of an inch thick and about 20 inches long. Now we're going to combine
these with some copper and some 1084 steel. I've ground one side of each twisted bar
clean here and I've stacked up the copper and put the 1084. We're ready to weld this up and get it in
the forge. It's important to weld up all the seams just in case we get it too hot. We
don't want to melt the copper out of it. Now it's back in the forge and back
in the press to squish this down. This billet was so long I had to heat it up
in sections and press each one separately. Now i'm using these aggressive rounding dies
to put valleys every inch or so. That'll give a nice wavy pattern in our copper. Now it's just
a bunch of repeated stretching and flattening, stretching and flattening, until we
get the length and thickness we need. This billet was so long, I had to
pull my press away from the wall so it wouldn't hit the back wall with the billet. Now I'm just fixing the curve in the billet just to make sure it matches
the curve i want on the blade. All right folks, there we are, finally done. The
forging on this one took a really long time because I could only heat up about this much of the blade
at a time. Looking at the thickness, it's 320 thousandths of an inch thick, which is fine. If
you look, I just ground this side and you can see the core. The core is about 1/8 of an inch
thick, which is great. That's what I want because you definitely want the core to have a good
thickness here because that's the strength of the blade. For everyone that says "you didn't
forge it to shape", you don't forge these to shape. You cannot forge these layered constructions,
particularly the ones with copper, to shape. You'll just ruin it. You have to do stock removal on these
after you've forged out the steel, there's just no way around it, because if you try to start to forge
it and hit it on the edge it will just delaminate and you'll destroy it. So we're going to cut
it out of this billet and start to grind it. I'm starting to do the rough
profile on my 2x72 grinder. This takes a little while. I'm not
used to a blade being quite this long. Now i'm grinding all that forge scale
off the side to get down to clean steel. I managed to get it down to about 240 thousands of an inch. Almost 1/4 of an inch here. Tt tapers ever so slightly down to about 210 thousandths of an inch down here. All the while keeping the copper and
core centered so the coppers even. Next is... what you may not know about Japanese swords
is that the profile actually looks something like this: Obviously this is not to scale, but something
like that, where there's a bevel that goes up and then there's a little angle here.
I'm going to do the top and i'm going to just do this like i do a false edge. I'll
mark the top and i'm going to grind this. Here i'm using a scribe and some layout
fluid to give me a line that i can grind to. Now it's time to grind in the bevel. This is the really tough part folks, because
you want to get this as even as you can. I have one side done, now to
do the other side and make a match. It's time to clean up the tang area and
file in the transition between the tang and the ricasso. On Japanese blades that's
where the collar is going to be, or the "habaki". All right, here it is after the initial
grind. You can see the copper. I've done that little bevel at the top. It looks pretty good. It is now time to heat treat. We're going to heat treat it
in the forge after some normalization cycles, and then do some final grinding. The first step
is to put the blade in the forge and heat it up to around 1600 degrees fahrenheit then let it
cool. That relaxes the steel and "normalizes" it. After a couple of normalization cycles we're
ready to put this in and heat it up to about 1500 degrees fahrenheit and quench it in oil. That's
what's going to give us our hardened blade. Because the tang was sticking out and it's
still hot, it was hard to get this flame out. Here we are, fresh out of the quench. I've cooled it
between aluminum plates. It is perfectly straight, PERFECTLY straight, so that's awesome!
This is a 65 hrc file, let's see how we did. It's not even touching it at 65 hrc.
That's just taking off the scale. That's really good. Okay, so
now we need to temper this and that is going be a little different because
this won't fit in my oven. Big thanks to my buddy, and fellow ABS journeyman smith, Rick Hall,
for giving me this idea on the oil temper. Now the blade's is tempered and I've
brought down the hardness to give it a little more toughness. We're going to check with the
hrc tester to see actually what we ended up with. We ended up with about 58 hrc, which
is a little high, but we're going to go with it. It's time to do the final grinding on
this blade. We're going to bring the bevel up a little higher and we're
going to make that edge much finer. It's time to hand sand the blade. Yes folks,
this takes hours but with the miracle of video editing, you're only going to
have to watch it for a few seconds. "Thanks Dad, I hate hand sanding".
Trust me, Molly, we all do. The blade's been sanded to 800 and
we're all ready to do the collar, otherwise known as the "habaki". We're
going to be doing this with 1/16 inch copper. I'll be heating this up to anneal
it and then bending it because this is square right here. So bending that square and
then we're going to solder it together. Unlike steel, heating up copper and quenching
it in water actually makes it softer. Now i'm putting a piece of silver
solder coated in flux on the inside. Then we're going to heat up the hibaki and that
will melt the silver solder and fill that gap. Now we're just going to grind the hibaki to make
it look pretty and move on to the next piece. The next piece is the guard. I'm
cutting it out a piece of mild steel. It is just from a piece of square tube that i
had lying around. Next i'll drill and file out the hole where the tang's will fit.
I will also put in some holes and decoration. There's our guard so far. Now i want to put a
channel all the way around the edge because we're going to inlay some copper. I've got the dremel
chucked up here in my vise so i can just spin this around with a cutting disc to put that
channel in. Let's give it a try. I wanted to use the dremel here because it spins at about 15000
RPMs where my mill or drill press is much lower. Time to hammer in some copper wire that's
just a little thicker than that channel. I decided I needed some more embellishment on
the guard so i used the hand engraver and put in some wave patterns. Well folks, this just came. This is a huge block of basswood. This is what i'll be using
to make the handle and the scabbard. I just split these in half. I milled these out using the mill, just to make sure that the tang would fit.
Sorry i didn't film it. Now we are just going to glue these together to make
one thing and then we'll form our handle. After cutting out the rough shape
on the bandsaw, I am at the 2x72 grinder just giving it some shape and contour. Now that the handle shaped, it's time to move on
to the butt-cap. I've ground a little concave area in this piece of wood and now i'm using
that as a mold for this piece of steel. It's time to weld these pieces together
and then we'll take them to the grinder and finish them all off.
It looks like there was never a seam. Okay, finally done with the fittings for the
handle. Here's the one with the opening and then the butt-cap. There's
Japanese names for these which i forget. Next step, we're going to be putting some stingray
skin on here. The way we want to do this is we want this pattern on one side. It's going
to wrap around and you want the seam here. Sorry, you want the seam on the top, sorry
that's what i meant. Because the way the wrap happens, it will hide the seam so we need to make
sure that that's how it turns out. Let's cut it. Now on to the "menuki". These are the
little ornaments that are underneath the wrap on the handle. Of course
they're going to be little copper sharks. All right, i've got this all wrapped but i'm
actually going to redo it for a couple of reasons. First, the diamond is off centered a little bit.
I'm fine with where it is on here because i want the menuki to be opposite it, so that's
fine, but i don't like that it's offset this way. The other thing is this gap here. I thought it
would be fine because i thought the wrap was going to cover it but when I
was just playing with the wrap, the first side is is right up against it, which is
fine, but then when it crosses you see a gap here. I was i was going to fill that with
epoxy but it just won't look good. I'm going to end up re-wrapping it. The other thing
is, I don't like how the wrap is raised up above this. I want it to be even. What i'm
going to do is, instead of wrapping the whole thing, i'm going to grind down on the
handle, the sides, and just embed the wrap on either side. It'll be recessed
and that should make it flush with the sides. I've got a new piece of this. I can
probably save this one, so let's rewrap it. All the steel fittings are
done but they're all silver. We want them black, so we're
going to use some hot salts to get them nice and black. After about 15 minutes
in the hot salt they come out nice and dark. Now that the fittings are done we can move on to
the long arduous process of wrapping the handle. It's time to move back to the blade
and put my maker's mark on the tang. I'm also engraving "Tyrell Knifeworks" in
Japanese on the other side of the tang. All right, I've washed it in acetone
it's time to put it in the acid. First, we're going to get some
distilled water and get it wet. And now in it goes. After a few dips in the acid, the blade goes
into hot coffee that's going to make it nice and black. Now we're going to move on to doing
the scabbard. I've cut two halves of the scabbard and i'm using the mill to just mill
out the inside where the sword is going to go. Now i'm just cleaning up the edges with a chisel.
I'll move on to putting some felt on the inside to protect the blade, glue it up and then we're going
to shape it on the grinder, sand it, and paint it. This is the final step. Are you guys
ready to see the finished product? Oh you better clean that up honey!
