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Hey everyone! I want to acknowledge right away that what I'm doing here is questionable and very much non-traditional. In truth, I'm not quite ready for the challenge of a traditional blade made in a traditional way, but I hope to get there someday. This project aims at taking what I learned from a wakizashi I made last year and attempting to 1) not make the same mistakes again (only new ones are allowed!), 2) improve on the technique I've been learning and developing for this particular style of blade, while 3) also aiming for a greater challenge. This katana's construction will be similar, with a twisted wrought iron cladding, because I ultimately want those blades to be a pair. I began with a billet made of 7 layers of wrought iron (1/2" each) and 8 layers of O1 (1/8" each), for a total of 3" by 1.5" by 4.5". This will eventually be used for the outer layers of a san mai. I welded these, then drew the billet out to about 30" by 3/4" square, before hacking it in two and twisting each half (CW/CCW), then flattening them to about 16" by 1/2" by 1". I surface ground one side of each and started working on a second billet for the blade's core. This one will have one central layer of 1095 (7" by 2" by 3/8") for the edge, surrounded by two layers of 15n20 (7” by 2” by 1/4” each). I welded the billet and drew it out to the same width and approximately the same length as the cladding billets, then ground both sides and prepared for the final weld. This resulted in a 26" by 1" by 3/4" bar stock: At this point, and if my math was correct, I still had a *lot* of extra material. Since I wanted to make sure that my core was centered before continuing, I ground one side of the billet and etched it. Everything looked good. To help with my future profiling, I ground two 45-degree angles (see photo below), which I will flatten in the next forging step. Doing so will slightly upset the core on the side that will become the edge, giving it a better chance to line up with the final grind over the blade's entire length. My goal here was to lower the chances that any of the 15n20 would end up dipping into the edge in the final etch. Although that steel will harden too, it is only meant as a cosmetic/contrasting layer to separate the core from the cladding, and perhaps in a misguided way, to take the visual role of a traditional hamon. I don’t want it on the edge. I squared the billet and drew it out to the target width and height of my pre-sunobe stock: 1" by 3/8". This totaled 32", quite a bit more than I needed. To guide the forging of my sunobe, I drew much inspiration from a video from “Old Pueblo Forge”. In the past, for tanto and wakizashi-sized blades, I have pretty much winged this stage. This is the largest billet I have ever dealt with, so I felt I needed a little more care. I measured increasingly shorter sections, each of which will be of equal length once the sunobe is forged. The marks are fairly shallow (made with about 4 short strokes of the corner of a hand file) and will completely disappear as I forge each section to the same length, and to its respective target thicknesses. Ultimately, this ended up removing all of the guesswork, and the lack of fumbling around trying to get the shape right probably saved the centering of my core. I was glad I took the time to think this through. The near and far sections in the above photo are extra material. Despite the (massive amount of) forge scales, the several end-welds that were generously cut off, and the egregious grinding on the edge side, I still had about 8" extra on my final bar stock (now 24" by 1" by 3/8"). I’ll definitely adjust my quantities when I do this again, but for now, this feels very satisfactory. And this is my sunobe, on a dry wooden root, because “art”: At this point, the nagasa is 24.5". I’m aiming for a final 26.5" nagasa and 9" nakago (this will be on the short end of the range for a katana, but it is meant to be appropriate for me, I'm also on the shorter end ) I cut the tip at an angle, using the bandsaw to keep the layers alone. I of course could not resist looking at the end grain. You can see the slight edge upset at the top: The blade cross-section isn’t quite right in this diagram since I hadn’t yet beveled the blade, but that gives an idea of where this is going. I’ll be leaving the edge quite thick (a good 4mm, or 5/32") to preserve some of the core thickness that the edge upset gave me. On the other hand, I’ll be aiming to be close to the final thickness on the spine: I want each side of the blade to cross as much of the centerlines of the cladding as possible for maximum pattern activity. Those will be things to keep in mind at profiling time. Obviously, the twists aren’t laid out symmetrically. I’m OK with that. If previous similar blades are any indication, my beveling will introduce plenty of randomness in the final pattern anyway. I’m definitely not aiming for a perfectly symmetrically clad blade. Last forging steps. I “flipped the tip“ and started forging the bevels. This will be a hira zukuri blade, so beveling was a fairly simple process, just more of it than I had done before in one go. Here's a photo as I was getting started (the final tip ended up thinner than this, as I thought this was a bit too “bulky” for hira zukuri). And this is the beveled blade, after an overnight bath in vinegar: After a rough cleanup: And after a dirty etch to check my san mai geometry: I was really pleased because this showed that the core was still centered enough that I didn’t need to take any drastic measures. Success! (so far...) It was time for profiling: And finally, heat-treating. The temperatures I'm using are focused on the 1095 steel that’s on the edge (as opposed to the 15n20 and O1, which are cosmetic). I did a normalization at 1575F and used the heat to pre-curve the blade since I’m going to quench in oil. I did 3 descending heats/stress relief cycles after that, then quenched at 1475F, with little to no soaking time (just enough to make sure the oven temperature had stabilized). Going in! What went well: 1) no flashing (8x40 tank of parks 50 at ambient temp) and 2) the blade had pretty much zero warpage, only a minimal amount on the tang, which was fixed in seconds. My past experience dealing with this kind of wrought iron san mai construction made me expect a potentially severe warp. None of that happened, and I was very pleased. What went badly: this is me realizing I had just lost most of the pre-curve to the oil quench (look at my eyebrows, they're saying "wait, wha?"): There’s a thread about that in the “Metallurgy and other enigmas” board. Long story short, I was misinformed, and though no clay would mean no sori from the oil quench, negative or otherwise. I wasn’t sure where to go from here, and I kept mulling over this... I took the time to clean up the blade and do a quick etch before finally deciding that I was not fond of the Kanbun era style. Don’t get me wrong, it certainly has its charm, but I wanted this katana’s lines to be somewhat in harmony with the wakizashi it is meant to be paired with, and that ain’t it. So I went back to HT square 1, reset the pre-curve, giving it enough to compensate for the prior loss as well as the next. I re-normalized, relieved the stress again, and quenched a second time. I was much happier with the result. This is after a quick cleanup and a few corrections to the profile on the tang and the tip: Given that I didn’t differentially harden the blade, I didn’t want the edge screaming hard, so I aimed for 57-58HRC with two 2h 550F tempering cycles (begging the question as to why I am using 1095...). My understanding is that this may still be a bit high for a non-DH blade, but the shallow hardening of 1095 combined with the still fairly thick iron jacket might actually have allowed me to keep the edge harder. I lack experience here, I’m afraid (please do set me straight!). I’ve done some more cleanup of the profile since then, on the tip, spine, edge, and nakago, to help the lines flow a little better. I still have a couple of spots of decarb left here and there, a little bit of thinning of the tip to do, and I’ll eventually file-finish and engrave the nakago before doing the final etch. So there’s still quite a bit of work to do, but the blade is pretty much at final shape and dimension: nagasa: 66.1cm (26"), sori: 1.5cm, moto-kasane: 0.7cm, saki-kasane: 0.49cm, motohaba: 3.1cm, sakihaba: 2.1cm, overall weight: 658g This isn't the final polish and etch, but here’s a sneak peek: Next to its little sister: I'll be starting on the fittings, and I'll update this thread as I make further progress. Cheers!
Tosogu for a tanto A very pleasurable commission I received a while back was to make tosogu (metal fittings) for a tanto to match an existing katana. The tsuba was carved out of mild steel, the habaki, fuchi and kashira were made of copper, and the seppa were cut from brass sheet. I tried to get a bit of an aged feeling on the tsuba, it almost worked, seems I have a bit of learning and experimenting to do before I get it "just right". Comments and questions welcome