Check out http://www.hayesknives.com /">Wally Hayes site, if you haven't already. He also has a katana making video (stock removal), where he describes the steel he uses (I think it's 1050), size of the stock, and other details. Are you committed to using 5160? If you are after a hamon (maybe you're not), you may have better luck with something else.

In order to get a spring-back on your katana you'll need to do a full quench and then use a torch to back the hardness off on the spine until it's the appropriate color, probably a nice blue. Most smiths use the torch and polish off the oxidation three times, I think, just to make sure it's tempered. If you let the color (just the light straw color) creep down to the edge of the blade each time you'll temper the edge a little in the process as well, thus avoiding the need for an enormous oven. I think most start out with a light straw color and then test the edge to see if it's still too hard...you can always go softer by tempering again or going to a color that is further down the chart. You won't produce a hamon with this method, since the whole blade will be tempered martensite (even though it's differentially hardened, it is all martensite). (I just re-read your post--perhaps you were asking what temperature to temper the edge to get the right hardness for a sword and were not referring to the spine? Regardless, I think using color might be the best method if you don't have a huge oven or long salt tube.)

If you edge quench, you won't be able to get a spring-backed sword, since the spine will not be hardened at all. You'll have a soft back, which is traditional. If you use clay you'll have a soft back, and you'll be able to have more creative license with the hamon. What were the advantages of edge quenching over using clay?

Another method to temper is to heat up a piece of steel (orange heat) and then place the spine of your sword on that piece of steel. It's much slower than a torch, but it heats up the spine really slowly, so you can have more control. Some people are really effective with a torch, but I find it gets away from me way too often. I've had more luck using a red-hot piece of steel.

It's inspiring to hear that you are working on a katana. I haven't attacked that big of a project yet--quite intimidating.

(Other Smiths: Please feel free to correct anything I've written!)

Steve Morley

Joseph, katana have a lot of differences in measurement. Depends on wether it is an old tired blade that has been polished a lot or a healthy blade. In general measured from where the nakago ( tang) starts, they are usually between 24" and 30". Of course there are exceptions. This is taken from a healthy sword in my collection made in late 1943 by Nagamitsu. Width, right at 1 1/4". Thickness, slightly over 1/4". Length, 27 1/2". The tang is about nine inches. There are variations depending on blade style and school.

Steins sword index

This is a really good website on japanese swords. A lot of information.

If you are going to use 5160, I would full quench it and then draw the spine to a spring temper with edge in a water bath. You are probably going to have to have access to a long oven for tempering or be very careful with a torch or the hot steel as Steve mentioned. Once you get it tempered then you can draw the spine, probably at least twice. One thing Japanese sword edges usually run in the low 60's rockwell. They are hard and they will chip. I would not take 5160 that high.

Hope this helps.

Brion

One other thing with 5160 not mentioned is that alloy has a soft brittle range. I don't remember what that range is off the top of my head but I have run into it in sword making.

also is doing a full quench in 5160 you might get reverse sori depending on the crossection this can be a true pain as you will need to forge in the curve and it can end up with a kind of slow S shape.

Personaly in our shop we use salt pots for hardening and have a 54" vertical kiln for tempering. I have also torch temper swords but it is very difficult to do evenly and consistently about 1 in 5 we would need to re harden.

MP

Personally I would stick with 1075 or W-2 for katanas. Then you can get a hamon, which in my opinion is the focal point of such a blade. For a purley practical blade 1560 will work, just harden through and draw the spine.

For dimensions I think Brion gave pretty good advice.

For tempering, a low temp salt bath, or peanut oil will be the best bet. A simple trough with one or two bbq style burners will work. Just make sure the container is sound, as you don't want 400+ oil spilling. Your other option if this is a one time thing is go bribe a local cook with a sixpack. Just don't go at mealtimes.

Lastly you might want to check out the bladesmithing forum. There are a number of people who specialize in Japanese swords who post regularly.

Thank you all for the awesome advice- I must admit I do feel a little intimidated. Maybe I'm not ready for such a big project... I think I'll follow up on the advice and see if I can't torch the back, then bribe some cook. Again, great advice- those were very complete answers that gave me all the information I was looking for. Great websites too- I'll be checking those out.

I think I'm going to hold off on the katana... I think I'll try something a little more in my experience range like a chinese war sword, or maybe a wakazashi... holy cow, those are some complicated steps that could easily go wrong with making the ancient blade of the Katana!! And the idea of having the hamon is a pretty good point... I might as well try it with 1070 or somethin.

Alrighty- thanks again!! I can always count on this forum for great answers. I'll post pics of recent work. I'm already spinning the idea of a mix between a Chinese war sword, Katana, and Wakazashi... a little untraditional, but I'll see where the pencil and paper takes me with designing 🙂

Stay sharp!! I appreciate it!

Joseph,

A few things you may or may not know regarding Japanese style swords.

1. Basically there are three designations:

A. Tanto = 12" or less

B. Wakizashi = 12" - 24"

C. Katana = 24" or greater

2. Keep in mind that these measurements are not the overall lengths but cutting edge measured from the mune machi (notch on back) to the tip of kissaki (point).

3. As Brion said above there are many different dimensions and variations within these three groups.

If you wish to familiarize yourself with Japanese sword nomenclature and terminology as well as look at many genuine antique swords for ideas and dimensions, you can visit here: http://yakiba.com/

This is a direct link to the nomenclature/terminology page found under "Articles": http://yakiba.com/beginner_page.htm

Hope this helps.

Thank you Ed. It was good to meet you this weekend. There are some really nice swords to look at Joseph.

Brion

I've always been the just jump in type of person. I forged a katana welded up from cable as one of my first five or so blades. No it certainly wasn't of the quality to sell, and I didn't even polish it. It is however a very effective sword that I use regularly. Most importantly it was a lot of fun, and ultimately helped me get a better sense of what was realistic for my experience level. I haven't done another, frankly the idea of polishing that much blade scares me a bit, but I certainly will revisit the idea again.

So anyway my advice is, if it sounds like a fun project go for it. The worse that happens is you have some fun and learn some new stuff.