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MAtthew Boston

hamon on a duel edged katana - need help

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zx5mx5.png

 

i have been wanting to make this sword for a while now for my own collection. it is a katana , but it has a 2nd edge on the rear. for at lease the first 4in. so can i get some opinions on making a hamon for this kind of sword. my current trys have all cracked, or broken durring the quench. i have tried relieving the stress but still get a bad result. all opinions may help. ive had 4 trys so far and all have been failures and none of my trys have bleeders on them. my steel is 1095 hi carbon steel. im making it for my collection. and to prove to myself that i can do it. So any opinions- sorry for the pic being anime- its just easier to show it than trying to explain it in detail

Edited by MAtthew Boston

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Hi Matthew

 

Once again I am far from an expert, but I really love this blade shape and did a bit of research a while back. It seems that the edge on the back of the balde is more decorative in function and I have not managed to find a picture where it is actually hardened. By the way the blade shape, according to my research is called "Kogarasu Maru-Zukuri" which means "Little Crow"

 

Little Crow copy.jpg180px-KogarasuMaru1.jpg

 

Maybe a Google search will help.

 

Regards

Wayne

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Matthew,

You may want to use a lower carbon steel for such a large blade. Maybe something closer to 1070. Run normalization cycles prior to your final quench heat and make sure you are getting even heat over the entire blade length. (What is your quench media?) I've never attempted a sword and congratulate you for biting such a large project. From what I've read, they are much, much more than just a long knife.

 

I'm sure one of the sword makers will have more first hand knowledge. Good luck!

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my quench is in heated motor oil. it has worked for my other swords such as tantos, wakizashi, kadachi. yes i have been bitten by the japanese bug and i know it changes you.

 

i used to use 200 degree water , but it was a hit or miss on the quench.

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Matthew, 1095 should be fine, although many makers preferr to use a lower carbon steel. You may want to consider reducing the hardnenability of the steel &/or doing an interrupted quench in water, then oil. Quenching in oil may make the sword curve "tip downwards"

 

What you'll have to do is pre-curve the tip as this won't curve during the quench, make your claying up along the centre ridge of the "spearpoint tip" to make a hamon "around" the tip & to make the rear edge hard

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thus your suggesting to curve the tip and then quench with the water then oil. that sounds like a good idea. any other opinion. knowledge is power.

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HSOTD?

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Hey it got the point across. I actually found that anime interesting in the fact that it is the only thing Japanese that openly admits that Japanese swords aren't all that. The gun nut guy arguing and making good valid points with the sword gal. Not to mention THAT sword in the pic was made from foreign steel if memory serves me right. Notice there is NO hamon. Still it is treasured and cuts through zombies just fine. Very interesting in something from Japan. There is nothing wrong with anime btw. Of course most of the sword designs and the fact every sword can cut through steel girders stretches the truth a little. :lol:

Edited by Mike Sheffield

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Matthew,

 

Motor oil, even heated, is a poor choice of quenchant for 1095 steel. 1095 must cool extremely quickly during the first 30 seconds to harden. Now is where it gets more complicated. You can increase or decrease the ability of your steel to harden by the way you treat the steel prior to hardening. A larger grain structure will harden more readily but, results in a blade that will be weaker and has more problems in the quench. A smaller grain structure is harder to harden but, results in a tougher blade that will stand up to the quench better. Getting back to your motor oil... A "quick" oil will cool the steel faster than a "slow" oil - motor oil is not a quick oil. In order to get the 1095 to harden in motor oil it is likely that you are dealing with a large grain structure. You can improve your chances of successfully hardening this blade shape by: 1) Change your quenchant to a fast oil, something like Parks 50. 2) Change the steel from 1095 to a type that is easier to harden such as 1070 or 1080. 3) Properly normalize your steel and quench from the lowest temperature possible. 4) All of the above. The last option provides the greatest chance of success. Also, it would be a good idea to search the forums and learn more about the hardening process and how it relates to steel type, grain size, quench medium, and moon phase!

 

Yes, the back edge was hardened on these.

yougo_099.jpg

~Bruce~

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what other quench fluid matterials would work for this "quick oil" quench? ive never heard this term before so you have me listening well

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Matthew,

 

Look in the "Metallurgy and other Enigmas" sub-forum. Read through the back topics, especially ones that seem to coincide with your project. Lots to learn there and many of your questions have been answered, in many different ways, previously.

 

~Bruce~

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I use 1086, and quench it in 120F water (rain water or well water but nothing with dissolved chlorine) for four seconds, out for four seconds, then back into the water until it stops boiling the water around it. Laying out the hamon is just like any other blade, but the bit at the tip is only down the center exposing both edges. If you want the curve to flow evenly (it doesn't on the kogarasu maru), it must be pre-curved a bit out at the tip. Refine the grain size as small as possible with thermal cycling, then use a fairly low heat for the final austenitizing for hardening the edge.

 

I have made two kogarasu maru that survived, and three that did not. :)

Edited by Howard Clark

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I use 1086, and quench it in 120F water (rain water or well water but nothing with dissolved chlorine) for four seconds, out for four seconds, then back into the water until it stops boiling the water around it. Laying out the hamon is just like any other blade, but the bit at the tip is only down the center exposing both edges. If you want the curve to flow evenly (it doesn't on the kogarasu maru), it must be pre-curved a bit out at the tip. Refine the grain size as small as possible with thermal cycling, then use a fairly low heat for the final austenitizing for hardening the edge.

 

I have made two kogarasu maru that survived, and three that did not. :)

 

do you have any pictures of the ones that survived?

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No, no pictures in my files. I have very few pictures of things I have made. Sometimes other folks take pictures of them, I seldom do.

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zx5mx5.png

 

i have been wanting to make this sword for a while now for my own collection. it is a katana , but it has a 2nd edge on the rear. for at lease the first 4in. so can i get some opinions on making a hamon for this kind of sword. my current trys have all cracked, or broken durring the quench. i have tried relieving the stress but still get a bad result. all opinions may help. ive had 4 trys so far and all have been failures and none of my trys have bleeders on them. my steel is 1095 hi carbon steel. im making it for my collection. and to prove to myself that i can do it. So any opinions- sorry for the pic being anime- its just easier to show it than trying to explain it in detail

You've gotten lots of good tips here. I find vegetable such as corn oil good with high 10-series, and pre-heat the oil! Warm = faster quench. 1095 is not ideal for such big blades, and water-quench definitely is problematical. I know post-quench ht is not done by many makers, but some steels without it at full hard will just up and crack on their own without it done quickly, and I mean starting within a few minutes of the quench. Also, before the clay/quench, make sure you get the whole thing to red and slow-cool once if not a couple times.

Another issue is how long are you holding at temp? Spots may be getting overheat while you get the whole thing to critical.

 

I think personally you'd be better with 1060, or even 1050, easilly available as PGS shaft. (if you have a power hammer/press, makes things much easier.)

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