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Jesus Hernandez

Inducing positive curvature (upward sori) in a shinogi-zukuri katana using OIL

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Hey Brent

 

I only use 5 gallons of parks also. If you want sori forge it in now that's what I'm going to be doing to the two straight(chokuto's) swords i'm going to be requenching.

 

 

One thing I was thinking about and ran by Jesus was if it was possible that his parks had a bit of water trapped in it and maybe that water is causing the violent boiling (that hasn't happen with my parks) which is causing some agitation and somehow creating this positive curve?

 

 

Matt

Edited by matt venier

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Only 5 gallons?

 

That is only about 6" x 6" by 36". For some reason I thought it would take more volume to be effective. Maxim oil here in DFW sells the Parks. I will get some. I have about 20 small blades (kogatana size) ground from Aldo's W2 for testing purposes. I wonder if I can see anything on this small scale?

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Hey Brent

 

I only use 5 gallons of parks also. If you want sori forge it in now that's what I'm going to be doing to the two straight(chokuto's) swords i'm going to be requenching.

 

 

One thing I was thinking about and ran by Jesus was if it was possible that his parks had a bit of water trapped in it and maybe that water is causing the violent boiling (that hasn't happen with my parks) which is causing some agitation and somehow creating this positive curve?

 

 

Matt

 

 

Im kinda scared I will get a twist or get it outta whack bending it with all the bevels on it. A flat bar wouldn't be hard but this intimidates me as a forging newb.

 

Thanks for all the help guys.

Brent

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Hey Dan

 

The shorter the blade the less effect whether it's up or down curve at least on my end.

 

Brent

 

Once you get up to sword length you're going to need to develop some straightening skills, It is rare indeed for a sword to come out perfectly straight out of the quench (for me anyways)

 

Matt

Edited by matt venier

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Incredibly rare for them to not require some sort of straightening. Like maybe only six or seven in close to five hundred blades. So less than two percent for me. :rolleyes:

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Matt And Jesus, I had a blade that had a nagasa of 29 1/2" and a motohaba of 1 3/8" and tapering to 1 1/4" at the Sakihaba. I put in about an inch of sori prior to quench, I did my normalizing and such then clayed the blade with Rutlands, I heated to 1500f and let it set for a few minutes.

 

I quench in parks #50 as well except I have more about 20 gallons in an aluminum truck bed tool box. It is 12" wide buy 12" high by 69" long I think. Any ways I quenched this blade and lost all the sori and gained negative sori about 1/2". The Steel was Aldo's W2, no cracks and no warps just negative sori.

 

Now the funny thing is I watched the blade regain back all but an 1/8" of sori still remaining negative. I did a quick temper just to see what would happen, and I gained back almost all negative sori. The blade was in affect a straight blade and has a beautiful hamon on it. There is a very minute amount of negative sori in the blade.

 

Jesus I hope this helps in some short way, and I have no idea if this even fits your experiment?

 

Oh my parks was at room temp when I quenched it, in after thought I imagine that I would not have lost the sori if the oil had been around 120f

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Very intriguing.. I think that a mild agitation to the quench would make a difference, from what I've read. Maybe an 1/8 inch more? If I could get some parks ill have to experiment. Would a vertical quench make any difference as well? Or spots in the clay to give the hamon a distorted look? Also texture/ plasticity of the clay? So many possiblities when you think about it.

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Thanks, John. That's a different experiment.

 

I only have had one katana-length blade come out straight out of the quench. And I looked at it from different angles to make sure I was not seeing straight. No pun intended.

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Well I was figuring that since I did not gain any more sori, and lost it all and then gained back almost to zero, was close enough to what you were doing. But having reread your post I see that you are aiming for a different result.

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Everyone, I'm kind of excited. I've been thinking about this a lot every since I read it, and I think I may have figured it out. The boiling is the key. When two things are at two different temperatures, and at least one of those things is a fluid, convection will take place. In a quenching situation, that would be the hot blade and relatively cooler quenchant, so the quenchant in direct contact with the blade flows upward.

 

Now, here's the important part. Liquids have a higher convective coefficient than gasses, that is to say, they exchange heat a lot faster. Also, conveniently enough, fluids absorb large amounts of energy when they evaporate, speeding the process further.

 

To abbreviate all that, the idea is that there's more vapor in contact with the spine area than there is the edge, speeding the edge cooling and slowing it at the spine. Water does this naturally, but oil, as we are learning, takes a little coaxing.

 

This, of course, leads to another question. What would happen if you quenched something spine-first?

 

I've got a W2 wakizashi I'll try this on, mainly because I forgot to forge in the sori to make up for the effect of the oil.

 

Maybe it's just too late, and I just studied heat transfer a little too hard last semester...

 

-Ethan

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Only 5 gallons?

 

That is only about 6" x 6" by 36". For some reason I thought it would take more volume to be effective. Maxim oil here in DFW sells the Parks. I will get some. I have about 20 small blades (kogatana size) ground from Aldo's W2 for testing purposes. I wonder if I can see anything on this small scale?

 

My wife's heading down there in a week to visit her father. How much is a 5-gal bucket of Parks from Maxim?

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My wife's heading down there in a week to visit her father. How much is a 5-gal bucket of Parks from Maxim?

 

Yes, good question. I live in Oklahoma, and we visit DFW area at least a couple times a year...

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