Hamon alternative methods

O

Old oak

Joined
Jul 14, 2019
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Accidentally posted this under custom knives so I’ll just cut and paste to here.

Ok new to the forum but I’ve been using it for a few years now as I began into the world of knife making.

Haven’t seen anything pertaining to my question yet and I’m one of those people that firmly believe there is always a easier or better way to do things which I know is kind of a flawed idea in this hobby. But here’s the question.

By using the typical method of clay to make a hamon line the theory essentially is to differentally harden the blade with a finer line between the two extremes “the hamon” instead of having a larger distance of hardness change. At least this is what I’ve gathered from the last few years of doing this. So that being said and just excuse the shortened oversimplification of the process, If one were to take two plates of steel and clamp them on each side of the spine of the blade having the edge of the pieces where you want to have the demarcation line of the hardening difference then heat and temper the whole set together clamped, would this not provide a much thinner hardening/soft zone than simply edge quenching and possibly resulting in a hamon line due to the sandwiched spine cooling much slower(and probably not even hardening) than the edge would?

Anyway go ahead with the “oh he doesn’t know what he’s doing comments” because that’s one way I’ve learned a lot on here before I make the errors in trial and error...
 
It might work to do that, but having that extra mass also might make the rest of the blade “auto-temper” to the point that the edge was too soft...

I think if it was a reliable way to do it, people would be doing it that way already.
 
You would be better to try a partial quench and get a quench line.

Heat the whole blade to the target temperature and quench it in oil that is only 1/2" deep. Use a large pan to hold the oil, because you still need a gallon of it to absorb the heat. Rock the blade rapidly to make sure the tip is getting quenched, too. Expect to have the blade catch fire and make lots of smoke ... so do this outdoors. After about 10 seconds, just let go with the tongs, let the blade fall sideways, and go under the oil, That will make the flames go out.

You won't get a real hamon, but you will get a line a little above the oil depth.

I have not done this yet, but once I came up with the idea of cutting a slot in the edge of a 1" wide strip of 3/4" thick Insboard that the blade can slide into. Shape the Insboard edge in the shape of the hamon line desired. Put the blade in the slit with some satanite or similar refractory and HT the blade as with a normal hamon quench. Since I have never had a problem with claying the blade, I never saw the need to try the idea.
 
I’m just assuming the purpose of the clay is to retain the heat in that area longer during the quench which in turn causes it to not harden while the area out of the clay cools quickly. Just thinking that if you took a couple 1/4” or so pieces of steel and sandwiched the spine with them it would also take considerably longer to cool than the blade causing the same result.

Maybe doing the edge quench in conjunction with the sandwich plates would enhance the effect even more but possibly slow down the edge quench too much resulting in a non hardened edge.
 
If you're talking about clamping the steel with extra metal during heating and quenching, the problem is that the extra metal acts as a heat reservoir that can keep the edge from cooling fast enough. The hamon won't follow the shape of the extra metal anyhow due to this. If you Google it, you can find that it's been tried before and doesn't work well.
 
Why are you trying to reinvent the wheel? People use satanite clay or furnace cement without big problems, and I fail to see what could be more simple than putting it on your blade? If you want an even easier way to do differential hardening, then just edge quench and/or leave your knife thick at the spine. Google autohamon
 
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