Japanese Whaling/Camp Knife - Well almost.. :(

[SBranson]

Interesting comments.

@ Lorien...

are you saying that the soft back of the blade contracted more than the hardened and thinner edge area, and due to the width and additional leverage, pulled the hardened area enough to crack it?

Yes and sort of... The first part is why Japanese blades have a curve, or sori. The blade goes in relatively straight (depending on the intended curve) and when the blade hits the water, the edge contracts rapidly whereas the spine, due to clay (and mass?) cools more slowly so at first the blade curves down. But as the spine cools, it contracts further than the martensitic edge and thus causes the curve upwards.
I think, in this case, that with the very wide blade and the large edge area combined with a steep bevel created a small amount of mass in comparison to the spine. This combined with the clay caused too much stress on the edge as the spine cooled. If I had done something to slow the cooling, such as not putting it back in the water the last time or threw it in the oven quickly, maybe it wouldn't have cracked.

More mass at the spine might have made it worse but it most certainly would have had a negative effect on the hamon as the hamon is a surface phenomenon and the more you grind the more activity you lose. That's another part of the balance.. How far to take the main bevel and edge and risk ruin to the water but enough to leave the hamon as lively as possible.

@SC. That is interesting about the Japanese blades. I actually hadn't noticed the negative sori so much as when there is a shinogi bevel on the blade. Maybe that center of mass being 2/3 of the way up rather than at the spine has more of an effect than I was aware of. Another thing to watch...

 

[Storm Crow]

Stuart - I've seen it in non-Japanese style blades as well. What they all had in common was that they were relatively thin and narrow blades (compared with the typical bush sword I make). So I figure at a certain point that I need to make the blade have extra curve to make up for it straightening, but most of what I make falls outside that range.

A thicker spine seems to lessen the amount of curving in the quench, not exacerbate it. At least that's what I've seen with mine.

 

[David Stifle]

I don't know if this would affect the quench or the sori, but a lot of old Japanese swords I have seen have a rounded, or even triangular spine. I don't know if this was added after the HT, but my though is it may have been done beforehand to ease stress during the quench. What do you guys think?

 

[Lorien]

here is a pic of the knife in action, (where did that bald spot come from?);

and some cute kiddos;

 

[wnease]

I love this style of knife! I sketched a little one last night and have spent some time online looking for related designs but am coming up with very few. Is this typical for a Japanese whaling operation? Does anyone have the Japanese name? I need some context to refine what I'm building.

SBranson nice work... I'd personally shorten it at the crack satsume-age style but the lines you have there are super nice

Thanks!