Anyone see Some Assembly Required on Disc. last night?

Dennis in MA

Dennis in MA

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May 31, 2005
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They were making a Japanese Sushi knife in Seki City.

At one point, the guy says, "This isn't the sort of knife you'd find made in, say, Dayton OH."

ROTFL!!!! No. Not Dayton. But danged close, buster! Just about 250 miles NORTH!

Them old Japanese know how to weld low-carbon and high-carbon steel to make a flexible yet good edge holding knife. But can they differentially heat-treat a knife??? :)
 
I believe that the clay on the blade allows for differential heat treatment of the blade. I didn't see the show so I don't know if they did that step or not.
 
tedwca said:
I believe that the clay on the blade allows for differential heat treatment of the blade. I didn't see the show so I don't know if they did that step or not.
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yup, they did! :D It was an awesome "old school" demonstration of bladesmithing.
 
I liked how the host made a point of 'The cutlery factory is really a collection of back alley shops."

I'd love to have one of those knives.
 
I saw the show...it was amazing though how the blades tarnished so easily with little use.
 
The clay coatings allow for both that wretched prescence of pearlite towards the spine and allow the high-carbon low-alloy blades to be quenched in water without exploding and cracking all over. Very good stuff.
 
I saw this too (or at least parts of it). One thing that made me chuckle was when the host called them the strongest knives on the planet (or something like that). Those Japanese sushi knives are delicate things. You can ruin them simply by sharpening the edge wrong. They are very thin slicers with very very sharp thin grinds. They are by no means a tough knife. I would love to have a bunch of them, and it would be sweet to go over there and spend some time making my own.
 
Yea, he did seem to cross his info here and there. What I caught about the toughness thing was when he said the 1/4" thickness, duo steels, and differential hardening gave the best toughness, edge holding, and flexibility.

The easy rusting comes from that ultra high carbon steel, I have a Roselli knife out of his ultra carbon and it will patina by breathing on it. But the razor edge it takes is scary.
 
I was contemplating starting a thread when I saw the show come on to let everyone know about it, except I couldn't tear myself away. I too thought that it was rather comical that the Host mentioned Dayton, Ohio - because I live in Dayton, Ohio. Then I realized that the Host was Brian Unger, a native of Granville, Ohio which is in the dead center of the state and only a 120 miles or so from Dayton. He graduated from Ohio University, and was in fact the commencement speaker at my graduation there in 2006. Pretty funny guy, but he hangs pretty heavily to the left for me. Even so, I don't think he has any clue that there are knives made in his (our:D) home state that rival anything Japan has to offer.
 
Is it really differential hardening or the fact that it is two different steels??? Is not SR101 the same steel from edge to spine, differentially treated???
 
Both solid and laminated steels can be differentially hardened. The Japanese have been doing it for centuries. The one thing that gets me is how many ways they are smithing cutlery. I have done a lot of research on the medeival smiths, both laminating and folding seem to be neck and neck in use.

I have owned a few laminated knives that were differentially hardened so it can be done but its a mystery on how they do it, at least to me. This show didnt do well in describing exactly how they stack the two steels together. Normally its a thinner layer of hard steel sandwiched between two softer steels (san mai) Or in the case of a chisel ground blade the hard steel is on the un ground side and that may be why we only saw two layers of steel.

These ancient ways of bladesmithing are fascinating, and so varied one can research a lifetime and not find all the techniques.
 
Dennis in MA said:
Is it really differential hardening or the fact that it is two different steels??? Is not SR101 the same steel from edge to spine, differentially treated???
Click to expand...

it is more difficult to weld o1 to s30v (if it's even possible) then it is to weld 1095 to 1050. The steels being used in japanese cutlery, when made the traditional way, are from the same batch of steel. the higher carbon sections are broken off and seperated from the lower carbon sections. other then carbon, they have very similar make ups, with no additional materials like vanadium or chromium to differentiate them as different steels. only different grades of the same steel.

as an example, when you heat treat them together, your going for the best heat treatment of the underlying 1095, not the 1050. the 1050 takes the heat treatment slightly differently then the 1095, but maintains it's weld and is softer when using the heat treat thats meant for 1095, because it doesn't have enough carbon to raise it's rc like 1095 does.

so you end up with a 60rc 1095 edge, and a 50rc 1095 spine, but the 1050 steel is a soft 43rc.

at least, thats how i think it is??? :confused:

sr101 is modified 52100 throughout, with the spine being softer then the edge.
 
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