Hamon lines

Brad Lilly

Moderator and Awards Boss
I have been thinking about hamon lines and do they cause stress risers at the “peaks”? Hamons seam to be the thing to do today, but I am curious about the durability of a knife with highly pointed hamon. Anyone do any testing on something with a hamon line?

Most of my knives are made with 1084, edge quenched. Since there is no clay on my knife the “temper” line is smooth and uninterrupted from the riccaso to the tip. In my mind smooth means less stress, corners and fast transitions are stress points.
I could be wrong
 
I think stress risers are overated ! Japanese swords have Hamachi ( riser cut out on blade edge) and a munemachi (riser on the spine ) They have been well tested . There is a point I would like to make . On the Hamachi (Blade edge cut out ) Clay is taken past the riser about 1/2" or so into the tang.
So it is hard . As long as blade is well supported by handle , I have never had a problem , even while cutting harder targets . Most Japanese blades are about 1/4" thick at that point . Its possible you could have problems with a thin blade ? If you keep it thicker I dont see a problem . The tang of blade is also clayed with a thick coat. Thin coat on edge past blade edge riser .... If you are edge quenching I would quench past riser on blade edge ( hamachi)
 
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Interesting that the hardened portion runs into the tang I never knew that. I always thought the tang would be soft up until the guard (sorry I don’t know the proper term). I thought that the portion of the sword closest to the guard would have the most stress and used the least for cutting. Bubba when you use the term “riser cut out” is that a feature of the clay coating or a fuller? You will have to excuse me I’m not very familiar with Japanese swords
 
Brad , the hardened portion runs into the bottom of tang , just past the Hamachi , which is the 90 degree cutout that joins the tang to the blade edge. Actually the most stress is just below the middle of blade because , japanese swords cut with the upper portion of blade . The term riser cut out is refering to the hamachi ,"Ha" means the edge of sword . munemachi means the 90 degree cutout on top of blade , the spine . A good hamon runs just past the Hamachi into the tang about 1/2". Here is a japanese sword visual glossary . It can help explain part of what I am speaking of . I hopes this helps you .http://home.earthlink.net/~steinrl/glossary.htm Bubba
 
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