BK knife has soft spine ?

D

dingy

Joined
Feb 19, 2008
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Hi you all. today i stripped my well used BK7 , and what i found is that my BK7 has a soft spine , what i mean is that the spine on knife is softer than the edge. is it normal?

thanks
dingy.
 
interesting.
my understanding is that those are supposed to be through hardened, not differential.
OTOH, as long as edge retention is good, it shouldn't hurt anything.
 
dingy said:
Hi you all. today i stripped my well used BK7 , and what i found is that my BK7 has a soft spine , what i mean is that the spine on knife is softer than the edge. is it normal?

thanks
dingy.
Click to expand...

How could you tell it was softer?
 
I am not to knives as a buyer, but technically savvy far from it. However, I would like to know more on the technical side. How do you know or test for hardness?
 
I used stripper and a stainless tiny shovel (spoon like ) to to remove the paint on the knife ,when scraping paint with tiny shovel which contacted with knife tang ,spine and edge , i can feel the hard ness diffrence , cause i can scrap tiny tiny steel fillings from the spine of the knife , but i can not do so with the same shovel on the edge.
so i can tell the hardness diffrence on the knife that the spine is obviously softer than the edge.
 
interesting.
How far does the bevel does the softer steel go?
Differentially hardened blades are often desireable, if done right. Super tough.
 
I thought I heard a while back KA-BAR was now using the differential heat treat process on all their current knives. Maybe not?:rolleyes:
 
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my old bk5 (there are stamp marks on both sides of the knife , so i thought my BK5 is a older than my bk7and 9 which has laser marks .) has hard spine and the hardness on spine as hard as the edge .

you guys may do a test by youself with a steel file,

and my 5 and 7 both have soft tang.

i have not polish both knives , so can not found out the clue of hamon line.

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Or are you saying the spine and the tang?

It’s possible that is the case, although I have no idea if on purpose. If it is, that’s actually kinda cool as the blade will resist snapping better, and the edge will still hold an edge.

Many outdoor knives are treated this way. Anyone know if Ka-Bar does this on purpose?
 
what i found is that my bk7 has soft tang and spine,and my bk5 has hard spine and soft tang.


 
Inneresting.

Hardening requires rapid cooling to complete. It might be possible to cool the blades at an identical rate that would allow the lower-mass BK5 blade to harden fully, but not the thicker-spined BK-7. And tangs carry a lot of mass. Or they could do them differently. And things may have changed over time. Curious how they're going about it these days.
 
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