Bk-9 failure

Most manufacturers opt for a more obtuse grind to reduce warranty claims. Becker seems to be pushing the performance envelope. I admire that but I think they should thicken the grind on the BK-9. I don't think the steel/ heat treat is the problem. Obviously just pure speculation on my part but as I said I was chopping hard wood this weekend and while no edge damage per se, the "edge" rippled in a couple places. That's because there isn't enough steel behind the actual edge to support the force of a misaligned chop. So what if the steel moves a bit on a chop and then moves again and again - it work hardens and becomes brittle...just my opinion!
 
That same thing happend to my BK-9.. i love that knife for my camping/outdoor needs...
I would like to know what Ka-Bar does, although I suspect its not gonna be their problem.. Im planning to use mine til its all the way GONE!!

Guess Ill just have to buy another one..
 
Ka-bar is one of the great knife companies. They stand by their product, and are watching out for all of us. They are offering these blades at an unbelievable price point. Thanks Toooj :D
I ground out the chip and convexed the edge. I thickened it all the way up on the sweet spot and have had no issues since.
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cody1 said:
Ka-bar is one of the great knife companies. They stand by their product, and are watching out for all of us. They are offering these blades at an unbelievable price point. Thanks Toooj :D
I ground out the chip and convexed the edge. I thickened it all the way up on the sweet spot and have had no issues since.
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That looks pretty good, cody. Nice looking chopper.
 
I think the ka-bar cutlass machete is a real sleeper. 5/32" stock, 1085, 11.5" blade length. Stripped and convexed, it's hard to beat. I have abused this blade and it keeps coming back for more. All that fun for under $45. It's really a beast. :D
 
Hi Guys,

Emcarrol: Same offer applies to you too. Call the 800 number and we will exchange if you want.
Cody1: Thanks for the call and kind words. The offer still stands but it looks like your mods are doing well.
TiNi: The half moon chips form when the edge hits something harder than the steel. The point of impact is typically the center of the half circle. The vibration radiates outward into the blade until it; hits a non metallic inclusion; hits a section of Retained Austenite; hits a large brittle carbide string; or just exceeds the limit of the steel. A crack is formed. A small micro crack will eventually chip out. A large crack usually results in a sudden catastrophic failure. If the entire blade lets loose, there are usually multiple pieces and it will start as a half circle or chip and then explode the entire blade.
AF: A thicker edge will be stronger but it takes more force to penetrate an obtuse edge than an acute edge. A more acute edge will penetrate deeper with less force. It is always a balancing act: durability/performance/edge holding/etc;etc.
I do not believe that work hardening plays a large part in the fracure equation. Since the structure is largely Martensitic, it's BCT does not react to stress/strain as a ferrite BCC.
It will either withstand the impact, flex or break. However, I'm not a Metallurgist, I just play one at work. Maybe Mete or Scott Devana or other metals people can shed some light on the subject. I'm up for learning.


Best Regards,

Paul Tsujimoto
Sr Eng
Prod Dev and Qual
KA-BAR Knives.
 
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Thanks for the post Toooj! I have no idea what I'm talking about but I appreciate the response. I'm just an enthusiastic knife owner and user. I always carry a big chopper with me when I go hiking in the White Mountains. I use it to clear the trail or just play around with it off the trail. Oh and if I ever encounter an angry black bear - I'll use it for that too.
 
Oh and if I ever encounter an angry black bear - I'll use it for that too.
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AF,
Then you can write a letter to a knife company about how you K' abar and then that company will change it's name....wait I think that has already been done.
Don't worry, you have a lot of knowledge and you are quite correct about edge thickness and edge strength. If we were looking at total edge strength, you would be correct, but we (KA-BAR) and Ethan want it all: performance, strength and affordable price. So hence the juggling act.


Best Regards,

Paul Tsujimoto
Sr Eng.
Prod Dev and Quality
KA-BAR Knives
 
Hey Everybody......

Truly it is all a balance.......Ya can't shave worth a damn with a cold chisel and ya can't take down a tree with a straight razor (well maybe very, very slowly) and the in between is all shadings of gray......

A word to the wise no matter whose blade you are using if you are in the weeds in a world of hurt be as kind to your blade as you can be.......I baton with a Victorinox Rucksack, very carefully mind, and always lose 'em before I break 'em.......In a real situation I baby my stuff as much as I can.......I love to work 'em hard at home to find out what they WILL do.....You CAN throw an MP5 across the room on a concrete floor without damage but I do not suggest doing it just before a gunfight.........Who knows.....

All Best....

ethan
 
Ethan Becker said:
Hey Everybody......

Truly it is all a balance.......Ya can't shave worth a damn with a cold chisel and ya can't take down a tree with a straight razor (well maybe very, very slowly) and the in between is all shadings of gray......

A word to the wise no matter whose blade you are using if you are in the weeds in a world of hurt be as kind to your blade as you can be.......I baton with a Victorinox Rucksack, very carefully mind, and always lose 'em before I break 'em.......In a real situation I baby my stuff as much as I can.......I love to work 'em hard at home to find out what they WILL do.....You CAN throw an MP5 across the room on a concrete floor without damage but I do not suggest doing it just before a gunfight.........Who knows.....

All Best....

ethan
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i would never drop a gun or throw it. screw that ;)

though my shotgun can survive being in water all day, and just wipe off. it's not $30,000 trap gun, but i do okay.

imho, if one is going to hard-use a knife, and chop, convex that edge, and keep it tuned. no guarantees there, but it will be awesome.

very few companies offer pre-convexed blades, but that's one of the reasons i love the Northern Lights series from Fallkniven - but compare prices - machines can't convex (or crochet)... so, you get what you get...


Bladite
 
I always took better care of my weapons than I did of myself. Throw one across the room? Blasphemy!
 
Toooj said:
The half moon chips form when the edge hits something harder than the steel. The point of impact is typically the center of the half circle. The vibration radiates outward into the blade until it; hits a non metallic inclusion; hits a section of Retained Austenite; hits a large brittle carbide string; or just exceeds the limit of the steel. A crack is formed. A small micro crack will eventually chip out. A large crack usually results in a sudden catastrophic failure. If the entire blade lets loose, there are usually multiple pieces and it will start as a half circle or chip and then explode the entire blade.
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Man, would I have loved to be in on THOSE tests! If you come up this summer, we'll have to "test" my old Camillus BK9, she could use a little exercise.

1066vik said:
and that, my friends, is good customer service. :D
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ls1 said:
Yes it is!:D
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Amen. :thumbup:
 
Bushman5 said:
I would love to see a BK9 the thickness of a BK2....... ;)
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i'd buy that in a heart beat! the extra thickness of the bk2 really feels perfect in my hand. i've even thought about putting some kind of spacers under the bk9's scales to thicken the grip up.
 
Ethan Becker said:
Hey Everybody......

Truly it is all a balance.......Ya can't shave worth a damn with a cold chisel and ya can't take down a tree with a straight razor (well maybe very, very slowly) and the in between is all shadings of gray......

A word to the wise no matter whose blade you are using if you are in the weeds in a world of hurt be as kind to your blade as you can be.......I baton with a Victorinox Rucksack, very carefully mind, and always lose 'em before I break 'em.......In a real situation I baby my stuff as much as I can.......I love to work 'em hard at home to find out what they WILL do.....You CAN throw an MP5 across the room on a concrete floor without damage but I do not suggest doing it just before a gunfight.........Who knows.....

All Best....

ethan
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this is why everyone should be carrying 10+ knives on a woods outing! :thumbup: variety is the spice of life.
 
Bushman5 said:
I would love to see a BK9 the thickness of a BK2....... ;)
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JV3 said:
i'd buy that in a heart beat! the extra thickness of the bk2 really feels perfect in my hand. i've even thought about putting some kind of spacers under the bk9's scales to thicken the grip up.
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The Camillus BK9 was the same thickness as the current Ka Bar BK2 = a full quarter inch.


Edit: The thickness of the Camillus BK9 was in fact .210 inch.
 
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