Broken BK7

91bravo said:
Looks like you broke that blade some time ago as there is corrosion on the ends of the broken pieces.
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The pic was taken 1-2 hrs after it broke and I had made my way back inside. I live in the Pacific North West and it's pretty damp here. Notably, if you look at the piece of the blade on the left in the picture, how it is dark on the bottom portion of the blade, that difference in color was there right away; I noticed it as soon as it had broken. The spots appeared within that 1-2 hrs.
 
NCWA said:
I thought I was into knives but I had never come across this info about which ones to throw or not. Granted, I'm really not specifically into throwing knives. I thought maybe I was about to get into it... I watched a few videos about it and nobody mentioned anything about only throwing knives of a certain hardness or anything like that, so at least in my experience this isn't super common widely available knowledge. There are videos of people throwing Beckers even. No, I don't plan on doing everything I see on Youtube, but clearly: throwing a knife does not always equal instant fail, even though it did for me.

That BK7 was the first serious knife I bought, after a ton of research. In all the research and everything looking into it that I did, I never came across one breaking for pretty much any reason. I guess they aren't being used much for throwing, but obviously I'm not the first person ever to have thrown one. Given the reputation these knives enjoy; common phrases about them being things like how they can "take abuse," and being "something you can trust your life to," and "throw anything at them," etc., and in Ka-bars words: "Quality your life can depend on. Hardcore Knives. Hardcore Lives." I never thought twice about it.

"Using the proper tool for it's intended purpose" and all that. Yeah, obviously. On the other hand, though, the whole idea behind these knives, and the marketing, is specifically intended as something that you can 'do it all' with.

It is notable about the warranty, like has been mentioned, that it specifically states it also does not cover batoning, nor even 'normal wear and tear.' Every other post about these knives is somebody batoning them...

That BK7 had served me well enough for the past couple years of general use, camp chores, light batoning, light chopping, etc., but before this I really had never pushed it at all. Obviously, everything has its limits. Clearly, I didn't think throwing it was beyond its limits before I did it.

So now the knife community has a thread on a forum about don't throw Beckers, so I guess that might be useful to somebody.
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I have yet to break a Becker, and I've done just about everything short of throwing them (including batoning and chopping). If I remember correctly from older threads about broken Beckers, almost every broken Becker blade has been a result of the owner throwing it too often. Sure, the stress risers from the stamped logo certainly don't help the strength of the blade (which is why Ka-Bar moved to laser-etched logos), but throwing is the most abusive thing you can do to a properly-hardened knife outside of hammering it with a rock into a tree and standing on it.

The warranty discourages abuse of the blades, and while it specifically lists throwing and batoning as specific abuses, ultimately almost every Becker broken has been successfully warrantied because of how few of them actually break. Unless you're knowingly abusing the knife, Ethan has a reputation of being much kinder than the warranty would apply. But, the warranty says batoning and throwing will void it so that the company has a recourse for those tough warranty cases that are clearly abuse.
 
I stand by my statement that a proper 3/16 bk7 in 1095 hardened at 56-57 should have been able to be thrown into a log without snapping into.
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and you will still be incorrect standing there, if we are talking about knives designed to be blades, not projectiles.

Throwing sets up shock in the blade, torque, hamonics, and is very poorly controlled. IF you throw your knife at an appropriate target AND stick it EVERY time, then you will probably never break it, because sticking the point into the target is a relatively soft deceleration compared to deflecting off various things, including rocks, at weird angles, etc.. It would be quite expensive to make a good throwing AND cutting knife reasonable price point. This is dictated by metallurgy, not by your feelings. Certainly Ka-bar has not tried to do so, nor represented the blades as being appropriate for this.

Hard steel is brittle steel. Soft steel cuts poorly. That alone tells the story behind BK-7 vs. random Chinesium knife. Ka-bar picked a point on the hardness spectrum that gives darn good toughness while still making a good cutting tool. But That only goes so far.

Also, yes, laser etching will reduce the toughness compromise over stamping, but not make it go away.

That said, there may ALSO be a flaw in the steel, but certainly throwing is still a poor use of a cutting blade.
 
Goose 7279 said:
I disagree with the above posts i have thrown many hardened steel knives and never had this problem . Anything from esee, busse and my cpk knives @Lorien throws the every knife they make including the light chopper. Most problems that come from throwing a knife is scale breakage or a broke tip not a total complete break like this. I believe this was a problem with the knife but im not an expert.
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i agree with Goose, he's not an expert :D j/k

ESEE gets broken knives all the time too. generally speaking, same steel, similar heat treats. Becker and ESEE are buds. no drama there.

the biggest thing that happens with throwing hardened knives is those times you MISSED. bad times. i still wouldn't do it, even if you were perfect and using soft targets.

first time i threw with very hard knife, it was also brittle. my mom wanted to kill me for busting up her favorite knife ;) then i bought a set of stainless knives made for throwing. still have them 40 years later.
 
I still remember several years back some guy posting up that his BK2 was a piece of junk because it just broke and he wasn't doing anything to it.
after a few questions, he admitted he had just thrown and stuck it in the end of a log when it snapped -- but it shouldn't have, because he did the same thing he'd probably done 1000 times before........
it's generally not the first throw or miss -- it's the cumulative internal stresses.
50 years ago, 52-54 RC was considered a good hardness for a knife -- and coincidentally enough, this is "soft" enough in general to survive throwing.
for the past 20-30 years, knives have been getting steadily harder -- current Kabars are 57-59 RC, which is a good balance between edge holding, wear resistance, and toughness, but not tough enough to survive a lot of throwing. (or prying, batonning, hammering, etc... -- which is why knives break during these activities)

I am bummed for you that your knife broke.
on the plus side - it happened at a time you were goofing off, and not in a situation where it could have endangered you or someone else, and now you know what not to do to your quality survival tool. (for the record - the CS true flight thrower is an excellent design and while it doesn't have the edge holding of the BK&T knife, does work fairly well as a rough use field tool AND throws pretty well)
 
dang daiz, now I want a Chinesium knife!! are you making them?

To the OP, as you mentioned that dark spot was there as soon as you picked the pieces up, I'm going to hazard a guess, that maybe the knife had suffered a light fracture at that point in the past that went unnoticed. Combine that with throwing and stamp placement and snap goes the blade.
 
Air temperature can also be a add on factor on why it broke. If it was cold (i.e. this is winter now), that would make the chances of breakage even greater.
 
Becker knives are tough. They hold up - even for judicious batoning using generally acceptable methods.

Throwing is another story. A soft steel, which is malleable enough to handle the stresses of throwing impact won't hold an edge worth a darn. OTOH, a hardened blade can withstand more cutting without losing sharpness for a longer time - at the expense of being more brittle. Differential heat treat is a way some makers attempt to make the edge harder while keeping the spine area more malleable. There are different opinions on how effective this is in real world uses.

Becker knives strike a balance through material selection, design and heat treat to serve as a reliable outdoorsman's working knife; they're work horses - not show horses. They are not throwing knives, but tough working knives.
 
Anytime a knife breaks it is always a bummer.

I cant say I have ever broken one throwing (I havent thrown a knife since I was 12), but I have broken them chopping, batoning, prying. Never broken one slicing, ever. That doesnt mean I will only use my knife to slice.

I have learned to not mention broken tools around other tool users because they seem to love pointing out how you were using the incorrect tool or the tool incorrectly. I have also learned that most tool manufacturers will work with you on finding a solution to broken tools.

Sorry for your loss. Try not to hold it against Becker or Kabar.
 
Don W said:
I have learned to not mention broken tools around other tool users because they seem to love pointing out how you were using the incorrect tool or the tool incorrectly. I have also learned that most tool manufacturers will work with you on finding a solution to broken tools.
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This is the absolute truth! There is ALWAYS something to critique about usage of a tool, but, ultimately, what is a Becker? A tool. It's meant for real use, and sometimes real use breaks the blade. Does that mean I would recommend throwing it? Absolutely not, but hey, now you know that you need a different tool for throwing. Nothing's really lost (except money) and you've gained valuable information about Beckers!
 
To beat the horse further......

This discussion got me thinking about the amount of kinetic energy a BK-7 might impart or expend into a target if thrown.
some assumptions:
weight - 12.9 ounces or 0.8 pounds
speed - 36 mph (google fastest reported thrown knife speed)

KE=1/2 X mass X velocity squared equals 47 joules or 34 foot pounds.

If the knife sticks into the target every time, the knife expends that amount of energy into the target while undergoing some amount of recoil itself less than the 34 foot pounds. if you miss....and it whacks into the target, the knife takes the full 34 foot pounds itself as the target acts as an immovable object. wash, rinse and repeat and toss in a little weak spot (like the stamping or the hardening) and you eventually have two halves of a knife.

in the end, that doesn't take away the pain of breaking a knife but it does help to explain why even steels aren't unbreakable when thrown as projectiles.
 
turbosquirrel said:
To beat the horse further......

This discussion got me thinking about the amount of kinetic energy a BK-7 might impart or expend into a target if thrown.
some assumptions:
weight - 12.9 ounces or 0.8 pounds
speed - 36 mph (google fastest reported thrown knife speed)

KE=1/2 X mass X velocity squared equals 47 joules or 34 foot pounds.

If the knife sticks into the target every time, the knife expends that amount of energy into the target while undergoing some amount of recoil itself less than the 34 foot pounds. if you miss....and it whacks into the target, the knife takes the full 34 foot pounds itself as the target acts as an immovable object. wash, rinse and repeat and toss in a little weak spot (like the stamping or the hardening) and you eventually have two halves of a knife.

in the end, that doesn't take away the pain of breaking a knife but it does help to explain why even steels aren't unbreakable when thrown as projectiles.
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I believe the force would be even greater because you have rotational energy working into the equation as well, although you certainly can't calculate that without taking measurements on the individual throw.
 
True. I also simplified things by negating gravity and friction....which would lower the force slightly.

34 foot pounds sounds rather benign....so you need another actor like the weak spot from stamping to aid in the failure. You also need to throw it more than once.

I suspect there was a micro crack present before the last throw
 
turbosquirrel said:
True. I also simplified things by negating gravity and friction....which would lower the force slightly.

34 foot pounds sounds rather benign....so you need another actor like the weak spot from stamping to aid in the failure. You also need to throw it more than once.

I suspect there was a micro crack present before the last throw
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NCWA did state that there was a difference in color in the lower portion of the blade.
NCWA said:
The pic was taken 1-2 hrs after it broke and I had made my way back inside. I live in the Pacific North West and it's pretty damp here. Notably, if you look at the piece of the blade on the left in the picture, how it is dark on the bottom portion of the blade, that difference in color was there right away; I noticed it as soon as it had broken. The spots appeared within that 1-2 hrs.
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Just read Daizees post.
I understand now.
Sorry about your knife.
 
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I always enjoy hearing and reading daizee's explanations about knife related things. Once again, he is right.

Another nice knife wasted.

Jeremy
 
As a point of reference, ESEE has one of if not in fact the most generous warranties in the knife world. "You break it, we replace it, no questions asked." In fact, the warranty goes with the knife regardless of how many owners it has had. Warranties don't get much better than that. Having said that, the ONE thing they single out as "idiotic" (their word choice) is throwing their knives. If that doesn't put throwing knives into perspective, I don't know what does.
 
Gun Doc said:
As a point of reference, ESEE has one of if not in fact the most generous warranties in the knife world. "You break it, we replace it, no questions asked." In fact, the warranty goes with the knife regardless of how many owners it has had. Warranties don't get much better than that. Having said that, the ONE thing they single out as "idiotic" (their word choice) is throwing their knives. If that doesn't put throwing knives into perspective, I don't know what does.
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smoke mountain used to have an official ESEE display of "broken knives". that includes stuff people bought and then cut in half with a torch or angle grinder, so they could get a new knife. ESEE iirc, reserves the right to call people out for stuff like that, and infer using strong words aspects of their ancestry and general character ;) i think they have sometimes refused to replace a knife, but sometimes will, just so they can let the customer know their opinions :D
 
Bladite,

I do not doubt you at all. Having said that, I did check the ESEE website before I posted. To quote directly: "This means if you break it, we will repair or replace it. We will not question the validity of your warranty claim for a broken knife."

I do not doubt you that someone could push the above so egregiously that ESEE would call BS. But that in no way takes away from my point about their generous warranty combined with their only comment to be about the inadvisability of throwing knives clearly putting the practice into perspective. That was my real point.
 
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