Broken BK2

[Moosez45]

I may get chastised, but this has been eating at me for a while now. There was a post about someone who broke a BK2. I know, I thought it couldn't happen, but it has.

Kabar has a Broken BK2 in house, for study and review. Its the first. I asked Toooj about it and he thought gross abuse. I talked to Ethan about it, and he thought throwing it. Well they were both right, it was thrown repeatedly, and that, in my book constitutes abuse.

Becker/Kabars are not throwers. They temper their knives to be good, tough, edgeholders. When knives are thrown, the impact creates a vibration/harmonic resonance that hard tempered (59-60) can't take. Throwers are tempered softer (50-52) so they can withstand the impact. Hard tempered knives that are thrown, create micro fractures that grow larger with each impact.

The knife in question was "throw a hundred times, and never flinched" Then it was dropped into a stump, where it promptly "broke in half". Yep, that can happen.

SO, if you want to throw your Becker knives, get ready for them to break. They won't break right away, but they will soon.

SO, if you want to throw knives, buy a knife designed for it. If you want a great cutter that you can beat on, cut stuff, baton, and use hard, buy a Becker/Kabar.

Feel free to post your comments, but the science is sound, and the knowledge is not new, its quite old.

Moose

 

[wildmanh]

If you want to throw something into a hard wood target, get a hawk or 3. But if you are dead set on throwing a knife, a Soft target like Cardboard or Foam works really well.

 

[Battle Creek Knives]

yep, that's why the knives are labeled 'throwing knives'..

was this a intentional test condoned by kabar/becker?

or is this a, "lez cut down tat tree over thare, by trowin this here knife at it" sorta backwoods test by owner? and/or did the owner of the 2 surrender this information??

 

[disduster]

i agree, i did stuff like that when i was a kid with cheap knives and probly broke or lost a few. i would never dream of it these days, most of all not any of my beckers. throwing knives not intended or designed for throwing does constitute abuse in my mind.

live and learn.

 

[dawsonbob]

I'm astonished! Simply flabbergasted! In all my time with Beckers, I've never even heard of such a thing. There has never been a recorded case (that I'm aware of) of a BK-2 breaking for any reason . . . until now.

Sure, anything made by man can be broken, and I guess it had to happen sometime, but a BK-2? Never thought I'd see the day. Now I'm sure that the world is coming to an end, and I just saw a flock of pigs fly by, but break a BK-2?

But the guy was throwing it and, as Moose pointed out, that's just about the worst thing you can do to a knife that wasn't made for it. Throwing a good knife is just about as senseless as giving one to Noss for "testing": neither one is a good idea.

Personally, I'd never throw a knife at anything but a flying pig, but that's just me.

 

[jacktrades_nbk]

doesn't batoning create vibrations to, to some extent ?
i mean batoning with wood, not with steel hammers....

 

[dawsonbob]

doesn't batoning create vibrations to, to some extent ?
i mean batoning with wood, not with steel hammers....

Batoning will create stresses on a knife, but not the same kind of stresses that throwing it can cause. Oddly enough, batoning — proper batoning, with wood, not metal or stone — creates less (and different) stress than throwing, and is not considered abuse in Beckerland. Throwing, on the other hand, would be abuse in my book; just the thought of it makes me shudder.

 

[Battle Creek Knives]

doesn't batoning create vibrations to, to some extent ?
i mean batoning with wood, not with steel hammers....

DING, DING, DING we have a winner.. good point, everything that was created continues to vibrate, harmonic vibration is simply deflecting..

I'm sure at some level or another there are many harmonics taking place while battoning, wood itself has some harmonic value.

Ever hear a little ding/cling yada yada after blasting threw the wood? If you were to take the knife and baton right threw some wood put the pomel to your ear (just above your earlobe on your head) and press it against your head you would hear tonality, which brings a valued point in harmonics....

 

[Battle Creek Knives]

Batoning will create stresses on a knife, but not the same kind of stresses that throwing it can cause. Oddly enough, batoning — proper batoning, with wood, not metal or stone — creates less (and different) stress than throwing, and is not considered abuse in Beckerland. Throwing, on the other hand, would be abuse in my book; just the thought of it makes me shudder.

funny thing is, when I got my 2 yesterday I was thinking (if only for a moment) man I should have left the scales off before locite and tossed the knife in a tree a couple times

looks like a nice thrower and allows one to think its indestructible, but as you said earlier anything made can break.. if given the chance..

 

[Moosez45]

doesn't batoning create vibrations to, to some extent ?
i mean batoning with wood, not with steel hammers....

It creates stress but in a manner that the knife was made to absorb, what we are talking about is harmonic resonance or vibrations. Think tuning fork. When a knife is flying through the air, is building up energy, granted the energy is being depleted at a proportional rate, but when it impacts, all that kinetic energy is deposited into the target. Trees don't move, contrary to what drunk driver say. All that energy is then redirected BACK into the item delivering it, think bouncing a basketball. The ground doesn't move, so all that energy forces the ball back up.

The kinetic energy sent back to the knife, cause it vibrate like a tuning fork, and hardened metal isn't designed to flex like that, that fast. It creates micro fractures, unseen to the naked eye. Those fractures get bigger, and bigger with every toss, until, finally they manifest themselves in a FRACTURE, or break. The harder you temper a knife, the closer to glass it becomes, now I'm not saying that tempered steel is glass, but is shares some of the same properties, like brittleness.

Anyone heard of obsidian? Sharpest stuff on the planet, when knapped correctly, and won't dull no matter what medium you're cutting. What happens when you drop in on a hard surface, like concrete? It breaks.

I am sorry to be long winded, but this is something that has been bothering me of a while.

Moose

 

[Maniacal Pete]

I am bugged by the "broken knife" syndrome that keeps going around. ANYTHING will break given enough stress. I have seen quite a few knives, and I have never seen one that was more "tank-like" than my BK2. Could I break it? Sure. Under normal (harsh) use as a knife? No Way...

On a side note, I just got three sets of canvas micarta handles in for my three friends (BK2, BK7, BK9). I'll post some images when I get them attached.


pete

 

[Moosez45]

I am bugged by the "broken knife" syndrome that keeps going around. ANYTHING will break given enough stress. I have seen quite a few knives, and I have never seen one that was more "tank-like" than my BK2. Could I break it? Sure. Under normal (harsh) use as a knife? No Way...

On a side note, I just got three sets of canvas micarta handles in for my three friends (BK2, BK7, BK9). I'll post some images when I get them attached.


pete

Sweet, look forward to seeing the pics. Oh, and welcome to the Becker forum.

Moose

 

[Bladite]

It creates stress but in a manner that the knife was made to absorb, what we are talking about is harmonic resonance or vibrations. Think tuning fork

well, IF the knife hit point first, everything would be awesome. mostly. linear energy delivery, no deflection. thunk. you might MAYBE develop some tip damage, but well, i expect, mostly nothing would happen.

however, how many times did this guy MISS, smacking the knife amidships which is the worst possible outcome, causing deflection and oscillation? and what was he throwing at? what else did the knife bounce off of?

i bet if you took most knives, and put each end on a block, and smack the middle with a hammer, with about as much energy as the knife would receive from a hard throw... it's going to break. probably.

When a knife is flying through the air, is building up energy, granted the energy is being depleted at a proportional rate

well, not exactly physics says the maximum amount of momentum is fixed once released from the hand. it will lose energy from air resistance, and gain some maybe from the ballistic drop, but i'd call that a wash, of sorts

definitely sounds like abuse. i hope they don't replace it.


Bladite

 

[Moosez45]

well, IF the knife hit point first, everything would be awesome. mostly. linear energy delivery, no deflection. thunk. you might MAYBE develop some tip damage, but well, i expect, mostly nothing would happen.

however, how many times did this guy MISS, smacking the knife amidships which is the worst possible outcome, causing deflection and oscillation? and what was he throwing at? what else did the knife bounce off of?

i bet if you took most knives, and put each end on a block, and smack the middle with a hammer, with about as much energy as the knife would receive from a hard throw... it's going to break. probably.



well, not exactly physics says the maximum amount of momentum is fixed once released from the hand. it will lose energy from air resistance, and gain some maybe from the ballistic drop, but i'd call that a wash, of sorts

definitely sounds like abuse. i hope they don't replace it.


Bladite

According to Ethan, impact is what causes the vibrations that make the micro fractures, sticking or not. I say whichever way it hits, its not good for a hard tempered knife.

I agree, it slows down in every aspect, loosing energy once it leaves whats propelling it, but there is still plenty of stored kinetic energy to deliver up on impact. Sound good?

Moose

 

[Bladite]

According to Ethan, impact is what causes the vibrations that make the micro fractures, sticking or not. I say whichever way it hits, its not good for a hard tempered knife.

In long range shooting, we were taught that bullets only decrease in speed once the round leaves the barrel. True, same for a thrown knife. I agree with you. Ballistic drop on a knife would be negligible for the distance and velocity which some could throw it, so the ballistic coefficient of the blade would be very high, as its not a streamlined as bullet while the knife is tumbling end over end. But, the centrifical force of the spinning blade does increase the kinetic energy its generating during flight.

Moose

ah, but where the impact occurs is really important...

the knives can take significant impact on the point, that's why that pommel is there. for hammering the knife into things... but you never hammer knives sidways. they'll take flex/bend by hand forces but not impacts...

spinning or not, once the object is "free", it's not going to build up MORE energy. that's fixed once it's released (imparted energy).

http://en.wikipedia.org/wiki/Kinetic_energy - unless it accelerates (dropping), it's just not going to build and build.

now throwing a knife does impart a LOT of energy. more than probably chopping might. the impact area of a miss is small, and a lot of energy will cause breaks. don't ask me how i know

grrr, arrgh, grrrr knife abuse!


Bladite

 

[Moosez45]

I was editing while you were typing, after I read what I wrote, it didn't make sense, so I changed it. I agree with you an physics.

Moose

 

[Moosez45]

ah, but where the impact occurs is really important...

the knives can take significant impact on the point, that's why that pommel is there. for hammering the knife into things... but you never hammer knives sidways. they'll take flex/bend by hand forces but not impacts...

spinning or not, once the object is "free", it's not going to build up MORE energy. that's fixed once it's released (imparted energy).

http://en.wikipedia.org/wiki/Kinetic_energy - unless it accelerates (dropping), it's just not going to build and build.

now throwing a knife does impart a LOT of energy. more than probably chopping might. the impact area of a miss is small, and a lot of energy will cause breaks. don't ask me how i know

grrr, arrgh, grrrr knife abuse!


Bladite

I agree, but what we are talking about isn't sideways force, but the metal actually vibrating on impact. The best way I can explain my point is a tuning fork, you hit it and the tynes are in free air, vibrate for a period of time. When you so much as touch the tyne with finger, it ceases to vibrate. The vibrations created when impacting a knife, say batoning, are immediately dampened by your hand and the wood surrounding the blade. When a blade is thrown into a tree and sticks point first, the portion of the blade sticking out from the wood is free to vibrate until it disapated. Like the tuning fork, you have a hold of the handles, but the tynes still vibe. Most breaks that I have see from hardened knive being thrown into a tree or target disc, is where ever the blade width decreases. The changing of the geometry from wide to narrow, forces the vibrations to intensify, creating the microfractures there.

Moose

 

[Maniacal Pete]

Sweet, look forward to seeing the pics. Oh, and welcome to the Becker forum.

Moose

Thanks, I'm a Big Fan of the Beckers...

pete

 

[dawsonbob]

You folks are making my head hurt. This stuff requires way too much thinking about stuff I don't want to think about.

I don't know much, but it seems to me that what's happening here, basically, is that you have an object at velocity (doesn't matter how it attains that velocity) impacting a dense, solid object at rest. Whoa (literally)! The object at velocity is now coming rapidly to a full stop. It really doesn’t want to stop, but it’s forced to, and it doesn’t stop all at once: different portions will be stopping at different times (in the micro-mini-real fast scheme of timely things).

Lets say that the tip of the moving object arrives first and, due to its momentum, embeds itself in the solid thingie that doesn’t want to move. Okay, lets say it does that; but the after end — the one that hasn’t come to a stop yet — is still traveling. Sure, it’s going to come to a stop, too, but before it does, it’s going to impart a pretty fair amount of stress on the portions that have already come to rest. That’s where you’re getting your vibrations/harmonics from, boys and girls.

But wait! There’s more! All of the above assumes a perfectly straight impact with a perfect medium, which probably isn’t going to happen in the real world (knife throwing at wood). As the knife impacts, it’s going to try to twist and turn because it really didn’t want to stop, did it? Remember that after the tip stops, the rear hasn’t gotten the message, and is still trying to continue on its path. What happens then? Lateral stresses are loaded throughout the object (knife). Have you ever seen a thrown knife vibrate/quiver when it hit the target wood/tree? What do you think is happening during all that vibrating/quivering? How much of that do you think your knife can take? Not much, I think.

Now, all this may not be the best description, but I was on a bus once with an engineer, and I’m pretty sure that’s what he was thinking about.

Or maybe not: you can never tell with those folks. He may have been thinking about lunch.

 

[Moosez45]

Yes, I agree. I got a little obsessed there for a minute. I apologize to everyone.

Moose