M43 damaged

[HARPERSGRACE]

I would do as Yangdu suggests, return it so it can be evaluated and abide by that...speculation only goes so far...

 

[Bladite]

WV Hills lives about 30 min from me.

None of the pines we have around here should bend a khuk in the hardened area.

I can't see the pics but if as somebody said it's not in a sweet spot I would take a brass hammer and a hard surface and pound it back into line and re sharpen.

I personally would rather have the khuk a little soft rather than super hardened because the super hardened ones chip real bad and it is impossible to fix.

It could be that that softer area was drawn out a little thinner than it should be for the hardness if anyone knows what I'm trying to say

yah, you gots them yellow pine though, harder than our white pines... but i don't know what else you got. maybe he got a mutant, or was chopping right at the base of the branches and got some hard wood or is a beast. hard to tell.

the khukri could just be soft too, it happens, rarely, but it happens. one of these days soon, i got to get me a belt sharpening system - i've got too many edges, and doing it by hand just doesn't float my boat anymore. hammering out dings is just par for the course with working tools too.


Bladite

 

[hollowdweller]

Virginia pine is hard but it usually won't bend a blade. I did bend an AK Bowie on some once though.

Oak is the blade bender for me. It actually chops easier than say pine or ash but is more likely to bend the blade when you do.

 

[MrMike]

just curious when you mention the audible ping to check for temper... my kitchen knives do this but not my Khuk.... are you using your finger, a piece of wood, what?

 

[titus010782]

just curious when you mention the audible ping to check for temper... my kitchen knives do this but not my Khuk.... are you using your finger, a piece of wood, what?

My finger. Works with wood too.
just pluck the edge up and down the blade (without cutting your fingers off) and it will "ping" in the hardened area. Super cool. Bless Bura!
Read up on sonic resonance in composite materials. I got to learn about it through the kind of testing we do.

Your kitchen knives do it because they are a uniform hardness throughout and they are very thin and therefore vibrate easier, like a tuning fork.

 

[Yvsa]

Hmmm... For whatever my opinion's worth what the pics show me is a couple of things...

One - The bevel appears to be too much bevel and not enough convex... A short stint on a belt sander to properly convex the edge should fix 'er right up...

Two - The sweet spot appears to be a helluva lot shorter than what it should be... But if the kukri has served satisfactorily up 'til now it'll no doubt be alright until all the hardened area is used up and needs to be re-hardened...:thumbup:

But then pics can often be deceiving.

If 'twas me and I didn't have a belt sander I'd try to get one of the good ol boys here with one that knew what he was doing re-shape 'er edge to a proper configuration and give 'er another chance.:thumbup:



.

 

[titus010782]

Hmmm... For whatever my opinion's worth what the pics show me is a couple of things...

One - The bevel appears to be too much bevel and not enough convex... A short stint on a belt sander to properly convex the edge should fix 'er right up...

Two - The sweet spot appears to be a helluva lot shorter than what it should be... But if the kukri has served satisfactorily up 'til now it'll no doubt be alright until all the hardened area is used up and needs to be re-hardened...:thumbup:

But then pics can often be deceiving.

If 'twas me and I didn't have a belt sander I'd try to get one of the good ol boys here with one that knew what he was doing re-shape 'er edge to a proper configuration and give 'er another chance.:thumbup:



.

I think here is an observation I have overlooked, so I compared your pictures with a layered pic of my own M43.
My belly is bigger (wider) than yours!
Have you sharpened this knife alot? i mean on a grinder or sander?

Maybe the hardness has been used up, like Yvsa says.

You can zone harden it with a gas torch if you want. But I would only do that with something I was already going to throw away.

 

[Steely_Gunz]

I have a few khuks that will really sing when you give them a good thump. The beauty with the very best voice is my very first Kumar made 15" villager model. I swear, if there ever came a "there can be only one" moment, that little workhorse would get the nod. Kumar got me hooked with that one.

 

[WVHILLS]

I think here is an observation I have overlooked, so I compared your pictures with a layered pic of my own M43.
My belly is bigger (wider) than yours!
Have you sharpened this knife alot? i mean on a grinder or sander?

Maybe the hardness has been used up, like Yvsa says.

You can zone harden it with a gas torch if you want. But I would only do that with something I was already going to throw away.

Knife has only been used two or three times and has never been sharpened. It is exactly the way it was the day it came to me.

 

[Acinonyx]

Then might you not just have damaged the soft external layer I've heard can be found on some of these knives?

 

[titus010782]

Then might you not just have damaged the soft external layer I've heard can be found on some of these knives?

I know the guys have found this anomaly with some of their knives.
I just cant get my head around the science of it..

I cant see how, when using an external quenching method of hardening, one can keep the OUTER soft and harden the INNER of the steel.
You cant even due that with induction hardening.

If one of you clever chaps could explain this to me, I would be grateful. In fact, I will stop arguing with our metallurgist.

 

[titus010782]

Knife has only been used two or three times and has never been sharpened. It is exactly the way it was the day it came to me.

Okay.

 

[Karda]

I know the guys have found this anomaly with some of their knives.
I just cant get my head around the science of it..

I cant see how, when using an external quenching method of hardening, one can keep the OUTER soft and harden the INNER of the steel.
You cant even due that with induction hardening.

If one of you clever chaps could explain this to me, I would be grateful. In fact, I will stop arguing with our metallurgist.

I remember reading about this in the archives, although i cant point to the specific thread it was in.
It has something to do with the Outer layer of the steel being annealed during the buffing process on some knives. Perhaps when buffing the blade is getting extremely hot and produces a softer outer skin over the hardened areas.

 

[MrMike]

I know the guys have found this anomaly with some of their knives.
I just cant get my head around the science of it..

I cant see how, when using an external quenching method of hardening, one can keep the OUTER soft and harden the INNER of the steel.
You cant even due that with induction hardening.

If one of you clever chaps could explain this to me, I would be grateful. In fact, I will stop arguing with our metallurgist.

Agreed! I don't understand it either! My CAK is definitely softer than some. I stopped worrying about it. Time will tell if it holds up. BTW: No ping like you described.

 

[hollowdweller]

RE:

The Pinging.

Sometimes if it really Pings it will never roll but it can for sure chip

There's a balance there you gotta get.

 

[titus010782]

I remember reading about this in the archives, although i cant point to the specific thread it was in.
It has something to do with the Outer layer of the steel being annealed during the buffing process on some knives. Perhaps when buffing the blade is getting extremely hot and produces a softer outer skin over the hardened areas.

Ah ha! That could be it! If its heated up to annealing temp, that would do it. Especially on the edge.
Good thinking, Batman.

 

[starboard]

I'm very curious to learn the metallurgical verdict per Aunt Yangdu, and Yvsa's comment on edge thinness makes me wonder about that.

My primary wood destruction implement -- a CAK convexed using primitive means -- has taken significant punishment, including rock strikes (chopping over ground; debris in tree bark) and an embarrassing miss that sent the tip plunging into concrete (cratering the floor and sending up a spray of shrapnel -- thank goodness for safety glasses). What I have to show for it so far, that hasn't been removed by maintenance sharpening, is a small chip in the forward area of the sweet spot, and the tiniest amount of tip compression. :thumbup:

For no higher purpose than the pleasure of swinging a khuk, I went through some damaged/old high-grade plywood sheets which is pretty tough stuff due to the layered and multi-directional orientation of wood fibers. That pretty much left the edge untouched. I don't think I had to strop per se, but of course I did it anyway.

So I wonder what all factors contributed to the OP's less robust experience.

As an aside, I wonder whether a seriously sharp edge on a chopper makes it more robust than a duller edge, for similar primary bevel geometry. The hypothesis (pulled out of thin air) being that the sharper edge cuts deeper for a given swing and thus has more distance/time over which to decelerate, resulting in lower peak forces. OTOH, the sharper edge may be thinner, thus increasing force concentration.

 

[mohd]

Went to work with my M43 today limbing a pine tree that had fallen not too long ago. The wood was still green and at first the M43 was making short work of it, then the unthinkable...I looked down and there was a fairly large dent/roll in the blade about 4 inches up from the handle.

It happened to my Indian made Khuk (i.e. before I got my HI Khuks). So far my HI Khuks are not facing such problem. I guess it might be one of the case. Hope that the Khuk was not made during one of the festival time. Last time I have a not so balance Baraba Khuk (i.e. Balance Khuk) when it was made during one of the festival Actually Uncle Bill pointed that out in one of his thread.

Send it to Aunt Yangdu and she'll look into your Khuk's problem.

Mohd.

 

[GregS]

IMO, that edge appears to be way too thin, but WVHILLS said it is untouched from HI. And the damage occurred on green Pine? I live in Va., pine in these parts is soft, especially the green stuff. This doesn't make any sense, WVHILLS... you are hell on knives, wasn't it you that broke the tip on that Custom Shop SFNO?

 

[hollowdweller]

IMO, that edge appears to be way too thin, but WVHILLS said it is untouched from HI. And the damage occurred on green Pine? I live in Va., pine in these parts is soft, especially the green stuff. This doesn't make any sense, WVHILLS... you are hell on knives, wasn't it you that broke the tip on that Custom Shop SFNO?

I'll take up for Hills cause I've broke and bent a few.

IMO most knives are not really used or tested to any great degree. If you run into someone who is having breakage it is more likely that it is the fact that most knives are not really used.