Opinel Blade Failure

[Vivi]

Today when I was out in a patch of woods testing out the edges I recently put on some blades I had some surprising behaviour from my Opinel. I had a slightly seasoned branch of wood, nothing particularly hard or tough and was doing some chopping on it with it held up by my hand and the branch it was connected to. Generally it's better to have something underneath to support it, making the energy put into the chop more effective. After doing some of this I noted some serious blade deformation. I chopped even more vigorously after this in various spots of the blade and the same thing happened, confirming the problem. The branch was between 1 and 1.5 inches thick, swung at with angled cuts. When I started swinging harder to intentionally stress the blade I strung straight against the grain. The knife previously whittled shavings out of a similar branch with no ill effects.

Now, here are the variables I could think of.

-This was my first time using an Opinel #12 on anything but paper and cardboard to test it's initial sharpness. It's a nearly 5 inch blade.

-Temperatures this morning were just a few degrees above freezing. I had to defrost my car and scrape the windshielf a bit before heading out.

-This was my first time using my new diamond stone on an Opinel. I also gave it a slightly more acute edge than I normally do.

Looking at these things I could think of I see nothing that should of affected it in this way. I doubt cold temperatures would make the blade that brittle, but maybe I am wrong here? This is the Opinel mentioned in THIS thread. Something that gave me much suspicious with this knife early on is after I attatched the broken collar I gave it some spinewhacks to test how well it would hold. The part of the blade near the cutting edge visibly dented on the collar when doing this.

This is very surprising to me because I've done this exact thing numerous times with smaller Opinels (10 and 9). Also, I've never had an Opinel blade dent from the locking collar, though I've dented the collars with the blade while batoning. I repeated this action today with the #10 and with a SAK with an even more acute edge. Neither had any edge deformation aside from some very slight burring that would be expected, despite the SAKs known soft steel.

I suspect heat treat problems, or possibly lack of proper heat treat, because the carbon blade has behaved rather unexpectedly. If anyone can draw alternate conclusions they feel would be more verifiable, please educate me. I wish to understand why this happened.

Also, if you're someone with the right tools and knowledge, I'd like to consider shipping the blade off to you so you can inspect the blade steel and heat treat.

Related threads:

Heavy #10 Opinel use, no edge deformation
Locking ring problem with this #12

Gross blade failure:

Lock ring dent on blade:

 

[DWM]

Why would you chop with an Opinel?
You wouldn't cut with a hatchet, would you.

 

[Cliff Stamp]

Looking at these things I could think of I see nothing that should of affected it in this way. I doubt cold temperatures would make the blade that brittle, but maybe I am wrong here?

Blades do get brittle at low temperatures but that edge shows massive deformations indicating a lack of strength. If the problem was due to brittleness then the fractures would be tend to be sharp semi-circles.

The part of the blade near the cutting edge visibly dented on the collar when doing this.

That is the telling part, the blade should be far harder than the collar.

I suspect heat treat problems ...

Yes. Grind the edge back into the blade and turn it into a narrow boning or fillet knife.

Why would you chop with an Opinel?

It is a piece of tempered steel, it should not be so fragile that the primary grind explodes like that on a piece of wood. Now if you attached it to a stick and made a billhook, then yes, that is likely excessive.

You wouldn't cut with a hatchet, would you.

Of course, generally only the crude hardware store imitations of a hatchet can't actually cut very well, and with a few minutes with a grinder they can be so modified.

-Cliff

 

[gator68]

Not hardened? Take a dull file and see how easy you can dig into the blade? Compare that to the other opinel without problems.

 

[DWM]

Blades do get brittle at low temperatures but that edge shows massive deformations indicating a lack of strength. If the problem was due to brittleness then the fractures would be tend to be sharp semi-circles.



That is the telling part, the blade should be far harder than the collar.



Yes. Grind the edge back into the blade and turn it into a narrow boning or fillet knife.



It is a piece of tempered steel, it should not be so fragile that the primary grind explodes like that on a piece of wood. Now if you attached it to a stick and made a billhook, then yes, that is likely excessive.



Of course, generally only the crude hardware store imitations of a hatchet can't actually cut very well, and with a few minutes with a grinder they can be so modified.

-Cliff

I was making a point... and you know it!
The opinel is not made for choping, period. I had several of them, and just by looking at the angle of the grind I would never even try to chop with them.

Also, you can cut with eveything that has an edge. That doesn't mean you would start doing with a hatchet when you could use a knife! :jerkit:

 

[hardheart]

people skin game with hatchets

 

[samhain73]

I was making a point... and you know it!
The opinel is not made for choping, period. I had several of them, and just by looking at the angle of the grind I would never even try to chop with them.

Also, you can cut with eveything that has an edge. That doesn't mean you would start doing with a hatchet when you could use a knife! :jerkit:

This is a silly statement. There are skinning hatchets made for mainly cutting, with minimal chopping.

 

[DWM]

ok... i give in...

From now on I'll chop with an Opinel, since they make Hatchets for cutting.

Come on people. I am the only one that thinks that while you could be able to chop with it (since it has a tempered blade) you probably shouldn't?
It was not designed for it. It is designed to cut, and if I remember correctly they do that formidably.

I was not trying to step on anyones toes here, so no reason to jump down my throat.

 

[cerulean]

Whoa... You weren't kidding about the "blade failure", Vivi! When I read your description of what happened, I was expecting that the edge had just chipped or rolled a bit. Looking at the pic though, it's obvious that the whole blade is shot to hell.

I haven't done any hard use experiments with my Opinels, but I can't imagine that they would end up looking like that! There's clearly a very serious problem with the heat treat (or lack thereof). The relatively large dent in the blade from the locking ring is definitely not something you'd expect to see. As Cliff pointed out, the blade steel isn't necessarily brittle; it's probably just too weak.

I've seen a couple of reports of Opinels that had bad blades. Unfortunately, since they're so inexpensive, it wouldn't be surprising if some of them had inconsistent heat treats.

 

[Vivi]

I don't care what it was designed for, if the knife is capable of doing it and I want to do it, by all means I'll do it. Opinels are readily capable of this type of chopping and I'm curious as to why this blade seems to of been so improperly heated. First lemon I've had from any knife company so far though, so I can't complain much. This is out of about 10 Opinels I own or did own. Dissapointed the #12 didn't work out the first time though, it's got a lot of size. It dwarfs my 110 and is much lighter. I'll just buy another one in due time. In the meantime I'm going to take suggestions on good ways to guage the hardness of this knife. Maybe I should try chopping at its blade with some other knives I own and see what happens.

 

[gator68]

In the meantime I'm going to take suggestions on good ways to guage the hardness of this knife. Maybe I should try chopping at its blade with some other knives I own and see what happens.

Try files on each before you chop the blades together... There should be a big difference between hardened and tempered steel and annealed (unhardened) steel.

Obviously a properly heat-treated knife should be able to chop into wood with no damage. A hatchet is simply better designed for chopping, but that just means that the knife might take longer, not that it would self destruct.

 

[kel_aa]

This is pretty amazing. I would guess it is waaay soft.

 

[ausjulius]

looks like the blade is totaly unhardened,
as that blade collar isnt har atall,
i think youll find if you get a good pair of tin snips youll just be able to snip rite through the blade ..

 

[Cliff Stamp]

...suggestions on good ways to guage the hardness of this knife.

You already did that, twice. Just grind the edge into a stone or concrete and take note of how fast the metal is removed.

The opinel is not made for choping, period.

Of course it isn't, an Opinel is very light and thus has little power on the swing and thus has little chopping ability. However the grind is easily strong enough to not do the above if the steel is properly hardened. Now if he had complained that it didn't chop well, then your arguement would be justified because you would not expect it to compete with an axe. However he noted that it broke, when his others did not, and further that the locking ring was apparently harder than the blade. Both of these indicate it is defective.

Also, you can cut with eveything that has an edge. That doesn't mean you would start doing with a hatchet when you could use a knife!

All quality small axes are actually made to cut and not just chop, chopping after all is just cutting under a powerful impact. So there is no reason to expect that a blade which chops very well won't also cut very well. A Bruks Wildlife for example has the same edge geometry as larger knives like bowies and it is obvious those are made to cut and not just chop so it is absurd to argue the hatchet isn't as versatile in that regard.

-Cliff

 

[Easy Rollins]

Unacceptable personal attack removed by moderator

 

[canranger]

"I don't care what it was designed for, if the knife is capable of doing it and I want to do it, by all means I'll do it"

I use to mark papers in University when a student insisted their answer made sense I would have them read it aloud, usually after they did this they decided their answer wasn't so good.

You should have read your responce aloud before hitting send.

 

[knifetester]

Looks like a pretty cool new serration pattern to me. Very aggresive. It is the new tactical version of the Opinel, the nightshade. Totally killer. They just forgot to spraypaint the handle black is all. . .

Seriously though, Opinel makes like a zillion knives a day, even with astronomically low margins of defects and great QC, a few are gonna slip through the cracks. Maybe it was not hardened at all, and is just ground annealed steel.

Or maybe that branch was not really seasoned wood, but instead Opinel kryptonite.

I have a No.12 (although it may be a No. 10) I keep in my wicker picinic basket. It slices bread, apples and sausage like a champ, and I have used it to make shavings for tinder for my Kelly kettle to make a pot of tea. Very good knife for tasks like these.

I wish any number of knives 10-100X the price of an Opinel cut nearly as well as these humble knives.

Did you get a bad one? Maybe, for the price you can always buy another and find out. They will probably also warranty it out.

 

[Gerald McDonald]

"I don't care what it was designed for, if the knife is capable of doing it and I want to do it, by all means I'll do it"

I use to mark papers in University when a student insisted their answer made sense I would have them read it aloud, usually after they did this they decided their answer wasn't so good.

You should have read your responce aloud before hitting send.

Thats a great answer.

 

[Gerald McDonald]

"I don't care what it was designed for, if the knife is capable of doing it and I want to do it, by all means I'll do it"

I use to mark papers in University when a student insisted their answer made sense I would have them read it aloud, usually after they did this they decided their answer wasn't so good.

You should have read your responce aloud before hitting send.

Good one.

 

[hardheart]

"I don't care what it was designed for, if the knife is capable of doing it and I want to do it, by all means I'll do it"

I use to mark papers in University when a student insisted their answer made sense I would have them read it aloud, usually after they did this they decided their answer wasn't so good.

You should have read your responce aloud before hitting send.

You should have hit alt+F4 before hitting send.

Vivi, I order you to do what you want.