Opinel Blade Failure

[Cliff Stamp]

Knife breaking is not science, no matter how hard the practice is defended.

To do something in a scientific manner simply means you learn from it. Vivi obviously learned that the steel in that Opinel was severely flawed, which he confirmed with multiple tests which all showed the same thing.

There is of course a vast amount of materials testing which is designed around breaking the sample. Charpy impact tests for example break a piece of steel just by hitting it with a big hammer and tensile tests just pull it apart. Just like lock strength tests that Spyderco does on their folders, the bend tests than many ABS members do on their knives, and the impact tests that Busse does. All of these are done because those makers want specific standards and in order to know where the knives perform you obviously have to see where they fail.

This is no different than doing an edge retention test and cutting until the knife needs to be sharpened. You need a failure point to define the performance. You could hardly do a corrosion resistance test and stop before the sample rusted just like if want to know which knife has the tougher edge you have to see where they are damaged. Just like if you want to see which one is easier to sharpen you actually have to make both of them sharp.

-Cliff

 

[Ebbtide]

Sorry cliff, don't want to play the word/semantic games anymore.
You can have your opinion and I'll stick with mine.
XXOO
-Ebb

 

[Gryffin]

Unfortunately, this might be a "you get what you pay for" scenario....i disagree with the fact that you should be able to expect optimal heat treating on such a cheap knife.....for the profit margin they are turning on these, im doubting they care too much about perfect heat treating or the time and care it takes to get it right...

I think it's a mistake to condemn Opinels in general based on this one, obviously defective, specimen.

As long as I've been on here, Opinels have been held in very high regard as inexpensive folders that cut like the dickens. Now, based on one knife, they're suddenly junk? Hmmm.

Go read Vivi's other thread concerning hard use with Opinels, you'll see that his other ones hold up just fine. I've used a number of them as well, and never had one without heat treat like this. It's an anomoly.

Is it abusive to chop or baton with an Opinel? Again, based on Vivi's previous work, obviously not. (I believe Cliff's also pushed an Opinel or two pretty hard, as only he can.) They ain't space-age high-tech tactical wonder-knives, but they're certainly capable of much more than most users think. I'm glad to see someone like Vivi pushing the envelope, showing that even hard use doesn't require a pound and a half of 1/4"-thick super-steel.

 

[Cliff Stamp]

I think it's a mistake to condemn Opinels in general based on this one, obviously defective, specimen.

It would be very naive to believe that any knives are 100% free of defects, even customs would have to deal with problems inherent in the steel. Considering the price of Opinels, in general you would also be a bit more forgiving of any variances. Consider that even if 25% of them were defective like Vivi's (which isn't close to the case) that would just mean that the price is effectively 25% more. They are still a pretty good deal.

-Cliff

 

[Vivi]

I can't name any other folders off the top of my head with a near 5 inch blade that can be had for 15$ like the #12. Opinels are some of the most ergonomic and best cutting knives I've used, two of the main reasons they're the most prominent knives in my collection. I know from my collection alone this isnt how they normally behave. When I get my next #12 I'll do the exact same things to it I did with this one and I'm confident it will hold up.

 

[Vivi]

This was a chopping contest between a SAK ground thinner than out of box and the #12. Note the visible difference in edge difference. The SAK turned out a little blurry, but the edge is mainly just cosmetic damage. Those markings the red lines indicate are not penetrations like on the Opinel, though is did get some minor dent on the edge. If someone wants a more focused picture of the SAK blade I'll take it.

This was taken for another thread but shows what the Opinel looks like on a full scale.

 

[canranger]

To do something in a scientific manner simply means you learn from it. -Cliff

Cliff I am surprised at your answer here a Scienific manner does not mean that at all. It encompasses much more like establishing an hypothesis setting out to disprove that Hypothesis installing control recording data and drawing conclusions from this data I have yet to hear of anyone installing any calibrated equipment to guage the force of each strike on their batoning.

Face it destuctive testing really doesn't help anyone even those that sit around waiting for the end of the world(real life survival situation).

If you want to stand on a scientific hill then look over the valley of facts one knife could have been treated in a different oven from theother they could have been made from 2 different steels from 2 different foundries ground on a machine that didn't have the same rate of coolent flow many different factors of which you can't account for by posting results of the test of breaking one knife out of how many hundreds that are made.

Call us trolls if you wish but we wish for realistic use testing.

A knife could break now or twenty years from now but can I use that knife for prolonged periods of time is the handle comfortable the over all layout of the design ,does it produce excess torque while trying to cut or is the force from your hand effectively used. I have wasted enough time hear with this I will move on many more knives shall die in the namae of testing but even worse they probably won't be used properly before their death.

 

[shecky]

This test cannot be scientific, because Vivi didn't wear a white coat.

Face it destuctive testing really doesn't help anyone

On the contrary, destructive testing might be the most instructive, as it would tend to indicate more precise limits of gear. The most interesting part of Vivi's testing is that his testing would not normally be considered destructive, and that this knife failed so spectacularly under such conditions. At the very least, I found it very helpful and curious, as it opens up a mystery. Not that Opinels are uniformly bad, but that this failure must be an isolated incidence?

 

[canranger]

This test cannot be scientific, because Vivi didn't wear a white coat.



On the contrary, destructive testing might be the most instructive, as it would tend to indicate more precise limits of gear. The most interesting part of Vivi's testing is that his testing would not normally be considered destructive, and that this knife failed so spectacularly under such conditions. At the very least, I found it very helpful and curious, as it opens up a mystery. Not that Opinels are uniformly bad, but that this failure must be an isolated incidence?

Didn't call Vivi's testing distructive

 

[Dog of War]

Face it destuctive testing really doesn't help anyone ....

Tell that to the NHTSA, NTSB and countless others who perform such tests ... also tell the millions who benefit from such tests through improved product safety, quality and regulation.

Call us trolls if you wish but we wish for realistic use testing.

Rather than trying to impose your definition of what's realistic, why not just ignore tests and information that you don't find useful, and focus on what you feel is of value? Why attempt to be a censor and critic, and dictate what others should find useful? Why take these discussions down the low road? IMO there's enough bandwidth to go around.

 

[Vivi]

Chopping contest between Opinel and common household butter knife.

*Note - White labcoat donned during testing procedures to officiate the results.

I went to the Opinel site to contact them with a concise summary of what went on here, along with links to all the various photos. I couldn't find an English version to their contact page though. Does anyone know of a link for it or an English branch of their company I should contact?

 

[db]

I'm kind of surprised this is the first time I've heard of a bad heat treated knife on an Opinel. And I know there are alot of them out there even with us knife nuts. A big thumbs up for Opinel.

I really have to agree with canranger because he says.

Yes then lets say the Opinel was improperly heat treated and who ever thouight of the scratching test good job very clever.

Abe-

 

[hardheart]

Here's a question-how does anyone know that chopping a 1" branch is a destructive test for an Opinel?

 

[Easy Rollins]

Knife breaking is not science, no matter how hard the practice is defended.
Now actually using a knife well, that could be a science, but much harder to learn than breaking one.

Well said.

 

[Cliff Stamp]

Here's a question-how does anyone know that chopping a 1" branch is a destructive test for an Opinel?

The complaints are simply because it was damaged and it was used to critize the blade. You can find the exact same type of work which is used by makers to promote their knives like Fowlers extreme bends and none of the guys in the above will so chastize Fowler or call his methods useless.

By the way, destructive testing is defined as anything which either causes material loss or changes the structure. So if you submit something for non-destructive testing it means you expect it back in mint condition. So any cutting with a knife falls under the label of destructive testing as it causes material loss from the edge.

It encompasses much more like establishing an hypothesis setting out to disprove that Hypothesis installing control recording data and drawing conclusions from this data

Yes and the purpose of that is to learn something. Vivi actually did all of that several times. Read Feynman's books if you really want to understand what it is to be a scientist, it just means you seek to understand what you observe. There is a really nice section where he recalls a walk he sees another father instructing his son on the name of a bird. Feynman's father didn't know the name but instead remarked on what he say the bird do and thought about the behavior.

That is science, observe, explain, confirm. In general the more of it you do the more you will refine your methods so you can learn more and be able to make more precise distinctions and attempt to reduce the chance that you are wrong, and that is all you can do reduce it. The actual focus of my PhD thesis in solid state physics was to refine the procedures used in our lab, the goal of course was simply to obtain more information from the data.

I have yet to hear of anyone installing any calibrated equipment to guage the force of each strike on their batoning.

I have calibrated impacts against weighted drops to benchmark the impact energies, I have even done the drops themselves to provide the impacts. However there is absolutely no requirement for a specific amount of precision in scientific work. You can publish at even one significant digit, which Vivi could easily deduce (the impact energies would be of the magnitute of 10 ft.lbs, not 1 ft.lbs or 100 ft.lbs). The tolerance you use is determined by the size of the effect you are intending to measure compared to the size of everything else which will perturb it. Some experiments are very crude because you are just trying to see if there is any effect at all and you use these results to then determine how you need to proceed to make measurements in more detail.

Kevin Cashen has also noted there are measurements you make in a lab which would show a difference and then there is that which would be seen by a user. If your goal as a knife maker is to provide functional knives you would obviously set your final tolerances by what a person would descriminate. This of course is no different than if you walk into a lab and ask someone to weigh something which scale they use will depend on what you need the weight for because there is no use in moving beyond precision past a certain point and it gets progressively harder to quantify each decimal place.

-Cliff

 

[Thomas Linton]

A guy starts a thread by reporting what seems to be edge damage due to poor (or no) heat-treatment of a blade.

His subsequent posts show additional tests that show the subject knife to be significantly softer than SAK steel and "butter knife" steel.

The author of the thread gets criticised for "misuse" of the knife.

The thread becomes another chapter of "We hate Cliff or Why Destructive Testing is Worthless."

Let's solve this once and for all. I suggest potatoes at ten paces.

 

[canranger]

We could do potatoes at ten paces but I tend to like mine baked or in the case of all this I am a knife authority becuase I break knives half baked. All the other distructive testing that goes on is varied by multiples we have no time to go over hear in this forum. Like I said keep breaking them and those of us who use them will keep using them.

"We hate Cliff or Why Destructive Testing is Worthless."

Obviously this is a common thing that springs up because it does not seem practical and sure we should just let it go many will follow this form of testing and Cliff's advice it is a given after all 900 people drank poison coolaid at Jones towm I am sure Cliff can get some people to believe his testing is useful.

 

[Cliff Stamp]

Like I said keep breaking them and those of us who use them will keep using them.

Troll. Vivi has posted many times on how he uses his Opinel as it is meant to be used and the only reason it got damaged here was because it was not hardened properly. He even noted specifically it continued to get damaged even in food preperation.

-Cliff

 

[Ebbtide]

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.

The bold emphasis on this quote from the original post is mine.

Think about it.

Maybe the blade twisted in the moving branch?
The branch that was supported on both ends?
If the branch were only supported on one end (the tree) the branch would have slid along the blade if not cut through.
(Much like machete, parang and bolo work )
With both ends supported the branch would move, then stop, trapping the blade and bending the edge.

Maybe less bad knife and a little more like poor technique?

Either way, that aint science.

 

[hardheart]

What's worse is his technique with a moving plastic cutting board and moving carrots and almonds-causing even more damage to the edge.

Obviously, there is nothing wrong with the blade, one must simply avoid anything that can move while cutting.