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UffDa

UffDa

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Sep 11, 1999
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I have read with much interest the knife tests where various blades are broken. I am wondering if anyone has tested a blade made by one of the better bladesmiths. I understand that part of the test for journeyman and master ratings is to bend the blade about 90 degrees without braking or cracking. I also understand that some of these blade were straightend without damage to the blade or edge and were still usable.

These blades also have to pass cutting and chopping tests. It seems to me that the only real disadvantage to a good forged blade is that it will stain and rust if not cared for.

I wonder how a blade made by someone like Wayne Goddard or Charles Ochs would stand up compared to the various knives discussed extensively on the forum.

Any comments?
 
First off, let me dispell a myth for you: NO blade bends 90 degrees and doesn't break or crack. And there is NO way that a blade bent thus could be properly returned to true. Unfortunately, man has not progressed that far in technology. While I have broken some high end knives, NONE have EVER come close to a full 90 degrees before at least fracturing, couldn't tell you if either of the two makers you mentioned have ever been tested, but I can tell you that if this is the test criteria, they WILL fail. Hope this helped.

Joe

[This message has been edited by SycoticSamurai (edited 01-14-2000).]
 
Joe:

I didn't didn't say that the blade was returned to true, only that it was usable.
I seem to remember that it had a bit of a "kink" in it. Still, the edge must not crack to pass.

Remember that these blades are generally made of stuff like 5160 and usually have softer spines. I'll have to do a little research to verify my comment about the 90
degree bend. It's a figure that stuck in my head. I'll check and come back with refs.

Maybe a bladesmith will see this and correct me if I'm wrong.

Dennis
 
I found a couple of pretty good articles on the ABS Master test at www.knifeart.com.

See Testing Blades by Terry Primos and
another by Dave Ellis. They both state that
the blade being tested must flex 90 degrees without failure.

Sorry, sometimes I am right. (Not often, but sometimes.)

Dennis
 
Hello all!
Sorry,SycoticSamurai, but UffDa is right and you are as completely wrong as can be.

The criteria UffDa mentioned is not only one of the tests for the journeyman ranking of the ABS, but for the French Bladesmith Association, too.

I have made some blades from homogenous steel that passed this test. And if the blade is made in a three-layer construction (which is not allowed for the aforementioned test blades) like many scandinavian blades, having the cutting steel welded between two pieces of soft steel, this test is a piece of cake.
I made a three layer blade with a C125 (1,25 % C) edge steel hardened to 60 HRc and have bent it to 180 deg. and back without damage to the cutting edge.

Achim
 
I currently have a blade of 5160 in my shop that was made specifically as a test knife. It has been bent to 90 degrees.....18 TIMES.
The blade is certainly note arrow straight, but there are no chips of fractures anywhere. My intent with this blade was to prove a theory to myself, and also to see just how many 90 degree flexes a blade could survive. It's still going. Of course the blade is certainly not "arrow straight", but it has survived. I would be happy to post pics of the blade if further proof is required.
http://www.mtn-webtech.com/~caffrey

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Ed Caffrey
"The Montana Bladesmith"


 
Great suggestion, UffDa! I would love to see a quality forged blade in a good ole fashioned carbon steel thrown into the current series of testings.

In fact, I'd vote for a blade by our very own Ed Caffrey, who's one of the finest posters here on the forum, one of his 5160 or esp 52100 blades. I don't own one (yet?), but I'll bet that they'd fare VERY well in any performance test: cutting, chopping, toughness...

Might do much to advance the virtues of forging on the forum, too. I'm sure I'd learn a few things...

Glen


PS Terry Primos has a picture of himself flexing a blade at least 90 deg. w/a cheater pipe on his webpage (which is excellent in all respects, btw). Check it out at:

www.shreve.net/~primos

[This message has been edited by storyville (edited 01-14-2000).]
 
Why on earth would anyone intentionally bend anything other than a test knife 90 degrees?

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You are doing what you should be doing.
Otherwise, you would be somewhere else,
Doing something else.

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ATTN: all of you out there who believe that a useable knife can be flexed to 90 degrees without chipping or cracking. Go to a machine shop and ask for a bottle of Dykem (you'll probably have to pay for it, they run @ $5). Now, go find any knife that has been flexed that far. Lightly spray it with the Dykem. Those dark lines that you see are STRESS FRACTURES. While they may not be readily visible, THEY ARE THERE. I've worked with metals for a very long time. Nothing capable of holding a good edge can be bent that far without some dammage. While these knives may bend and return somewhat to true, they are not undammaged. But don't take my word for it, ask a qualified metallurgist. There's a good one at Lawrence Livermore labs on the West coast, and another at MIT on the East coast.

Joe
 
Joe,
I can agree to a point with your claim. There will be SOME damage done. Anytime an implement is stressed beyong it's intended limits a certain amount of damage will occur. The reason that the 90 degree flex test is part of the ABS standards is to show that the bladesmith has the knowledge and technique to produce a differentially hardened blade. In my previous post, I said that the test blade has be bent 90 degrees, 18 times. This is true, and outside of some "waves" from returning the blade to "straight", there is no damage that would effect the blade as a usable tool.
I hesitate to talk much about metallurgists, but suffice to say that over the years I have found that eventhough some hold Master's degrees in this disipline, they sometimes are not as open minded about different methods of heat treating,(and it's possibilities) as those of us who have learned through experimentation. An example of this: On three different occasions I have had metallurgists in my shop, observing my forging and heat treating methods. I performed the ABS tests for all three, including the 90 degree flex. All three, evnthough they had witnessed it with their own eyes, insisted that it was not possible, and stated that there must be some kind of "trick" or slight of hand involved. There is certainly no trick or slight of hand, it is simply a matter of having the control over a material, to achieve a desired outcome. The trick, if you want to call it that, it to create a blade that will hold and edge, will be flexible, and will be easy for the customer to sharpen. This is one reason why I would rather see makers who heat treat their own blades, test and make adjustments to their heat treating methods, rather than follow heat treat manuals to the letter. These manuals simply were not created with our application in mind. I'll crawl down off my soap box now. Sorry for being long winded.

http://www.mtn-webtech.com/~caffrey

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Ed Caffrey
"The Montana Bladesmith"


 
The test blade works because the thicker part of the blade is much softer than a "normal" knife blade while the hard edge is very thin. If you think of the bulk of the blade as being annealed (an exageration) it is not surprising that you can bend it 90 degrees without it cracking. I've often bent hot rolled iron to similar angles. The edge is bent at 90 degrees, but around a larger radius of curvature (at least 1/2 blade thickness greater). Think of the thin edge as like a thin strip of spring steel. As long as you don't bend it below a certain minimum radius it will bend elastically. I consider all this sort of a trick, but a good training excercise. Given the above description it is obvious that a laminated blade would be good for this test.

I wouldn't say that the blade was "damaged" in a general sense by the plastic stretching of the surface that is shown by Dykem on the surface. The cracks that you would see would be in the Dykem, not the metal. The Dykem doesn't stretch while the steel does. The primary "damage" to the blade is inelastic stretching which you can't neatly reverse and work hardening of the metal. You are creating dislocations in the crystal lattice structure of the metal which is primarily observed as work hardening.

For a using blade I would expect that I'd want the bulk of the blade significantly harder. I might also want the hard edge to extend farther to the back of the blade than in this test case.

[This message has been edited by Jeff Clark (edited 01-14-2000).]
 
While I dont do a whole lot of forging I do about 2 or 3 knives per year and Ed is right
I had and old Maker teach me this method of heattreating after I read an article in blade By Wayne Goddard ,and the older maker I know showed me how it was done an tested the blade for my self and it does happen just the way he say's the fellow that showed me was banging out knives when most of us were just a gleam in our daddy's eye

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TbarK Custom Knives
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Joe
I'm currently preparing some blades for my Journeymen test. Your welcome to come
to my shop. I'm only 45 minutes south of you.

mvknives@lightspeed.net
 
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