ABS Mastersmith Test (specifically the 90 bend part)

C

Cliff Stamp

BANNED
Prompted by a recent post by Dave Ellis :

http://www.mastersmith.com/Mastersmith.html

I glanced over his website and came across the following (which refers to a requirement to be a Mastersmith by the ABS).

A line is marked approximately one third distance from the tip of the blade. The blade is inserted point first in a vise and the blade is bent no less than 90 degrees. The blade may crack at the edge on bending but not beyond two thirds the width of the blade. If any of the blade chips, or any part of the blade or tang breaks off the applicant fails (this is true for any part of the test).
Click to expand...

For those that are ABS Mastersmiths or have done this to their blades :

How hard is this bend to do? Can you do it by hand? If you need a bar how long of a long is it? What does the knife look like after you release the pressure? Will it spring back at all? How much of a bend can it take before it will take a perm. bend?

For forum members :

Is this test of one of value? Does it indicate performance that you would want/require in a knife? Would you like to see the results of it on some of the knives tossed around on here?

For non ABS Mastersmith knife makers :

Can your knives do this? If not why is this not important to you?

-Cliff

[This message has been edited by Cliff Stamp (edited 09 July 1999).]
 
I could care less if any of my knives can do this. I have never used a knife in a way that requires lateral bending strength, although maybe others can conceive of a use for this? TO me it's simply a test that separates good knives from great ones, but if you took the knife that failed and the knife that succeeded and used them in the field, I'll bet you'd never be able to tell one from the other.

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My Custom Kydex Sheath pagehttp://www.geocities.com/CollegePark/Lab/1298/knifehome.html
Palmer College of Chiropractic
On Two Wheels
 
Cliff
This test is done with differentially hardened blades IE soft spine hard edge.
The most you will get from the standard knife steels is 30deg or so at knife hardness(58-60RC).
Except for 3v that will do it.
The bend is permanent, but the really good ones will return some.
The really good ones can sometimes be flexed back to 180deg from the first bend(some many times).



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Edward Randall Schott
Knifemaker
www.angelfire.com/ct/schottknives/index.html
edschott@javanet.com

 
First of all the test described is for journeyman testing not Mastersmith testing.
The test for Mastersmith is done with a damascus blade and there can be no chipping or cracking anywhere. Second the bending is only 1/3 of the entire test. First thing to occure is to cut a free hanging 1" manilla rope 6" or less from the end. Then chop a 2 x 4 all the way through twice and still be able to shave hair off your arm. Then the bending. The entire test is one that will show that a blade is tough. Bladesmiths that do the test don't treat their knives that way, but it will show that when the cutting edge won't crack or chip under that kind of stress it can take a lot under lesser conditions. There were a lot of posts under a thread asking if anyone had broke a blade before, even just the tip isn't acceptable to me. If I get in a real jam I want the confidence that my knife will hold up no matter what I ask of it!
How far the blade will bend without a permenent bend depends on how the blade is heat treated. Most blades that are made for the test are made to bend and not break or crack and usually have a kink in the bend and don't return a great deal to original. It can usually be done by hand but some need a pipe put on the end. The blade can be no longer than 10" to where the handle starts and overall no more that 15"
I've probably left something out but it's a
start. If anyone's interested I can possibly
(If someone can tell me how to attach a pic.
to a post) put a pic of a test knife.

goshawk

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http://www.imt.net/~goshawk The race is not always to the swift, but he who hangs loose.




[This message has been edited by goshawk (edited 09 July 1999).]
 
Its not to important for me really. I mean its nice to know if I bent it that far I could straighten out but I am pretty sure I would quit prying or whatever before any blade of mine got past teh 30 degree mark. However, it does indicate blade toughness pretty well so yeah I wouldn't mind seeing the test done but its not the most important to me.

What I do like to see is at what degree it can be flexed to and then return to true. This tells me the limit to what I can take my knife. I would like to see the test performed repeatedly as well so that I know its not just a one time deal.

Another important thing is how much it take to flex teh blade which is often left out. I mean if a blade won't bend even a little bit with a 6 foot cheater bar or whatever thats fine because I don't think I will ever to be able to generate enough force to hurt it then--kind of like the 20in AK you couldn't bend it but it wasn't brittle but rather very strong.

thanks and take care
collin
 
Most knives would not be made to pass this test. For most applications you would want the blade hard enough that this bend would break the blade. It looks like this test would be of a special knife constructed to demonstrate mastery of alloy selection and differential tempering skill.

If I had to make a knife to perform this function I would use a laminate with a ductile outer layer and a moderately hard inner layer. This was often a selling point of Swedish Mora knives with laminated blades. Even in a laminate steel knife I would rather have a spring temper to the outer layers rather than a ductile layer.
 
Ed, thanks for the details :

The most you will get from the standard knife steels is 30deg or so at knife hardness(58-60RC). Except for 3v that will do it.
Click to expand...

Ed, do you mean 3V will take a 90 degree bend without cracking? I recall you posting some testing results awhile back (I hope the search gets turned on soon). Will it take more than a 30 degree flex with taking a set?

Rudy :

What I do like to see is at what degree it can be flexed to and then return to true.
Click to expand...

That's the most important aspect to me as well as how hard it is to do it.

Jeff :

For most applications you would want the blade hard enough that this bend would break the blade
Click to expand...

This is what I was wondering about. R. J. Martin discussed this in detail awhile back as well. I would much rather have a blade maximized to resist deforming and have a low fracture tolerance than resist fracturing strongly and have a low deformation limit. Of course I would want the first only assuming the fracturing limit is high enough for a usable knife. The magnitude of this limit of course varies from knife to knife depending on its designed use.

-Cliff
 
Hmmm.. not sure, but isn't this the same test that Cold Steel was proud of with their Imperial Tanto line of knives before? I think those were made of Damascus steel, right?

Dan
 
Cliff and everyone

the flex test I did with a 3V 10" blade was past 90deg it did take a 35deg set.
flexing to 30deg did not produce a set the blade returned to true.
I had to use a 24" cheater bar to flex it.
I did finely break the blade by flexing to 90deg and putting all my weight on the bar and pushing hard and fast.
A pic of a piece of this blade being flexted to 45deg or so will be on my site soon.
This piece is 5" long.


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Edward Randall Schott
Knifemaker
www.angelfire.com/ct/schottknives/index.html
edschott@javanet.com

 
"How hard is this bend to do? Can you do it by hand? If you need a
bar how long of a long is it? What does the knife look like after you
release the pressure? Will it spring back at all? How much of a bend
can it take before it will take a perm. bend?"

I think those are the questions that a knife user wants answers to, and since the test doesn't answer a single one of them ... that test seems to me completely useless. It's like testing bread by squeezing a slice into a ball and bouncing it off the floor to see how high it'll bounce -- WHO CARES??? That's not what we buy bread for! We want to know if bread tastes good and if it has any nutritional value, not how high it can bounce.

(If anyone disagrees with me you'll want to know that Wonder bread bounces higher than any other bread tested.)

I would like to know how much weight a knife can bear without damage, and it's also useful to know how many degrees it can be flexed without damage -- the first to help me decide whether to buy it, the second so I know when to stop. What happens to a knife if you continue bending it after you've already ruined it is of little interest to a knife user....

Seems to me if the Guild test shows anything at all it's that the knife was in fact differentially tempered -- but it doesn't give any clue as to whether the knife was any good.

-Cougar Allen :{)
 
The bend test whether for Journeyman or Mastersmith is primarily a test of the smiths heat-treating skills. The key is a differential temper (hard edged, soft spine). On my mastersmith test knife (of 320 layers of Damascus-a203e and 1095 my knife bent 90+% and sprung back to approx. 30% with no chipping anywhere. I tested under Wayne Goddard. The knife was bent by hand not with a cheater bar. I built it I should be able to bend it. It was not the easiest task.
Dave Ellis, ABS, Mastersmith

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An addendum to my previous post. The three parts of the American Bladesmith Societies (not the Knifemakers Guild) test when looked at overall test the smiths skill. The rope cut tests edge geometry and sharpness, the two by four cut tests for hardness (too hard the edge chips, too soft the edge bends) and the bend tests for proper heat-treat applicable for this test only. After this youi shave hair off your arm to show edge retention.
Dave Ellis, ABS, M.S.

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Dave, can you heat treat the spine so that its so hard that you couldn't flex it by hand far enough to warp/crack it? If so wouldn't this be a better blade? What is the advantage of no damage at 90 degrees if this is that easy that it can be done by hand (and produces a perm. set)?

-Cliff
 
Cliff - perhaps a larger context might make more sense. There are "Smiths" about that make blades for customers with specific needs. These blades are going to be carried "deep into the bush" and will be used for all of the survival needs and requirements of a cutting tool.

Now two customers comes along, Mr.Jim Bowie and Mr. Cliff Stamp, both want "Blades" upon which they can trust to perform "no matter what". They ask Mr. BF Coal for his credentials.

Now keep in mind that "The most important feature of a survival knife be that IT DOES NOT BREAK!" Breakage on the battlefield is not only embarrassing, it is not good for your health. Now we're out in the bush. No UPS, no Email, no roads, no Warrantees...just you and "Mowgli's tooth" and the world about you.

The next most important feature is that it will cut well and continue to cut for a long time.

Mr. BF Coal presents his credential that he is an ABS Mastersmith. Now you know that he has the skill and has been approved of by the body that approves. Think of it as UL approval.

The tests required by the ABS ddemonstrate that the maker has the ability to produce a knife that will withstand even a 90 degree bend (not break) and still have an edge hard and sharp enough to make difficult cuts (free hanging rope) and continue to do so while not losing its edge (2 x 4 cut & shave).

It is the test that demonstrates Mr. BF Coal's ability to forge steel and differentially heat treat well enough to accomplish these goals. A skill that requires both knowledge and practice.
sal
 
As to what this test symbolizes, I'm more or less with Sal. I wouldn't say that the tests themselves prove one way or another that the smith in question is any good, more that the tests are neccessary to get certified by a regulating body that makes sure it's members have a degree of technical proficiency and understanding of the work at hand.

The harder you make a blade, the higher the tensile strength and the lower the shock resistance. Steel piano wire has more tensile strength than kevlar, but kevlar's higher shock resistance makes it more suitbale as a balistic fiber. This has no bearing on knives except to illustrate that there are many ways to measure strength, and that strength must be judged according to desired result.

For me, well I know how to sharpen a knife, so edge retention is really not at the top of my list of desirable criteria. If the knife gets dull, I sharpen it. No big deal. However, if my knife gets broke, that's another story. Nothing I can pack into the wilderness is gonna put my broken knife back together. Toughness is high on my list of desirable attributes on a knife. High hardness reduces toughness. My knives get pounded a lot, the also get stuck up into the vitals of some really dangerous animals. I would hate to stick a boar and have the blade snap off. There was a famous mountain man who killed bears with knives. He prefered a break before bend knife. I am not comfortable with that, but apparently he could make it work. I also suspect he carried, and used up, many knives.

That said, I don't particularly like differentialy tempered blades. It all depends on how they're done, but they tend to bend comparatively easily. That's not to say they bend easily, just comparatively so.

 
Cliff- When I bent my Damascus Blade I weighed 260 and needed every pound to bend the piece. I am now down to 207. A fully hardened blade is preferable to some. My opinion is for a large blade that will be used for chopping I like a hard edge, Softer Spine and a dead soft tang. Cold Steel seems to do quite well with their fully hardened Bowie. Again the ABS test has you produce a blade that will pass their test, not necessarily the optimum using knife.

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A few of my thoughts.

These are good tests of the knife makers skill.

Some properties of steel.

If the blade is 10 inches long the force to bend it is dependent principly on the thicknes and secondarily on the width. So talking about the force to bend the knife without these dimensions are meaningless.

The amount of the bend is independent of the type and hardness of the steel.

Harder steels can spring back from and be bend further because they take higher stressess without yielding.

The harder the steel the closer its breaking point is to its yield point.

I don't know if this add anything to the discussion because you guys may know this anyway.

 
Sal :

The tests required by the ABS ddemonstrate that the maker has the ability to produce a knife that will withstand even a 90 degree bend (not break)
Click to expand...

Would it not be more functional to have a blade that will not take a set or break at a specific torque limit (functionally high enough to be past hand stresses)?

Snickersnee :

High hardness reduces toughness.
Click to expand...

Not exactly. High hardness produces very low compressability which makes for a very tough edge compared to a low RC edge which will impact rather readily in comparasion. For example the CS blades at about 59 RC will chop out softer iron and scrap metal without edge deformation. If that was down to about 56 RC then the edge on the knives would start to deform under the impacts. Comparing the two I would call the 59 RC edge the tougher one.


Now the lower RC blade would probably have a much higher breaking point but the higher RC one has a much higher deformation limit. In terms of functional use I don't see the value of high breaking points if the deformation points are that low you can set them by hand. I would much rather see lower breaking points and much higher deformation points.

Ellis :

My opinion is for a large blade that will be used for chopping I like a hard edge, Softer Spine and a dead soft tang.
Click to expand...

Is this for durability or performace issues?

If you had hardened your blade, say from A2 to a uniform RC of 56-58, do you think you could have put a set or bend in it by hand?

-Cliff
 
Performance and durability. Soft spine to take the shock of chopping, harder edge to take and hold it's edge. Never worked with A-2 would think a fully hardened A2 blade Rockwell high 50's would probably snap at 90 degrees as opposed to taking a bend.
Dave

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Cliff, perhaps I should replace "toughness" with "shcok resistance". Edge deformation isn't a problem for me as I don't hack up scrap metal. When dealing with aligator bone, which has the highest hardness and compression strength of any material I'm gonna use a knife on, I either you the old bolt cutting trick or a solid whack with the spine.

So I should have said, "I prefer the shock-resistance of a softer knife over the edge-retention and resistance to deformation of a harder knife."
 
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