show me your bend tested knife..

Karl B. Andersen said:
Does it "NEED" to excel?

I can't say if it needs to or not. I can do it, and have done so many times.
.
Click to expand...

You wrote:
"After which the blade is then taken to a full 90 flex. You really don't want it to take a set/bend.
....A properly done blade, as well, would have RETURNED nearly straight after going 90 degrees with no cracking in the hardened portion.
If any part of the test fails, the knife fails."

I doubt that the 4" long blade with 1/4' in the spine will do that. Let's assume that "near straight" means 10 degree residual deformation angle. I doubt that this geometry blade can be even bent to 90 degree if it has any considerable hardness. The steel has it's limits. Sorry.
 
Thanks for posting all that Karl! :)

While I don't normally heat-treat my blades the way I did for my performance test (and many practice pieces over the last several years! :) )... I feel just like Karl does.

This has become one of those things where so many people have read/heard that it isn't the be-all/end-all test (which it's not) that they start saying as much (even though many of those guys have not tried to do it).

Really, it's just like anything... it's really easy to say you could do something... it's something else all together to actually DO something.

I personally feel that many folks would be surprised to see their blade break into 8 pieces :eek: ;)



Like I said!!! :) I do NOT feel the ABS performance test is the be-all/end-all test. But I don't know ANYone in the ABS that does either, including guys at the very top!!! It's simply a standardized test that proves you have enough understanding of something to achieve said standard.

I don't know any college professors that give an exam, and think that one single exam can/will encompass everything you might need to know for whatever it is that they teach. ;) :)

As for the OP :) It looks like a hardening line right where the break stopped. So you definitely got a differentially hardened blade, but.... First of all, water hardening 52100 is very tough to do. It can be done, but you have to look at the risk to benefit ratio. Secondly, I would recommend you put the tip of the blade in the vise, not the handle.

A hunter sized blade, with a hard edge and softer spine.... can and will bend... but just like with big blades, a lot of it has to do with geometry. You need to have a thinly distal tapered blade. A blade that is 4" long, but 1/4" thick from butt to tip without any taper, would have a very small chance at successfully bending, unless it isn't hardened ;)
 
Dmitry.M said:
You wrote:
"After which the blade is then taken to a full 90 flex. You really don't want it to take a set/bend.
....A properly done blade, as well, would have RETURNED nearly straight after going 90 degrees with no cracking in the hardened portion.
If any part of the test fails, the knife fails."

I doubt that the 4" long blade with 1/4' in the spine will do that. Let's assume that "near straight" means 10 degree residual deformation angle. I doubt that this geometry blade can be even bent to 90 degree if it has any considerable hardness. The steel has it's limits. Sorry.
Click to expand...

Sorry for what?

I've got them laying in my living room to show others.
Actually, the two are more like 5 1/4".
Hardened up 1/2 way from the cutting edge to the 1/4" spine.
Flexed to 90 degrees one direction.
Then reversed in the vise and flexed 90 degrees the OTHER direction.
On one I have written "31". Meaning it flexed 90 degrees from one side all the way to the other side 90 degrees 31 times before the hardened cutting portion cracked.

Sorry.
 
Karl B. Andersen said:
Sorry for what?

I've got them laying in my living room to show others.
Actually, the two are more like 5 1/4".
Hardened up 1/2 way from the cutting edge to the 1/4" spine.
Flexed to 90 degrees one direction.
Then reversed in the vise and flexed 90 degrees the OTHER direction.
On one I have written "31". Meaning it flexed 90 degrees from one side all the way to the other side 90 degrees 31 times before the hardened cutting portion cracked.

Sorry.
Click to expand...

Sorry too. But your example is about bending the blade back by force. Not about blade so flexible and springy that it will return to "near straight" shape by itself. From your first post I understood that the blade should reflex back not to be bent back. My apology.

P.S. There is no magic in bending unhardened steel without failure. It's a given steel property.
P.P.S. Sorry for starting that discussion. Really.
 
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Here is my blade after taking the ABS JS Performance Test with Steve Dunn last month.

20101018pics10071.jpg


I started out with 5 blades all similar in size and shape, heat-treated all the same and cut, chopped, shaved and bent the 1st one. It wouldn't hold an edge after the chopping and bent rather easily and abruptly. I tweeked my heat-treat on the remaining 4 blades after anealling them and repeated the proccess. The second test blade just barely shaved after the test and didn't crack the edge, repeated the proccess a 3rd time and that blade performed perfect just like the 4th one pictured above. I gave the 5th one to my brother for chopping brush arround his farm.

As others have mentioned this is a test and only a test, this is not the way I heat-treat the knives I sell, unless, someone ask for a blade that will meet the same criteria as the test.

Steve Seib
 
Dmitry.M said:
Sorry too. But your example is about bending the blade back by force. Not about blade so flexible and springy that it will return to "near straight" shape by itself. From your first post I understood that the blade should reflex back not to be bent back. My apology.

P.S. There is no magic in bending unhardened steel without failure. It's a given steel property.
P.P.S. Sorry for starting that discussion. Really.
Click to expand...

OK - Gotcha.
My test blade returned back to within 18 degrees of straight on its own qualities, without any influence from me.
This, after a full 90 degree flex as witness by Don Hanson III.
As well as performing the hardness and cutting portions of the test.

I'm not sure about the "magic" you refer to. In a differentially hardened blade, we all agree the upper portion is not hard.
There's no magic insinuated.
What is fun to see is that if you get the hardened portion to "crack"!, it stops right at the transition from hard to un-hard.
 
actually the ABS rules state ," the blade is allowed to crack at the edge on bending, no to exceed 2/3 of the total width of the blade,
if it cracks more than 2/3 of the width of the blade it is then considered a failure."

this is a copy of the rules in the link below

http://www.caffreyknives.net/ABSperformancetestarticle.html

the reason I bend mine upside down is because I have wooden teeth in my vise, and the blade doesn't stay in, it's just for safety. either way for me it is a bend. the edge cracks at the hamon line.

I actually thought that you had to bend it far enough, that it would stay at 90 degrees when you released it. But, the way I see it now is, you bend it 90 degrees and if it springs back, thats ok..


palmer..
 
NickWheeler said:
Thanks for posting all that Karl! :)

While I don't normally heat-treat my blades the way I did for my performance test (and many practice pieces over the last several years! :) )... I feel just like Karl does.

This has become one of those things where so many people have read/heard that it isn't the be-all/end-all test (which it's not) that they start saying as much (even though many of those guys have not tried to do it).

Really, it's just like anything... it's really easy to say you could do something... it's something else all together to actually DO something.

I personally feel that many folks would be surprised to see their blade break into 8 pieces :eek: ;)
Click to expand...


Thanks, Nick. Well stated.
 
Virgilio said:
actually the ABS rules state ," the blade is allowed to crack at the edge on bending, no to exceed 2/3 of the total width of the blade,
if it cracks more than 2/3 of the width of the blade it is then considered a failure."

this is a copy of the rules in the link below

http://www.caffreyknives.net/ABSperformancetestarticle.html
Click to expand...

Actually the JS Performance Test Rules as per the ABS site's pdf document states that the blade can only crack 1/3 of the width... 2/3rds has to remain intact.

That said, Mr Caffrey is a well known ABS judge.... perhaps the rules need to be updated on the site.

ABS site
pdf Js Rules
 
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Dmitry.M said:
Sorry too. But your example is about bending the blade back by force. Not about blade so flexible and springy that it will return to "near straight" shape by itself. From your first post I understood that the blade should reflex back not to be bent back. My apology.

P.S. There is no magic in bending unhardened steel without failure. It's a given steel property.
P.P.S. Sorry for starting that discussion. Really.
Click to expand...

I had this secondary thought that you seem to be focused on making a blade that bends and flexes, but never mention that the SAME blade we are discussing is hardened over a large portion of its mass and cuts and chops without failure.
My example was NOT about forcing blade back to straight, but rather bending a majorly hardened blade not just 90 degrees, but bending it over a 180 degree arc repeatedly without failure. That same knife was also hardened to the point of performing cuttings tasks with authority!
One thing we haven't mentioned in any of this is grain size.
If persons experience failure with breakage, and consider any of what we are discussing as not possible, I expect they are not controlling grain size as well.
I've proven in my shop the strength of fully hardened, yet UN TEMPERED blades. The blade made with steel where grain size was not controlled, will fail easily at many tasks and breaks quite readily.The blade with properly manipulated grain size will be nearly indestructable, and not even be tempered yet!
I find nearly all of my successes and failures can be traced back to grain control.
Anyway, back to............whatever it was I was doing:D
 
Rick Marchand said:
It deformed and would not be considered flexible, IMO. I have my doubts about the edge, too. The thickness of the secondary bevel shoulder is rather large and retained some deformation near the crack. To me, it looks like the whole knife was too soft. I have read your heat treat process a few times over and have my doubts about that as well. I think your 2 second water quench isn't cooling down the body of the blade enough. It could be that the remaining heat auto-tempered the edge a bit too much.

... but I'm still green and can only speculate.... forgive me, if I offend.


Rick
Click to expand...

the only thing I can say Rick, is that I could make a blade that was springy but, I couldn't diff. harden a blade in water. Until I talked with Charlie Ochs, at www.oxforge.com . He showed me how to do it. He has a dvd called "How to make the Special Op's Bowie Knife", he goes thru the whole process from beginning to end and shows how he makes Bowie knives for our troops in Special Operations, thats our special forces in our military. I would be glad to talk to you about it, but it would be easier to get the dvd and learn yourself.. unless you wish to phone me. What ever .. the knife is real, Charile Ochs is real and he makes a great knife for our troops, he is a great guy and willing to help anyone.

I do this test randomly in my shop to test the completed knife/knives I have made. I don't have a boss that comes around and checks my work, so I have to take it upon myself. I bent the knife past 90 degrees, it's plain to see. it is still at 90 degrees. No, it's not springy, can I make one thats springy, Yes I can. That just personal preference. For this particular knife I wanted an edge that was rc 59.5 and I got it.

Good luck,

Palmer...

and "no", I am not offended, Hope I didn't offend you ! If this doesn't help.call me I will explain.thats the best I can do....
 
Well, I'm glad you didn't take offence... I have never heard of water quenching like that... I will have to look into more.
 
Karl B. Andersen said:
I had this secondary thought that you seem to be focused on making a blade that bends and flexes, but never mention that the SAME blade we are discussing is hardened over a large portion of its mass and cuts and chops without failure.
My example was NOT about forcing blade back to straight, but rather bending a majorly hardened blade not just 90 degrees, but bending it over a 180 degree arc repeatedly without failure. That same knife was also hardened to the point of performing cuttings tasks with authority!
One thing we haven't mentioned in any of this is grain size.
If persons experience failure with breakage, and consider any of what we are discussing as not possible, I expect they are not controlling grain size as well.
I've proven in my shop the strength of fully hardened, yet UN TEMPERED blades. The blade made with steel where grain size was not controlled, will fail easily at many tasks and breaks quite readily.The blade with properly manipulated grain size will be nearly indestructable, and not even be tempered yet!
I find nearly all of my successes and failures can be traced back to grain control.
Anyway, back to............whatever it was I was doing:D
Click to expand...

Do you happen to have an RC number for the edge?
Also, what steel? 1095 per chance?
 
V. Palmer- I think Charlie is a great guy and I have a lot of respect for him. Charlie actually talked to me about water quenching 52100 when I was messing around with it several years ago (down at the OKCA show).

Because of things I've learned/experienced since then, I feel that I get a better blade by quenching 52100 in a commercial quenching oil after being brought up to heat in a digitally controlled salt bath.

The process can bring to life a blade that cuts extremely well, but is also quite RESILIENT to bending in the first place. I'm trying to understand why you wanted your blade to take a set and stay bent? You mentioned that you see if it springs back it's "ok"... To me, that is ultimately what you want... as in way better than okay! ;) :) Maybe this is a lot of miscommunication... do you think of a "springy blade" as one that isn't fully hardened or over-tempered?
 
Virgilio thought the 90deg flex test meant the blade had to take a set at 90degs.

Virgilio said:
I actually thought that you had to bend it far enough, that it would stay at 90 degrees when you released it. But, the way I see it now is, you bend it 90 degrees and if it springs back, thats ok.
Click to expand...

I don't think he was implying that a springy blade is less than adequate.



Rick
 
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NickWheeler said:
V. Palmer- I think Charlie is a great guy and I have a lot of respect for him. Charlie actually talked to me about water quenching 52100 when I was messing around with it several years ago (down at the OKCA show).

Because of things I've learned/experienced since then, I feel that I get a better blade by quenching 52100 in a commercial quenching oil after being brought up to heat in a digitally controlled salt bath.

The process can bring to life a blade that cuts extremely well, but is also quite RESILIENT to bending in the first place. I'm trying to understand why you wanted your blade to take a set and stay bent? You mentioned that you see if it springs back it's "ok"... To me, that is ultimately what you want... as in way better than okay! ;) :) Maybe this is a lot of miscommunication... do you think of a "springy blade" as one that isn't fully hardened or over-tempered?
Click to expand...

Nick,

we all have our own opinions, and the overall opinions in the knife world change from decade to decade. that being said.

I believe a springy blade is a tough durable blade ! But, it is not the only kind of blade that can be made or the only kind of blade that serves every purpose. I feel that a blade smith should know how to make several different kinds of blades, differentially hardened, springy, Damascus, etc, etc. I don't know them all. But, I learn more every day I work steel.

I started making springy blades when I started because I couldn't make a differentially hardened blade. Then I learned how to do both, And now I am more knowledgeable about steel, by pursuing it's ability. Thats what I like to do, keep learning.

(Hope I didn't offend you. )


Can you make a shaving razor thats springy, with a rc hardness of 60 ?

Would you want to make a machete that wasn't springy ?

Different steel treatments serve different purposes..
And one steel treatment doesn't serve all purposes.

Palmer...
 
Springs stay in the elastic region of the stress vs strain diagram. If you have permanent deformation, that's in the inelastic/plastic range. In other words, that blade you have pictured is not springy. A blade that springs back to it's original shape is springy.
 
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