Why does it need to flex over 90 degrees?

D

DrGrip

Guest
I keep seeing this question; "will the blade flex over 90 degrees and come back?"

In WHAT situation would one need this?

Perhaps I am behind the times, but 90 degrees bend seems a bit steep...

WTH is that question all about?

Charlie
 
The ABS Journeyman test requires one to make a blade that will withstand a 90 degree bend. I think this has been misconstrued by a lot of folks as a standard for general use knives, which I disagree with. The bend test is meant to demonstrate the student's understanding and ability in creating a differentially hardened blade and I think it has little bearing on most cutting applications or knife use in general.
 
As Justin said, the intent is to demonstrate the abiltiy of the maker to differentially heat treat the blade. No where does it state that the blade must come back to true. The ABS test guidelines state:

4. BENDING: THE PURPOSE OF THIS TEST IS TO SHOW THAT THE APPLICANT IS ABLE TO HEAT TREAT A KNIFE WITH A SOFT BACK AND A HARD EDGE.
"The applicant will then bend the blade ninety (90) degrees. The supervising Master Smith will signal the applicant when the ninety (90) degree angle has been reached. The blade is allowed to crack at the edge on bending but not beyond approximately one third (1/3rd) the width of the blade leaving two thirds (2/3rds) of the blade intact. However, if any part of the blade chips or any part of the blade or tang breaks off, the applicant fails. Because of the many variables in the size, geometry, and temper line of the blade, the Master Smith using his/her judgment, shall determine if the extent or location of the fracture line is acceptable."

I have omitted a good portion of Step #4 guidelines to only show the exact information. Keep in mind that it does not state that the blade must go back to true. All of the test blades I have seen have a bend remaining in the blade after testing. I did hear rumor of a batch of 5160 which the ABS school recieved not long ago. It was used during class and a couple of students used it to produce thier test blades during class. I was told that the blades not only passed the the bend test, but the blades returned to true. Like I said, I was told this and I can't remember the source, therefore I will call it rumor.
 
murphda2 said:
As Justin said, the intent is to demonstrate the abiltiy of the maker to differentially heat treat the blade. No where does it state that the blade must come back to true. The ABS test guidelines state:

4. BENDING: THE PURPOSE OF THIS TEST IS TO SHOW THAT THE APPLICANT IS ABLE TO HEAT TREAT A KNIFE WITH A SOFT BACK AND A HARD EDGE.
"The applicant will then bend the blade ninety (90) degrees. The supervising Master Smith will signal the applicant when the ninety (90) degree angle has been reached. The blade is allowed to crack at the edge on bending but not beyond approximately one third (1/3rd) the width of the blade leaving two thirds (2/3rds) of the blade intact. However, if any part of the blade chips or any part of the blade or tang breaks off, the applicant fails. Because of the many variables in the size, geometry, and temper line of the blade, the Master Smith using his/her judgment, shall determine if the extent or location of the fracture line is acceptable."

I have omitted a good portion of Step #4 guidelines to only show the exact information. Keep in mind that it does not state that the blade must go back to true. All of the test blades I have seen have a bend remaining in the blade after testing. I did hear rumor of a batch of 5160 which the ABS school recieved not long ago. It was used during class and a couple of students used it to produce thier test blades during class. I was told that the blades not only passed the the bend test, but the blades returned to true. Like I said, I was told this and I can't remember the source, therefore I will call it rumor.
Click to expand...

OK, makes sense now... I was wondering if this was some new thing that folks judged normal knives by... For a while there I was skeert! :D

Thanks for the clarification guys...

Charlie
 
When you read the requirements for the JS and MS stamps the guidelines states right up front that the blade will be tested to distruction. One could make a blade that will bent to 90 degrees and then return back straight but it would be too light and flexable to be a usable blade. Just like Murph and Justin said, the object of the test is to have the examinee show that s/he has the skill to make a knife a certain way that requires a higher skill set than it takes to make a basic knife blade. One can make an acceptable blade that cannot bend 90 degrees without breaking, or cut through the free hanging end of 1" natural fiber rope, or chop through a 2X4 twice and still have a hair shaving edge, it just won't pass the performance test.

Doug Lester
 
Hi DRGrip, Good advise here. The purpose of the bend test is to show that you have the skills to selectively heat treat a blade. This is NOT how I would build a knife for a customer. You are building a knife for a specific application, ie , to pass the performance requirements as laid out by the ABS for the JS rating. Just keep that in mind if you decide to pursue the JS rating, it's more of a test of your knowledge than of a knife.

Brad Singley
ABS Journeyman Smith
 
DrGrip said:
...and come back?"
Click to expand...

I think that even if you look at ABS test blades, you won't find any that have sprung back to straight.

It is a specialized test to show that although the hardened edge may crack, the remaining spine will not break through.

The people asking the question may have the ABS test in mind, but have an unrealistic expectation that it will spring back.
 
I think,it was in one of Wayne G. book that I read
an example of a test blade that was flexed 90 degrees
and returned back to ''almost straight''

Just my .02 cents.

God bless,Keith
 
DrGrip, Please clarify your question as to what you mean by "I keep seeing this question; "will the blade flex over 90 degrees and come back?"
Are you refering to the ABS Test or just your own testing. There is a difference and it would help to understand what what you are referring to. If it's the ABS test is is very CLEARLY stated what is expected of you in the performance phase of the test. Just trying to help.

Brad Singley
 
Hi Brad,

I've seen the question posed on several different kinfe boards and was wondering why people would ask that kind of question. At the time I didn't realize that it was a test performed by the ABS.

I personally have not been asked that about any blades, just saw it a few times here and some other places.

I appreciate the info.

Charlie
 
Hi Charlie, No worries about not knowing about the ABS test. The new and greatly improved ABS website will answer all your questions concerning the test. Just wanted to make sure we were answering your question to your satisfaction. Not sure if I mentioned it before but Ed Caffrey a Mastersmith out of Montana has wrote to be what I consider the definitive article on creating a knife on passing the performance test of the ABS JS test. If this is something you are considering doing or even just for your own knowledge please read this article. It will be worth your time, I promise!

Brad
 
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