Bend test basics

J.Marsillo

J.Marsillo

Joined
Nov 8, 2000
Messages
1,255
What are the parameters for the bend test? I just tested and broke a blade and I should have looked up what I was doing first :o

I had it clamped in a vice between wood blocks,about halfway up the blade.It broke a little before 90 right where the vice was and the break was pretty clean.
The victim was a drop point blade ground from 3/32" cold rolled 1095 tempered @ 415. The edge test went well so I went for broke.....literally :)
 
from the abs website, view at http://www.americanbladesmith.com/ABS_JSTest.htm

"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 bending of the blade is the final test. Safety gear should be worn. At the discretion of the applicant or the Master Smith, the edge may be dulled prior to bending. The Master Smith will mark a line across the width of the blade approximately 1/3 distance from the tip of the blade. The blade will then be inserted into a vise, tip first, such that the blade is placed into the vise up to the mark on the blade. If the vise jaws are rough, smooth metal inserts shall be located on each side of the clamped portion of the blade to protect the blade, when bending the test knife. The blade shall be bent by force applied to the handle. A leverage device, such as a pipe may be used as long as it does not pose a safety risk. The use of such a device is at the sole risk of the applicant and at the discretion of the supervising Master Smith. 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 two thirds (2/3rds) the width of the blade. 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. The decision of the Master Smith is final."


loks like you could have held it in the vice less which im wil guess might not have allowed to it break... but i could be wrong
-matt
 
samf said:
Either you need to draw the spine back or edge quench
Sam Fogler
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why exactly does he need to do this? I'd be perfectly fine with a knife that could bend almost 90 degrees before snapping, It'd return to true after a much heavier bend than the soft back would, and I have no use for a bent knife
 
To become a JS in the ABS.

This test is just to show that the smith has control over the forging and heat treating. I personally don't want a blade that will bent 90 degrees easily.
 
Sorry, didn't know he was trying to go for JS. In that case it seems like a little tougher steel might be better? Just a thought...
 
I don't think he is doing an ABS JS test knife. I agree that there is no reason to be ashamed of any knife that will bend 90 degrees before breaking.

J.Marsillo - One problem with the test you did is the amount of blade in the vise, and the blade length. Most tests are done with about 3" of a 9-10" blade in the vise. This is enough metal to allow bending. On a shorter blade,and with half in the vise, I would suspect that any blade would break. Yours sounds like an exceptionally well made and heat treated blade. I wouldn't change anything.
Stacy
 
Well I'm not going for my JS anytime soon, a guy can dream right :) I see all the torture tests that the accomplished makers put there knives through, I thought why not me?
The blade was only 4 1/2" and I had about 2" in the vice and it took some muscle to bend it.If that blade was thicker i might have needed a can of spinach.
Thanks for all the replys. :thumbup:
 
Joe, if you are working towards the ABS test in the future I would be more than happy to give you plenty of tips on how that can be quickly accomplished, but if you wish to emulate "accomplished" makers I would ask that you reconsider and find your own path through the Labyrinth of hype, slick marketing and misinformation. I too have made many a blade that would easily bend to 90, initially because I believed the advertising, then to get my ABS ratings, now only to research and show how counter productive it can be for where I am going with my blades. The only time I think a person should do anything just because more accomplished makers do it is if it seems to really be working for sales, and then one needs to weigh it heavily against their own conscience.

The fact that I could show you all kinds of tips on how to easily accomplish 90 degree bends should be a red flag that it is mostly showmanship. Things like proper long term edge holding on a wide array of materials, or reasonable impact toughness with excellent strength in the blade have no tricks or shortcuts or convenient plays with words, they can only be achieved through diligent heat treating practices and skills developed through truly understanding what is happening when working the material.

I guess what I am asking is that you should take pause and examine your gut feelings about what you really want from a knife and then follow the path your common sense guides you towards. What are knives for? What are they intended to do? Do you want a tool that will do its intended task excellently, or do you want a Chinese made RonCo supermatic that will excel in mediocrity at that task because it can’t make up its mind what it wants to be when it grows up? It may sell like hotcakes but when you strip away the sales pitch does it really excel in it primary use?

Sorry for the soap box, but the idea that something has to be right because well known guys do it, is a disease that knifemaking desperately needs a vaccine for before it is too late
 
J.Marsillo said:
Well I'm not going for my JS anytime soon, a guy can dream right :) :
Click to expand...

I also went ahead and did a few 90-bend tests this winter to see if my blades could pull it off....LOL

I did a few tests, I learned a few new things.
I learned that clay-coating my 52100 didnt work at all, as far as being able to keep my blade from fully hardening. Im not sure why yet, but the one blade I tried that on sure didnt pass this test at all..LOL (I wish I would have some video of that test and the look I had on my face when she snapped)

I learned that tempering is a bit more important than I have always thought.
I ended up bumping my oven temp up higher to 450. (However this might be only because my kitchen oven has wide mood swings)

And I learned not to overheat my steel before the quench. (I have always had trouble pulling the trigger and quenching)

The things that have changed with the way I do knife now, is that I pay close attention to the Normalizing and Annealing stages.
With the last few blades I have added a 2nd Normalizing just to make sure it takes.
I have always Annealed by allowing the blade to cool inside the forge, but I'm thinking now that this might not work so well if the temp of the shop is well below freezing.
I asked members of this forum for the amount time my steel needs to take to cool to be fully Annealed?, and the answers I received got me to believe that now Im not so sure the forge stays hot enough for long enough once it's turned off.

The one question/suggestion I have is about how you were able to bend the knife?

From a photo I saw in BLADE mag. I made a type of a clamp with a big bolt welded to the side of it. The bolt head allowed me to attach a socket wrench and so the force of pulling down was spread out more even.

Also, I think doing such tests are great because they allow you to do the very same test as others.
Most of the other tests people talk about are hard to copy time and time again.
Even many cutting tests are hard to copy again to judge one knife against another.
(I have never been happy with my cutting tests, Am I testing the knife steel, or just my ability to sharpen an edge and be more carefull cutting this time over last time?)

But a test that is easy to reproduce in the future on other knives allows me to stay on a path where I end up with the knife I aim to have.
 
Kevin R. Cashen said:
I guess what I am asking is that you should take pause and examine your gut feelings about what you really want from a knife and then follow the path your common sense guides you towards. What are knives for? What are they intended to do? Do you want a tool that will do its intended task excellently, or do you want a Chinese made RonCo supermatic that will excel in mediocrity at that task because it can’t make up its mind what it wants to be when it grows up? It may sell like hotcakes but when you strip away the sales pitch does it really excel in it primary use?

Sorry for the soap box, but the idea that something has to be right because well known guys do it, is a disease that knifemaking desperately needs a vaccine for before it is too late
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Well consider me vaccinated ;)

Maybe a bit of hype has alot to do with it,most of it is conscience.I have been at it for a year and a half and havnt sold one knife I gave lots of them homes but no sales.I cant justify selling a knife with my name on it that isnt going to perform to it's fullest.

While my fit and finish needs improvement I was in a big shadow as to where my HT and tempering were.I can't really see how well a knife is made (without an electron microscope;) ) besides a few belt marks I missed or a sloppy gaurd fit,I just needed more proof.Another reason I get so picky is that I dont really have faith in the general public.If I try to sell a handmade knife to the average guy for lets say 80 bucks when the price for a similarly constructed knife made by Buck or Gerber is 30 or 40 I expect to be greeted with some sarcasm.If I was selling to a custom knife nut that is a different story.

Starting on any future knives ,I have purchased a thermocouple and a bucket O' quench oil.Now I can focus more on making the knives look right instead of putting each knife through tests.I only get about 8-10 hours in a good month in my shop.It would be fruitless to spend that much time testing,testing and more testing.

This summer coming up I have been given the oppertunity to sell knives at the rennaiscance fair.I think I'm sweating it a bit with some performance anxiety.:foot: There are a couple of makers down there most of their stuff is fantasy, staged combat or high end.I am trying to get the user grade niche' covered.....wish me luck:)
 
J.Marsillo said:
This summer coming up I have been given the oppertunity to sell knives at the rennaiscance fair.
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Just once in my life I would love to be that guy down in the far tent with a forge.

I would use my gas forge, (coal is so smelly and the wind blows the smoke all over the park) and make forged little knives with a wood handle.
Sharpened with a file and sold to the guys who watched it being made.
And talk about knives the whole day....

Oh, and I would have a dog sleeping in the tent ,
 
Joe, leave the microscopes to fools like me who think that staring at steel is more interesting than making knives out of it. If you don't have immediate access to a hardness tester and wish to be a little more certain about your results, feel free to quench a flat sample (heck 1"x1" will do) polished to 400X and drop it in the mail to me. I will be happy to let you know the HRC and if it would resist bending until the user got tired of trying ;)
 
While we are talking about how to do a better Bend test, and concidering the type of hardness testers that some knife makers use.

Would any such testser be able to tell the difference between parts of the same small sample thats been HT to show both very hard steel in spots, and not hard in other spots?

I have often had the idea that if I made a small section of steel, but heat-treated it in such a way as to end up with different parts of the same small sample showing different hardness levels would the guy doing the test be able to know (if I didn't tell him) what end was hard?
 
Allan Molstad said:
.....I have often had the idea that if I made a small section of steel, but heat-treated it in such a way as to end up with different parts of the same small sample showing different hardness levels would the guy doing the test be able to know (if I didn't tell him) what end was hard?
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Yes.....................
 
Kevin Davey said:
Yes.....................
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I have always had a question about the hardness testers used by knife makers and their ability to test different areas in the same steel.
My guess is that the normal curves of a blade could be a challenge, but what if you just had some straight bar stock?

One day Im going to send to be tested a few samples from my forge to see if the tester could find out what I attempted to harden, where I attempted to make very soft?
 
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