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The Composition of Infi and What it Means

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thebrain said:
Mr. Carothers says they all have the same edge angle in the video. As a machinist by trade I would bet he can both create and measure the edge just fine. I only posted here out of concern for misinformation.
Mr. Larrin posted test done by someone else many years ago on a knife or knives unknown to him, then says "This is INFI" my problem is this.....Is it??? He cannot say with any level of certainty it is. The proper way to do this would be aquire an example without the knowledge of Busse combat and have it tested himself. I'm not saying he has to buy it many here would likely allow a knife to be tested and returned. Of course this would need to be a recent model. Also the reason for a knife to not be provided by Busse Combat would be to ensure that it was a regular product and not a special or altered sample. All to ensure the science is sound. I don't claim magic steel or anything other that not conclusive science being pushed as fact.
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Maybe , but they are too thick behind edge ....they are chisel ! And they are not same thickness behind edge as bottom one !! And / by accident / the one with standard/factory HT is thinner behind edge ????? JUST look in edge bevel width on all three blade ?
And that 3V with special HT is much thicker behind edge then both other knives ???
 
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I had almost forgotten about that thread from 2006. The main problem with having been on various knife forums since 2004 is that there are posts from me that are just as far back. I don't go back and read things from myself from that long ago for the same reasons I don't watch the VHS of Little Shop of Horrors from my senior year. Fortunately Knifeforums.com exploded to hide some of the evidence. At the 2006 Blade Show I was at the Crucible booth hanging out when I heard someone say my name. I turned in the direction of the person and I saw someone a booth or two down talking about an annoying guy named Larrin on the forums claiming that Infi was the same as A8 mod and that he didn't know what he was talking about. I walked past him and saw that his name tag said Jerry Busse on it. I've still never met him.
 
The edge is all that is being tested, it wouldn't matter if the blade was 1" thick at the spine. Mr. Carothers is testing the edge only and states the edge angle, he is doing his best to compare the steels equally . Farther up the blade has nothing to do with edge stability. Again Mr. Carothers is a machinist by trade and is quite capable of measuring.
 
thebrain said:
The edge is all that is being tested, it wouldn't matter if the blade was 1" thick at the spine. Mr. Carothers is testing the edge only and states the edge angle, he is doing his best to compare the steels equally . Farther up the blade has nothing to do with edge stability. Again Mr. Carothers is a machinist by trade and is quite capable of measuring.
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Are you kidding me ? You test EDGE on three different knife in that way that you use same angle on all three but all three have different thickness behind edge ????? And that was valid comparison between this three knives ??
he is doing his best to compare the steels equally...??? EQUALLY ? With different thickness behind edge ?????
PS . And I m quite capable to see that this three blade HAVE NOT same thickness behind edge ! And that was cheating my friend :thumbsdown:
 
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I should not have to explain bevel hight to a knife enthusiast. Bevel hight changes with edge angle, a knife with thick stock and a low edge angle will have a taller edge bevel than a thinner stock knife with a lower edge angle. I thought this was apparent to anyone who uses knives of differing stock thickness and changes the edge angle from time to time. The edge bevel at 18 degrees per side would be the same angle no matter the overall stock thickness or blade hight.
 
thebrain said:
The edge is all that is being tested, it wouldn't matter if the blade was 1" thick at the spine. Mr. Carothers is testing the edge only and states the edge angle, he is doing his best to compare the steels equally . Farther up the blade has nothing to do with edge stability. Again Mr. Carothers is a machinist by trade and is quite capable of measuring.
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Thickness behind edge ...........behind edge , my friend .That MATTERS ............ not spine thickness:) Look again in end of that video and see by your self .That 3V blade with super-duper HT have almost no bevel.......and is much thicker behind edge than other one in 3V .And that Busse ..................chisel , no wonder pass this test without demage .I can sharpen 18 degree per side /and 2-3mm behind edge :D / HSS steel in over 65 HRC which will pass this nail test !!
 
Thickness behind the edge has nothing to do with this test, you are confused. Thickness behind the edge only matters in cutting and overall durability of a knife.
 
You understand that this angle is measured from a center line right? So a thickness behind the edge is only possible up to a point.
 
Natlek said:
Well , just before end of that video on 5 : 07 min. the top two knives have thicker edge then all chisel I have .My cheapest chisel can cut nail all day without any damage !! And because of that I call this test cheating :thumbsdown:
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Natlek calm down a little, you're seeing a part of a test that was a demonstration of a part of a process, you're not seeing the whole picture. I'd appreciate it if you didn't accuse me of "cheating". There is no cheating, it isn't a competition, it a part of a process that I thought folks might think was interesting. The nail is a dramatic part of it but it's not even the primary part of the actual test. You're just seeing a small piece of the whole picture.

There is a very good reason my test blanks were thick, they didn't have bevels. They were test coupons in a knife shape. There were a bunch of them and they were used in comparative testing to each other to evaluate the effect of certain heat treat tweaks. There was a matrix of variables leading to a LOT of test samples. Those knife shaped test coupons didn't get bevels.


Yes, it is true the thickness behind the edge can be important. Less so to damage that doesn't go above the edge bevel but certainly when evaluating things like bent bevels and chipping that does go above the bevels. And, in my testing, thickness behind the edge can affect damage at the edge by changing cut dynamics when the media is thicker than the edge bevel height.


This is the picture that got your shorts in a twist:

tweak_10CA.jpg~original



This is a picture where the cut was duplicated in a real test blade with normal primary bevels using the at-the-time new optimized 3V heat treat. Incidentally with a thin edge. As you can see it still did extremely well even with the edge quite thin.

tweak_10CA2.jpg~original


^ those are all carefully controlled 18 DPS

The discoloration above the cuts aren't damage, it's where the softer nail has rubbed off on the harder steel and where oxides on the steel left over from heat treat has rubbed off.

Incidentally this does illustrate a little how behind the edge thickness might have some effect on the edge. You can see the nail was much thicker than the edge height. The blade with the thicker behind the edge thickness would cut with more drag. This might help spread the cut saving the edge, or the higher cutting forces involved might lead to more instability in the cut leading to damage at the every edge. In theory. In practice it didn't matter, as you can plainly see in these two pictures.

There are a few observations I'd like to make

1: holy crap, my old photobucket account still works. how?

2: I have the highest respect for Jerry Busse and Infi. I chose that steel as a gold standard, a goal to reach when evaluating a particular property, gross edge stability in rough use.

3: Infi is tougher than optimized 3V. But optimized 3V is much tougher than most knife steels and has similar edge durability and overall significantly better edge retention than Infi. There are trade offs between the two. They're both very tough and have good edge retention. Personally I would use optimized 3V for most applications because I value edge retention over unbreakability, but there are applications where I would use Infi. I've asked Jerry if I could use it, I have projects where it would be great. It is a great steel.

4: There are a lot of people calling "hype" on subjects they don't understand. Many of these knuckleheads have no ability to control or measure edge geometry accurately enough to form a meaningful judgment. The difference between a knife at 18 degrees per side and one at 22 degrees per side is HUGE and is a variable many don't control. Most. There are a lot of "experts" on the internet with opinions. There are fewer folks who have actually done the homework.

5: whoever thinks their wood chisel can be ground to 18 DPS and then cut a 16 penny nail without much damage needs to put up or shut up. I say you're full of sh*t. It's people making unfounded assertions like this without having actually done it that mess up otherwise informative threads. 20 DPS perhaps. 24 DPS, sure. 18 DPS (relative to center line, not "measured" with a wedge) in .150" cold drawn work hardened steel wire? I doubt it, show me.


footnote. 3V with the industry standard heat treat was developed for stamping dies where preventing part growth and minimizing risk of cracking and distortion was more important than stability in thin sections. But knives frequently go dull from poor edge stability more than abrasive wear. Particularly in choppers. 3V was a cool steel with a lot of potential but it needed a new heat treat to perform up to its potential in knives. A number of people took educated guesses and came up with something better than standard. I was one of the first. And a group of us collaborating were the ones who developed the optimized heat treat for it. We named this final change "Delta" to differentiate it from earlier incomplete tweaks. It finally reached the levels of gross edge durability in rough use as the gold standard, Infi.
 
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This topic just keeps on giving and giving!:thumbsup::thumbsup::thumbsup:

The question of INFI being A8 mod was asked (apparently 12 years ago as well) and Larrin is giving us his best educated guess based on the information available to him. I can appreciate that.
Mr. Busse has also done his job extremely well in keeping the mystery alive! (as can be seen in the fact that for at least 12 years this has remained a topic of great interest, strong opinions and continuing questions) I can also appreciate that.
Nathan the Machinist Nathan the Machinist , Thank you for chiming in with that explanation of this particular testing. I don't think you are a cheater at all!;)

I feel that even without definitive answers, I, for one, am learning a lot!:thumbsup:
 
Nathan thank you for posting. My using your video was mostly to illustrate how others have tested INFI. It was hard to tell how thin the test blade was ground above the edge but also I was only concerned with your Delta and INFI conparison and not the standard heat treat test blade. Again you show your input into the knife world is informative and well thought out.
 
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thebrain said:
Thickness behind the edge has nothing to do with this test, you are confused. Thickness behind the edge only matters in cutting and overall durability of a knife.
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If you say that 0.2mm behind edge and 18 degress per side and other blade with 2mm behind edge and 18 degrees per side is SAME thing when you cut nail , then I m confused :thumbsup:
 
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No one was talking about knives at such thin cross sections that the only outcome would be catastrophic in a test like this. That is what I meant when I said overall durability.
 
Natlek said:
If you say that 0.2mm behind edge and 18 degress per side and other blade with 2mm behind edge and 18 degrees per side is SAME thing when you cut nail , then I m confused :thumbsup:
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your point was well taken, but in this case they did happen to be the same. Did you look at the pictures and understand the text. Are you confused? Are you concussed?
 
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