Murray Carter's 3 finger test

[jackknifeh]

At cartercutlery.com Murray Carter makes, sharpens and does just about anything else with knives I guess. I think a lot of people here know this. Anyway I've gotten his emails with six steps of sharpening and one thing mentioned is the 3 finger test to test the shaprness of a blade. I'd like input from anyone who has tried this. The "feeling" he talks about on a really sharp edge fells like the feeling I get with a really sharp toothy edge after just the coarser stones. By going through to the finer stones, 1000 grit or higher I still have what I think is a really sharp knife but can't get the bite "feeling" he talks about. I emailed him and is reply was it depends on the quality of the steel. I've tried this on AUS-8, VG-10, and ZDP-189 (all stainless of course). He uses carbon steels for the core of his knives. If anyone has tried this test what were your results?

Jack

[Dr. Snubnose]

I do know what Mr. Carter is talking about for sure and I feel it after using the edges of the white stone...but I was wondering what the reference to "three fingers" means in his testing....Doc:D

[jackknifeh]

I do know what Mr. Carter is talking about for sure and I feel it after using the edges of the white stone...but I was wondering what the reference to "three fingers" means in his testing....Doc:D

He says to put your thumb on the spine and 3 fingers on the edge of the blade and slide them along the edge (not across). Use 3 fingers instead of one for more nerve endings sending messages to the brain which hopefully will say "DON'T PUSH TOO HARD". With a scary sharp edge there should be microscopic teeth on the edge that grabs your skin and will resist your fingers from sliding along the edge unless you are cutting yourself. With an edge that feels like this you should be able to shave your face (I suggest shaving cream though. We are not Crocodile Dundee). I'll put his tip 2 below so you can see exactly what he says.

Jack

Tip #2

The Three-Finger Test for Blade Sharpness

In your first FREE Knife Maintenance tip, I discussed some reasons why knives get dull, and what to do to prevent edges from getting dull prematurely. In your second FREE tip you'll discover the quickest and most accurate way to see if a blade is as sharp as possible. At the end of the essay, read my incredible offer to you to get set up for hand sharpening with the best equipment available anywhere in the world for a whopping discount.

There are many conventional methods of testing blade sharpness. One of the most common is to scrape the thumb of the left hand from right to left over the edge of an upward pointed blade. Another test is to see if a blade will shave hairs off of the forearm or slice newspaper. Herein lies a problem as a dull knife with a burr can pass the first test, and a buffed knife (using a motorized buffing machine) can pass the second test of shaving. However, the buffed knife can usually be much sharper. Buffing of the blade results in an edge that resembles the tip of a ballpoint pen microscopically; the edge is round where a hand-sharpened blade will have a completely triangular cross-section.

Another thing that deserves mentioning is the controversial debate between what experts call a "smooth edge" vs. a "toothed edge". The usual conclusion to this debate is that each type of edge will perform a certain cutting task better. I claim that the ideal "scary sharp" edge is one which is triangular in cross section, has microscopic teeth which give the blade "bite" and will also shave hair and slice newspaper with abandon. This kind of "scary sharpness" can easily be detected with the human fingers.

The technique used is as follows

The blade's handle is held in the right hand of a right-handed person, close to the body, with the tip of the blade pointed to the left and the edge facing downwards.
The thumb of the left hand is placed on the spine (or back) of the blade for safety and the first 3 fingers of the hand are pressed together side by side. This adds an element of safety, as surface pressure from the blade will be distributed over a larger area. Additionally, there are more nerve endings available to send messages to the brain. (Consider the sensitivity of the nerves of 3 fingers compared to the thumb.)
The 3 fingertips are brought into contact with the blade's edge, and ever so gently, you attempt to slide the fingers not across, but along the edge of the blade. The blade is tested this way along all parts of the edge.
A totally dull edge will allow the fingertips to slide back and forth. No sense of danger will be perceived. A buffed blade that shaves will also allow the fingertips to slide, albeit the fingers will sense that the edge has a thin cross-section and the brain will receive the message "don't push too hard".
At a certain point of applied pressure, the round buffed edge would break the surface tension of the skin, resulting in a cut; but the brain will tell you to stop before that happens.
An edge accomplished in step 5 (grinding the primary edge) in our 6-step procedure (watch for my Tip #4 and Tip #5: The 6-Step Sharpening Procedure) will give the fingertips the sensation of sharpness as little teeth in the blade's edge immediately want to "dig into" the fingers and therefore the blade won't slide along the 3 fingers. Your brain tells you to not even attempt movement. However, the blade will probably not shave at this step.

Upon completing step 6 (edge honing, 6th step of my 6-Step Sharpening Procedure), the fingertips will perceive yet a new level of sharpness, often referred to as "scary sharp". The little teeth in the edge of the blade are barely perceptible, and yet there is no sliding along the fingertips. The blade will also shave hair at this point.

Watch for Tip #3, coming from me in a couple of days, where I will show you how easy it is to sharpen a knife.

Feel free to share this report with your family and friends. If they would like to receive their own Knife Tips, then please direct them to CarterCutlery.com.

[Dr. Snubnose]

yikes...:eek:break out the box of band-aids first!!!!:eek::eek:Doc:eek:

[jackknifeh]

yikes...:eek:break out the box of band-aids first!!!!:eek::eek:Doc:eek:

No kidding. That's what I thought after reading how to do his test because Dad always said NEVER slide your fingers along the edge. Good advice Dad. Dad showed me how to sharpen a knife when I was I don't know how old. Within a week I cut myself and actually felt the blade slam against the bone. My pocket knife folded on me. So he bought me a hatchet. He may have had an additional agenda concerning my safety. lol

Jack

[wongKI]

My answer?

I just took my GB up to 2000 grit sandpaper (which, IIRC, is equivalent to a little higher)
and stropped for a while.

The test worked pretty okay. But I think we have a new contender: a polished edge that is actually, as you say, triangular in C-section.

I got little bits of finger print coming off.

[Evil D]

I've got all the emails, read them all, and i'm a big fan of Murray and his work, but this test honestly doesn't do much for me. Either my knives just aren't that sharp (despite the fact they shave etc) or my skin is so thick and calloused that i just don't feel what he's talking about. Obviously i know better than to really push and slide my finger down the blade...my mind just won't let me do it even before i go through all the different stones and hone the blade out...just like the OP said even after my course stone when i'm reprofiling i know better than to TRY to run my fingers down the blade because even that will slice you open if it's not burred real bad.

He offers a knife sharpening service, i believe $20 a knife. I'm really tempted to send him a knife and see exactly how much difference there is between my rookie work on my Lansky and his 18 years training as a sword smith.

[ChrisR]

Blimey, there's nothing on God's Earth that would induce me to run 1 finger, let alone 3, along the edge of a knife I had just been sharpening and stropping. I mean, you'd have to have skin made out of Kevlar to be able to put enough pressure to feel something and not get sliced :confused:

[Evil D]

Blimey, there's nothing on God's Earth that would induce me to run 1 finger, let alone 3, along the edge of a knife I had just been sharpening and stropping. I mean, you'd have to have skin made out of Kevlar to be able to put enough pressure to feel something and not get sliced :confused:

There is actual logic behind using 3 fingers. It's the same principle that allows circus acts to lay on a bed of nails and not get impaled by them. It's all about distributing your fingers along the surface of the edge enough that it would take more force than normal to cut yourself. The surface area is increased and your fingers stay side by side, in essence making one very wide finger, which is much harder to cut than just one finger. Another part is how sensitive your finger tips are and your own inner will to not cut yourself. I've heard people say "oh touch the blade to your finger and you start bleeding"...that's BS, they must have some really fragile skin because i can push my thumb down on a razor blade with reasonable pressure and not get cut.

I've felt the difference, like Murray says, between a dull blade and a sharp blade. Go and find a blade that is DULL, that won't cut through paper, that you're reasonably sure won't cut your finger, and do this 3 finger test. Your fingers will slide down the blade with EASE. Now try it with a sharp blade...not even the sharpest one you have...and your fingers will NOT slide down the blade for 2 reasons....one because there's "bite" from the blade, and second because your brain tells you not to push or try to slide your fingers any further. The idea is that, the sharper the blade, the less "slide" you will get because of these 2 reasons.


My problem is like the OP said, i get this feeling of "don't push any harder" right after i go over the edge with a course stone, and i can't tell any difference between that edge and a finely honed and polished edge. The feeling for me is the same so it doesn't give me a good idea of how sharp the edge really is.

[jackknifeh]

I've got all the emails, read them all, and i'm a big fan of Murray and his work, but this test honestly doesn't do much for me. Either my knives just aren't that sharp (despite the fact they shave etc) or my skin is so thick and calloused that i just don't feel what he's talking about. Obviously i know better than to really push and slide my finger down the blade...my mind just won't let me do it even before i go through all the different stones and hone the blade out...just like the OP said even after my course stone when i'm reprofiling i know better than to TRY to run my fingers down the blade because even that will slice you open if it's not burred real bad.

He offers a knife sharpening service, i believe $20 a knife. I'm really tempted to send him a knife and see exactly how much difference there is between my rookie work on my Lansky and his 18 years training as a sword smith.

I agree about the test not being for me either, for now anyway.

I've been temped to send him a knife also after reading the test procedures and results and not getting the same results he describes. He said in an email I sent him everything is explained in detail on his DVDs. He may be trying to sell his product but there is nothing wrong with that. I want them and two Japanese water stones he sells. Somewhere around $160 I think. If you already have great stones just the DVDs should do if you wanted them. I'm happy with the edges I get now but would like to have his DVDs because I'd like to learn as quickly as possible how to sharpen by hand. I've done it for most of my life and could shave my arm but never gotten a knife hair whittling sharp before. If I undertook sharpening by hand I'd want instruction from an expert so I don't need to learn from my mistakes. I could learn the right tips and secrets from someone who already knows them.

Jack

[The Deacon]

I'll stick with my fingernail test because, given the lack of feeling in my fingers, I wouldn't dare try that trick. Maybe I'm missing something. But it seems to me that "sharpness", like "horsepower" becomes an end in itself for some, rather than a means to an end. It also seems the net results are similar, something to brag about. At the very least, there's a point of diminishing returns. At worst you sacrifice reliability on the alter of performance.

[araneae]

No way I'd run my fingers along an edge like that. The email sounds like self marketing to me.

Get a sharpmaker and maybe some diamond hones and save yourself some cash for a new knife. You can get lots of great advanced info for free here and on other knife forums. There is no substitute for 1st hand experience in sharpening. You can watch a dvd, but IMO practice is where you'll learn the most. Sharpen your knives, sharpen your friends/neighbors/relatives kitchen knives. That's where you'll learn the most.

[jackknifeh]

No way I'd run my fingers along an edge like that. The email sounds like self marketing to me.

Get a sharpmaker and maybe some diamond hones and save yourself some cash for a new knife. You can get lots of great advanced info for free here and on other knife forums. There is no substitute for 1st hand experience in sharpening. You can watch a dvd, but IMO practice is where you'll learn the most. Sharpen your knives, sharpen your friends/neighbors/relatives kitchen knives. That's where you'll learn the most.


You may be right. The DVDs which could be replaced by other input and definately practice and experience. I don't know if I'll get the DVDs because they are on a back burner for expense for me. Other things I want more. However if I spend any money on hand sharpening I'll get those unless I see something else by the time I want to spend money or time on learning to get a scary sharp edge by hand. Everything I've heard about Mr. Carter (I did talk to him briefly on the phone once) is very professional. As far as buying something from someone I don't know, I'd trust him as I have others.

I'm not sure I have the patience for that undertaking anyway.

Thanks for your comment,
Jack

[Evil D]

I would LOVE to attend one of his classes and learn directly from him...that'd be great. He's a business man like everyone else and of course he's not gonna email you the info he's trying to sell in the DVDs, but if you go on You Tube and watch some of his videos you'll see that he definitely knows his stuff, to say the least.

I don't think buying/watching his DVDs would make me a better sharpener but it sure couldn't hurt. I'd buy them for sheer interest alone.

[jackknifeh]

I would LOVE to attend one of his classes and learn directly from him...that'd be great. He's a business man like everyone else and of course he's not gonna email you the info he's trying to sell in the DVDs, but if you go on You Tube and watch some of his videos you'll see that he definitely knows his stuff, to say the least.

I don't think buying/watching his DVDs would make me a better sharpener but it sure couldn't hurt. I'd buy them for sheer interest alone.


Have you checked out the tuition for his classes? Is it "worth" it? My answer is it depends on if you can afford it and how much you would like it. That holds true for anything. This is the first thing to learn if you ever go into sales. I don't care how bad people say the economy is there is money out there for the salesman who can get you to WANT his product. It's kind of funny. Yup, I was in sales as a part time job for a few years. For me the answer would be yes, I would take his classes if I could afford it which I can't right now. I've seen people spend rediculous amounts of money on things I wouldn't spend a dollar on. I've done the same thing as far as they are concerned I know. Actually I'd never have spent $100 on a knife until a few years ago. NEVER. But I've always wanted better quality knives but never looked into it. A lot of it is getting used to what things are going to cost if you really want them. First I spent $40 on a knife, then $60, then $100. Most I've spent is $175 a couple of months ago. I'm sure some on this forum may laugh to know that knife is in shipping back to me FROM THE REPAIR SHOP! Guess why. You guessed it, it's not a Spyderco. Less than 2 months old and the spring for the lock broke. The blade just flops around like my, never mind. I hope it stays not broke. I really like the knife. I'm not going to go into it right now but I'll just say this. I've bought several tools from that company. I have had a 100% failure rate with the folding knives. That's just one more reason I appreciate the quality I've seen in the Spyderco knives I've gotten. I got long winded again. I need a hobby.

Jack

[tonydahose]

i guess i dont get my knives super scary sharp because i use the paper wheels but my knives get sharp enough for me and it only takes 30 seconds of my time.

[Evil D]

Have you checked out the tuition for his classes? Is it "worth" it? My answer is it depends on if you can afford it and how much you would like it. That holds true for anything. This is the first thing to learn if you ever go into sales. I don't care how bad people say the economy is there is money out there for the salesman who can get you to WANT his product. It's kind of funny. Yup, I was in sales as a part time job for a few years. For me the answer would be yes, I would take his classes if I could afford it which I can't right now. I've seen people spend rediculous amounts of money on things I wouldn't spend a dollar on. I've done the same thing as far as they are concerned I know. Actually I'd never have spent $100 on a knife until a few years ago. NEVER. But I've always wanted better quality knives but never looked into it. A lot of it is getting used to what things are going to cost if you really want them. First I spent $40 on a knife, then $60, then $100. Most I've spent is $175 a couple of months ago. I'm sure some on this forum may laugh to know that knife is in shipping back to me FROM THE REPAIR SHOP! Guess why. You guessed it, it's not a Spyderco. Less than 2 months old and the spring for the lock broke. The blade just flops around like my, never mind. I hope it stays not broke. I really like the knife. I'm not going to go into it right now but I'll just say this. I've bought several tools from that company. I have had a 100% failure rate with the folding knives. That's just one more reason I appreciate the quality I've seen in the Spyderco knives I've gotten. I got long winded again. I need a hobby.

Jack

I haven't even looked...because i know i can't afford it. The fact that he shows/trains you to forge your own neck knife was enough to tell me it's out of my wallet's league, since his neck knives start at something like $400. It's one of those things that i wouldn't want to put much thought into the price, and just look at it as learning and experience that i probably can't get from anyone but a guy like him. Or, maybe that's just his sales pitch...although there are lots of testimonials on You Tube as well, such as guys shaving their heads with the neck knives he trained them to make.

[jackknifeh]

I haven't even looked...because i know i can't afford it. The fact that he shows/trains you to forge your own neck knife was enough to tell me it's out of my wallet's league, since his neck knives start at something like $400. It's one of those things that i wouldn't want to put much thought into the price, and just look at it as learning and experience that i probably can't get from anyone but a guy like him. Or, maybe that's just his sales pitch...although there are lots of testimonials on You Tube as well, such as guys shaving their heads with the neck knives he trained them to make.

I don't know if he has classes just for sharpening. I don't think so but his knife making classes (some classes require one or more other classes first, just like college) would run several thousand dollars. Then to put that knowledge to the test you would need a shop and some of the equipment/tools look like they are as big as a man or bigger. No telling what that stuff would cost. He will send a shop tour DVD of his shop. It's only a few minutes, might even be on youtube. Even if I could afford the classes with no problem I don't think I would unless I was going to set up a shop or at least be somewhere I could get a job using those skills. Even after any classes or training I've gotten once you start working with people in that field I've realized the classes raised my level of knowledge from nothing to stupid. You don't get good for quite a while much less what you would call experienced. Sure would be fun though I bet.

Jack

[Evil D]

"from nothing to stupid"...yeah i know what you mean lol

[dsvirsky]

Murray Carter gave a seminar at Blade a few years ago. He started with a knife that was demonstrably shaving sharp and then proceeded to show us the difference between that and the level of sharp that passes the 3 finger test. However, there is nothing magic about his method of sharpening. Murray Carter can get 3 finger test sharpness because he sharpens at an acute angle and is able to manage an amazing level of consistency in his sharpening strokes (thus achieving a triangular cross-section where most of us don't). The only thing he does differently than how most of us were taught (differently, as opposed to better :D ) is he back bevels every time he sharpens and he uses a trailing stroke.

Oh, yeah -- he also laughs at people who are afraid of scratching their knife. :p

[Slick]

I admit I have not read all the way through this thread but this three finger thingy sounds dangerous. I have done similar but there are better ways. Different uses require diffent edges. My favorite edge is toothy S30-V. Polishing the edge is great for shaving but will not cut rope very well. I do not shave with my Spyderco knives. One try was enough. Candling the edge will show you if you've sharpened out all the nicks. I do not need a hair splitting edge. I really don't want a hair splitting edge. If I can lop off pieces of a free hanging hanging hair I'll go back and rough up the edge with a medium (Edge-Pro) stone.

Different strokes and all that but please don't put your flesh at risk to check the edge of a scary sharp knife. There are safer ways.

[jackknifeh]

I admit I have not read all the way through this thread but this three finger thingy sounds dangerous. I have done similar but there are better ways. Different uses require diffent edges. My favorite edge is toothy S30-V. Polishing the edge is great for shaving but will not cut rope very well. I do not shave with my Spyderco knives. One try was enough. Candling the edge will show you if you've sharpened out all the nicks. I do not need a hair splitting edge. I really don't want a hair splitting edge. If I can lop off pieces of a free hanging hanging hair I'll go back and rough up the edge with a medium (Edge-Pro) stone.

Different strokes and all that but please don't put your flesh at risk to check the edge of a scary sharp knife. There are safer ways.

What is candling?

Jack