Do you use the MC three finger test?

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303tango

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Nov 12, 2012
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Do you use the three finger test for sharpness? Is it your "go to" test? If yes to the question, how difficult was it for you to get to that level of expertise? I thought I had some pretty sharp knives, but I always seemed to have trouble with the phone book paper test. My knives would cut beautifully with the grain, (long way) but, fail miserably going across the grain. So, I'm trying all the usual stuff, but not getting satisfactory results. One day I see the Murray Carter three finger sharpness test video on you tube. I thought I could probably do this test without cutting myself, so I gave it a try. Let me say that there was no way that my knives would pass the three finger test. I'm embarrassed, and I thought they were pretty sharp! So, if you have thoughts or information related to the test I'd be grateful for your comments and advise. Regards, Jeff
 
Well, I just tried it. My go to has been the thumb test, but I just checked my knife, and it passed, but I go up pretty high on the grit scale.To get to my level, it's taken me about 3 years of coming home and sharpening every day for at least an hour. What is your finishing grit?
 
I'm an impatient kind of person. The three finger test is just a way to use up a boat load of band aids. ;) I learned awhile back my "thumb test" is also useless. I had just gotten done sharpening my Griptilian, tested the edge with my thumb "eh, need to spend more time on the stone". Decide to try some phonebook paper, and "ZIPPPP" one long, clean slice. It's the only reliable test for me. :)
 
No.

I test sharpness with my eyes. I look at the blade, and I look at the paper I cut.

Three fingers. Why three, why not four, or two, or one?

I respect what MC has achieved, but occasionally, I recognize his chatter, as PT Barnum-ism.

I rank his three finger test right up there with his sharpening breakfast cereal spoons.

I do not put my finger on the trigger of a gun, unless I intend to fire it, and I do not place a blade against anything I do not intend to cut.
 
I inspect it with my thumb, to gague the sharpness. If it passes the test, I go so far as to shave a bit of hair off the inside of my forearm... When I say shaving sharp, I mean it.
 
If I am not mistaken the 3 finger test has a bit of a bite when you try to move your fingers along the blade and it feels like it digs in. I have gotten blades that sharp occasionally but not consistently. And I am not sure what a true version of it feels like, a knife sharpened by someone who has mastered sharpening as I've been at this for around 3 months now. It has a bit of a bite when you try to move and your fingers stick and your brain screams "STOP YOU IDIOT, you cut yourself if you continue".

I have learned a lot but there is still quite a bit left for me to learn and I know there are completely different levels of sharpness I haven't even touched the surface yet. I actually use this type of test to figure out how the blade is in terms of sharpness and where I need to make corrections if any.
 
I used it before I knew that Murray Carter had his name associated with it and I use two fingers (i.e. my middle and pointer). It's more useful than many people may think--for example, I can even estimate whether or not the "shoulders" have been knocked off of a microbevel.
 
My knives will all mow trough 8 oz. leather and phone book paper and news print etc., and none of them pass the three finger test. How freakin' sharp do they need to be?
 
I think the 3 finger test is highly subjective to the individual. Just take it as your brain either doesn't like you or you likes to live dangerously. There is also a whole lot dealing with the body as an individual concerning how it react to the knife in this test. But it sounds like a knife that pass this test for most of us may not pass it if we were hand it to you. That is my guess.
 
I'm afraid I'll mistake his instructions and cut my fingers off. He's famous for calling the cutting bevel the "primary" bevel and the main grind of the blade the "secondary" bevel, exactly the opposite of me. I mean, if we can't even agree on these terms, how the hell am I gonna know if I'm following his instructions correctly? :D

No, I don't use it. I keep a pile of those newspaper like things they always send in the mail with coupons and such printed on them next to where I sharpen. When I can get clean cuts on those, I know the knife is sharp. :thumbup:
 
Thanks to HeavyHanded for the link to the previous post on the three finger test and his thoughts. There is a lot of information in the previous post. From reading it all I'm pretty sure that I understand where I've been going wrong. In my experience, I noticed that on my knives, doing the TF test, the edge was very smooth, almost slick. From that I concluded that I've polished the toothyness off the edge with the strop. I'll have to change the way I strop. I think having a toothy edge is a good thing. Now I have to learn to optimize that characteristic of the edge. I think the three finger is a good test, I'll continue to use it. Thanks for all the good information. Rgds, Jeff
 
On one hand I want to agree with you but on the other it's hit or miss passing that test no matter which grit I use minus the coarse side of the silicon carbide economy stone which seems more difficult to do. So this includes the norton india economy stone as well as DMT C/F/EF and I strop on some cheap green compound on a notecard. For me it just seems more dependent on skill which causes me to have the hit or miss issue.

I have passed the test on a coarse DMT than went up to Fine and failed it which forced me to go back and fine tune it more, than I could pass the test again. Same story with everything else while going higher up in grit, it almost seems like there is a slightly smaller margin of error to pass it as you go up in grit though that could be in my mind. Hopefully someone with more experience and who have gotten more refined edges can chime in on this as I am curious about this now as well if this is true or just in my head.
 
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I never understood this method.

Over the years, I eventually just trust my skin by touching the edge lightly (there will be zero movement or I will slice into meat).

If I want to show off to coworkers, I cut rolled wax paper (nearly every knife will bounce off rolled wax paper or snag tear it). An extremely sharp knife will cut through it at any angle.
Also I use printer paper and while any sharp knife slices printer paper, my knives do it near silently.
 
I have gotten cuts on the pads of my fingers, so nope!

I will judge on smoothness of phone book or receipt paper slicing, or if I am showing off to non knife people I will shave a bald spot on my arm. It works for so many other people, so it must be good enough.
 
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