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shinbone

Idle pleasures - knife sharpening

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shinbone
I have tried multiple times to get my knife edges hair-whittling sharp, with no luck.  I can get a blade sharp enough to pop hair off my arm, but I could never get to the next level of sharpness, hair-whittling.  I have no practical need for such a sharp edge, but I am an engineering/science nerd, so I never let lack-of-practicality get in the way of having some fun.
 
I have worked with a few different types of steels, the latest three were S35V, Elmax, and M390.  I can get each edge super sharp, but can't whittle hair.  I use a Buck Honemaster sharpening guide.  I know it is old school and there are much fancier sharpening guides available, but the Honemaster works perfectly well for the one angle it is set to.
 
When sharpening, I check the bevel with a 20x loupe as I progress.  With the loupe, I can check to make sure that the scratch pattern on the bevel is being successfully refined at each step so I know I am going in the right direction.
 
My typical sharpening routine is to start with a progression of DMT diamond hones.  The DMT diamond hones are monocrystlline diamond crystals bonded to the surface of a precision-flat steel plate.  I use the hones dry.  If I am setting a new bevel, I use the XX Coarse hone, which DMT lists as 120 mesh equivalent.  I then progress through all the DMT diamond hones, raising a burr on each side of the blade before moving to the next hone.  I end the DMT hone progression at Extra Extra Fine, which DMT lists as 8000 mesh, or 3 micron, equivalent.  I should note that once the edge bevel is set on the XX Coarse diamond hone, I can raise a burr on the subsequent hones pretty quickly, say 10 - 20 strokes per side.  This is true even for the super hard M4 and CPM 10V steels.  I interpret this to mean the hones are cutting quickly and the Honemaster is accurately holding a constant angle, i.e. I am doing things right.
 
Next, I hone the edge with a Spyderco Ultra Fine ceramic stone, which is generally accepted to be about 3 micron equivalent, but, being ceramic, it does refine the edge beyond the DMT EEF hone.  On the ceramic stone, I use a mixture of water and liquid dish soap to minimize clogging the stone.  Again, I raise a burr on both sides with this ceramic stone.  Since ceramic doesn't cut as fast as diamond, it takes a little longer to raise a burr.
 
After the ceramic stone, I strop the blade on flattened basswood strops using DMT diamond paste.  I use a trailing-edge motion and go slow with light pressure.  Grit progression is 6 micron, then 3 micron, then 1 micron.  Due to being on a flexible substrate, the diamond paste does not cut as coarse as its diamond hone equivalent.  Again, I check the progression with a 20x loupe, and can see the scratch pattern continually being refined at each step.  I have 0.5 micron DMT diamond spray, but I haven't used it, yet.  Seems to me I should be able to whittle hair with an edge stropped on 1 micron diamond grit, if I am doing things correctly.
 
So, after all this sharpening, I borrow a hair from my Ms. Shinbone (cue the eye-rolls), and damn I can't whittle it.  I've tried moving the blade in both directions along the hair, and at different angles, but no luck.  The blade is so sharp it practically reaches out and grabs the skin on my thumb, but it won't whittle hair.  
 
It is raining today, so I had to put my normal outdoor activities on hold.  I decided to take advantage of the forced down time to work on my pursuit of a hair-whittling knife edge. 
 
The latest blade I tried to sharpen to the point of hair-whittling sharp is a Real Steel Megalodon in M390 steel hardened to about 61 HRC.  On this knife I've taken it down to the 1 micron diamond paste in the past, but still couldn't whittle hair.  Today, I redid the diamond paste progression (6 micron, 3 micron, 1 micron) and then finished on a clean leather strop.  This is the first time I have ever stropped a blade on clean leather.  Holy cow, the 20x loupe showed the leather strop really polished the edge!  I was shocked at the polishing effect simple leather had on hardened steel.  I think it was the leather strop that made the difference that put me past the goal line.  Bevel angle is 35 degrees included.
 
The photos below show a hair cut tip-to-root.  I couldn't whittle going from root-to-tip, which is even more difficult than tip-to-root due to the directional scale-like surface structure of the human hair.  That will be a fight for another day.
 
DSCF0719-XL.jpg
 
DSCF0719%20%282%29-XL.jpg

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mart

I use Japanese water stones for my planes and chisels but have never tried them for knives. I've used a Lansky for many decades on my knives followed by a good quality steel. Can't say I get them as sharp as your blade above but they are sharp.

 

My plane and chisel blades though are extremely sharp. I warn people not to stare at the edge of one of my chisels  or plane blades for fear their eye may start to bleed.:D

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Mike da Carpenter

Knives and single bevel broad heads get sharpened on my KME knife sharpener then on to a leather strop with jewler’s rouge.  Come hunting season, there is no hair on my forearms.  As for my chisels and planes, a wet stone to polish the flat side to a mirror finish then a micro bevel on the angled side (just one stroke on the stone with just the tip of the bevel touching), then stropped on cardboard.  

 

It’s simply amazing how well a tool works when sharpened properly.

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SelbyLowndes

They can be too sharp. If you need that sharp, try Obsidian knapping...SelbyLowndes

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Dakota Dogman

I have 10 kids and can't find time to sharpen my knives past screwdriver... You have my awe. Well done.

God bless,

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lee sykes

"To boldly go where no man has gone before"   Bravo to you for reaching out to conquer the mysteries of micro cosmological infinity. 

I have long ago, determined that I will have to settle for "sharp enough".   This goes for most things, literally and figuratively, in my case. 

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gunsrus

I am impressed , I didn't realize that a blade could get that sharp . Does the edge become more "brittle" for lack of another word , if that edge is that fine ? I know nothing .

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oak stob

I have been plagued with fat(or husky) hair all my life....I should have sold some to knife testers and made some soft money.

 

Good job, by the way.

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Crazy Horse

The sharper the edge the more likely it will become dull with use. Knives need not be as sharp as a surgical scalpel. We're not doing any brain surgery.

 

If you really want a super sharp edge try using a piece of glass with some emery paper on it. Start with 400 grit and you can work your way up to 2000 grit (even higher). Fine emery paper is available in most automotive parts stores (Pep Boys, etc).

 

To get a super sharp edge after using the emery paper get a flat piece of white pine and rub some jewelers rouge on it and stroke the blade on it. The sharpness will amaze you.

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Cooter Brown

Kinda splittin' hairs there, ain'tcha boss?

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shinbone
13 hours ago, gunsrus said:

Does the edge become more "brittle" for lack of another word , if that edge is that fine ?

 

Crazy Horse is correct that the finer the apex of the edge, the more fragile the apex becomes.  But, that is where modern powder metallurgy super steels like M390, S110V, etc., come in to play.  These highly alloyed, super-clean, sintered-powder steels have micro-fine grain structure and more carbide forming constituents to make a steel that will hold an incredible edge for a long time.  Once that hair-whittling edge gets worn down, then the edge is reduced to, and stays at,  "just" hair-popping sharp for a long time.

 

https://www.bohler-edelstahl.com/en/powder-metallurgical-steels-1587.php

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topdog1961

I use a $4.95 sharpener I bought a a discount store maybe 15 years ago. It has a steel X on one side and a finer ceramic X in the other. I can respect a quest for perfection, if one has the time, and is so inclined. But a few draws through each side and my blades do all I could ask, including processing 4-5 deer per year and a whole lot of fish. That's about as demanding as my needs get. 

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shinbone
10 minutes ago, topdog1961 said:

I use a $4.95 sharpener . . .

 

 

Different strokes for different folks.  Literally, in this case.  :-)

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Zoli 16ga.

bought an edge pro clone off amazon for $49. Works very well...so well I cut my finger...have you heard about that?

 

I like my knives 'sticky' sharp. 

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