Knife sharpening techniques for all

x SF med

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#1
Barbarian and I discussed starting this thread, and I'm holding him to helping me spread a little knowledge.

This is going to be a work in progress for a bit, there is a lot that goes into sharpening properly:

Before you even start to sharpen you need this information:
  • What material is the Blade?
  • What is the Grain size of the material?
  • What is the hardness of the material to be edged, and conversely, of the cutting medium?
  • What will the edge be used for?
  • What shape is the edge of the knife in? - this could be from raw shaped to overused and rounded off or anything in between.
  • What is the desired final edge geometry?


You have the information, now you need the tools:
  • Good initial sharpening medium which may have to start with files.
  • Good secondary sharpening medium- usually natural or manufactured stones.
  • A good lifting medium - it keeps the slurry suspended and keeps the stones cutting - people use everything from spit to simple green to honing oil to food grade mineral oil - some even say dry sharpening is the way to go - I was taught with lifting media as the key.
  • Good tertiary sharpening (honing) medium. - we will definitely hit this later - it may be your secondary media.
  • Good final sharpening (stropping or polishing) media. (we'll discuss this later too)
  • A magnifying device of a minimum 8 power, a magnifying glass or jeweler's loupe works best, and I have 8x, 10x, 15x
  • Good lighting.
  • A solid, very solid, work surface with a cover/pad that will keep blades from getting 'dinged' or 'nicked'.
  • Lots of rags.
  • No fear of failure, you will fail, miserably, many times before you hit your stride.
  • Practice, practice, practice.

More to follow.

ETA: Just a note to all - any input, questions, different technique, tools, or ideas are welcome. Barbarian and I are facilitators in this, but it's for everybody.
 
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pardus

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#2
I've been waiting for this for a long time.
I hope you/someone posts video's as well.
The angle has always worried me.
 

Barbarian

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#3
There are blades made from obsidian, titanium, ceramics, fossilized unicorn penis, and a handful of other exotic materials, but steel is usually the most practical blade material. It's also the most common material, so I'll start here.

Steel is composed of crystals called carbides that are bound together by a matrix of iron, sort of like bricks and mortar. It is the carbides that do the cutting, and it is the job of the sharpener to expose the carbides at the edge of a knife.

When steel is heat treated, these carbides arrange themselves into a grain structure. Under magnification, this structure resembles the grain in wood. The size of the grain structure determines how fine a cutting edge the steel can support. The smaller the grain, the less brittle the cutting edge will be. The size of the grain structure is determined by the chemical composition of the steel, the quality of its manufacture, and the quality of its heat treatment.

To be continued.......
 

x SF med

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#4
The additions to steel are not only simple carbides like Carbon, but more exotic metals, niobium, vanadium, chromium, nickel, and other carbide forming items (those that bind better to carbon than the actual iron) have other properties when in conjunction with the steel matrix. think of steel as the mortar and the carbides as the aggregate, they add strength, toughness, flexibility, harness and reduce the 'spalling' of the matrix. The smaller the carbides, the finer the edge, but for every change you gain and lose something... multiple carbides are best delivered in the powdered metals category of tool/knife steels - Elmax and the Crucible steels are the best known among non-metallurgists... they blend most of the good properties of small carbide steels, and also retain the toughness and resiliency of the carbon only steels.

There are so many steels out there that this could be a long post.... go look at the Knife Steels Material Science thread on Professional Soldiers, it covers more than most people want to know, to include martensiting, austenization, matrix reliability, how different tempering and hardening and heat treating methods effect different steels. Bill Harsey et al did an amazing job of putting it all together.

All this is said to point out that no steel is 'better' than another, each steel has it's use, and any one steel can be treated to perform different tasks. A 440C bladed knife is an amazing tool, it works, if heat treated and tempered properly it is hard and tough and sharpens well with a moderate grain size. Conversely, Elmax can make a horrible blade if it is not treated properly.

Another caveat- Particle metals are best suited for stock removal techniques of knife making, and the poured steels are better for forging where the knifemaker has the control of the matrix normalization during the hammering into shape. (read the referenced thread on the other site)

more to follow....
 

x SF med

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#5
Well, now we understand a little about the steel.... we need to start thinking about the multiple geometries of a knife blade.

Would somebody besides barbarian and me post a series of pics of what you think the are the important geometries of the knife blade.
 

CDG

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#6
I would guess the angles in this image, specifically the grind line, termination radius, plunge, and cutting edge. My assumption is that these angles all indicate the ideal angle for sharpening the knife. I would guess the type of edge and the type of point you want also comes into play.


http://jayfisher.com/Knife_Anatomy_Parts_Names_Definitions.htm



http://www.survivalnewsonline.com/index.php/2013/01/essentials-of-knife-sharpening/






http://www.knife-depot.com/learn/pocket-knife-buying-guide/

ETA links to all pics posted. I ran a Google search for "knife blade geometry" and these were the pics I decided on posting. I visited Jay Fisher's site and read a little more in detail. The second pic is also the original product of that site, but I had trouble finding it and posted the link Google gave through the "Visit Page" button.
 
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x SF med

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#9
Can I just mail you my knife? Then you can send it back when it's sharpened. :wall:

:D
I will sharpen your lovely HH6's kitchen knives for her, happily. and for free. You, need to learn... so shut up and read Marine.:p


@ CDG.... Boo Hiss.... I meant pics of one of your knives with what you thought were the important geometries.... BUT.... I have that page bookmarked in my favorites. You need to add the link to your post, and give full credit to the author, it is his intellectual property.
 
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Barbarian

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#12
While we’re waiting for someone to post a pic of their knife blade, let’s talk about edge types, and how they relate to sharpening, since @CDG went through all the trouble of finding and posting that stuff. Thanks, by the way.

Take a close look at the "V" ground edge, Hollow Ground Edge, the Compound Edge, and the Chisel Edge. These are the types that you're most likely to see on folding and fixed-blade knives, so let’s discuss them.

The “V” Ground edge is one of the oldest known edges, and is often referred to as a “Scandinavian” grind. It has been found on Norse, Roman, and Greek blades, and even outdates the use of iron. It consists of one set of flat bevels that taper from the full width of the blade, down to the sharpened edge, and allows the sharpener to lay one large, flat surface against the sharpening abrasive. While being easy to hold at the correct angle while sharpening, it also requires the removal of much more steel to bring the edge back to its original sharpness, thus taking longer to sharpen. Another difficulty associated with this type of edge, is that the abrupt taper from full width to cutting edge makes cutting more difficult in instances where the entire blade must pass through the object being cut.

The Compound Edge is comprised of two sets of bevels-the long and gradual “master” bevel, and the more obtuse micro-bevel which functions as the cutting edge. This edge configuration generates the least amount of friction when passing through an object and lends itself toward activities such as food preparation, carving and “batonning”.

The Hollow Ground Edge, like the Compound Edge, is made up of two pairs of bevels: one long and shallow, one short and somewhat steeper. The difference is that the master bevels of the Hollow grind are concave. This allows the blade to have a better reinforced spine, while keeping the same cutting edge geometry. It is sharpened (in most cases) just like the Compound Edge.

And now the Chisel Edge…. The chisel edge is rarely seen on factory knives, and is most often seen on high-end semi-custom or full custom blades. Occasionally it’s seen on kitchen knives. The Chisel Edge excels at cutting even. Many prefer this type of edge due to its perceived ease of sharpening, as it is completely flat on one side. The other side usually resembles a Compound or Hollow ground edge. While the beveled side of the blade is sharpened like normal, many overlook that the flat side of the cutting edge needs attention too. Sharpening only one side leaves a wicked burr or “wire edge” on the flat side, and this must be remove for the knife to reach its full potential sharpness.

Ok, now lets see some blade photos….
 

Ooh-Rah

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#15
@x SF med and @Barbarian :

Okay, in the spirit of attempting to follow simple directions, here are five of my blades that get regular use.

- Benchmade Barrage - my EDC

- ESSE 3 - something I bought to have for my SHTF bag

- Wanderer - from our very own @Barbarian

- Benchmade Mini Griptillian - my EDC when I have to wear dress pants (I like the serrated edge, can this be sharpened?)

- Cold Steel Tanto - one of my favorites because I like the tanto look but have no idea how to sharpen the front

Regarding the geometries - I have not touched the ESSE or the Wanderer yet, but I think that I would want to stay at an angle of the silver part of the exposed blade. If I get into the black or brown paint, my angles are all off.




- The sharpener's I have been using. Neither of which I really have any idea how to use properly

When sharpening I try to keep the same consistent angle and if I am be honest, use the thumb buttons as guides to hold an angle on the diamond sharpener.

The deal with the blue handle is supposed to be great, but I've never understood if I should keep the blade straight up and down, or at a slight angle.

I seem to have the most success sharpening the tanto, I believe because it is a straight edge (minus the tip). The two Benchmades screw me up because of the angled tip.

When I sharpen I tend to push the blade forward 3 times, flip and repeat. I do this about three times. Then I finish it off on a leather strap.

That's all I'll post for not about my knife sharpening, because that is all I know.

If when I am told that I am fucking up more than I am helping, and that I'd be better off not doing anything at all vs. what I am attempting to do, I will not be butt hurt. I just want to learn.

 
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Ranger Psych

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#16
Personally, I'm not a fan of the carbide sharpeners. They literally scrape material off the knife in order to reshape the edge. Part of what makes it cut is the fact that if you really look close, the edge is sorta serrated across the entire blade once you use one of them. It's a quick and easy way to screw things up, especially since you can't configure angles and use media to sharpen that is appropriate for the metal the blade's made of.
 

x SF med

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#17
the edge is sorta serrated across the entire blade once you use one of them
and..... one point is already raised.... any microserration on the edge of a blade should only be from the carbides standing out from the matrix, not introduced/left by your sharpening media..

@compforce - the series is great for kitchen knives. I'm not a fan of the pull method of sharpening, I prefer the push method. One reason being I find the burr raises too quickly on the pull method while also removing more material from the edge. I have used a modified circular method too... it is a push pull, but requires lots and lots of practice to balance both sides of the edge
The guy in the video raised an excellent point about feeling the edge on the stone - you must do that throughout the sharpening process, as well as listen and watch...the least reliable of the 3 is watching from my experience.

@Ooh-Rah - step away from the carbide sharpener, step away slowly and keep your hands in the air until told to drop them.
The only time to use one of them is if you quickly need to rough angle an edge that is basically flat.... it is an atom bomb sharpener.... have you noticed curls of steel or large amounts of powdered steel collecting when you use it? It's because it literally planes off large amounts of steel on each pass.
The Cabela's branded e-zlap you have is great.... for reshaping blade tips when somebody uses your knife as a screwdriver.... ever noticed the edge of your knife looks like wood somebody has gone after with 100 grit sand paper when you use it? It's because that's exactly what you've done... keep reading.... we will get to recommended equipment in a little while.

@Ranger Psych .... a Devil's Toothpick? Now that is badass...

I guess I will have to post a pic of sharpening project knives I have around here... an old Effingham Blackjack Mamba.... multiple recurves and the previous owner(s?) look to have used the 'belt sander' or grinder method of sharpening.... it does not look like the temper is gone, which is good.... another is a hugely abused Gerber MkII with the original aluminum handle and a 4 digit serial number (six digit for the military contract, but leading zeroes are not counted for placing purposes) - this one may never be worth a lot ever again, but I will try... somebody used too shallow an angle for years when sharpening, and somebody else used too steep an angle... the belly of the knife is no longer truly discernible....
 
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x SF med

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#19
As far as sharpening goes, I think the overall curve of the cutting edge, the angle and type of the edge, and the grind of the blade are important to the overall process.
Yes. It looks like you may have sharpened that Spartan Hunter with a diamond system... it doesn't look like the polished edge that Mark sends out after using the Wicked Edge system. I may have seen a few of their knives in all stages of manufacture, from prototype to full production.
 

policemedic

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#20
It's actually a Difensa (kind of perfect for me with its Canadian heritage and US manufacture), and I haven't taken a stone to it yet. Haven't had to, and honestly I don't want to mess with it until I'm more confident. The photo is just probably not showing the edge detail very well.

Is the Wicked Edge system usable by lay people, so to speak?
 
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