Author Topic: Knife Sharpening - How to get your knife shaving sharp!  (Read 7260 times)

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Offline PetrifiedWood

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Knife Sharpening - How to get your knife shaving sharp!
« on: January 31, 2014, 08:50:39 PM »
I was asked by a fellow forum member to make a video on knife sharpening. Today I decided to do that, and I also decided to use it as an opportunity to take a shot at the folks who get all bent out of shape about the way a video is presented.

So, in order to do this, let's first define "knife sharpening". Knife sharpening is the process by which a knife blade is made sharp. That's it. Simple as that. In this thread (and the attached video) I am going to show you how to sharpen a knife. I am not going to acknowledge any other way to do it, because my way works, I like my way, and I don't need to know any other way. There is no better way to do it than the way I am about to describe, because my way gets them sharp. Furthermore, I am an expert at knife sharpening. I can prove this because when I sharpen a knife, it becomes sharp.

Anyone needing credentials will just have to trust that I have been using and sharpening knives for approximately three decades, and I have made my own knives from raw materials to a finished, sharpened product. That makes me an expert. I don't want to come across as arrogant, but take it however you want to take it. I'm an expert knife sharpener, and if you read this thread and watch the video, and do everything exactly the same as I do, you will have a sharp knife.

To sharpen a knife, you need to remove steel from the edge in order to create an acute angle. Any nicks, chips, flat spots or other flaws in the edge will reduce the knife's cutting ability. A knife with such flaws cannot be called "sharp". Sharpening is the process of removing those flaws to leave an unbroken, consistent edge angle the entire length of the blade. Removing steel requires an abrasive material harder than the steel itself.

For over a thousand years, man has used hard stones to remove metal from the edges of blades to sharpen them. It is only in the last century that technological innovations have attempted to re-invent the wheel, and various new methods for removing the steel have surfaced. These new methods range from effective to laughable. But many of them rely on electricity, complicated sharpening jigs, stones in proprietary mounts, and other devices that may or may not put a good edge on a blade. Most of these methods attempt to correct or dispense with proper knife sharpening technique, which you will learn as you read on.

One of the biggest mistakes most knife users make when attempting to sharpen a knife, is to use a pocket knife sharpening stone. This is a mistake because these small stones must be supported by one hand, while the knife is used in the other hand. In order to create a consistent, unbroken edge angle, the blade must be held at a consistent angle to the stone while sharpening. When you hold the knife in one hand and the stone in the other, each hand is attempting to hold an object at a consistent angle relative to the other. They are constantly making minute corrections and are "fighting" each other trying to maintain a consistent angle. This is a recipe for failure and will result in a "faceted" edge made up of multiple tiny flat spots from each successive pass across the stone.

The solution is amazingly simple. The stone must be held stationary, and you must use BOTH hands to stabilize the knife and hold it at a consistent angle. By mounting your stone to a table or bench (and even better, using a full size bench sharpening stone) you eliminate one source of error, since the stone is now stationary and it's angle will not change. This frees up a second hand to be used cooperatively with the first one to maintain the blade at a consistent angle relative to the stone. Now, with the stone held solidly in place, and two hands to guide the blade, you have a much better arrangement for making a consistent angle the entire length of the edge.

The next step is understanding what happens to the edge while you are sharpening it. Most sharpening stones that come with instructions tell you to push the blade forward as if you are slicing a layer off the top of the stone. This is for good reason. If you pull the blade across the stone with the edge trailing behind, you will develop a much more severe "burr" or "wire edge" along the edge of the blade. This wire edge is formed by the very thin steel at the extreme edge of the blade becoming so thin that it bends out of the way rather than being abraded off by the stone. By pushing the blade toward the stone, you can minimize or eliminate the wire edge. The wire edge MUST be removed in order to have a truly sharp knife.

There are several ways to deal with the wire edge. The first method, and the one suggested by most traditional sharpening stone kits, is to only push the blade forward, and move progressively up through one or two finer grit stones, leaving a polished edge. This method works, but it works best with edge angles on the wider end of the spectrum, between 30 and 45 degrees inclusive. Finer edges like a fillet knife, chisel, carving knive, etc. can benefit from stropping to remove the wire edge.

Stropping serves two purposes. Removing any trace of a burr or wire edge, and polishing the edge itself. I prefer this method because I believe it allows you to sharpen a knife faster. With the traditional "push" method of sharpening, you take longer and have to repeat the process on multiple stones. I use a "push-pull" method to remove more steel, faster. Then I follow with a couple of "push only" passes on each side of the edge to minimize the wire edge. after that, I follow it with a stop to polish the edge and remove any remaining traces of wire edge. This leaves you with a clean, polished edge that is... SHARP!

Stropping can be done with a variety of materials, but it is always done by pulling the blade with the edge trailing, otherwise the edge would cut into the strop. This ruins the strop, and can dull the edge. I most often use a paint stirring stick with a bit of leather glued to it. The leather is loaded with tripoli polishing compound. Any fine metal polishing compound will work. I have also used cardboard and paper loaded with compound as a strop, simply by placing the paper or cardboard on the edge of a table and stropping. This is effective, and the paper darkens as metal is removed, allowing you to actually see the stropping in action. Still, leather is best.

So, on to my method.

First, you need to determine how dull your edge is and select the proper grit for your starting stone. if you are regularly maintaining your knives, you will probably only need to strop to restore the edge to wicked sharpness. A knife that doesn't get stropped regularly but does get used regularly, will probably need to be sharpened on a medium to fine grit stone. A coarse grit stone is almost never necessary unless the knife has been abused by cutting unsuitable materials, cutting materials on a hard surface, digging with it, using the cutting edge to strike ferro rods, etc. Your knife needed sharpening way before it got bad enough to need a coarse stone. Don't let it get that bad again.

Looking at the edge can help you determine how bad it is and what grit to use. A sharp edge will not reflect light. If you can turn the edge in every angle in a strong artificial light or bright sunlight without seeing any reflections along the very edge, you probably only need to strop to restore full sharpness. If, when examining the edge, you see the occasional very fine bright line along the edge, this indicates a dull spot, wire edge, or the edge folded over. Also tiny chips and nicks will appear as single bright points. An edge with this appearance should be stropped first then checked for sharpness. If it still snags here and there when slicing paper, then you can go with a medium to fine grit stone. If you see light reflected along the entire length of the edge and there are flat spots, nicks and chips that are readily visible just by casually looking at the blade, you will need to start with a coarse to medium stone and progress to the medium to fine stones. Since you will be stropping, you don't really need to use the fine stone.

Once you have selected a stone with a grit appropriate to the degree of dullness on the edge, you can begin sharpening. Place a good bench stone of the appropriate grit (as outlined above) on the edge of the table. Holding the knife handle in one hand and stabilizing it with the other, lay the blade flat on the stone. Gradually raise the spine of the knife until the blade is at the correct angle. This is when the actual edge bevel is in full contact with the stone. This angle varies from knife to knife. It is most easily observed on a Scandi grind blade because the large flat bevel is easy to see and feel when it is in full contact with the stone. Saber grinds, flat grinds and other grinds that have a secondary edge bevel require a bit more care and attention to make sure the edge is flat against the stone because it is narrower and harder to see.

With the angle thus established, push the blade across the stone with moderately firm pressure while maintaining the angle. At the end of the stroke, pull the blade back toward you, keeping the angle consistent. Do this for several passes, ten or so. Then reverse the blade and do the same procedure on the opposite side. After you have done ten passes on each side, examine the edge to see what kind of progress you have made. A magnifying glass helps a great deal. what you are looking for is the formation of a wire edge, a thin burr along the entire length of the blade that bends to the opposite side of the side you most recently sharpened. Keep repeating the sharpening process until you see the wire edge formed along the entire length of the egde. You are then ready to strop. A properly maintained knife will not require much sharpening before it is ready to strop.

Stropping is simple. Lay the knife flat on the strop and lift the spine a little past the edge angle you used on the stone, and pull it away with light but firm pressure. Repeat on the other side. Repeat until the blade will slice paper cleanly without snagging.

That's it! You have a sharp knife.


Offline ncnurseryman

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #1 on: January 31, 2014, 08:58:26 PM »
A lot of good info there.  I still struggle with getting a really sharp blade from end to end.  I guess I need to get to work a practice my sharpening.

Offline WheelBuster

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #2 on: January 31, 2014, 09:09:42 PM »
Good info, thanks PW! This is definitely a skill I want to improve on.

Offline wolfy

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #3 on: January 31, 2014, 09:10:54 PM »
Link please!
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Offline PetrifiedWood

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Offline wolfy

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #5 on: January 31, 2014, 09:12:00 PM »
Thank you!
The only chance you got at a education is listenin' to me talk!
Augustus McCrae.....Texas Ranger      Lonesome Dove, TX

Offline PetrifiedWood

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #6 on: January 31, 2014, 09:15:14 PM »
You're welcome!


Another tip for folks using a wax based compound on a strop... You can heat the strop up by the fire, or using a hair drier or heat gun carefully (to avoid it catching fire) and then rubbing it with an old rag while the wax is soft and warm. This removes the surface glazing and makes the strop work more efficiently.

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #7 on: January 31, 2014, 09:16:04 PM »
Well done, PW!  I think you should make it a sticky so it will be easy for folks to find.  A dull knife is a dangerous thing.

Offline PetrifiedWood

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #8 on: January 31, 2014, 09:20:55 PM »
Well done, PW!  I think you should make it a sticky so it will be easy for folks to find.  A dull knife is a dangerous thing.

Thanks! But we have limited space for stickies so I will stick a link to it in the tutorials thread. ;)

Offline Yeoman

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #9 on: January 31, 2014, 09:27:48 PM »
Nice technique. Good demo. Thanks for sharing.


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Half Axe

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #10 on: January 31, 2014, 09:37:48 PM »
Well done, PW!  I think you should make it a sticky so it will be easy for folks to find.  A dull knife is a dangerous thing.

Thanks! But we have limited space for stickies so I will stick a link to it in the tutorials thread. ;)

Perfect!  I've got a couple of kids that need to watch this video.

Offline Old Philosopher

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #11 on: January 31, 2014, 09:39:07 PM »



Nicely done.
I only do what the voices in my wife's head tell her to tell me to do.

Offline MnSportsman

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #12 on: February 01, 2014, 03:53:02 AM »
 :thumbsup:


   Excellent! 
 :D


ETA: I forgot to say, "Thank you!", for sharing this!
:D
« Last Edit: February 01, 2014, 04:17:21 AM by MnSportsman »
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Offline crashdive123

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #13 on: February 01, 2014, 04:32:06 AM »
Well don, and a really important video IMO.

It doesn't matter all that much how sharp a knife maker sharpens his/her knives if the end user cannot keep them sharp.  Good vid.

Offline BigHat

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #14 on: February 01, 2014, 05:00:52 AM »
Nice, thanks for sharing.
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Offline WI_Woodsman

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #15 on: February 01, 2014, 09:07:20 AM »
I'm one of those guys that uses a pocket stone...   :-[  I'm a believer in your credentials PW!   :hail:

Looks like I'ma be getting a bench stone...   :P

Offline Bryan Breeden

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #16 on: February 01, 2014, 09:22:17 AM »
Ron,  That was nicely done. 
Most people  if not all should
be able to sharpen there knives
after seeing how you sharpen
your knives. 


Bryan
My vendor Subforum  Breeden knives.
Breeden Knives

Offline Dano

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #17 on: February 01, 2014, 09:47:14 AM »
Well done again PW, thanks!!

Offline Unzinators

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #18 on: February 14, 2015, 06:15:47 AM »
Thanks! Great video. Need to get a bench stone and practice. What is the angle you hold the blade at most often?

Offline zammer

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #19 on: February 14, 2015, 08:26:08 AM »
Good to revisit this thread... :thumbsup:


And the narrative of those first few paragraphs were hilarious.... ;D
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Offline PetrifiedWood

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #20 on: February 14, 2015, 08:46:04 AM »
Thanks! Great video. Need to get a bench stone and practice. What is the angle you hold the blade at most often?

The angle depends on the knife itself. Most commercially produced knives with have between a 30 and 40 degree edge, so you will hold between 15 and 20 degrees per side. The best way to find the angle is to lay the blade flat on the stone, then lift the spine until the edge bevel is in full contact with the stone.

Offline Unzinators

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #21 on: February 14, 2015, 09:25:49 AM »
Perfect Thanks!

Offline wsdstan

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Re: Knife Sharpening - How to get your knife shaving sharp!
« Reply #22 on: February 14, 2015, 10:11:54 AM »
Good video PW and I think well presented as to technique and, most importantly, you make it look very easy. 

It is the method I use for most of my knives although I do use the sandpaper and mouse pad for the convex blades.

 
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