Sharpen a Knife Quickly and Easily





Introduction: Sharpen a Knife Quickly and Easily

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

If you have a carbide tipped saw blade, you have an excellent tool for sharpening a knife quickly and easily.  Just clamp it to a tabletop or lock it on your saw's arbor so it cannot turn.

Step 1: Draw the Knife Edge Against a Carbide Tooth

Draw the cutting edge of the knife against a front corner on a carbide tooth.  You do not need to use a lot of pressure.  A few repeated passes will do wonders to a blade.  The green lines represent the angle of the tooth face and the angle at which the blade is held.  The brown lines represent a vertical line and the angle from the vertical at which the knife is drawn across the corner of the carbide tooth.  Draw the knife slowly.  Hold the blade with two hands to keep the edge on the relatively small corner of the tooth.  

Step 2: Do the Other Side

After a few strokes on one side, turn the knife over.  Use the same angles relative to the carbide tooth that you used for the first side, but draw the knife from the other side of the saw blade.  Alternate sharpening one side of the knife blade and then the other every few strokes.     

Step 3: Test for Sharpness

I have often seen people pull a knife edge across the soft skin on a fingertip.  That is a sure way to receive a cut.  Much better is to scrape the blade laterally on a fingernail as shown by the green arrow.  If the knife is sharp, a curl of fingernail will roll up in front of the cutting edge.  If the knife is not quite sharp, powdered fingernail will gather in front of the cutting edge.  If the knife is quite dull, nothing will appear in front of the cutting edge.  Test at various points along the length of the cutting edge.  Some parts of the cutting edge will be more dull than others and will need more attention.



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    24 Discussions

    That would not end happily for you, for the saw, or for the knife.

    I have used the commercial carbide sharpener set in a V and found it removed a lot of material fast, great for knives that should have been sharpened long ago or just need to be trued up quick. I would not want to use it as my first go to every time i sharpened my knife as the knife would disappear faster than necessary. It also left it almost serrated as cojonc mentioned, which is great in the kitchen but not so good in the wood shop.

    1 reply

    I would agree. The commercial carbide tipped knife sharpener I saw was a simple bar of steel with one piece of carbide on it, which allowed adjusting the angle and the pressure. We bought a sharpener ith to pieces set in a V like you describe to use in another location in a pinch. The single piece sharpener is more gentle.

    judging by your picture, I don't think you have much room to question someone's color

    Thanks. Poor lighting coupled with inadequate photo correction software.

    I have not done this often, nor on the same tooth. I cannot perceive any degrading of the saw blade. Commercially available sharpeners are often two pieces of carbide set in a "V."

    You are probably correct.

    I often look at things microscopically as I did after using one of my blades to test your sharpening methods on a knife. To my amazement, the crisp edge on the carbide had changed. The steel in the knife I sharpened was harder than I initially thought, and rounded the carbide. Microscopically yes, but damage was apparent. The knife blade was also damaged as the sharpening attempt caused chattering creating nicks and lands. While this created somewhat of a sawtooth effect and the knife still cut, it would not "pressure" cut. It had to be used in a sawing action. Most will not understand this and I won't elaborate. For most, lets say it will probably work. It depends entirely what level of "sharpness" one considers workable. Most of the people I know have very dull, very dangerous blades. I am certain my standards are different, and more scientifically driven than the average person.

    Interesting. I saw the knife sharpener I mentioned in a store and thought I could do that with a saw blade. The blade I showed is an old framing blade I do not use much. I expect the tips do most of the cutting, and they are untouched in all of this.

    Thank you, Osvaldo.

    One day several years ago I was in a hardware store. Someone local was making knife sharpeners and the store was selling them for the maker. They were a piece of steel about 8 cm long. A carbide tooth for a saw blade was brazed onto one end. I thought I could just stroke a knife along the corner of a tooth on a carbide tipped saw blade and save $8. It worked.

    This evening my wife asked me about the Instructable she knew I posted today. After I explained it, she had me sharpen her favorite kitchen knives with the saw blade in the photo. It worked very well.

    Very good idea. Haven't tried it yet but could you put 2 blades together (reverse angle forming a "V") and sharpen both sides at once?

    Yes, you can, although that is a much slower method and leaves a black mark on the bottom of the mug.

    Does the carbide remove bits of metal from the knife edge? Or does it simply straighten the edge, like a "steel"?