Testing knife tip sharpness?

G

Gideons

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Hey BF,

I've seen countless methods on how to test the sharpenss of a knife, but none specifically for the blade tip. Depending on the knife, I find the tip becomes dull long before the belly of the blade. That is why I'm interested in how do you test the sharpness of your knife blade tip/point?

-Gideons
 
Gideons said:
Hey BF,

Just curious, I've seen countless methods on how to test the sharpenss of a knife. Depending on the knife, I find the tip becomes dull long before the belly of the blade. That is why I'm interested in how do you test the sharpness of the tip of your knife?

-Gideons
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I lay a piece of paper down flat ontop of a piece of cardboard and try to do “xacto knife” cuts on the paper with the tip of the knife.
 
Lapedog said:
I lay a piece of paper down flat ontop of a piece of cardboard and try to do “xacto knife” cuts on the paper with the tip of the knife.
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With how much pressure/force on the knife? I'm guessing if it doesn't completely slice through it fails?
 
Ed Fowler said the best way was to place the tip against a sheet of paper (being held up as if to cut it) and, with the "spine" toward the paper, see how easily the tip pierces the paper. From Knife Talk II.
 
Gideons said:
With how much pressure/force on the knife? I'm guessing if it doesn't completely slice through it fails?
Click to expand...

When you do this test with a few knives and compare how well each one cuts you will know what’s sharp and what isn’t. Certain blade shapes like wharncliffes and sheepsfoots seem to do the test more easily so you kind of have to know that.

Basically if it easily cuts the paper with little pressure then it is sharp. You don’t want to use very much pressure because if you push the tip too far through the paper and into the cardboard then it is no longer really the very tip that is cutting.

If it doesn't slice through easily and cleanly and completely then it can be sharper.
 
Like all my other edges, even drill bits, I just take the tip at a fairly low angle to my thumb nail; if it skates across it is dull, if it scrapes / shaves a little nail off it is sort of sharp, if it catches and digs in it is sharp.
 
Stop with the tip of the blade still on the Sharpmaker. That will prevent the tip rounding.
 
Wowbagger said:
Like all my other edges, even drill bits, I just take the tip at a fairly low angle to my thumb nail; if it skates across it is dull, if it scrapes / shaves a little nail off it is sort of sharp, if it catches and digs in it is sharp.
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This is my method as well.
 
Lapedog said:
Yeah stop the stroke with the tip still touching the rod. This will help prevent rounding.

I was rounding my tips like crazy until I figured that out.
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Just got to work on my form. Sometimes I overshoot the stroke and that is when the tip rounds. With a shaprmaker were you able to bring back the tips? Primarily my SAK that lost it's tip, wondering if it is worth it to try to bring it back.
 
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I hold paper towel with my left hand and start the cut in the middle somewhere with the tip. A bit of piercing with mostly slicing. You can do same with paper but paper is easier.
You can really tell when tip is sharp it starts cutting it with ease.
 
Gideons said:
Just got to work on my form. Sometimes I overshoot the stroke and that is when the tip rounds. With a shaprmaker were you able to bring back the tips? Primarily my SAK that lost it's tip, wondering if it is worth it to try to bring it back.
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Honestly i use the sharpmaker rods freehand so I can’t say how much of a pain it will be for you.

What I would do is focus on just the tip. So instead of doing heel to tip strokes trying to restore the tip; put the tip against the stone and just go up and down on one side and then the other on your medium rod. Grind one side until you can feel a little burr then do the other side.

It will be easier to control the tip from leaving the side of the stone if you’re just quickly grinding the tip to the front 1/10th of the blade. Test the tip on paper laying flat on cardboard. You should be able to get a good cut on it using the medium. Make sure you can using the medium rods before proceeding to my next step.

Once you’re done doing these quick strokes on the medium to the first 1/10th to tip of the blade THEN you switch back to doing heel to tip strokes controlling not to let the tip fall off the end of the stone this time. That will help you blend the work you did to the tip with the blade.

When doing these long heel to tip strokes I recommend you begin with medium again before progressing to finer grit rods.
 
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