How To Why can't I get a knife sharp?

B

Bo-dacious

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Aug 13, 2016
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Hi guys. So when I buy a new knife, it's pretty sharp but the edge is covered in deep scratches. When I sharpen a knife, the edge is much smoother, yet it's not as sharp as the new knife. So the problem must lie somewhere else. I'm pretty sure I'm getting the right angle. I'm starting at low grit 30 strokes per side, move up to 1000 grit with 90 strokes per side and so on. Right now I'm getting to 1000 grit and noticing its not cutting paper very well. Should it cut paper at 1000 grit? Can someone give me some tips or ideas to fix this problem?

Thanks guys,

Bo
 
I use a sharp maker to sharpen but I would look into a few YouTube videos along with the advice here. Free hand takes some time to get good at. I would also check out the maintenance and tinkering section here.
 
Bo-dacious said:
Hi guys. So when I buy a new knife, it's pretty sharp but the edge is covered in deep scratches. When I sharpen a knife, the edge is much smoother, yet it's not as sharp as the new knife. So the problem must lie somewhere else. I'm pretty sure I'm getting the right angle. I'm starting at low grit 30 strokes per side, move up to 1000 grit with 90 strokes per side and so on. Right now I'm getting to 1000 grit and noticing its not cutting paper very well. Should it cut paper at 1000 grit? Can someone give me some tips or ideas to fix this problem?

Thanks guys,

Bo
Click to expand...

It sounds to me like you are polishing the shoulders of the edge without hitting the actual apex when sharpening. Use a sharpie marker to cover the entire edge with black ink. Now as you sharpen the ink will be removed. Where the ink is not being removed you are missing when sharpening. Adjust your strokes until you make sure you are removing all the sharpie on each side.
 
Try using a sharpie to mark the shoulder of the grind/angle to the apex. I mark about half of one side to make sure I’m getting to the very edge/apex of the blade. It also helps to determine the sharpening angle correctly. You’d be surprised that a couple of degrees can be the difference between reaching the very edge and forming a burr like sharp_edge mentioned and not hitting it at all.
 
Once you get the bur and the thing is STARTING to get sharp.
Go with one stroke per side.
Then even less than a stroke (don't use the full length of the stone) just a couple inches of stroke per side and really light.
 
Are you finishing at 30 strokes per side? If so, you've got a burr still.

There's some great instructional content on youtube. I'd start there.
 
Hello,
The sharpie method is a great place to start. I purchased a $4 lighted loupe from fleabay and found out I was rounding my edge as it polished. Being able to visually confirm you are doing it correctly will speed up your learning process. This is the one I use and it works great.
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You can cut paper just fine with 320 grit. My 600 grit is often where I finish up.
There are great videos on YT.
 
Make sure you strop after to remove any bur. What's the low grit your using?
 
How are you sharpening? If you are using sandpaper, applying a little too much pressure can round it over the edge, thus dulling and polishing at the same time
 
Take a magnifying lens or microscope and look at the edge; is the scratch pattern consistent? Also you can try to do some 3 strokes or so per side at the end with a higher angle, only with the last grit stone you're using. This will create a tiny micro bevel that really boosts the sharpness if you haven't quite sharpened all the way to the apex
 
Jus like many other friends already told here, my method is:
1-Sharpie on the bevel,
2-Low grit leading and trailing strokes until reach a burr on one side,
3-Turn the blade and repeat step 1 and 2,
4-Remove or minimize the burr before go to next stone. I use leading stroke only to burr removal.
Whit grit progression come together pressure decrease.
My stone grit are 240, 600 and 1000. But usually I stop at 600.
Then few passes on strop with trailing strokes on green compound.
Patience, practice, and time.
Don’t try be hurry, don’t try over pressure, don’t try skip steps to get quick results.
Try to be perfect.

Edit: to check the small burr you can use a cotton swab. When sliding, the cotton yarn stick on burr.
 
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Think of a dull edge as being like a trapezoid when viewed from the side. When sharpening you're trying to remove material from the sloped sides of the trapezoid until you have re-shaped it into a triangle. As others have mentioned, it sounds like you're polishing up the sides without having caused the bevels to meet at an apex in the middle. There's little point in changing your grit until you've first brought the edge to a proper apex. From there on out you're working on refining the scratch pattern of that apex to reduce its toothiness.
 
brasileiro said:
Jus like many other friends already told here, my method is:
1-Sharpie on the bevel,
2-Low grit leading and trailing strokes until reach a burr on one side,
3-Turn the blade and repeat step 1 and 2,
4-Remove or minimize the burr before go to next stone. I use leading stroke only to burr removal.
Whit grit progression come together pressure decrease.
My stone grit are 240, 600 and 1000. But usually I stop at 600.
Then few passes on strop with trailing strokes on green compound.
Patience, practice, and time.
Don’t try be hurry, don’t try over pressure, don’t try skip steps to get quick results.
Try to be perfect.

Edit: to check the small burr you can use a cotton swab. When sliding, the cotton yarn stick on burr.
Click to expand...

This works too, but note that not everybody thinks it's a great idea to raise a burr intentionally. A lot of folks--including me--are trying to avoid burr formation in the first place. As I'm learning myself too, this requires alternating strokes per side, very light pressure, and attention to detail so that when you see a burr starting to form, you immediately work on it and get rid of it. Hopefully it all gets the same result in the end, but it seems like burr formation is generally a bad thing and sometimes they're really hard to get rid of, so why do it intentionally?
 
maximus83 said:
This works too, but note that not everybody thinks it's a great idea to raise a burr intentionally. A lot of folks--including me--are trying to avoid burr formation in the first place. As I'm learning myself too, this requires alternating strokes per side, very light pressure, and attention to detail so that when you see a burr starting to form, you immediately work on it and get rid of it. Hopefully it all gets the same result in the end, but it seems like burr formation is generally a bad thing and sometimes they're really hard to get rid of, so why do it intentionally?
Click to expand...
I believe this is a next step in sharpening.
Im trying to reach very small burr each time I’m sharpening. Or even don’t reach it.
But for me sometimes still is difficult for me. :thumbsup:
 
When one is still trying to figure out why(?) their knife isn't getting sharp, or maybe just still trying to get a better feel for when it's sharp enough, it's always, always, a GOOD idea to form and look for a burr along the full length of the cutting edge. Otherwise, one never knows (as a beginner) if they've gone far enough to a complete apex.

Trying to avoid forming a burr in the first place is a strategy for endless frustration, when still trying to learn sharpening. As experience is gained, it gets a lot easier to see when you're close to forming a burr, and then take steps to minimize how large it gets (decrease pressure, and keep watching). Once you're that far along in experience, it's still better to form just enough burr to ensure your edge is as sharp as it can be, at the first stage.

Worrying about avoiding a burr entirely is of little value. Make one, but just learn how to make it so it's smaller and thinner, before you start to remove it; at which point, it'll be that much easier to deal with.


David
 
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As an example of the differing views on burrs, this video for instance was suggested as a good trainer video in earlier threads on sharpening, and the guy says: "You don't want to grind to a burr...ever." :)

I'm not going to debate on the "best way", but it's what I've been following, and have also had issues with tough burrs anytime they formed on some larger carbon steel knives. It seemed like things went better when I tried to avoid, or at least minimize, burr creation.

 
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