What is dull actually?

[LawyerSam]

In deciding what sharpening system to use, I am told that so and so (Sharpmaker) is more for keeping knives sharp and maybe waterstones or DMT ALigner is better for profiling (reads to me as a dull knife)

I have new folders and two really sharp kitchen knives. I have about another 7 kitchen knives that do cut, but are not as sharp as my really sharp knives.

I am thinking that a Sharpmaker makes sense since I would not want to change any angle that I do not have to, and then if there are problems with a knife, maybe the sandpaper.

So, how can I tell if I need to invest in one system or the other? Like, my Delica I got yesterday shaves arm hair but the one month old Persistence does not, but each slices open letters like no one's business.

 

[The_Dave]

As long as you're not reprofiling, and as long as there's no damage to the edge of the blade, and the edge angles correspond to the sharpmaker angles available to you (30, 40 degrees inclusive) then I should think the sharpmaker would do just fine.

 

[TKAZ]

IMHO, When a blade can't easily or safely cut or chop what you need or want it to then it's dull. One thing to remember, a dull blade is more dangerous than a sharp blade. a sharp blade will need less force or pressure to do it's job thus less chance of slipping/falling off of what your cutting and then cutting yourself.

 

[swamp]

IMHO, When a blade can't easily or safely cut or chop what you need or want it to then it's dull. One thing to remember, a dull blade is more dangerous than a sharp blade. a sharp blade will need less force or pressure to do it's job thus less chance of slipping/falling off of what your cutting and then cutting yourself.

+1 Sometimes when visiting my family I will notice they are using way too much force to cut something like an avocado, tomato etc. I end up spending a few hours sharpening all 15 blades.

I always make them sharper, but not too sharp. Because no matter how long I keep my mothers knives sharp for (for her to get used to how they should be) she always cuts herself, everytime. Even though I warn her. She likes them better sharp, but just doesn't pay enough attention I guess.

OTOH, I hear Pro Chefs cut themselves quite often also. So maybe kitchen knives are just used to cutting a lot of meat?

 

[almasy87]

Last night I accidentally ran the edge of a cheap serrated knife across my knuckles while opening a package because I almost dropped my phone. Didn't even get a scratch...I'd consider that pretty dull

 

[Sep]

If you're purely interested in keeping your knives sharp or making it sharper without changing factory angle, then the Sharpmaker is good enough. If, however, you later got the hankering to reprofile your edges and take it to the next level, then you gotta get the Aligner or EdgePro or even a power sander.

 

[DennisStrickland]

dull is a relative situation, what is sharp for me might be marginal for knifenut1013. if you rest the edge on your fingernail & it grabs, that's probably good enough for goverment work. dennis

 

[knarfeng]

dull is a relative situation, what is sharp for me might be marginal for knifenut1013. if you rest the edge on your fingernail & it grabs, that's probably good enough for goverment work. dennis

I'd agree with all of that. Though the knife has to grab when at a 30° angle for me to be happy.

 

[Joben]

Yeh dull is so relative...even from the point of view of the same person it might change based on context.If I'm checking over my pocket knives and one isn't sharp enough to shave I say "Oh that's dull" and fix it. On the other hand I generally don't keep my big chopper to quite that standard, it doesn't seem to need it. If I'm doing a significant task a true razor edge doesn't last long probably, and the knife is only "dull" when the effort required becomes noticeably higher.

If I had to guess I would say that for the purposes of the OP people mean dull in the sense of most non-knife people's kitchen cutlery: If you run the edge over your skin you don't start bleeding. To fix that sort of thing would indeed be laborious on medium and fine grit ceramic rods.

 

[KennyB]

Just kind of depends on what the knife is for. I let my kitchen knives get dull enough to wear they won't pop arm hair but will work for what I want, but my EDC I like to be sharp enough to shave with.

Generally though any time I get a small dent or a rolled edge I have to sharpen it to fix it.

 

[knarfeng]

In deciding what sharpening system to use, I am told that so and so (Sharpmaker) is more for keeping knives sharp and maybe waterstones or DMT ALigner is better for profiling (reads to me as a dull knife)

I have new folders and two really sharp kitchen knives. I have about another 7 kitchen knives that do cut, but are not as sharp as my really sharp knives.

I am thinking that a Sharpmaker makes sense since I would not want to change any angle that I do not have to, and then if there are problems with a knife, maybe the sandpaper.

So, how can I tell if I need to invest in one system or the other? Like, my Delica I got yesterday shaves arm hair but the one month old Persistence does not, but each slices open letters like no one's business.

Maybe a couple of clarifications of your basic premises are in order.

"Re-profiling" does not really have to do with whether the knife is sharp or not.
The Sharpmaker has two settings:
30° inclusive, which is 15° per side
40° inclusive, which is 20° per side.

If the factory bevel is not at one of those two angles, it has to be re-profiled, that is, the edge angle needs to be changed to match one of those Sharpmaker settings. Until the angles match, you really are not sharpening, you are just changing the angles. Changing angles using the rods supplied with the Sharpmaker can be quite time consuming. Once the edge angle of the blade matches that of the Sharpmaker, it matters not if the knife is sharp or dull, the Sharpmaker will quickly sharpen it up.

Coarse DMT stones (Extra Coarse, or Extra Extra Coarse) are recommended for changing edge angles. Finer DMT stones (medium, fine, and extra fine) are recommended to sharpen a knife that is already at the correct angle.

I find that kitchen knives, because they have typically thinner blades actually can be re-profiled on a Sharpmaker without a horrendous amount of work. And it sure is easy to sharpen them once the angles match.

Hope that helps.

 

[LawyerSam]

Knarfeng: Think I can go with the Sharpmaker then and then the sandpaper to attach? Get better at it and then see? Or say a 220/1000 Norton stone, learn freehand and then maybe a 4000 Norton?

 

[Obsessed with Edges]

+1 Sometimes when visiting my family I will notice they are using way too much force to cut something like an avocado, tomato etc. I end up spending a few hours sharpening all 15 blades.

I always make them sharper, but not too sharp. Because no matter how long I keep my mothers knives sharp for (for her to get used to how they should be) she always cuts herself, everytime. Even though I warn her. She likes them better sharp, but just doesn't pay enough attention I guess.

OTOH, I hear Pro Chefs cut themselves quite often also. So maybe kitchen knives are just used to cutting a lot of meat?

I think this nicely sums up why people injure themselves with knives.

On the 'dull' end of the spectrum, having to use excessive force to cut something might result in injury if you slip or lose control while 'leaning into' a cut.

At the 'other' end of the spectrum, in the hands of a 'professional' who's feeling rushed and is probably thinking about multiple things at once, a very sharp knife will do a lot of damage if the user loses focus for even a second.

 

[Jason B.]

Dull is dull, still being able to cut makes no difference because blade geometry can keep you cutting long after a edge has become dull as a butter knife. If you can see flat spots or feel bumps and other irregular deformations in the edge then you more than likely need to sharpen your knife. Keeping up on a blade weekly or every few days (depending on steel quality and amount of usage) will keep your knife sharp and keep you from needing to do major stock removal when it comes time to sharpen.


A factory edge is a poor example of what sharp is, its very random in its sharpness and more than often random in angles/edge geometry. To better judge sharpness set your standards higher, find or buy a fresh utility razor and inspect its edge. Feel the sharpness and cut a few small things like paper and 550 cord, then compare to your knives. When you have a sharp knife you cut with less effort making the action safer, some still argue this point but that is simply because they cut themselves with sharper knives due to lack of respect for how sharp the edge is. There is a learning curve to handling a sharp knife and in this learning curve expect to get cut. Go back 18 years and hand me a knife like I have today and I would have cut the crap out of myself, in time you learn to keep that edge away from your body parts.

When you cut something learn from that cut, look what it has done to your edge and remember how the knife cut that material. Think of how sharp the blade was at that point and after a sharpening or 2 or 100 with changes in angle, grit finished, and style of cut used, ask yourself how it all changed.

 

[knarfeng]

Knarfeng: Think I can go with the Sharpmaker then and then the sandpaper to attach? Get better at it and then see? Or say a 220/1000 Norton stone, learn freehand and then maybe a 4000 Norton?

When I changed the edge angle on my kitchen knives, I used just the brown rods on the Sharpmaker. I used the 40° setting in order to get a more robust edge. It did not take all that much time. I've used sandpaper on other knives that had harder steel and thicker blades.

To know when you have matched the angles, mark the bevel with a sharpie, take a few strokes on the rod, then look at the edge. If the outer edge of the bevel is still black, your edge angle is still more obtuse than the Sharpmaker setting and you have not yet matched the angle.

 

[KennyB]

Dull is dull, still being able to cut makes no difference because blade geometry can keep you cutting long after a edge has become dull as a butter knife. If you can see flat spots or feel bumps and other irregular deformations in the edge then you more than likely need to sharpen your knife. Keeping up on a blade weekly or every few days (depending on steel quality and amount of usage) will keep your knife sharp and keep you from needing to do major stock removal when it comes time to sharpen.


A factory edge is a poor example of what sharp is, its very random in its sharpness and more than often random in angles/edge geometry. To better judge sharpness set your standards higher, find or buy a fresh utility razor and inspect its edge. Feel the sharpness and cut a few small things like paper and 550 cord, then compare to your knives. When you have a sharp knife you cut with less effort making the action safer, some still argue this point but that is simply because they cut themselves with sharper knives due to lack of respect for how sharp the edge is. There is a learning curve to handling a sharp knife and in this learning curve expect to get cut. Go back 18 years and hand me a knife like I have today and I would have cut the crap out of myself, in time you learn to keep that edge away from your body parts.

When you cut something learn from that cut, look what it has done to your edge and remember how the knife cut that material. Think of how sharp the blade was at that point and after a sharpening or 2 or 100 with changes in angle, grit finished, and style of cut used, ask yourself how it all changed.

You know, I bought a little thing called an "EdgeTester" from "Razor Edge Systems, Inc." John Juranitch talked about it in his book. Anyway, I'm mentioning it because I thought it's interesting you'd mention the razor blade, as the EdgeTester isn't much more than just a pen-like device made of some kind of plastic that one can do a few tests with. It's really good at feeling dents the eye can't see, and it recommends starting out with a razor blade to get an idea of what a razor edge should feel like.

Just thought I'd mention it since they're like ten bucks and it fits in right well with what you're saying. Sometimes if I cut something that feels like it might have been a bit too hard or rolled the edge, instead of trying to see a dent or roll in low light, I just use the edge tester, and more times than not it lets me know when I need to sharpen far before my edge ever gets "dull".

I do agree a lot with what you're saying about edge gometry. I re profiled a pocket knife for my friend about three months ago. I put a 30 degree inclusive angle on it and the last time I was there I checked out how it was doing. It had several large dents and definitely did not having the biting feeling it had when I would touch it when it was new, but it's still cutting everything he needs it to and is still "The sharpest knife he has." if it me I wouldn't even consider the thing sharp at all anymore; makes me wonder if it will ever reach "dull" for his standards.

 

[Jason B.]

By the time he considered it dull you would have a hard time telling the edge from the spine

 

[jayinhk]

OTOH, I hear Pro Chefs cut themselves quite often also. So maybe kitchen knives are just used to cutting a lot of meat?

Most chefs aren't knife knuts, just like most cops aren't gun nuts.

 

[Noctis3880]

For me, anything that doesn't whittle, pop, or split hairs is dull.

And even when it does, I still try to cook up ways to make my knife even sharper.

 

[swamp]

Dull is dull, still being able to cut makes no difference because blade geometry can keep you cutting long after a edge has become dull as a butter knife. If you can see flat spots or feel bumps and other irregular deformations in the edge then you more than likely need to sharpen your knife. Keeping up on a blade weekly or every few days (depending on steel quality and amount of usage) will keep your knife sharp and keep you from needing to do major stock removal when it comes time to sharpen.


A factory edge is a poor example of what sharp is, its very random in its sharpness and more than often random in angles/edge geometry. To better judge sharpness set your standards higher, find or buy a fresh utility razor and inspect its edge. Feel the sharpness and cut a few small things like paper and 550 cord, then compare to your knives. When you have a sharp knife you cut with less effort making the action safer, some still argue this point but that is simply because they cut themselves with sharper knives due to lack of respect for how sharp the edge is. There is a learning curve to handling a sharp knife and in this learning curve expect to get cut. Go back 18 years and hand me a knife like I have today and I would have cut the crap out of myself, in time you learn to keep that edge away from your body parts.

When you cut something learn from that cut, look what it has done to your edge and remember how the knife cut that material. Think of how sharp the blade was at that point and after a sharpening or 2 or 100 with changes in angle, grit finished, and style of cut used, ask yourself how it all changed.

The crazy thing is after I sharpen my knives, I find them "much" sharper than any utility razor. And I think many other people here including yourself make the blades much sharper also. I guess were doing good, because if your knife is sharper than a razor, it should be sharp. Maybe we need to start a scalpel analogy?