What do you strive for when sharpening?

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Slikna99

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Apr 3, 2021
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This is a confusing subject for me, maybe just because I have not mastered it, but I am wondering what you strive for when sharpening? When is "enough," actually enough? I am more concerned with kitchen knives in this particular instance. I have sharpened kitchen knives that will shave my hairs but wont cut a tomato. I have sharpened kitchen knives that will cut a tomato easily but wont shave hairs. Both with go through newspaper/phone book with ease and not get hung up. Is there some magical test I should be doing otherwise?

I sent a knife to a friend and I was shaving the hairs off my arm, but when he got it he said it would not cut through anything with "skin" (tomato, bell pepper, etc.) So it lead me to testing some things and I have gone down a rabbit hole and don't know what to aim for anymore lol

What is the thing to shoot for? I use paper wheels now on a bench grinder and I am trying to figure out when to call it good...
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All my kitchen knives are 15 degree angle. Everything in my kitchen gets 325 dmt edge. One and done. Except for my chopper which is a santoku which I refine to 1200. I don't cut sushi which may be important to some people. Paper wheel is great. But I find a toothy edge to be superior.
 
Bill3152 said:
All my kitchen knives are 15 degree angle. Everything in my kitchen gets 325 dmt edge. One and done. Except for my chopper which is a santoku which I refine to 1200. I don't cut sushi which may be important to some people. Paper wheel is great. But I find a toothy edge to be superior.
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Right, so my thinking after some reading and what it seems like you are suggesting is that possibly the paper wheels are over polishing the edge and without that “tooth” it’s not able to grab and cut into the tomato skin?
 
What, exactly, is a 325 dmt? DMT uses descriptive terms, like "Fine" or "Course." If they are using numbers, where are the numbers?

Thanks.
 
Perfectly even bevels on a sharp apex. Then I decide if I want a coarser toothy edge or polished push cutting edge.
 
Dmt come in xxc(140 grit), xc(220 grit), c(325) f(600), ef (1200) mef(4000) eef(8000). You can also get a plate with grits on both sides.
Slikna99 said:
Right, so my thinking after some reading and what it seems like you are suggesting is that possibly the paper wheels are over polishing the edge and without that “tooth” it’s not able to grab and cut into the tomato skin?
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Yes. Paper wheel can make a knife edge razor sharp. 325 edge has plenty of tooth. Try doing less on the paper.wheel. just enough to knock off the bur. Bring some cherry tomatoes close enough to your machines. And try em out. I'm sure you can get this done with what you already have.
 
IMO you could be creating a sharp burr or a wire edge but not properly removing it. This may explain why you can cut through softer materials like zipping through newspaper or shaving arm hair but not cut through the tough skin of vegetables because the burr is folding over.
 
I have no idea why shaving hairs is some sort of a sharpness test. I don't shave with a knife, though I have tried, and based on real world experience, it is a bad idea.

This is the most important sharpening tool I own.

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Which is the magnifying lens tool on this SAK. With this magical device, I can look at the edge, and see what I am doing! What was invisible is now visible!!! I examine the bevel to see that my stone is maintaining one flat bevel. Multiple bevels create a rounded edge. And I look at the edge to determine if the edge is centered, and whether the bevels on either side are even. This is so critical, if you cannot see what you are doing, you will be totally clueless as to why your knife does not cut well. I can also see the wire developed when an edge rolls. When I see that wire, I pass the edge lightly over the stone till it goes away.

I have an outstanding sense of touch, until my fingers get too wet, and based on my touch, I decide if the knife is sharp or not.

My standard for a sharp edge is a tomato slice. If I don't have to saw through a Roma tomato, if the blade cuts through the skin nicely, then the knife is sharp.


I do not batton my knives, I do not attempt to chop redwood trees down with my knives, I use my knives primarily on food. If you use your knife for deforesting large wooded areas of the American's, then your edge requirements will be different.

I do recommend, if you plan to use a knife to cut roofing shingles, get a cheap razor blade knife. Attempting to cut very abrasive materials will ruin even a good knife blade, so you might as well ruin a cheap knife blade.
 
Functionality - the knife is used for food prep, not shaving. If a tool can't do it's primary task, it's failed. Doesn't matter what else it does.
You might not not leaving enough tooth with your shaving edges - polishing too much.
Try no more than a medium stone, then strop. If you apexed the edge, you should be fine with a tomato and shaving, though it won't be the smoothest shave.
 
I don't chase the polish anymore. It's time consuming and I don't enjoy sitting there for an hour or more chasing the whittled hair edge.

I test the edge with my thumb and can tell when it's good for me. The ability to cleanly slice receipt paper is sorta where I end up.
 
I strive to produce the best possible edge for each blade, and that is dictated by intended function, and by blade material.
For me there is no one answer.
I don’t always use a 10,000 grit stone or diamond paste coated strop. Not every blade will be better because of it.
Each blade needs to be evaluated individually and then sharpened to an appropriate edge.
 
Do you know what steel you have for the knives you’re sharpening?
Is the steel thin or thick ?
On some steels, a polished edge doesn’t necessarily equate to a sharp knife. Do you know if you’re leaving a wire edge and maybe that’s the reason you’re having the inconsistent results.
 

What do you strive for when sharpening?​

in order of importance:
1. sharpness. the sharper the better i did.
2. time. the faster the more impressive. only important when live audience is present.
3. consumption. the less steel removed the better. this becomes critical with certain folders if one needs several attempts to get to sharpness. less of a concern with kitchen knives.
4. energy. the less efforts (steps, sweat, mess, mental energy) the better and more enjoyable.
5. misc. any other aspect such as finish, mirror polish, toothiness, etc

On kitchen knives i doht care about finish. On my expensive small folders steel consumption is very critical. In general over the years ive become the lazy sharpener and try to use 1 step only haha and sometimes even skip the stropping step. If i can get the same sharpness result and in faster time with 1 step only while some other gal needs 10 steps and 4x the time, then who
 
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For mainstream kitchen knives in typical stainless, nothing fancy is needed. Set the edge to 25-30 inclusive. Then finish with a somewhat toothy bite (320 - 600). I like a Fine India stone (360-400) for mine - but something like a 600 DMT can also work very well. Then, MAKE SURE THE BURR IS CLEANED UP. The issues with shaving-sharp edges failing to cut a tomato are very likely due to a remaining burr folding over. Maybe also due to overpolishing the tooth out of the edge.

When using a powered apparatus like the grinder with paper wheels, you'll also need to be careful to avoid overheating the apex. That could leave weak, heat-damaged steel near the edge, which will fold just like the burrs do.

And kitchen knives don't need to shave hair. If they do, and they do it repeatably while still accomplishing everything else, that's gravy. But sometimes, pursuing shaving sharpness is counterproductive and will diminish what the knife was meant to do by design.
 
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