Which Gets Sharper
- This topic has 35 replies, 8 voices, and was last updated 11/27/2017 at 6:04 pm by
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Well I was going to do a fresh WEPS on my Shun Blue (non stainless edge) and Kramer Essential (higher end stainless) and then compare the cut test on bent shiny ad paper scallops. Before starting I figured I would try the test and see what happens. Low and behold they both passed my test. They have previously been thru similar WEPS progressions and don’t get used a lot because I have too many knives – LOL. Without entering a Ramon Landes or Cliff Stamp type of exercise I figured I would share. See the pics and videos below. Bottom line is I can get blue steel and AEB-L to similar sharpness levels. Not sure about retention though. To me this follows what Verhoeven says.
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I think you’d see more differentiation between the before and after cut tests if you move the knives slowly. If you swing them quickly at the paper they will have a much higher likelihood of cutting the paper than if they are moving slowly. In theory, you should be able to apply the same quantity of force with a slow cut and a fast one, but in practice it is not easy. If I’m doing that type of cut test I usually rest the knife edge on the paper and then slowly slide it down the curved surface of the paper. If the knife is truly sharp it will catch and cut cleanly. If it is not as sharp it may catch and cut, but not as cleanly or perhaps it won’t catch at all.
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I’m also curious if the tests were performed both slowly as David says and with less stiff paper like news paper that will give under pressure?
Marc
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Magazine paper is actually good for that particular test because it is glossy and your blade has to be pretty sharp to bite in. Phone book paper is tough to cut like that as well, but not quite as tough. I like to use wax paper (the stuff they sell in the baking aisle) because it is very thin and slippery.
I find this test tougher than slicing newspaper. There is no before/after. My Henckels will not pass it.
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I was really surprised when I tried the paper “chop” test. It is much easier to cut with a rapid motion than with a very slow one. I particularly like the slice on a folded piece of paper standing on edge. Cuts really cleanly with a quick chop, but probably won’t cut at all with a slow slice.
Now, whenever I see a video of someone swinging their blade at a sheet of paper, I think: Yeah, right. Show me the slow cut.
That said, I’ve never tried to cut the folded (uncreased) sheet as in Redheads’ video. Looks interesting. Gonna have to try it.
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It is much easier to cut with a rapid motion than with a very slow one.
There is probably a pretty big difference in force between a chop and a slow cut.
-Clay
It is much easier to cut with a rapid motion than with a very slow one.
There is probably a pretty big difference in force between a chop and a slow cut.
-Clay
All you have said is true, however, this was a comparison of the sharpness between 2 knives (one high grade stainless and one high grade non-stainless). It was not meant in anyway to attempt how sharp they are (ie. can they whittle hair, etc). It does introduce a question though of how to determine “how sharp” with some amount of repeatability especially when still mounted in the WEPS. This is important because some steels and or profiles will require many more strokes to get the same level of sharpness (i.e. S110V, … ). The benefit will be minimized time and steel removal. WDYT ?
Also, I have not touched these 2 knives since yesterday and will try a few other comparison tests.
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I like to push cut thin paper with the blade still mounted. It’s by no means a perfect test, but it does give me tactile feedback that can help me diagnose any trouble spots as well as provide me with a qualitative measure of how sharp the blade is. I posted in another thread about the inherent difficulties of quantifying sharpness, but I think a quantitative test is the only way your’re really going to be able to repeatably differentiate similarly refined edges on one knife against another. You could probably design a testing apparatus that would measure the force in grams to cut a membrane of cord of some kind with the knife mounted in the clamp by modifying a tree beam balance.
The bottom line for me is that a blade will either be sharp enough or not sharp enough to use it how I want to. If it feels smooth while push cutting phone book or magazine paper, I find that it will be plenty sharp for my needs so that qualitative test is sufficient. It is fun to push the limits and go after that truly effortless, smooth cutting ability (that’s why most of us are here), but if I’m honest I don’t need that level of performance from a knife. I’m not a world class chef or a surgeon or even a carpenter, I’m just a internet dweller who likes sharp things. Also, I find that the extra 10% of sharpness that takes an edge from sharp to SHARP is lost pretty quickly once you actually use the knife for more than cutting paper and hair. The good part is that every knife will eventually need to be sharpened again 🙂
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I don’t clamp a knife to sharpen with a game plan of how to sharpen it based on a past sharpening experience, or sharpening result. I might have a planned stone progression, clamping position and a bevel angle that may have worked well in the past, that I’ll intend to follow. I sharpen each knife objectively and give it the time, attention and strokes necessary to achieve the results I am satisfied with during this current sharpening session, and try to do nothing more. What worked in the past and how many strokes has no bearing on this session because too many factors have influenced the condition of the edge. Such as the length of time since the last sharpening, how much I used the knife during that period of time, how worn it feels and how severe the wear is. The amount of metal I remove now correlates to this sharpening session and what amount of sharpening it requires to achieve the final results I’m satisfied with. I may even put out a little extra effort to try to improve the edge over the last time I sharpened it.
That being said, the first time I sharpen a knife that I’m unfamiliar with, it may be hard to judge when I have achieved the best edge I can. I may have to put extra time in, to finally reach that point of sharpness that I am satisfied is my sharpest effort. I may after spending more time and effort than was necessary realize I haven’t improved the edge and should have stopped sooner.
I believe most of the metal loss or removal in the sharpening process is with the earlier coarser grits. I use visual inspection of the evenness of the scratch pattern and removal of the previous grits scratch pattern as the cue it’s time to move on. After I work up to the finer grits in the progression I believe I’m doing more finishing and refinement work and very little real metal removal. I don’t think that if I limited my strokes it would have any real bearing in the overall amount of metal removed. I have found that these are the stages where extra strokes and extra effort does have the most bearing on the final knife edge sharpness.
When I sharpen the knife for the first time even if I’m able to match the existing bevel extremely closely it still is in essence a profiling process. I am removing more metal then to even out the bevels to the exacting ability of the WEPS then I will the next time I sharpen that same knife. I find it will be generally quicker and easier each subsequent time than the time before. Unless the edge has been totally destroyed, I believe with each sharpening there still is a remaining shape and evenness of the profile from previous sharpening sessions. Usually there is a time savings and an effort savings over the last time I sharpened it. In general the desired results should be easier and quicker to achieve. Of course these are generalities I have experienced while sharpening the same knives repeatedly, usually my own, and they don’t always hold true especially when sharpening knives for others.
Marc
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Hey thanks for the advice. You must type fast. I redid my 2 knife sharp test on bent shiny paper scallops more slowly and found satisfying similar results. After the test I decided to take my shun blue into my new diamond films, however, I ran into an interesting issue which jives with your scenario description.
While doing the presharpen exam under my USB scope I noticed dips in the edge near the handle which I suspect is from my wife slicing hard baby carrots. I decided to fix the profile using the 200 grit as a file across the edge causing me to start from scratch. Good bye to the history on the blade like you say.
While reprofiling and examining under the scope I realized that it is not easy to do perfectly by free hand. Without a fixture you tend to follow the dips (chips are probably easier). Is there a good technique to use ?
Also, how much time does it take you to do a knife the way you describe above ?
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