Problem sharpening 10″ Shun chef knife

[Kenneth Krone]

I am having trouble sharpening the tip and first 1 1/2″ of my chef knife. If I mount the knife so that the blade is flat, which is the 7″ or so from the handle, the curved portion doesn’t seem to be well-sharpened (judging by cutting a tomato. The tomato slices easily with the 8″ or so nearest the handle, but the tip and first 1 – 1 1/2″ requires a little pressure. Is that an issue of how I have mounted the knife or perhaps just the physics of the knife, as there is more weight exerting a downward force the further toward the handle the section of the blade is that is cutting? Is it reasonable to adjust the holder during the sharpening to do the flat 7″ and then lower the handle to get the tip and first 1 1/2″ level?

Thanks
Ken

[Steven N. Bolin]

Thanks for the question!

The issue you’re having really isn’t even an issue at all. Well, it’s still an issue but one that has a solution. It’s very common to have a small section behind the tip that didn’t get as sharp as the rest of the edge. I’d say it’s because your pressure slightly lessens as you move towards the tip with alternating strokes. There’s nothing wrong with NOT covering the entire length of the edge with alternating strokes.

I often have to go back and make 10-20 passes at both the tip and the heel.

Another thing you can try, something many of us do, is edge leading strokes from the tip to the heel. This means resting the bottom 1/3 of the stone flat and secure on the tip, then pulling the stone back towards you, which should put the top of the stone near the heel.

Hope this helps.

[Kenneth Krone]

Thanks for the answer! What you say makes perfect sense, and what I did after I posted the question was to work on the heel and the section just behind the tip, as you had then said.

While I have your attention, I have done the marking pen on the edge thing and find that I am only sharpening about 1 1/2 millimeters, not the entire 3+ millimeters of the bevel. It seems to work for me–I am sharpening my Shun and Tojiro kitchen knives at 17 degrees. Am I not doing it correctly?

Thanks

[Steven N. Bolin]

If you’re not removing all of the Sharpie, you’re either too shallow or too steep with your angle. Since you said you’re sharpening a Shun at 17dps, I’m assuming you’re only removing the Sharpie at the apex? I typically sharpen Shuns at 16dps since that’s what they’re at when they leave the factory; or I simply move the knife around until I’m close enough to the factory edge.

If you want to reprofile the edge to 17dps and you’re not getting a wide enough bevel back down to the 200s and with medium pressure make 10 or so passes. Then inspect the edge.

Another thing to keep in mind is the amount of material behind the edge at the shoulder. For example, if it’s a hollow grind there may not be enough surface area to allow for a 3mm bevel from apex to shoulder… If that makes sense?

Invest in a X20 loupe so you can see exactly what’s going on as you sharpen. Keep practicing. And stay patient 🙂

[Kenneth Krone]

Again, thank you very much. Yes, I am only removing the sharpie at the apex–about 1 1.5mm. There is another 2-3 mm before the steel changes to the Damascus pattern. I will re-do the edge at 16 degrees, then, if that is what they are from the factory. I must have mis-informed myself along the way about it being 17 degrees. Thanks for the info and the help!

Ken K

[Leo Barr]

I think you will find that to touch the rest of the VG-10 before the damascus that this area should be considered a thinning bevel, if you look at a new Shun the edge bevel will be less than 1 mm( probable <0.5mm) on each side the thinning bevel is considerable lower than 16˚probable less than 10˚ I would imagine about 8˚.
Don't let your edge bevel get too wide you should ideally thin the thinning bevel each time you sharpen the knife although this is difficult unless you have the low angle vice (or are confident enough to sharpen freehand) and you can probable get away without attending to the thinning bevel each time but you will need to sooner or later if you want to maintain the high performance of the blade.

[Kenneth Krone]

Thanks, Leo and KnifeNerd. If I understand you correctly, then Leo, I am fine. I decided to go to a 16 degree angle on two knives and the edge bevel is only about 1 mm or so, so I am far away from the Damascus pattern. I do not have a low angle vice and hope to not have to purchase one for a while. We do take quite good care of our knives, and now that our kids have been out of the houe for years, I find that I don’t have to sharpen the knives as much as I used to…!

Thanks again for all of the help and support,
Ken K

[Steven N. Bolin]

I think you will find that to touch the rest of the VG-10 before the damascus that this area should be considered a thinning bevel, if you look at a new Shun the edge bevel will be less than 1 mm( probable <0.5mm) on each side the thinning bevel is considerable lower than 16˚probable less than 10˚ I would imagine about 8˚.
Don't let your edge bevel get too wide you should ideally thin the thinning bevel each time you sharpen the knife although this is difficult unless you have the low angle vice (or are confident enough to sharpen freehand) and you can probable get away without attending to the thinning bevel each time but you will need to sooner or later if you want to maintain the high performance of the blade.

Leo,

Now I'm confused. Can you please further explain what you mean when you refer to sharpening the thinning bevel?

Thanks you

[Leo Barr]

Essentially if the material behind the edge is not thinned it becomes thicker imagine having your foot trodden on with a stiletto heal or a tennis shoe it really does not matter how sharp the edge is if the bevel of the edge is very wide because of the thickness of the knife. There is another benefit to keeping the blade suitable thinned it will be considerable easier to sharpen the edge bevel since the width of the bevel will be very small so less to sharpen. Any knife that thickens up towards the spine will need to be thinned . Laminated knives which include many Japanese knives get wider towards the spine.
Some knives like Victorinox which are not laminated do not flare out towards the spine therefore it is not as important to thin them.
Thinning a knife will supercharge the performance even cheap knives will benefit from been thinned.
Another thing to picture especially when deep cutting say cheese or slicing steaks if the knife is not suitable thinned the effort to cut will be greatly increased imagine the main body of the knife are the shoulders with a smoother transition from the cutting bevel to the shoulders the knife will perform a lot better even when the edge has become blunt.
Many non cooks only use their knives to cut pre sliced processed foods where it is pretty unimportant what the blade profile is like but if the knife is to be used to really cut food then it is important to have a good profile.

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[Kenneth Krone]

Thanks for the explanation. I think I understand (the image is difficult to read, even when magnified, but the illustration is clear). Over time, the width between the shoulders becomes wider as more and more steel is removed by the sharpening process. I have a cheese knife that is uniform from edge to spine, and I understand why that is the case with regard to cutting through cheese. The question that I have is how does one determine when to thin the edge (shoulder) without taking micrometer readings and recording them, and how is it done well by the home cook without resorting to a grinder and running the risk of screwing up the knife? I can see that one way to thin it would be to use a lesser angle for the shoulder, say perhaps 10 degrees (I don’t know what angle would be recommended but that is apparently the lowest angle that can be achieved by the small angle adapter), presumably by using the Wicked Edge Small Angle adapter extension gizmo for the Wicked Edge while keeping the blade angle at 16*. Clearly the geometry changes over time depending on how often a blade is sharpened and how much material is removed.

[Leo Barr]

Ideally the back bevel or thinning bevel should be attended to when sharpening that way it saves a lot of work at a later date.

[Kenneth Krone]

So, basically what I understand from what you have written, it is like a compound blade, with two angles, say 10* along the shoulder (back bevel) and 16* for the edge. Sounds like I need to purchase the extension gizmo. Thanks

[Leo Barr]

Pretty much I would sort of compare it in an odd way to flattening a stone much easier to do it in time and less depressing seeing lots of steel go.
Best bet have a look at a new Shun noting the width of the edge bevel and try to keep the bevel the same width as new.

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