Looking for help sharpening flat blades

T

Trek Vandecar

Joined
Jan 31, 2020
Messages
11
Hoping to get some advise on a issue I have been having when sharpening very flat profiles like a vegetable chopper / nakiri.

I use the wicked edge system currently.

I am having a hard time ending up with a flat edge. I will get a slight re-curve in one or more spots. If you hold it blade down on a flat surface you can see a sliver or light in some areas, indicating high and low spots. This is translating to push cuts that are not complete.

I have attempted to fix a couple of these with some luck, by taking them and "flattening the edge" on some 600grit taped to a glass top. Still it seems like a struggle to keep them flat throughout the re-sharpening process that follows.

I'm trying to work out where I am going wrong, or if the wicked edge style system is an effective system to sharpen this style edge profile.

Thanks as always for any knowledge and advice! Happy to clarify any additional details in my process upon request.

Picture of most recent build \/
https://www.instagram.com/p/CK1MmR_jSVB/
 
Recurves in edges are actually very common and most common with machine grinding. The issue is usually related to the amount of steel being removed from a given area. Small contact area + uneven pressure = high and low spots in the edge. For example: when you push your stone down the blade there is an uneven amount of pressure spiking in the middle of the push and because most make several "pushes" down the edge to completely grind from heel to tip you get several "dips" in the edge. If you could walk the flat bevel of your edge it would be like rolling hills instead of a flat road.

Blades like this need to be hand sharpened to get the straightest edge. With hand sharpening you hold a much more consistent pressure from heel to tip allowing for a much flatter bevel and on large kitchen knives this becomes a critical point. There is also the rare issue of a highly flawed primary grind, lets just say you have a behind the edge thickness of 0.015 and two low spots of 0.008, when you sharpen a knife like this the thinner metal grinds faster and you can never grind the surrounding thicker metal fast enough to keep up with the low spots. This will also produce "recurves" in the edge and are only corrected by correcting the primary grind.

Also, with the wicked edge, it is my observation that the "speed sharpening" I often see of quickly overlapping the stones down the edge could easily cause an uneven grind. The repeated action will eventually hit the same areas over and over again and the areas with the highest pressure spikes with have the most material removed.
 
It would help to see some pictures. I have a WE130 and have never seen anything like what I imagine that you are talking about. But I have only sharpened two kitchen knives so far.
I don't use my WE like I'm trying to win a race like some do in the videos. I go pretty slow and try to always use the entire stone. I also use only enough pressure to keep the stones against the blades. Diamonds don't need much pressure in order to cut. That's my experience so far. It's possible that I am completely misreading your post.
 
I would bread knife the edge on the side of a stone to straighten and then start over on the largest stone I had. Free hand....
 
Thanks again for the advice!

I am going to order naniwa 1000 grit stone (it's one of the larger ones about 3.5" wide) and start practicing some free hand sharpening. From the sounds of it, I was probably going a bit hard with the Wicked Edge System. I will consider trying agian with lighter strokes and less pressure as well.

As always, it's been great to be able to bounce these things off folks with much more experience and knowledge.
 
Not aware of any Naniwa stone 3.5 inches wide. Your average Japanese waterstone is 8x 2.75... sometimes 3 inches wide but I don't think I can name any standard size stones wider than 3 inches.

Also, what Naniwa stone? Not all are created equal and your selection can be important. What steel is the knife and how hard is it?
 
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