Sharpening a Japanese type skiving knife with DMT Whetstone

[BMH]

Hi there,

I have what will most likely seem like a silly question to many but I am still learning the craft and don't have much experience with sharpening.

I have recently bought a DMT diamong stone to sharpen my knifes and it's been great, except for my Japanese skiving knife. I am not sure of how I should be sharpening it on the stone. In the past I just used a wet stone and would go up and down with my blade in a straight motion like this. However, all I have achieved doing this with this specific knife on the diamond stone is to make it dull.

I have then switched to moving the blade from one corner of the stone to another in this kind of motion:

This works fairly well, but I am not sure it's the best way of doing it as I have been told I should pass the blade on the stone in this way instead (the blade is parallel to the stone and goes up and down)

What would you guys recommend?
(By the way my stone is a fine one, I am just using this picture of a coarse one for the sake of illustrating my question). 

[Hardrada]

Are you keeping the angle consistent?

[JayEhl]

could use a refresher, too.  

[BMH]

19 minutes ago, Hardrada said:

Are you keeping the angle consistent?

Well, I try to keep the angle as consistent as possible. Like I said, I don't have a lot of experience when it comes to sharpening so my movements aren't perfect yet, but I try to watch the angle as closely as I can.

[Hardrada]

What does the edge look like?

 

Now, this is just an idle thought of mine—who knows if I'm wrong. But I see that the polka dots in that DMT stone, which are plastic, form a kind of track where the diamond suface is cut and then resumed, cut and then resumed; whereas on the sides of such "track" there are unbroken lines of continuous diamond surface. My take is that this might be creating an uneven sharpening of the edge. My belief is reinforced since you  mentioned that you don't have issues with your whetstone, so I think that a continuous abrasive surface, such as the kind you have on a whetstone or a diatoma diamond plate abrades the edge through and through, unlike this patchy DMT plate.

I'm positive that, according to the manufacturer's literature, such polka-dotted surface should have no effect on the edge, but maybe that's because they sell these plates to sharpen knives that are swept at an angle across the plate, rather than from top to bottom—maybe this oblique sweeping reduces the effect of the breaks in the surface—I can't tell, but maybe that's why you get better results when you zig-zag the blade across the stone versus when you run it parallel.

Edited February 15, 2022 by Hardrada

[zuludog]

I've just read Hardrada's comments, and yes, you could be better using a stone that has a more continuous surface. A Japanese Water Stone is the common for this, but you could use others - I use oilstones, and don't forget the strop.

A good cheap option is to use this -

The full system is a bit expensive but the sample sheets are cheaper and  just right for Japanese Leather Knives; but find your own sheet of glass or similar hard surface. This is a British supplier but you should be able to find a US supplier. Most abrasives are measured by the grit size, but these use microns, however it's easy enough to find a conversion on The Net

Also Search YouTube for Haku Handmade Leatherworks. He has some good videos on sharpening & using a JLK; mostly in Japanese but with clear filming, diagrams, and English subtitles. Also Search YT generally for using, and sharpening JLKs

http://www.workshopheaven.com/hand-tools/sharpening-tools/scary-sharpening.html

Edited February 15, 2022 by zuludog

[chrisash]

Have you tried using a dark sharpie to mark the cutting edge so that when you have done a coupe of strokes you can see where the ink has been removed, so you can learn to get a even sharped across the whole of the cutting edge

Plenty of video's on YouTube that may help

[BMH]

58 minutes ago, Hardrada said:

What does the edge look like?

 

Now, this is just an idle thought of mine—who knows if I'm wrong. But I see that the polka dots in that DMT stone, which are plastic, form a kind of track where the diamond suface is cut and then resumed, cut and then resumed; whereas on the sides of such "track" there are unbroken lines of continuous diamond surface. My take is that this might be creating an uneven sharpening of the edge. My belief is reinforced since you  mentioned that you don't have issues with your whetstone, so I think that a continuous abrasive surface, such as the kind you have on a whetstone or a diatoma diamond plate abrades the edge through and through, unlike this patchy DMT plate.

I'm positive that, according to the manufacturer's literature, such polka-dotted surface should have no effect on the edge, but maybe that's because they sell these plates to sharpen knives that are swept at an angle across the plate, rather than from top to bottom—maybe this oblique sweeping reduces the effect of the breaks in the surface—I can't tell, but maybe that's why you get better results when you zig-zag the blade across the stone versus when you run it parallel.

I'll try and get a picture of the edge asap but to me after stropping the edge looks clean. And don't get me wrong, when pushing the blade from one corner to the other the blade gets sharp. But I was led to believe that it would extremely sharp by using this plate and nope, it's not extremely sharp. I can skive alright, but not with as much ease as I'd like and I am fairly sure this blade could get sharper. Your explanation does sound very interesting and I think you could be right

24 minutes ago, zuludog said:

I've just read Hardrada's comments, and yes, you could be better using a stone that has a more continuous surface. A Japanese Water Stone is the common for this, but you could use others - I use oilstones, and don't forget the strop.

A good cheap option is to use this -

The full system is a bit expensive but the sample sheets are cheaper and  just right for Japanese Leather Knives; but find your own sheet of glass or similar hard surface. This is a British supplier but you should be able to find a US supplier. Most abrasives are measured by the grit size, but these use microns, however it's easy enough to find a conversion on The Net

Also Search YouTube for Haku Handmade Leatherworks. He has some good videos on sharpening & using a JLK; mostly in Japanese but with clear filming, diagrams, and English subtitles. Also Search YT generally for using, and sharpening JLKs

http://www.workshopheaven.com/hand-tools/sharpening-tools/scary-sharpening.html

I heard of the scary sharp method but decided against due to the recurring cost of having to buy refills. I was told that the DMT diamond plate would be really great, but it doesn't seem to be befitting for this type of knife and I think I'll switch back to my water stone. Thanks for the advice and the resources!

6 minutes ago, chrisash said:

Have you tried using a dark sharpie to mark the cutting edge so that when you have done a coupe of strokes you can see where the ink has been removed, so you can learn to get a even sharped across the whole of the cutting edge

Plenty of video's on YouTube that may help

Yep I've done that. When going up and down in a straight line like this I am hitting the right spot, but it just dulls the edge.

[BMH]

2 hours ago, Hardrada said:

What does the edge look like?

 Without a macro lens this is the best I can do:

 

If I get the light just right I can see all the grooves left by the diamond plate which I hadn't noticed without the taking a picture with my camera:

 

[Spyros]

What grit is your stone?  From the photo your knife's edge looks ok-ish, just needs a few passes on a lower grit to get rid of those scratches on the edge.  And then a few passes on some leather strop to polish it.

Everybody moves the knife on the stone in a different direction/pattern, don't worry about that, just pick any movement that you feel best helps you to keep the angle consistent.  

A Jap skiving knife is pretty much the easiest thing to sharpen because it has this giant bevel that you can lay flat on the stone, no secondary bevels, no curves, no complexities.  But I can see you have removed a bit more material towards the middle/right somehow.   Are you sure this blade is flat?   Have you flattened it from the other side?

Edited February 16, 2022 by Spyros