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

[Hardrada]

5 minutes ago, Spyros said:

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?

Actually, Japanese knives have a micro-bevel, which must be ground at ~20°.

But, yes, the back side of the knife must be totally flat.

[Spyros]

15 minutes ago, Hardrada said:

Actually, Japanese knives have a micro-bevel, which must be ground at ~20°.

But, yes, the back side of the knife must be totally flat.

Man, I was actually just looking at the photos again and I was wondering if that knife actually has a secondary bevel.  I have two of them and they don't, why on earth would anyone put a secondary bevel on a knife for leather?  Secondary bevels are typically used in *some* wood chisels and planes because the very tip doesn't have a hope of lasting very long against something as hard as wood.  But leather???  Maybe those table top splitters need one, at most, because they sometimes get dozens of belts put through them every day, directly vertical against the blade, and the sharpening wouldn't last very long without it.

If I had a skiving knife with a secondary bevel I'd just grind it away personally.  I don't see the point of having one other than making your life miserable when sharpening it.  You need a well-tuned jig, no way you can sharpen two separate bevels freehand.

Edited February 16, 2022 by Spyros

[BMH]

This knife does have a bevel and I noticed that I removed more material toward the right middle, it most likely occurred when I was trying to figure out the angle. The back side of the knife is indeed flat.
As far as the stone, DMT doesn't give a grit for their diamond stones, it's just a "fine" one and the finest one they have is their "extra fine" IIRC.

 

[Spyros]

Get a knife without a secondary bevel.   I'm sorry, this is honestly the best advice I can give you, hand to heart.  Secondary bevels are a pain in the butt and (IMHO) unnecessary in skiving knives.

[Hardrada]

16 minutes ago, BMH said:

As far as the stone, DMT doesn't give a grit for their diamond stones, it's just a "fine" one and the finest one they have is their "extra fine" IIRC.

Actually, they do: https://www.dmtsharp.com/sharpeners/bench-stones/diamond-whetstone-bench-stone/6-in-diamond-whetstonetm-sharpener-coarse-with-hardwood-box.html

Click on the "Grit Chart" image.

[BMH]

Thanks! That's good to know.

[zuludog]

I have two JLKs that I use for both cutting & skiving and a 'chisel type' skiving knife I made myself from a piece of 40mm hacksaw blade. None of them have a secondary bevel and they work well enough

Search YouTube for 'sharpening a japanese leather knife'. There are several videos, and they will all help to show how it's done. I don't think any of them make a secondary bevel. They usually have a long low angled single bevel and flatten the back 

 

[Samalan]

Grind it to one bevel in one direction and that's into the bevel until you feel a slight wire on the flat side turn it over holding the flat side down on the stone very light pressure move it side to side until the wire is gone then the most important part strop with a leather strop charged with white lot's of people say green bar but in my opinion white is best be very carful not to roll the tool up at the end of the stroke one stroke on the flat side with the tool completely flat on the strop the bevel should look like a mirror don't do to much stropping get it to the mirror and stop you should be able to strop at lest ten times before you need the stone again and at that point the stone should take jus a few passes then strop again white bar is aggressive so not to much stropping I have been sharpening my carving tools this way for thirty years with the best results I can sharpen any one of my chisels to a razors edge in less than sixty seconds sharpening should be fast and easy hope this helps this is all IMHO.

[TomE]

My experience with DMT sharpeners is they are more agressive than my Arkansas oil stones.  The DMT sharpeners in blue (medium) and red (fine) are a good substitute for coarser stones to shape a blade.  I'd use a finer grit to finish. 

[chuck123wapati]

15 hours ago, BMH said:

 

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.

that young man is using a fine grit stone for one thing, you are using a more aggressive grit and by the pictures you are cutting a new angle, i can see at least three angles so your not hitting the right spot,  not even touching the original edge yet. Take a black sharpie and cover you r edge then make a pass and you can see where you are removing metal. You will have to correct what you have created first so stick with you diamond stone until you get one nice flat angle. Once you get the angle repaired then go on to finer stones. then what ever you use to polish your edge, strops are ok but another learning curve i would suggest a vey fine sandpaper glued to a very flat surface like your pounding granite or even a piece of glass i use a 1000 grit then a 2000 grit. The reason i suggest the sandpaper is its the same process as you use with a stones so you don't have to learn another technique.  Sharpening isn't hard or rocket science , its about repeatability and practice you don't need an exact angle but you need one straight flat angle of about 15 degrees+ -

You can always buy something like this it will solve you r problems!!   https://www.woodcraft.com/products/honing-guide?utm_source=bing&utm_medium=cpc&utm_campaign=PLA&utm_term=03A21&adlclid=72d0de072a781159cccebc0a28524759&msclkid=72d0de072a781159cccebc0a28524759&utm_content=All Products

[zuludog]

Here is one of several videos on sharpening a JLK, but it really is worth watching all, or as many as you have the stamina for, on using & sharpening a JLK and similar 'chisel' type skiving knives, such as Chartermade

How To Get a Razor Sharp Edge - Leatherwork Knife Sharpening Tutorial - YouTube

Corter Leather, Leathertoolz, and Haku - Handmade Leatherworks are good - just click on and follow the Links & Prompts to watch others, as many as you can.

Oh, just one thing - you should stand up to sharpen a knife, especially something like this type, or a plane blade, so that you can apply even pressure and keep the bevel flat on the stone. If you sit down to sharpen there is a tendency to slightly lift the cutting edge off the stone as you push the knife away from you.

Edited February 16, 2022 by zuludog

[AzShooter]

zuludog:

Thanks for that wonderful explanation.  I've definetely learned a new system for sharpening.