Keep Chipping a Yoshihiro

[Steven N. Bolin]

I have a little Yoshihiro petty knife I’m sharpening for a guy at work. I’ve yet to sharpen a kitchen knife with high carbon steel. I’ve sharpened plenty of survival knives with high carbon steel, but this is completely different.

Bottom line – I keep chipping the edge. And not just a few chips. It spans across the entire length of the blade.

400s seem to be the very lowest I can go. And I’m annoyed that even with my 400s I can’t seem to detect a burr… Or even if I’m creating one due to the peaks and valleys on the edge. I’ve tried cleaning the shoulders then moving the angle out a degree then jumping to the the 600s to remove the chips… And it seems like stropping (when I THOUGHT) it was relatively sharp) makes it even duller.

Please, give me your expertise?!

[Mr.Wizard]

I suggest not taking diamonds all the way to the edge. Use diamonds to remove the bulk of the material needed, then switch to something more gentle, if you have it.

[Mark76]

This is pretty weird. I googled Yoshihiro and they seem to use various steels, ranging from VG10 to blue steel and Aogami super.

I have quite a few knives with these steels and they’re great to sharpen. Normally I start by putting a new bevel on them with the 100 grit stones. That works fine: no chipping. I get a burr very quickly, usually within a minute or so. And then I refine the edge.

Apparently this doesn’t work for you. The standard method in those cases is to use higher grit stones in order to minimize the possibility of chipping. And use low pressure: let the stones do their work. Don’t get involved in stropping and high-grit stones yet. You should try to get a burr first with your diamond stones. (This is possible with the 400 grit stones, too, it just takes a little longer.) And this bevel-setting should be done without chippring. If it chips at this level, higher grit stones or even stropping won’t solve the problem.

But to be honest, my idea is that (if you apply the proper procedure) these steels shouldn’t chip. If they do, there could be something wrong with their heat treatment. In that case you may want to contact the seller and ask them what is going on.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Mark76]

Just to add. Don’t go lower than 15 degrees. If the chipping issue remains, try 20 degrees. If it then still chips, you should ask the maker what is wrong with this steel.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[tcmeyer]

I recently had a problem with my new 800g stones chipping my ZDP Delica. I think I identified the problem as a cluster of diamonds which didn’t get knocked off during the break-in period. These clusters happened to be rather long strings of abrasive oriented in the long direction of the platens. This makes for a very securely attached cluster which resists knock-off with normal break-in use. Instead it provides a plow effect, digging deep troughs which are seen most readily as chipping at the edge.

Test to see if you can feel any “clicks” as you make a normal (but slow) stroke with the stones over a smooth edge. If they seem to happen at the same place every stroke, you probably have the same problem.

Early on, I had the same problem with my 200g stones and it made me reluctant to use them anywhere near an edge. May have been the same cause.

[Steven N. Bolin]

TC,

Wow. I’m pretty sure you just hit the nail on the head, my friend. I plan on making a video tomorrow afternoon in order to start some dialogue. I’m in awe that you had this response… I thought it was something that was all in my head. Although, I knew it was reality.

[tcmeyer]

I couldn’t seem to get my 800s broken in, so I resorted to working the stone along the edge of a straight piece of glass. Once the edge was smoothed, I could easily detect these anomolies and I’d scrub the stone in that area until the “clicking” subsided. This seemed to work really good and I wouldn’t hesitate to recommend it to others. I now have a “break-in glass” in my box of Wicked edge tools.

But while we’re on the subject, here’s a couple of photos of my “problem”:

The first photo is at 58X on my monitor (photo is about 6mm high and 8mm wide) and shows the cluster which I think was chipping my Delica:

The next photo is of the same cluster, but at about 180X on my monitor (photo is about 1.95mm high by 2.6mm wide):

To show more clearly how these clusters can form, here’s one that appeared just off the edge of one end of one of my 800 stones. Located where it is, it doesn’t get knocked off.

Tonight I looked for examples of the diamond clusters and only found a few at the end of one of my new 1000 grit stones. Here’s some before and after photos, pointing out some of the clusters:

Before work on the glass edge:

After about ten stroke under normal pressure on glass edge: You can see the grey area where the clusters have been removed

I found a way to find the clusters visually, with the handheld microscope. You focus carefully on the substrate (the level of the field of diamonds). When you come across a blurry area, slowly lift one side of the camera. If the blurry area is an elevated lump of diamonds, it will seem to come in and out focus as you raise and lower the camera.

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[Steven N. Bolin]

TC,

Thank you so much for the in-depth information!

I’m sitting outside with my 600s trying to get them to make this “clicking” sound we’ve been talking about. I’m using a cheap chef’s knife that belongs to my girlfriend, but I can’t hear anything that even faintly sounds like clicking. However, now that I’m thinking about it, the only 2 times I’ve heard it have occurred while sharpening 2 different knives with high carbon steel… Perhaps I’ll try again with one of those knives?

We’ll go from there, I suppose.

I’ll keep you posted.

[Zamfir]

I could more feel it than hear it..maybe I was hearing it also..hard to say. But for me it was my 1K. Seems it would be harder to notice on the 600.

[tcmeyer]

You are absolutely right – it isn’t so much that you hear the “click”, you feel it at the same time. But it’s definitely a distinct and repeatable impulse you sense as the stone passes over the edge. As your stone is “broken in” the number of these goes from a symphony of scratches to a few taps on the snare drum that you sense in the background of the violins. When you zero in on one and “scrub” the stone back and forth over a specific “bump”, the thump becomes a tap and then a tick and then it disappears completely. The more securely your “cluster” is attached, the longer it takes.

[Daniel maloon]

I agree with everything tcmeyer mentioned here. If you’ve eliminated the stones as a cause then like Mark said, then somethings wrong with the knife. This happened to me once with a J.A. Henckels Twin Pro S 10-Inch High Carbon Stainless-Steel Chef’s Knife. No matter what I used to sharpen it, the chips still formed in the edge.

[tcmeyer]

Dan:

This is almost an unreasonable question, but do you by any chance have photos of what those chips looked like? Whenever I come across something abnormal, I try to take a picture. Of course, being the highly disorganized person that I am, finding them later is always a challenge.

Here’s an example of a strange chip fault I once had on a Seki AUS-6 knife. It cleaned up OK and hasn’t recurred.

Attachments:

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[Leo Barr]

Two thoughts that may be causing chips that may be worth considering – if the motion used with the stones is a slapping action as opposed to a smooth soft touch this may aid chipping & what angle are you using very low will help cause chipping although the Rockwell figure is not that high (60) .
I would expect the bevel to be around 15˚ per side if you have Choseras they would be more suited to this knife.
You should be getting a burr otherwise check what is going on with a loupe .
It sounds as if the bevel possible has more than one facet I think you will need to stick to one bevel angle and pursue it until you have a clean edge.

[Author]

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