Single Bevel Deba Trouble - Cannot Hit the Edge

[trancher]

Awhile back, I picked up an Okeya W#2 single bevel deba. Out of the box edge was dull, and a generous? micro-bevel was put on it of about 1mm. So to sharpen it, I started out with a 400 for about 30 minutes, and finally realized that I needed to bring in the big guns for this, 140 diamond plate. I monitored my progress the whole way with the sharpie trick, highlighting the whole bevel. Initially, I thought I was doing well, as I was removing all of the sharpie easily, and getting to the very edge, as best as I could see. My technique was finger pressure at the shinogi line for the first pass, making sure the blade is not wobbling beyond it and laying flat, second pass fingers as close to the actual cutting edge as possible.

The trouble is, I have still not formed a burr, and that's after 2 1/2 hrs on the 140 diamond, and now it's almost impossible for me to reach that sharpie at the very cutting edge. Did I take too much metal off at the shinogi line causing a slight change in the angle of the grind making it difficult to reach that area? Any suggestions for what's going on here and a method to correct it?

Last pass attached.

Also, I have been at this with edge trailing strokes (@ about 30 degrees from parallel to the long axis of the stone) which might be a mistake, as I have never found it to remove metal quickly, but I was following along in a video. Is edge leading okay to sharpen these?

Thanks!

[taz575]

You are flattening the bevel and thinning it at the same time. You need to remove more metal just above the edge or use a slightly steeper angle at the edge to raise a burr. Single bevels have a convex blade road typically, so the angle changes as you get to the edge. If you are going for a flat blade road, you will need to remove a ton more material to get to the edge than if you keep the convex blade road.

[trancher]

Single bevels have a convex blade road typically, so the angle changes as you get to the edge. If you are going for a flat blade road, you will need to remove a ton more material to get to the edge than if you keep the convex blade road.

Ah, okay. I was under the incorrect assumption that the blade road was already flat from watching my sharpie disappear rather evenly. I'll rotate it up ever so slightly to get that very edge.

[aporigine]

Single bevels have a convex blade road typically, so the angle changes as you get to the edge. If you are going for a flat blade road, you will need to remove a ton more material to get to the edge than if you keep the convex blade road.

Ah, okay. I was under the incorrect assumption that the blade road was already flat from watching my sharpie disappear rather evenly. I'll rotate it up ever so slightly to get that very edge.

I ran into a similar situation when dealing with my first high-grade yanagi. Once I learned that the blade road was not supposed to be dead flat, life got easier. A slight convexity made shorter work of returning the blade to sharp.

[trancher]

I ran into a similar situation when dealing with my first high-grade yanagi. Once I learned that the blade road was not supposed to be dead flat, life got easier. A slight convexity made shorter work of returning the blade to sharp.

Great to hear others have wrestled with this quirky nuance, thank you! It was getting to the point where frustration was starting to bubble up after each pass.
It'll be easy to return to now.

[aporigine]

I ran into a similar situation when dealing with my first high-grade yanagi. Once I learned that the blade road was not supposed to be dead flat, life got easier. A slight convexity made shorter work of returning the blade to sharp.

Great to hear others have wrestled with this quirky nuance, thank you! It was getting to the point where frustration was starting to bubble up after each pass.
It'll be easy to return to now.

For me the moment of clarity was when I watched a Youtube of I forget whom doing it all with the fingers on the back of the blade. Some passes on the stone were with pressure (and not much by the look and sound of it) way forward by the edge, and others had the fingertips just forward (like a coupla millimeters) of where the shinogi was.

I thought, what the (your worst word here!), might as well try. And wouldn’t’cha know, it worked. (Same word) yeah! The convexity established itself with no need for intermediate finger placement. I haven’t looked back.

[weeeeeeum]

Additionally if you want a really nice kasumi a slightly convex bevel is very important. Also I would recommend getting a coarse waterstone, thinning on an atoma will wear it out fast, especially hagane. I didn't know this at first and I thought the atoma was junk (I was using it for knife restorations) and now I feel like an idiot haha. Anyways my atoma 140 is now slower than an 800 grit diamond plate

[Drewski]

I found the following video from JKI by Jon Broida to be indispensable on the matter. Best of luck!
https://youtu.be/kA0vdeDDSJI?

[ared715]

Yeah there are many videos on YouTube explaining hamaguri sharpening of single bevels/wide bevels. Once you get used to the 3 points of contact, you'll get the results you're looking for. Also, great knife to practice this on! Good luck with the burr!

[salemj]

This might also be a point where the mention of mud is relevant.

I don't have experience with this, but my impression has always been that Japanese sharpeners use mud specifically and effectively to help polish the "gaps" that are created with the convex shape. Even if the mud is not grinding away metal, it is still abrasive, and it can help create a consistent finish when only a very specific 1mm (or less) is in contact with the actual stone. This should be especially true when using low pressure, even if that seems counterintuitive!

I mention this because you don't get mud with diamond plates. I would recommend that, even when using a diamond plate, you use another stone to create some mud on the surface of the plate as you sharpen, and try to use less water overall. It will likely improve your easy of sharpening and get you to a nicer finish. You can of course do the same thing as you move up your progression: it is perfectly fine to "mix" grits by using a stone to clean and create mud on one of a higher finish before the knife ever hits the stone.

Sorry if this is all a bit obvious! I guess I should add that the point here is that trying to get an even finish without having the mud help you means constantly trying to polish a rounded surface on a flat stone...which means being constantly at risk of flattening the rounded surface, which you do not want to do! Using the mud makes it easier to main the proper geometry, etc., and to avoid "overworking" the knife/steel.