Problems to sharpening a knife

[Hydrazin]

Hello everyone,

I am having difficulties sharpening a chef's knife. I have three in total: a small Boker Damascus Black chef's knife with a VG10 cutting edge, a Boker Cottage-Craft chef's knife with a C75 blade hardened to 58 HRC and a Japanese Santoku from Goko Hamono with a Shirogami 1 steel cutting edge, which the manufacturer claims is hardened to 63 to 65 HRC. I sharpen the VG10 and the Shirogami 1 blade at an angle of 15°, the C75 at an angle of 20°.

To sharpen the blades, I use a Tormek T1 without a honing wheel for the actual sharpening. The "finish" is done using the Spyderco V-Sharpener with the fine rods and, if necessary, honing leather.

I achieve satisfactory results with the first two knives. However, the Japanese knife does not want to be really sharp and I currently have no idea what the reason for this could be. Does anyone have any advice?

Best regards
Hyde

[John Hancock Sr]

The "finish" is done using the Spyderco V-Sharpener with the fine rods and, if necessary, honing leather.

These appear to be Aluminium Oxide which is not suitable for high hardness Japanese knives. I would suggest that you deburr using the T1 wheel only, or a leather strop.

[Royale]

Just on a hunch, use a marker pen to mark the secondary bevel on your Japanese knife, and try a few light passes. See where the marker has worn off.

I typically sharpen Japanese knives at about 10-12 DPS.

My suspicion is that your sharpening angle of 15 DPS may be a bit too obtuse for the original edge.

[smcinco]

My sense is the steel is just so hard and brittle that the burr hangs on and makes it feel really dull.  I get that a lot with A2 steel.  Like John said I think the amount and manner of stropping is the culprit.

[Ken S]

I am not saying that either the T1 composite wheel or the Spyderco V-Sharpener is either capable or incapable of proper deburring. I don't see where conclusive evidence has been presented to make either case. After sharpening with the T1 diamond wheel, honing with the T1 composite wheel using the black marker would be a logical next step. That would rule in or rule out if the honing is being done at the proper angle. Do not move on beyond this step until the bevel angle is correct.


I have a Spyderco sharpener. I have no complaints with it, especially if it is used at 15° or 20°. However, did you decide to switch to it because youfelt the T1 composite wheel was not working or some other reason? Admittedly there is a  bit of a learning curve with it. Did you master that curve before deciding not to use it? Having worked with the Tormek Design Committee, I think very highly of their work, and would not dismiss it lightly. (I do not mean this as a criticism of the Spyderco sharpener.)


If two of your three knives are satisfactorily sharp, you are obviously well along. I believe a little more focused effort will produce a sharp third knife. I encourage you to stay the course and achieve your goal.

Ken