sharpening single edge blades

[jeffs55]

Is there anything I need to know about sharpening single edge blades like on Japanese knives? I am quite proficient at double edge blade sharpening.

[Jeff Farris]

Just do one side.   

Sorry about that, couldn't resist.  The angle will be much flatter, and depending on the blade, you may not be able to use the jig.  I think most are in the range of 15 degrees or even less.

Hone the flat side VERRRYYYY carefully. It's quite easy to raise the angle too high and round the edge. Same for the bevel side...it's so flat that you really have to mind what you're doing to keep from rounding the edge.

[jeffs55]

Which side? LOL I couldn't resist either! I know it is the side with the grind marks on it and not the flat side. thanx

[tb444]

In all honestly i wouldn't touch a single bevel japanese knife on a tormek unless it was a very cheap knife that i didn't care about. They have a complex geometry with the Uraoshi (slightly hollow flat) on the back side needing careful maintenance with gentle strokes on a very flat and very fine stone with pressure only on top of the edge. The main bevel sould be lightly convexed (hamaguriba profile) to assist with food release. Further the Shinogi line needs to be kept crisp and parallel to the edge.

Whilst i fully respect Jeff and will say that the Tormek can be used to maintain double bevel knives admirably, single bevel japanese knives are entirely different and it would be very easy to ruin the geometry very quickly.

[Jeff Farris]

Of course, the careful hand maintenance that you describe is something that takes a great deal of dedication to learn and master. I'm pretty sure that a knife owner that knows a Uraoshi from a Shinogi (which I did not before this post, thank you for that) would not attempt to sharpen on a Tormek, nor seek a sharpening professional that uses a Tormek as their sole sharpening system.

Which brings up a point for the professionals out there. Do take the time to interview your customers about the tools they are trusting you with. It can be hard to distinguish the difference between a $90 knife and a $900 knife. If the $900 knife is completely mangled when it comes to you, I doubt you can do it anything but good. However, if a customer brings a valuable knife in for a touch up, be sure you know how to touch it up correctly.

[tb444]

You raise a good point, it's definitely worth understanding the value of what you are sharpening before agreeing to work on it.
Although, most tools are difficult to damage through sharpening on the tormek, the advantage of a jigged system.

[Ken S]

If, and it's a very big if, I owned a $900 knife, I would be extremely picky about who sharpened it and how it was sharpened.  I would probably sharpen it myself, unless I knew a bona fide sharpening master.  And, I would sharpen it very slowly by hand.

I also don't think I would use such a knife for everyday chores.

In fairness to the Tormek, I believe these rare knives are outside of the design parameters of the machine.  Probably man made water stones are outside, also.

Ken

[jeffs55]

Hmmm, I did buy a mere $50 knife to gain experience but you guys are making me lean to leaving it alone. I dont see the shinogi line being compromised by sharpening the single bevel judiciously. I mean they are a long ways apart. I am going to try and get up the nerve to do something while remembering the Hypocratic oath. Do no harm! If I destroy it, who is in the market for a slightly used yanagiba? LOL Is the consenus here  that it cannot be done on a Tormek?

[Jeff Farris]

Jeff, if you mess it up, I might be in the market...it may not have the perfect Japanese profile, but I guarantee you, the Tormek and I can make it cut.

Smooth stone, light touch, watch what you're doing, think about the geometry. You'll do fine.

[tb444]

i'd change the angle of attack to be much more skewed so that instead of approaching at 90 degrees you are much closer to 30, that way you won't hollow out the bevel.
I'd paint the whole bevel in magic marker too....