An answer to a question posted on youtube... thought it might be helpful to some
question: What angle will you recommend on the primary and secondary egde on a yanagiba?
answer: The exact angle will depend on the knife/maker/etc. However, these things can be quite easy to follow from initial sharpening. The angle doesnt change much between the two angles... its mostly pressure that changes. The main part is you know where you need to sharpen and you are trying to keep the distance from the shinogi line to the edge the same so as to maintain geometry. Hope this makes sense and helps.
question: Hello. Okay I will try to replicate the sharpening angle used before. It seems like it is about 11 deg at the primary egde.
answer: are you using a guided device for this? You may find that the angle changes a bit from heel to tip as well. This can make using a guided device a bit more tricky.
question: I do not use a guided device. Only freehand But I did not know that the angle is changing from heel to tip. Is it because it is impossible to keep a constant angle when freehanding or do the knife makers do it on purpose? Another question: On the sharpening video on the old channel you are sharpening a Aristugu A-Type Gyuto. What type of bevel do this knife have, single?, 30/70? Is this knife possible to buy?
answer: not all makers do it this way, but those that do have explained to me that the tip is thinner for more delicate work relative to the heel. On the A-Type sharpening, i actually dont recommend that kind of sharpening. It was just to show what i was doing to one of my knives at the time. That knife is still being sold at some places. The sides are asymmetrical, as well as the bevel. Probably somewhere close to 70/30, but numbers like this are over-simplifications.
in reality when talking about symmetry, people rarely use specific and exact angles. Likewise for the sides of the knives. These kinds of explanations are general over-simplifications japanese knife-retailers/wholesalers and sometimes makers use to help people who dont know japanese knives better understand one of the ways in which they are different. In fact, i just had this conversation with many of the makers no more than a few days ago.