Ginga/laser sharpening questions
I'm struggling a little bit on how to word this. I hope what I'm asking will come through clear even though I'm probably butchering some of the knife jargon. It's a rookie question and I tried searching the forum for answers but had trouble finding a concrete response.
Basically I own a Ginga 210mm petty & 270mm gyuto. Both wonderful knives that cut like a dream. They are my first lasers and I am extremely happy with them.
Being so thin, I am a little confused on how to best sharpen them. They came as exceptional cutters OOTB and while it's probably one of Jon's basic edges, it's got me going down the rabbit hole and questioning all my previous results. They both have no visible primary (or cutting) bevel. Feeling the edge on my fingers didn't blow me away but they absolutely drop through everything I throw at them and have had really surprising edge retention. So far I've maintained them with very light sharpening on 5-6k stones and stropping, paying attention to not set a new, cutting bevel.
My petty in particular I've had longer and been using a lot at work - I think the steel is starting to get a bit fatigued and while it still cuts, I'd like to bring it back to razor sharpness, while maintaining the original geometry.
I've seen folks write that with lasers, because they are so thin, you should treat the secondary bevel/blade face as the 'actual edge', and instead of setting a primary bevel, you should sharpen/polish higher up behind the edge, instead of trying to hit the edge. Does this make sense, and is it true? Should I be doing this by putting them to the stones at a much lower angle than I normally do? Just using higher grit stones to polish and only dropping down to coarse/medium grit when the metal is extremely fatigued?
I know you have a wealth of experience sharpening knives and have also spent a lot of time working with the people from Suisin in the past - so I bow to your knowledge of maintaining laser knives and would really appreciate some advice on how to best sharpen them.
Ginga/laser sharpening questions
Edit: sorry just noticed that this is in Jon's forum, if I am out of line in answering this question or you disagree with anything I've said please delete this post.
The reason the primary bevel is so small and as you said not visual is due to the thinness behind the edge and it most likely being a micro bevel . Having very little metal behind the edge the primary will be quite small. I'm not sure about your comments about only polishing at low angles.
You need to treat this knife the same as any knife in that you start your sharpening at the shoulder ( where the secondary meets the blade face) make a few passes, check where you are abrading metal ... Adjust your angle to hit the right spot, then slowly raise the spine working your way to the edge until you form a burr.
your primary edge angle doesn't matter as much as you think due to the thinness. I have my kono hd about 4-8 degrees secondary with a very small 12 deg primary.
i think a lot of people over think this... because the knives are so thin, and people cant really see the bevels, they assume the angles are lower. This is not correct. Like many other japanese knives, the angle is somewhere between 10-15 degrees (though the knife is capable of being a bit lower and and bit higher than that). Pick and angle and go for it. If its not doing what you want, make adjustments. But, 10-15 degrees is a safe bet. The bevel will get larger as you sharpen, but not because you're doing anything wrong... rather, its because you are working up into a thicker section of the blade. Eventually, you will need to thin, and then you can sharpen at a much lower angle. If you wanted, you could thin from the spine, but its often not necessary. Somewhere from 3-5 degrees is a safe bet for thinning,
If you notice chipping or lack of edge retention, you can either adjust to a less acute angle or try a microbevel (which is best suited to super thin and/or super hard knives). If your knife is not moving through food as you had expected, you can either try a lower angle or some thinning, but be careful to not go overboard.
Most often, you will not need to go below a medium grit stone for this work unless there are chips. If you are diligent about it, you can often just touch up on finishing stones often, and not have to drop below that for quite some time.