Are Compound Uras Necessary On Single Bevel Knives?
It is SO much work. Making this knife is already difficult in itself, and doing a compound one adds to that complexity significantly more, for such a SUBTLE difference. Why is it even done? Jon said it’s to aid food release without going too deep, and promote longevity of the uraoshi over repeated sharpenings throughout the years. If we exaggerate the cross section, it makes sense. If one were to sharpen this knife over and over, keeping that tighter radius will help you maintain that crisp flat section for an amount of time - you’re essentially delaying the point of time of which you would need to regrind the ura.
There’s also an inherent difference in how use and maintenance is viewed between Japanese and Western makers. Over here we generally shoulder all the work including repairs and long term maintenance, where I think in Japan that’s not really the work flow they have. So the logic behind a compound ura makes sense for Japanese makers to basically design in the ura geometry to promote its longevity over repeated sharpenings, but for western makers it’s more normal to be able to just regrind a simple ura when needed.
Another take on the compound ura is that it allows you to control the depth of the ura throughout the length and width of the knife. If you stuck with just one single radius, it could end up being ideal for one section of the knife but be compromised everywhere else. For a large radius, it might work out over the wider sections of the knife towards the rear, but going towards the tip it gets shallower and shallower. Let’s say we’re working on an usuba now, which is significantly wider than a yanagi. To maintain your depth you’d have to go to a much larger radius, and then the angle between the radius and uraoshi is incredibly obtuse - when sharpening, this would very linearly and quickly widen that flat section, which exacerbates the problem more and more each further sharpening.
Does it truly matter for most people though? WHO would actually notice and care? Jon Broida does, because he sharpens and deals with these knives more than anyone else I know. Would it matter to an experienced cook? Maybe not? Because they have technique that can compensate for any differences. What about a new cook? Maybe. When learning, you generally want something that cuts fairly standard. If it cuts or maintains way different from the norm, it could easily make things incredibly frustrating especially trying to troubleshoot something that’s not quite working.
This stuff matters more to these single bevels than any other knife, because the philosophy and approach to using them is so much more tightly focused and regimented than any other style of kitchen knife. Sure, there are minor differences from maker to maker, but the core principles still apply throughout. What’s the right answer? I don’t think there is one. I think the maker has to choose their own answer, balancing the pros and cons, and establish an agreement with their customers on how they approach the problem.
