How do you make a nice urasuki?

[Guirotin]

Hi folks,

Everything is on the title.
I can make nice s-grind, but havink an urasuki on the whole height of the blade seems much more complex to me.

How do you make it? What is the radius of the tool you use?
Do you polish then by hand sanding, or just finer grit sandbelts?

Cheers!

 

[ethompson]

I’m by no means excellent at grinding work, but I’ve been playing around with this some recently. I use a large 72” radius platen. I adjust the angle and placement of the blade to achieve the contact area I want. With the limited volume and time I dedicate to this craft, I imagine it would take me several decades to become truly proficient. As it is my results aren't ready for the light of day.

A great ura isn’t a simple radius, but a complex grind in itself. The radius should be smaller the closer you get to the edge and shallower in the middle. This will help with sharpening over time and the ura will stay thin longer. Achieving a very even extremely thin sharpened area is immensely challenging and perhaps the greatest feat in knife-grinding I know of.

Oh, and you’ll spend more time straightening than sharpening from my limited experience.

This video is a great place to start for a more detailed explanation.

 

[Guirotin]

Uneven radius ! My god...
Thanks so much for these explanations ! I'll have a look at this video.