Sharpening hollows in long flat blades

scott kozub

scott kozub

Joined
Jan 1, 2018
Messages
861
At this point I've made about a dozen knifes. I'm learning with each one and try to do something new on each knife.

One thing I have trouble with is flat edges. One of the first blades I made was a nikiri with a flat bottom thinking it'd be great for chopping vegetables. When sharpening it I kept getting hollows in the middle of the blade. I'm sharpening on a jig but I think the issue may be from a slightly inconsistent bte thickness. Even a .002 of seems to cause problems. I don't have any issue with even slightly curved blades.

Any tips?
 
I am not sure I understand what you mean by getting hollows. Pictures would help.
So your kitchen knife is flat ground and has a straight edge...if you mean that when you sharpen it you don't get a straight line on your edge the reason could simply be that some sections of your blade are thinner than the others...meaning that you have an uneven grind.
 
i think he means when he has the knife flat on a cutting board, he can look from the side and see light between the middle of the blade and the cutting board. a very slight curve would insure that the whole knife edge will contact the board with a rocking/cutting motion.
 
john april said:
i think he means when he has the knife flat on a cutting board, he can look from the side and see light between the middle of the blade and the cutting board. a very slight curve would insure that the whole knife edge will contact the board with a rocking/cutting motion.
Click to expand...
Ya this is what I meant. Repofiled the edge to slightly increase the curve and took more care sharpening.
 
It is human nature to apply less pressure at the beginning and end of the sharpening stroke. Try and avoid that. Wider stones or diamond plates helps, too. If belt sharpening, it is easy to over sharpen the center and make the "hollow edge" you have. Start with a slight curve to the edge and it will end up straighter. On some blades where the edge needs to be very straight, I sharpen vertically on the flat platen.
 
If your using a wicked edge or something close, I've found using smaller movements perpendicular to the cutting edge rather than parallel with the cutting edge helps with what your describing. You can then be sure to apply even pressure throughout.

However if your edge is thinner in the middle from grinding, try to be sure to "color" in the lines. You should scribe your grind lines and be sure not to cross them. Much easier said than done but achievable.
 
You must log in or register to reply here.
Back
Top