Recommendation? Blade grind discussion thread

Status
Not open for further replies.
B

bigstevek

Joined
Dec 24, 2024
Messages
19
I searched but didn't find much in the way of a comprehensive discussion, so here goes. What are the advantages and disadvantages of the different blade grinds? I particularly like saber (Sabre?) grinds, but I also have flat, scandi, and hollow-ground knives, but no convex. I know each has its place, but what do you prefer or like, and why? Photos would be lovely!!!
 
Saber is Strong, easy to make, but Clunky
Flat slices, might be easier for makers to make too?
Scandi are overrated.
Hollow is pretty good/ok

I like convex, or more closely flat to convex.
Slices great, but strong edge. Easy to maintain
 
I tend to lean toward the flat/convex hybrid edge. A wise forum elder who has since passed/walked west used to say that all knives that are sharpened free-hand basically end up convexed. As you move the stone, you find the edge. If you finish this edge with a strop, it's going to convex at least a little bit.

It's one of my favorite edges with flat being a strong second.
 
A.L. said:
Unpopular opinion:
Convex is just rounded vs straight. Might be strong, might be weak. Depends.
Click to expand...

If I'm chopping, sight unseen, I'll take a convex every time. :)

Might be weak, but generally has a better chance of being strong even in a "primitive" recycled steel, but that is my heavily biased and clutched to opinion of 20+ years of swinging khukuris.

I still concur with your point, though 👍
 
So...here is my take. It depends. I used to prefer full flat, and still do for the most part. However, I have been experimenting with a very shallow hollow grind at full height, ground on a 27 inch radius platen. Essentially a flat grind with a bit more material removed in the center. Offers the benefit of a full flat with a reduction in material where medium like meat or vegetable matter might get hung up. Has become my favored grind for edc.

And it looks good.
 
Last edited:
Synov said:
Airplane wings are designed to produce lift and minimize drag by deflecting air flow, not just slicing through air. Neither are applicable to cutting solid material.
Click to expand...

Uhhhhhm?
 
In the grand scheme of things, I really only need a sharp blade. I can adapt to just about any blade grind but here lately, I have been appreciating thin full flat ground blades.

I don’t need them but I sure do like them.
 
Crag the Brewer said:
Uhhhhhm?
Click to expand...
Drag is force of the air against the direction of flight, produced mainly by turbulent flow at the end of the wing, which is why wings don't just end abruptly in a vertical surface like a knife. Solid material doesn't flow so turbulence is not a concern. The closest thing to drag would be friction from material sliding along the surface of the knife. A convex grind can lower friction if the material being cut only touches part of the curve instead of the full flat surface. But the convex grind also increases the amount of force needed to cut, so it's a balancing act between thinness behind the edge and friction.

Because you are usually holding the material being cut with your non-dominant hand and holding the knife with your dominant hand, some advanced kitchen knives have an asymmetrical grind that is thinner and flatter on your non-dominant side, where the material is going to be pushed against the knife anyway, and more convex on the dominant side to reduce friction with the freely moving material.

Lift means the material above and below the wing are providing a force moving the wing up, something you probably don't want happening to your knife. This is why the front of wings are convex rather than wedges. The intent is to divert the air, not just cut through it. HOWEVER, in the case of the advanced kitchen knives discussed above, the asymmetrical grind can actually produce an analogous force that steers the blade to the non-dominant side since there is more deflection off the curve of the more convex (dominant) side. This is corrected by making the dominant side bevel shorter and more acute than the non-dominant side bevel, which steers the knife to the dominant side, counteracting the "lift."

In conclusion, knives are generally not designed like airplane wings. Some kitchen knives have analogous design principles to lift and drag, but these are irrelevant for most cutting tasks, which are more about balancing thinness behind the edge vs. strength of the knife. Hollow grind, flat grind, and convex grind offer different balances of those properties so all are relevant depending on the task. There is no best one.
 
Last edited:
Unsolicited opinions

Best all around performance - Full Convex Zero ( once you understand how easy it is to sharpen ).

Flat or Saber with a convex secondary is great.

Scandi - vex on thin stock ( 1/8 to 3/32 ) is fun to use as well.

Every knife I own winds up with a convex secondary after 2 or 3 sharpening sessions.. I love the way a convex glides through materials.
 
Status
Not open for further replies.
Back
Top