Blade morphology. Grinding types 2.

Blade morohology

-Grind types 2-

Let's see the main features of each type of grinding, the most common that we can find in the global cutlery:

Partial flat ground

Partial flat ground goes straight from the beginning of the grinding to the edge, in this case it is partial because not drop from the back of the blade, this method ensures that we have a great strength as there is a lot of material on top of the blade to withstand stress and effort, but also you are going removing the blade material smoothly, straight up to the edge. This grinding finds the strength cutting. While we think that the sharpening angle will give us the ability to actually cut, which is true, it remains also true that once introduced the blade material through the edge it will not slide as easily depending on how thin is the material, creating the "wedge effect" that prevents progress.

It is clear that for each millimeter of the blade that penetrates the material when you cut, if the angle of the blade material is greater will be harder than it can move forward.

This type of grinding would be good for a knife or survival tactic for very hard work, some leverage, wood or even “batoning” but carefully, because with folder knives is not recommended practice this technique, especially locked.

Although a knife or a folder knife, if it is sharp, is always going to cut is no less certain that the type of the grinding influences a lot in the tasks. Can we peel fruit with this grinding? sure, but is not the most appropriate, especially if the thickness of back is very large (thick). Thin slices of tomatoes (is a typical example for the tough skin they have)? for again depending on the thickness of back I have not so clear that it can be done correctly, remember the "wedge effect" when it comes to the width of the blade where we find that the grinding ends and how it has separated the two sides cut.

Partial flat ground blade detail

Hollow grind

This type is trying to combine strength with cutting power so that we have a part of the blade without grinding to a certain height in which begins the grinding, that is produced as if we faced two wheels of a mill (that was the way to do this once). That makes the edge to slide more easily in the element, but having less material than the previous example, the partial flat gorund, it is much more fragile. It is not recommended to do “batoning” with this type of blade as it could nicked if the material is hard or if the wood had an internal knot or break when not withstand the stresses that occur.

Therefore this type of blade would not be advisable to use it for very hard tasks, to hit or “batoning” but simply to cut, which will do fine, but also we will find a wedge effect when the part of the grinding end and start without grinding the back of the blade, but the concave area should be sufficient to cut most things.

But if the blade has a sufficient thickness it is not going to have problems for more difficult tasks, but it will never be as strong as a partial or full flat ground or a convex one, especially near the edge that is where less blade material has a hollow grind.

Brands like Muela or Cudeman have much of their models with this grinding.

Partial flat ground blade detail

Full flat ground

In fact, this type of grinding is one of the oldest and we can see in many non tactical knives, multipurpose etc, and it consists of a straight line from back to edge. It provides strength because it has more material than the hollow grind in the cut (although less material on top) and also has no wedge effect thus cutting big things never will be unable to advance, in theory at least. Almost all serious kitchen knives have this type of grinding to allow the maximum smoothness in cutting food. While it is not so easy to find in tactical knives, most prone to partial flat grindings. Curiously it is easier to find these full flat grounds on survival knives that on survival folder knives, although brands like Spyderco have many models with this type of blade.

Its use can be of many types, of course for culinary tasks, but also kind of survival, without  "wedge effect" when you are making "batoning" on wood. And it is certainly one of the most appreciated grindings by many people in the world.

Full flat ground blade detail

Convex grind

Undoubtedly the greatest strength and more material, drawing a curve on the sheet outward rather than inward as would a hollow grind, just the opposit. The problem is that this gives us more difficult to penetrate the element to cut, n addition to sharpening it is more complicated because the blade does not end in a final edge, but it cuts with the end of the grinding and it does not serve us the normal sharpening techniques in stone.

Scandi grind

Its name comes from "Scandinavian" and is a type of grinding typical on nordic manufacturing knives, In it, the grinding is similar to the partial flat ground but it does not end in a final bezel (self edge) like the others, but simply that grinding when reaches the end makes the edge, like if it was a triangle upside down.

It is famous for its cutting power, plus if you sharpen with the stone sharpening at hand you must not keep any sharp angle, enough to support the side of the blade and devastate, because as we have mentioned, there is no bevel end.

Probably the most famous knife in the world with this grinding type is Mora of Sweden (Morakniv).

Conclusion

No grinding is bad, we simply have to choose the one that suits what we're going to do, if you care about most is to cut you'll probably want a hollow grind, if you want more strength and do not want "wedge effect" you're going to want a full flat grind. If more strength is needed and do not mind the "wedge effect" you’ll want a partial flat grind or convex grind.

Also comment that not everything is the grinding, because of course if we have a “hollow grind” on a 5 mm blade thick, you can not say that it will be weaker than a blade with “full flat grind” with 2 mm thick… and even if they had the same thickness, depend on the flexibility, the type of steel, if it’s stainless steel, carbón steel... We can not be guided only by the type of grinding on a blade.

Therefore, all are good for what they were designed, it just comes to choosing correctly. Would you choose a sport car to go dirt roads and stones on the field? No. And an "all terrain" for racing circuit? No. Everything is conceived and designed for something.

Note: each grinding can have multiple interpretations and variants, varying the angle of grinding or have second bevels before reaching the edge, to create stronger, although these second bezels are usually given on tools like chisels and not cutting blades.