One Grind to Cut Them All?

[golok]

Sometimes, a collector sees an uncommon combination of grinds on a single blade.

Apart from aesthetics, it is presumed that the grinds do serve some purpose. This issue begs the question: What type of grind is best for ordinary usage. Specifically, maybe office work and to a certain extent, household chores.

I understand that with certain grinds, penetration is more effective to a large degree. Then, there are the other grinds. Some of them look unusual, probably are, but to what purpose.

Has a classification been done to make clear to knife knuts as to what types of grinds are best for what purposes?

 

[Cliff Stamp]

golok :

For such a light use knife, you want something completely optomized for light cutting. A full spine to edge flat grind would give very high cutting performance, but be hard to sharpen as you would need to hone the entire bevel. If you lightly convex the edge, or add a distinct secondary edge bevel, this would speed up sharpening significantly, but of course reduce cutting ability. The ultimate geometry for that type of use is a full hollow relief grind (not the "T" hollow grind) from spine to edge, with the blade then sharpened flat to the hone. This has greater cutting ability than the full flat grind, and sharpens faster than a full flat grind with the secondary edge bevel. It also has the benefit of a built in angle guide.

In understanding the performance of the grinds, realize that hollow and convex are at the extreme ends of the spectrum with flat grinds being a compromise between them. For example, *on the same stock*, a convex grind is far stronger than a hollow, and flat is in the middle. In regards to the cutting performance of those blades, the hollow grind will get better penetration, then the flat and then the convex. In regards to taking side impacts or shocks, it is convex, flat and then hollow. In regards to edge prying, you want convex, flat and then hollow. In regards to eliminating wedging or binding in soft woods you want convex, flat and then hollow. Which grind on which blade depends on the performance you want. There will always be tradeoffs as each grind has areas where it outperforms the others.

Complications arise when you combine the grinds. For example a hard wood cutting axe has a convex edge to handle the twisting and hard impacts such a tool can take in use. It has a large hollow relief in the main body to aid in enhancing penetration, as if the convex grind was carried all the way to the eye, the axe would never go far into the wood. The same axe works poorly on soft woods, because the penetration will be too high and it wil stick. Soft wood axes are comvex grind all the way because they don't need to worry about penetration but binding is the critical problem. Splitting mauls are ground the same way, but even thicker as they have the same problem but are used with far more force as gravity enhances their swings so the impacts are heavier, but hampers felling axe use.

-Cliff