Types of cutting shafts and fastening of knives on wood shredders.

Option I.
The knife shaft has a square or triangular cross section. The side of a square or triangle is formed by a "chord" of a circle. Knives are pressed to the side of a square or triangle and fixed with bolts.

Manufacturers:

Nadkov - Czech Republic

Rebaki-24 - Poland

Kukucka - Poland

Pulley - Ukraine

Grizzlies - Ukraine

RUBIN - Russia

BENEFITS
The knife begins to cut into the wood at an angle greater than 90֯   (ideally 90֯   - perpendicular to the wood).

DISADVANTAGES
Large amount of machining (milling).
The knife is larger (more expensive). As a result, the cost is higher.

Option II
The knife shaft has a cross section in the shape of a circle. Knives are inserted into the grooves. In a body of a shaft as well as in the first case, fasten bolts.

Manufacturers:

Urban - Czech Republic

Arpal - Ukraine

That is, Option I and II have the same method of attachment to the shaft with bolts. But they have a difference - the location of the knife relative to the axis of rotation of the shaft.

BENEFITS
Smaller volume of machining (milling).
The knife has a smaller size (lower cost). As a result, the cost is lower.
DISADVANTAGES
The knife does not crash, but begins to press the back of the wood (smaller than in Option I, the angle of contact with the wood).

Manufacturers themselves decide which option to use in the production of wood chippers. One of the manufacturers (Option II) in the description of his product indicates “The design of the working shafts greatly increases the working torque transmitted from the drive to the shredder blades. And unlike a square shaft, the load is perceived not by the knife but by the body of the shaft itself, as a result of which the service life of the cutting element is much higher. This is nothing more than an advertising slogan. If the advantages praised in this advertisement were so "much" obvious, the engineers of the manufacturers listed in Option I would have long ago abandoned the "square" shafts. But for some reason they (engineers) are in a hurry to do it.