Cleaving axe

A cleaving axe or cleaver is a form of axe used within green woodworking to split wood lengthways. Cleaving (riving) is used to turn a log into lumber or billets (short or thick pieces of wood) into firewood. Splitting axe is sometimes described as an old name for a splitting maul or froe.

A cleaving axe resembles a felling axe but is heavier, more wedge shaped, not sharp-edged and the pole is flat for driving wedges. The edge is of medium length, almost straight with just a slight camber, and symmetrical top and bottom. A section through the edge is that of a simple splitting wedge. The edge itself does not need to be sharp: cleaving relies more on wedge action than chopping (cutting) with an edge. The section of the axe should be triangular though, with flat sides, rather than the deeply hollow-sided forged and welded axes, or the modern convex-sided "apple pip" axe grind. Nor should the edge be ground at a bevel. The work of using the axe, and its ability to split cleanly, depends on having flat sides with the minimum of friction, rather than all the force of the timber being concentrated on one protruding line. The handle is straight and fairly short, around 18 inches, as the cleaving axe is only held, not swung. As the axe head must penetrate fully into the wood, the poll is minimal, narrower than the axe cheeks, and is never used for pounding other tools, lest it damage or mushroom the head.

Cleaving is done by driving a wedge between the fibres of a log, so as to split fibres apart along their weakest path. This work may appear strenuous, but is far less effort than rip sawing by hand. It is first done radially, to split the log into wedged segments. Timbers with medullary rays, such as oak, may be hard to split through these radial rays and so careful alignment is made to split between them. Segments are halved symmetrically at each step, as this encourages them to split more evenly than attempting to cleave off thin sheets repeatedly from one end.

...
Wikipedia