Why does a sharp nail split wood and a blunt one wont?



I have always been taught when putting a nail into wood which could split, you should tap the point of the nail to dull it first. I have done this enough to say it works. A blunt nail will not split wood when a sharp one will.

In: Physics

Think of wood like a bundle of tubes. Tree vascular tissue (generally) all runs one way (knots are where branches were and curves are natural as not all trees are straight), which is why wood splits in one direction.

In really simple terms, a sharp nail forces between the fibers of the wood which forces them apart. Blunt nails break some of the fibers while still retaining enough pressure to hold in the wood.

The sharp nail acts like a wedge almost like a tiny splitting axe. A blunt nail acts as a whole puncher.