An old carpenter’s trick to keep nails from bending when they are pounded into hard materials is to grip the center of the nail firmly with pliers. Why does this help?
We are required to find out any advantage if a nail is held at the middle with a plier while pounding them into a hard material.
If the hammer used to hit the nail strikes the latter at a certain angle, the nail may bend from a straight position. This bending will cause shear strain on the same. If a plier is used, the bending possibility is reduced, thereby reducing the possibility of a shear strain. The nail would mostly remain straight while getting into the hard material.
Moreover, holding the nail at the middle would provide it an equilibrium state so that it is not damaged or broken during being hit by a hammer.