When nailing a nail, the carpenter will beat the round head of the nail before nailing it. Why?

When nailing a nail, the carpenter will beat the round head of the nail before nailing it. Why? Some relatives do carpentry and often make cabinets and desks for people. The frame is tenon-mortise structure, but sometimes some plates are nailed without inlay. Very impressive. The carpenter has a nail in one hand and a hammer in the other. When he put the nail cap on the anvil, he beat the nail cap with a hammer until the thickness is almost the same as the diameter of the nail rod, and then nailed it into the furniture (now the carpenter is much happier, and the nail caps of the air-row nails are all flat).

The purpose of doing this is clear. In order to nail all the nails into furniture, even use the elasticity of wood to nail the nails deeper than the surface of wood. Then put putty on it, sand it with sandpaper, and paint it. There's not a trace of nails. If you don't nail it in, there will be a protruding part at the nail.

As for why we should knock it flat before using it, this involves the problem of pressure. According to the pressure formula p = f/s, the pressure is constant, and the smaller the stress area, the greater the pressure. The contact area between nails and wood is less than half of the original, so the pressure generated by nailing nails with the same force is obviously increased, and it is easier to nail the nail cap into wood. I don't know if you nailed the nail. If you don't smash the nail cap flat, it's difficult to drive the nail cap into the wood, but you can't increase the impact too much, which may damage the furniture and outweigh the benefits.

In addition, I don't know if you have noticed that the master who repairs shoes in the street sometimes smashes the nail cap before nailing, and finally hammer the nail again with a chisel, so that the nail is completely submerged in the palm of the shoe. The purpose is to prevent the pulling force of nails on shoes and soles from falling off after the nail cap is worn off when walking.

It doesn't have to depend on what is nailed. If flattening is needed, it is usually on the nail surface. After flattening, it will hit below the plane, so the putty will be very flat. .......