How hammers are made

People used hammers 3.3 million years ago, long before any metal ones.

stations: 8
things upstream: 62
raw sources: 21
steps from the ground: 10

The short version

Toolmakers cut a steel bar to length and forge it hot, at 1200 to 1300 °C in one account, in shaped dies. A trimming tool removes flash, and broaching sets the size. Induction heating hardens only the striking face, and electrostatic coating protects the surface. A wooden handle is lathe turned, pushed through the eye and spread with a wedge.

Cut and heat the bar

The bar is cut to an optimum length that wastes little steel, then heated to 1200 to 1300 °C.

1200-1300 °C

Goes in
Steel
Forge in dies

One die is fixed and the other drives down on a piston, often in stages with several shapes. Forging keeps the steel's grain unbroken, which helps a part that takes repeated blows.
Trim the flash

A special trimming tool shears off the surplus metal around the forging while keeping the scrap as light as possible.
Broach to size

Broaching takes the forging to its correct size.
Induction harden the face

Local heating and tempering at the impact surface give that spot a high hardness while the rest stays tougher, for a longer service life.
Coat the surface

Electrostatic coating protects the steel from rust.

Goes in
Paint
Turn the handle

Selected ash is cut to size, turned on a lathe, polished and protected. Steel-handled hammers instead use a rod pressed through a shaped hole.

Goes in
Lumber
Wedge in the handle

The wood is pushed up through the eye of the head and a wedge is driven in to spread it tight.

End of the lineHammer

Worth repeating

Stone hammers date to around 3.3 million years ago, found at a site near Kenya's Lake Turkana.
A hammer's steel head is springy on purpose, since that elasticity helps pass the energy of the swing into the nail.
The claw hammer is the type most often found in North American households.