Hammers are used to work metals on an anvil, smash Chalk, Dolomite, Limestone, Marble stones and Borax to create flux and to use the chisel to work the different stones (Both the hammer and the chisel must be in the hotbar. When using the hammer with the chisel, it does not take damage, unlike with the chisel). Hammers may also be used to break logs, yielding 1-3 sticks.
Hammer heads can also be crafted by using ingots on an anvil with a hammer. This is the only option for higher tier metals that cannot be cast. The durability depends both on the metal used and the skill of the smith forging the tool.