Millstone

The Mill Stone is one of the first machines the player should generally make. It is used to process a variety of materials. It has three input slots and will process one item at a time from right to left. It will drop the output items on the ground nearby when it is finished processing. It is powered through Mechanical Power, most particularly the Hand Crank in the early game and a Windmill after.

Its progress can be seen in the bar in its GUI by the Wooden Gear, which slowly fills up as the item is processed. It will emit smoke from the top of the block when it is finished.

Main Uses:

Grinding hemp into plant fibers and durable fibers
Grinding wheat into flour which can then be turned into bread.
Grinding spectral silt and fallen stars to make magic powder.
Grinding leather into scoured leather.
Grinding netherrack into ground netherrack which can be used to create hellfire dust and create braziers.
Grinding down flowers and mushrooms to most efficiently obtain dyes and powders.

Notes[edit]

The Millstone is the most efficient grinding tool before the industrial era, beating even its horse-operated variant.
Mechanical power also includes the Watermill, but that requires saws and glue to make.