Brief description

A machine used to separate grain from the stalks and husks on which it grows. It replaced the manual process of beating the grain with a flail.

Use / Function

• Primary use: Separating grain (wheat, rye, etc.) from its straw and chaff.
• Secondary uses: Cleaning seeds.
• Scale: Industrial/Agricultural.

Operating principle

The machine works by feeding the crop through a rotating cylinder and a stationary concave.

1. Feeding: The cut stalks are fed into the machine.
2. Beating: A rotating drum with pegs or rasps beats the grain against a concave surface, loosening the kernels.
3. Separation: The grain and chaff fall through a screen, while the straw is moved along and discharged.
4. Winnowing: A fan blows air through the falling grain and chaff, blowing away the lighter chaff and leaving the clean grain.

How to create it

• Level: Advanced.
• Mechanism: Requires a rotating drum and a system of sieves and fans.
• Power: Historically powered by hand, horses (using a horse power), or steam engines.

Materials needed

• Essential materials: Wood (for frame), Steel (for the drum and screens), Iron (for bearings and gears).
• Tools: Forge, woodworking tools, metalworking tools.

Variants and improvements

• Meikle’s Threshing Machine: One of the first successful designs (1786).
• Combine Harvester: Integrated the threshing machine with the reaper.

Limits and risks

• Complexity: Many moving parts that can fail.
• Fire Risk: Dust and friction can lead to fires.
• Safety: Extremely dangerous; hands or limbs can be caught in the rotating drum.