Brief description

A mechanical device used to harvest cereal crops such as wheat, oats, and barley. It automates the process of cutting the stalks, which was traditionally done by hand with a scythe or sickle.

Use / Function

Primary use: Harvesting grain crops at scale.
Secondary uses: Reducing labor requirements during harvest time.
Scale: Industrial/Agricultural.

Operating principle

The reaper uses a reciprocating cutting bar that shears the stalks as the machine is pulled or pushed through the field.

Reciprocating Motion: A blade with triangular teeth moves back and forth through stationary guards.
Reel: A rotating reel pushes the standing grain toward the cutting bar and then onto a platform.
Platform: Once cut, the stalks fall onto a platform to be gathered and bound.

How to create it

Level: Intermediate/Advanced.
Mechanism: Requires a way to convert the rotation of the wheels (as it is pulled by a horse or tractor) into the reciprocating motion of the cutting bar (using a pitman arm or crankshaft).
Cutting Bar: Made of sharp steel sections.

Materials needed

Essential materials: Steel (for blades), Wood (for frame and reel), Iron (for gears and shafts).
Tools: Forge, woodworking tools, metalworking tools.

Variants and improvements

McCormick Reaper: One of the earliest successful mechanical reapers.
Self-binding Reaper: Later versions that not only cut but also bound the grain into sheaves.
Combine Harvester: Modern version that reaps, threshes, and winnows in one operation.

Limits and risks

Terrain: Requires relatively flat ground.
Maintenance: The cutting blades must be kept sharp and the moving parts well-lubricated.
Safety: Moving blades and gears pose a significant risk of injury.