Granite millstones runner and base

Granite millstones consist of two main parts: the runner stone (top stone) and the base stone (bottom stone), traditionally used in grain mills for grinding wheat, corn, or other grains into flour. Here’s a breakdown of their roles and characteristics:

1. Runner Stone (Top Stone)

• Function: Rotates atop the base stone, driven by wind, water, or animal power.
• Design:

– Usually slightly concave or convex to control grain flow.
– Has a central hole (eye) where grain is fed.
– Carved furrows (harps) radiate outward to channel ground flour to the edges.

• Material: Dense granite for durability and effective grinding.

2. Base Stone (Bed Stone or Bottom Stone)

• Function: Remains stationary while supporting the runner stone’s grinding action.
• Design:

– Often flatter than the runner stone but may have complementary patterns.
– Furrows help direct flour outward for collection.

• Material: Also granite, sometimes slightly harder than the runner stone to minimize wear.

Key Features

• Balance & Alignment: Critical for smooth operation; stones must be precisely dressed (maintained).
• Furrow Patterns: Vary by region and grain type—common designs include quarter dress, sickle dress, or radial patterns.
• Tapered Gap: Adjustable distance between stones controls fineness of flour.



Historical Use

• Powered by watermills (water-powered millstones) or windmills.
• Later replaced by steel rollers in industrial milling but still valued in artisanal production.

Would you like details on maintenance (dressing millstones) or how they compare to modern milling methods?