Crank-driven rotary grindstone
Muela de afilar giratoria con manivela
- Date
- c. 830 · confidence medium
- Place
- Hautvillers, Marne, France
- Credited to
- Carolingian craftsmen (Utrecht Psalter miniature)
- Field
- Tools
⚠️ Disputed: the sources disagree.
What it is
A circular stone turning on an axle with a crank worked by an assistant, leaving the sharpener both hands free to hold the blade. The Utrecht Psalter illustration, made near Reims around 830, is the earliest known image of a continuous-rotation crank in Europe.
The Utrecht Psalter miniature may copy a late antique model; rotary grindstones and hand cranks existed earlier in China and the Mediterranean world, so the date is an upper bound for Europe.
What it led to
- rapid, regular sharpening of sickles, axes and knives
- the crank as a continuous-rotation mechanism in medieval mechanics
- pedal and water-driven grindstones in workshops