Brief description

Wheel construction, or wheelwrighting, is the craft of building and repairing wooden wheels. While a solid wheel is simple to make, the spoked wheel is a complex engineering feat that requires precise joinery, understanding of wood properties, and metalworking skills to create a lightweight yet strong structure capable of bearing heavy loads over rough terrain.

Use / Function

• Manufacturing: Producing wheels for carts, wagons, and chariots.
• Repair: Maintaining wheels that have been damaged by wear or impact.
• Optimization: Creating wheels specific to the load and terrain (e.g., wide rims for mud, large diameter for speed).

Operating principle

A spoked wheel acts as a suspension system in tension and compression.

• Compression: The weight of the vehicle travels down the spokes from the hub to the ground.
• Tension: The metal tire, when shrunk onto the rim, compresses all wooden components together, holding them tight without glue.
• Dishing: Spoked wheels are often “dished” (cone-shaped) to resist lateral forces when the vehicle sways.

How to create it

The Spoked Wheel Process

1. The Hub (Nave):
   • Turn a block of seasoned elm (resistant to splitting) on a lathe.
   • Mortise holes for the spokes. These must be staggered to prevent the hub from cracking.
2. The Spokes:
   • Shape straight-grained oak into spokes.
   • Drive them into the hub with a heavy hammer. They must fit perfectly to avoid wobbling.
3. The Rim (Felloes):
   • Cut curved sections (felloes) from ash or bend straight wood using steam.
   • Drill holes in the felloes to accept the ends of the spokes (tangs).
   • Fit the felloes onto the spokes to form a complete circle.
4. The Tire (Straking/Hooping):
   • Strakes: Nail separate curved iron plates across the joints of the felloes (older method).
   • Hoop: Forge a continuous iron ring slightly smaller than the wooden wheel.
   • Heat the iron tire to expand it.
   • Place the hot tire over the wooden wheel and immediately quench it with water.
   • The cooling iron shrinks, pulling the felloes, spokes, and hub tightly together.

Materials needed

• Hub: Elm (doesn’t split easily).
• Spokes: Oak (strong in compression).
• Rim: Ash (flexible and resilient).
• Tire: Iron (durable).
• Tools: Lathe, spoke shave, adze, traveler (for measuring circumference), forge.

Variants and improvements

• Solid Wheel: Three planks pegged together and cut into a circle. Heavy and prone to breaking across the grain.
• Dished Wheel: Spokes are angled outwards to provide lateral stability.
• Suspension Wheel: (Modern bicycle wheel) Spokes are wire and under tension, hanging the hub from the top of the rim.

Limits and risks

• Wood Movement: Wood expands and contracts with humidity. A wheel built in damp conditions may become loose in dry weather.
• Tire Failure: If the tire stretches or breaks, the entire wheel can disintegrate.
• Rot: Constant exposure to mud and water can rot the wood, especially at the joints.