Solid Wheels

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The Wheel
Solid to spoked design
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Solid Wheels
First wheels from planks

Solid Wheels

Part of Roads and Transport

Building functional solid disc wheels from planks — the first wheeled vehicle technology.

Why This Matters

The wheel is one of the most significant inventions in human history, and solid disc wheels were its first form. Invented around 3500 BCE, solid wooden wheels enabled the first wheeled transport, reducing the labor required to move goods by a factor of five to ten compared to carrying or dragging. Before the wheel, everything that moved had to be carried — after the wheel, one person with an ox could move what ten people struggled to carry.

Solid wheels are heavier and less efficient than spoked wheels, but they offer important advantages for a rebuilding community: they can be built with minimal tools, require no bending steam, use no complex joinery, and can be constructed by any competent woodworker. They are not the final answer in wheel technology, but they are the starting point from which spoked wheels evolved, and for slow, heavy work on rough ground, a solid wheel is perfectly adequate.

Understanding solid wheel construction also teaches the fundamentals that apply to all wheel design: the importance of grain orientation, the hub as the critical structural element, the need for a hardwood rim contact surface, and the role of metal reinforcement in extending wheel life.

Wood Selection

Wood choice determines the strength and longevity of a solid wheel.

Best species for wheel blanks:

  • Elm: The traditional choice for wheel hubs and solid wheels. Has interlocked grain that resists splitting under repeated impact. Tough and shock-resistant even when seasoned.
  • Oak: Dense, strong, and widely available. Tends to split more than elm at the hub, but excellent for the rim portion.
  • Ash: Excellent shock resistance. The grain can be matched to the stress directions.
  • Hickory: Very tough, used extensively for wheel spokes and hubs.
  • Hard maple: Dense, hard wearing surface, good for wheels with metal tire.

Avoid:

  • Pine and other softwoods: Too soft, wear too quickly, compress under heavy loads
  • Poplar: Too light and weak
  • Green (unseasoned) wood: Will check (crack) and change dimensions as it dries after construction

Seasoning: Wood for wheel-making should be seasoned for at least 12-18 months (air-dried under cover, not in sun). Kiln drying is faster but requires equipment. Unseasoned wood will dry after construction, causing cracking, loosening of joints, and dimensional changes that throw the wheel out of round.

The Three-Plank Design

The earliest solid wheels were made by edge-joining three planks into a square panel, then cutting a circle from the panel. This approach:

  • Uses planks from the available lumber supply
  • Avoids the cracking problems of a single large cross-cut disc
  • Allows the grain of each plank to run in different directions, reducing the risk of a single-plane split failing the wheel

The problem with single-plank wheels: If you cut a wheel from a single slab, the grain runs in one direction. The quarter of the wheel where the grain runs perpendicular to the load is vulnerable to splitting through the grain under impact. A three-plank laminated wheel distributes this vulnerability.

Plank orientation: Set the center plank with grain running vertically (12 o’clock to 6 o’clock). Set the outer planks with grain running diagonally (roughly 10-2 and 8-4 positions). This cross-grain arrangement distributes stresses.

Construction: Step by Step

Preparing the Planks

  1. Select three planks of seasoned hardwood, each approximately 40 cm wide, 5-8 cm thick, and long enough for the intended wheel diameter plus 10 cm margin.

  2. True the joining edges. The planks must be jointed (planed flat) on the edges that will contact each other. Any gap in the joint creates a weak point. Use a jointing plane (or a carefully positioned flat stone as a surface plate) to ensure the edges are straight and square.

  3. Mark and drill dowel holes. To align and reinforce the joints, drill holes 2-3 cm in diameter every 15-20 cm along each joint. Holes must be precisely aligned between the mating planks — use a marking gauge to ensure they match.

  4. Cut hardwood dowels. Slightly larger than the hole diameter so they require light hammer blows to drive in. Each dowel should be 3-4 cm shorter than the combined depth of the mating holes (this allows for glue expansion and prevents the dowels from bottoming out).

Gluing and Assembly

  1. Prepare glue. Traditional woodworking glue: hide glue (made by boiling animal hides and hooves until gelatinous, then allowing to dry into cakes, then remelting in a double boiler for application). Applied hot. Sets by cooling, not chemical reaction. Strong enough for most woodworking. Alternatively, fish glue from fish heads and bones.

  2. Assemble the panel. Apply glue to all mating surfaces and dowel holes. Drive dowels into one plank. Align and bring the mating plank together. Clamp tightly with wooden wedge clamps or stone weights. Allow full cure time (24-48 hours for hide glue).

  3. Assemble the third plank to the opposite side of the center plank with the same procedure.

  4. Allow the full panel to cure under clamping pressure for 48 hours.

Marking and Cutting the Wheel Disc

  1. Find the center. Draw diagonal lines from corner to corner of the assembled panel — their intersection is the center.

  2. Scribe the circle. Drive a small nail or peg into the center. Tie a string to the peg and to a marking tool (a nail or scriber). The string length equals the wheel radius. Draw the circle.

  3. Mark the hub hole. The hub hole (for the axle) is typically 5-8 cm in diameter for a light cart, 8-12 cm for a heavy vehicle. Mark it precisely at the center.

  4. Cut the outer circle. Use a frame saw or large bowsaw to cut along the marked circle. Cut slightly outside the line (5-10 mm) — you will refine the edge afterward.

  5. Drill or chop the hub hole. For a round axle, drill and ream to the correct diameter. For a square axle (traditional), chop a square mortise with a chisel. The fit should be snug — 1 mm clearance for a fixed axle wheel bearing on a greased axle.

Shaping and Finishing

  1. Refine the rim. Use a drawknife, spoke shave, or adze to smooth the outer rim to the marked circle. Check roundness by placing the wheel on a flat surface and rotating it — any wobble indicates a high spot to remove.

  2. Check for run-out. A wheel that has areas of higher or lower thickness (axial run-out) will wobble side to side when rolling. Check by mounting the wheel on an axle and spinning it — the wheel face should remain in a flat plane.

  3. Chamfer the rim edges. Remove sharp corners on both rim faces with a drawknife. Sharp edges chip and splinter on gravel roads.

  4. Dry-fit on the axle. Before adding any metal reinforcement, verify the wheel spins freely on the axle and that the hub hole is correctly sized.

Hub Reinforcement

The hub is the highest-stress point on a solid wheel. The axle hole concentrates stress here, and the wood surrounding the hole is prone to splitting under heavy loads or side impacts.

Iron hub liner (recommended):

  1. Forge or find an iron pipe or ring that fits inside the hub hole
  2. The liner should be 3-4 cm shorter than the wheel thickness
  3. Drive it in with a hammer — it should seat tightly
  4. This iron sleeve protects the wood from wear and reduces friction

Wooden hub ring (simpler alternative):

  1. Cut a ring of much denser hardwood than the wheel blank (ironwood, boxwood, lignum vitae)
  2. Turn or file the outside diameter to match the hub hole diameter
  3. Drive in with glue — the denser wood provides a better bearing surface

Rim Protection

Without protection, the wooden rim wears rapidly on gravel roads and at ruts and rocks. Even without full iron tires, add basic protection.

Rawhide wrapping: Wet rawhide strips wrapped around the rim and allowed to dry shrink tightly onto the wood. Provides some protection and significantly reduces splitting. Must be replaced every season.

Iron tire: The definitive rim protection — see Metal Tires for the shrink-fitting process. An iron tire transforms a solid wheel from a seasonal consumable into a multi-year component.

Nailed iron strap: As an alternative to a full shrink-fit tire, nail segments of flat iron bar around the rim circumference. Less effective than a continuous tire but achievable without a forge large enough to heat a full tire.

Limitations and When to Upgrade

Solid wheels are appropriate for:

  • First-generation carts where no spoked-wheel capability exists yet
  • Very slow, heavy work (dragging stone, heavy hauling at walking pace)
  • Temporary or emergency vehicles
  • Small diameter wheels (under 60 cm) where weight is less critical

Solid wheels are inadequate for:

  • Fast travel (heavy wheel requires more energy to accelerate and maintain speed)
  • Long distances (rolling resistance is higher with heavier wheels)
  • Rough roads (no flex in the structure means shocks transmit directly to the load)
  • Large diameter wheels (a 120 cm solid wheel is impractically heavy)

When your community has sufficient woodworking skill, upgrade to Spoked Wheels. The labor investment is higher but the result is 60-70% lighter and significantly stronger for the weight.