Make a solid disc wheel by edge-joining three hard, dense planks 4-5 cm thick and 60-70 cm long with hardwood dowels and glue or wet rawhide, clamping the panel flat until dry, then scribing a circle of 25-35 cm radius from the centre, cutting it round and boring a hub hole that matches the axle arm. For a 70 cm disc each plank must be at least 23 cm wide, and one wheel weighs about 9 kg.
Part of Cart & Wagon Construction
A solid disc wheel is a round slab of edge-joined hardwood planks with a central axle hole, the simplest working wheel for a hand-built cart.
Size The Planks From The Circle
The disc must fit inside the panel the planks make. Three planks of width w make a panel 3w wide, which must be at least as wide as the finished diameter D, and each plank must be at least D long. For the parent article’s 25-35 cm radius, D is 50-70 cm:
- Plank width: for D = 70 cm, w ≥ 70 / 3 = 23.3 cm, so about 23 cm; for D = 50 cm, w ≥ 16.7 cm
- Plank length: at least D, so the 60-70 cm planks the parent specifies allow a disc up to the plank length
The planks are 4-5 cm thick. For the weight, assume an air-dry oak density of about 700 kg/m³ (a recalled figure for oak, not measured) and take a radius of 0.30 m and 4.5 cm thickness:
- Volume = π × 0.30² × 0.045 = 0.0127 m³
- Mass = 0.0127 × 700 = about 9 kg per wheel, so 18 kg for the pair
Solid Wheels uses wider and thicker planks, 5-8 cm, and gives a different layout of the grain; choose the stock you have, and keep the sizing rule above.
What You Need
- Three planks of hard, dense wood, seasoned (Wood Seasoning)
- Hardwood dowels and hide glue, or wet rawhide for wrapping (Hide Glue)
- Clamps or weights to hold the panel flat while it dries
- A string, nail and scribe for the circle
- A saw or axe, an auger, a rasp or sandpaper
Method: Join, Scribe, Cut, Bore
Step 1: Join the planks. Drill matching dowel holes in the mating edges and drive hardwood dowels through, with glue or a wrap of wet rawhide.
Step 2: Clamp flat. Clamp or weight the panel until it dries completely.
Step 3: Scribe. Find the centre and drive a nail. Tie a string to a scriber, with the string length equal to the radius, and scribe the circle.
Step 4: Cut round. Cut with a saw or axe just outside the line, then dress back to it.
Step 5: Bore the hub hole. Match the axle arm. A hole too loose makes the wheel wobble, and one too tight seizes; this is the critical step.
Step 6: Smooth the bore. Finish the bearing surface with sand or a round rasp.
Step 7: Reinforce. Add cross-battens, nailed or pegged across the back at right angles to the plank joints. Add iron bands or a rawhide rim if available.
Why Reinforce Across The Joints
In a disc of parallel planks the grain runs one way everywhere. A crack that starts at the stress concentration around the hub hole therefore runs along the grain to the rim and splits the wheel, and the plank joints are also lines along which the wheel can open. Cross-battens at right angles to the joints hold the planks together across that line, and an iron liner or hub ring spreads the load around the bore. This is reasoning from the grain direction rather than a measured test, so inspect the hub area first when checking an old wheel.
Common Mistakes
- Planks narrower than a third of the diameter — the circle does not fit and the rim has a flat spot.
- Gaps in the joints — joint faces must be flat and tight, or the panel works loose.
- Bore sized by guess — measure the arm and bore to it.
- Using green planks — the disc dries and cracks.
Safety
Cutting a big circle
Sawing or axing a heavy plank panel can kick the work or glance the blade toward your legs. Fix the panel firmly on a stable bench or blocks, keep your free hand and legs out of the line of the cut, and never swing an axe with another person within reach.
What’s Next
- Learn next: Axle Pin & Retention — keeping the finished wheel on the arm
- Combine with: Wheel & Axle Repair — mending cracked discs