A soft ball for a community game is a stuffed or wrapped core inside a sewn cover, and a 20 cm ball cut from 8 gores needs each gore 7.85 cm wide at the middle and 31.4 cm long from pole to pole, plus seam allowance. Test its bounce with a measured drop and its hardness by pressing it, and keep any hard-wrapped ball away from games that send it toward heads. Do not inflate animal bladders by mouth.
Making stuffed, wrapped and bladder balls, cutting a cover that fits, and testing bounce and hardness before anyone plays.
Three Kinds Of Ball
- Stuffed ball. Cloth or skin sewn into a sphere of 15-25 cm and stuffed with dried grass, hair, wool, crumpled cloth or sawdust. Soft, low bounce, safe for children. Grass and sawdust absorb water and go heavy when wet, and damp stuffing rots, so keep the ball dry.
- Wrapped ball. String, yarn or cloth strips wound tight under tension into a firm ball, optionally with a leather cover. Dense and heavy; suited to hitting games and hard enough to injure if thrown at a person.
- Bladder ball. An animal bladder inflated and tied, optionally covered in leather. It bounces, but the bladder comes from a slaughtered animal.
Cutting A Cover: The Arithmetic
A sphere of diameter d has circumference πd and a pole-to-pole arc length of πd ÷ 2. A cover cut from n identical gores (orange-segment shapes) has each gore as wide at the equator as πd ÷ n. At a distance s along the arc from a pole, the width is (πd ÷ n) × sin(2s ÷ d), with 2s ÷ d in radians.
For d = 0.20 m and n = 8:
- Circumference: π × 0.20 = 0.628 m = 62.8 cm
- Gore width at the equator: 62.8 cm ÷ 8 = 7.85 cm
- Gore length, pole to pole: π × 0.20 ÷ 2 = 0.314 m = 31.4 cm
| Distance from pole s (cm) | Angle 2s ÷ d (radians) | Width (cm) |
|---|---|---|
| 0 | 0 | 0 |
| 5 | 0.5 | 3.77 |
| 10 | 1.0 | 6.61 |
| 15 | 1.5 | 7.83 |
| 15.7 (equator) | 1.571 | 7.85 |
Add a seam allowance of about 1 cm each side (choose to suit your thread and leather). Surface area is π × d² = π × 0.20² = 0.126 m² = 1,257 cm², which is the leather or cloth needed before seam waste. A ball sewn from fewer, wider gores has the same total area but shows more corners.
Test The Ball Before Anyone Plays
Bounce. Drop from a measured height h₁ onto hard ground and measure the rebound h₂. The coefficient of restitution is e = √(h₂ ÷ h₁). From 1.00 m, a rebound of 0.45 m gives e = √0.45 = 0.67. A dead stuffed ball may rebound very little; an overstuffed or wrapped ball more.
Hardness. Press hard with a thumb. If you cannot dent it, it is too hard to be thrown at a person. Energy alone does not set injury, because contact area and stiffness also matter, but the energy tells you the scale: a 0.4 kg ball at 20 m/s carries ½ × 0.4 × 20² = 80 J, while a 0.3 kg soft ball at 10 m/s carries ½ × 0.3 × 10² = 15 J. Pick the soft ball.
Weight. Weigh it. A 0.15 kg ball at 10 m/s carries ½ × 0.15 × 10² = 7.5 J. I recall that a regulation cricket ball weighs about 156-163 g (not verified), a good scale for a hard ball.
What You Need
- Cloth, skin or leather for the cover; see Leatherwork
- Stuffing that stays dry: wool, hair, cloth scraps
- Strong thread and a needle; see Two-Ply Twist
- A scale and a measuring stick
Method: A Stuffed Ball
Step 1: Cut 8 gores to the table, with seam allowance.
Step 2: Sew the gores edge to edge, leaving a gap for stuffing.
Step 3: Turn right side out and stuff firmly, packing in layers so the ball is round.
Step 4: Close with a tight stitch and test the bounce.
Common Mistakes
- Wet stuffing. It rots.
- Uneven stuffing. The ball is lopsided and bounces oddly.
- Pulling stitches too tight. The seams pucker; use even tension.
Safety
Animal bladders and hard balls
A bladder from a slaughtered animal of unknown health can carry infection; use bladders only from animals you know to be healthy, and inflate them with a tube or bellows rather than by mouth. Balls wrapped hard enough that you cannot dent them with a thumb are for striking games with a clear field, not for games where they are thrown at people. No game should send any ball at heads.
What’s Next
- Learn next: Adapted Team Games — using the ball
- Combine with: Hide Preparation — if you cover it with leather