Phase 01 — First days: water, fire, shelter / About year 1
01.07
Bow-drill fire set
spindle, hearth board, bow and socket
AWhat it needs
Needs 3 other products in all, 2 of them directly.
View
- 01.07 Bow-drill fire setMaking Year 1 needs 3 products
- 01.03 Sharp stone flakeMaking Year 1 needs 1 product
- 01.02 HammerstoneMaking Year 1 raw materials only
- 01.05 Twisted plant-fibre cordMaking Year 1 needs 2 products
Open a box to see what it needs. A dashed box is a product already drawn in full: click it to jump there. In the org chart, drag to move around.
BWhy
There is no fire on the island until someone makes one. The bow drill turns arm strength into heat by spinning a wooden drill against a wooden board until the wood dust itself begins to glow.
CYou need
- Drill and hearth board of the same soft, dry, dead wood with no sticky sap: willow, poplar, lime, cedar or hibiscus. A thumbnail should dent it.
- Bow: a stiff, slightly curved branch as long as the arm
- Socket: a palm-sized stone with a natural dimple, a sea shell, or a knot of hard wood
- Cord (01.05) as thick as a finger bone, a stone flake (01.03), a little grease or a green leaf, a dry leaf or bark chip, a tinder nest
DSteps
- Drill: straight, thumb-thick, a hand-span long. Round the bottom end bluntly. Shape the top end to a blunt point.
- Hearth board: thumb-thick, three fingers wide, flat on the underside so it does not rock.
- Bow: tie the cord to both ends, just slack enough to take one turn round the drill.
- Cut a shallow dimple in the board, a drill's half-width in from the edge.
- Wrap the drill once in the cord so it sits on the outside of the string. Put its blunt end in the dimple and the socket on top, greased with a crushed green leaf.
- Kneel on the right knee. Put the left foot on the board beside the dimple. Lock the left wrist hard against the left shin and press down on the socket.
- Saw the bow back and forth in long level strokes until the dimple is black and seated. Stop.
- Cut a notch from the edge of the board to just short of the centre of the black hole, shaped like a slice of pie one eighth of the circle. Put the dry leaf under the notch.
- Drill again: slow and long at first, then pressing harder and faster as smoke thickens. Dark brown dust fills the notch.
- When smoke pours out, give twenty fast strokes and stop. If the dust heap keeps smoking by itself, there is an ember in it.
- Do not hurry. Fan it gently with the hand until it glows. Tip it into the tinder nest, fold the nest round it, and blow long soft breaths from underneath until it flames.
EIt worked if
- The dust is fine and almost black, and the heap goes on smoking after the drill is lifted away.
FWhat goes wrong
- Squealing, and a shiny hole. The wood has glazed. Drop a pinch of dry sand in the hole and press harder.
- Pale, coarse dust. Not enough speed or pressure. Use the whole length of the bow.
- The cord slips on the drill. Tighten it, or roughen the drill's waist with the flake.
- The drill jumps out. The wrist is not locked to the shin, or the socket is too shallow.
- The socket smokes instead of the board. The top point is too blunt or dry. Sharpen it and grease it.
- Smoke but never an ember. Damp wood, or a notch that is too small. Cut the notch nearly to the centre and dry the set in the sun or against the body.
GIn the story
The first night is spent cold. On the second day Adam drills until his arms shake and gets only smoke. The ember comes when he finally lets Kofi take the bow while he holds the socket. He notices what that means, and says nothing.
HFigures
