One-cushion system — CD = 4 − AB
Where ball 1 touches the opposite cushion after grazing ball 2, without side spin
Example: AB = 2 (ball 2 is 2 diamonds from the starting cushion), so CD = 4 − 2 = 2. Blue dashed line: the aim line, extended to the aimed point (the 0 of the count). Dashed circle: ball 1 at the moment of contact, at half-ball. Yellow dashed line on ball 2: it is pushed to the right. Yellow circles: the reference points counted on both scales.
The formula
CD = 4 − AB
Here AB is measured from the starting cushion to ball 2: it's this distance that sets the path left to ball 1 after contact. Diagram: AB = 2, so CD = 4 − 2 = 2.
The three reference points
- AB: how far ball 2 sits from the starting cushion, in diamonds (left-hand scale, level with ball 2).
- The aimed point: where the aim line, extended, would land on the opposite cushion — the 0 of the count, at the top.
- CD: the gap, in diamonds to the left, between that aimed point and where ball 1 actually touches the opposite cushion.
The same stroke, always
Ball 1 aimed at half-ball on ball 2, hit high, with no side spin at all. Ball 2 goes right, ball 1 is sent back to the left of its path.
Three positions
| AB (diamonds) | 3 | 2 | 1 |
|---|---|---|---|
| CD (offset) | 1 | 2 | 3 |
Always to the left of the aimed point. The closer ball 2 is to the starting cushion, the bigger the offset — and the more any unevenness in the hit shows up at arrival.
Adding side spin
CD = 4 + doses − AB
| Side spin | None | 1 dose | 2 doses |
|---|---|---|---|
| CD for AB = 2 | 2 | 3 | 4 |
Each dose of side spin adds one diamond to the offset, at the same position.