Learn one cushion: read the arrival before reaching the rail.

Learn the natural line first

A rolling cue ball without side spin provides the most repeatable departure reference. Play from one fixed position through a cushion toward a wide target zone and change only the contact thickness on ball one. This separates geometry from spin correction.

The angle of incidence is not exactly the angle of reflection. Rubber deforms, cloth slows the ball and the cue ball may still be sliding or spinning. Use mirror geometry as a starting picture, not the final answer.

Long-short and short-long

A long-short route reaches the long cushion after ball one and then moves toward the short side or second object ball. Short-long uses the short cushion as its first reference. The better route is the one with the larger arrival margin.

A cue ball travelling along the target line toward ball two tolerates more speed error than a line that crosses the target briefly.

• Seek an arrival line along ball two rather than across it.
• Predict where ball one travels after collision.
• Avoid routes with an early kiss between object balls.
• Prefer the line requiring less side spin when margins are equal.

Running spin, reverse spin and speed

Running spin supports the direction in which the cue ball wants to move along the cushion and generally lengthens the outgoing path. Reverse spin resists that tangential motion and shortens the line. The size of the adjustment depends strongly on speed and on how much spin remains at impact.

A very hard ball has a different contact and friction history from a quietly rolling ball. Train one line in small numbered spin steps at constant speed. Do not change spin, thickness and speed together if you want to learn from the result.

Spin that changes on the way

Draw and follow change as sliding becomes rolling. Side spin can remain longer but also decays through friction. Ball one transfers linear speed while some spin may survive.

On long routes, ask not only how much spin you apply but how much reaches the cushion. A slow long shot may be rolling naturally before impact; a faster shot from the same tip position may still be sliding.

Diamonds as simple references

A full calculation system is rarely necessary for one cushion. Use the diamonds to name departure, first-cushion and arrival zones. Play from one departure toward a fixed target and record which first-cushion value works with neutral, running and reverse spin.

The values are table references, not universal promises. Different cloth or clean balls can make a line visibly longer or shorter. Begin each session with two calibration shots.

Gathering through the cushion

A one-cushion shot can score and return an object ball. Control ball one into a cushion and bring it back toward the area where the cue ball and ball two finish. This is a return with a clear positional purpose.

Recurring families include long-cushion return, short-cushion return, rail-first shots and wider loops. Judge each by four questions: is the point large, is the kiss avoided, where does ball one finish and which ball becomes the next first object ball?

Practice block

Record how often the target zone is reached. A pattern that finishes inside a generous zone seven times out of ten is more match-ready than a perfect line that happens once.

• Play ten natural one-cushion lines without side spin toward one arrival zone.
• Repeat with one tip of running spin and one tip of reverse spin.
• Play five long-short and five short-long positions at the same finishing speed.
• Finish with ten shots in which ball one must return through a cushion into a marked gathering zone.

Sources and verification

Content last verified on 8 August 2026. In official competition, the current governing rulebook takes precedence.

• UMB — official carom billiards rules
• KNBB — Sam van Etten on one cushion and runs (Dutch)
• Mathavan, Jackson & Parkin — physics of ball-cushion impact (PDF)
• Erik Kiefl — sliding, rolling, spin and collisions