Reverse, or check, sidespin describes how spin acts at a particular cushion. It is not simply another name for outside spin, and it does not mean backspin. The useful question is what the cue ball is doing when it reaches the cushion, not only where the tip struck it.
Two reference frames, four labels
Running and reverse refer to the cushion approach. Reverse sidespin opposes motion along that cushion; compared with a similar running-spin shot it tends to shorten the rebound and reduce outgoing speed. Inside and outside refer instead to the object-ball cut: tip offset on the cut side is inside, on the opposite side outside. A shot can therefore be outside relative to its cut without being reverse at every cushion.
Name the cushion you are discussing. After the cue ball changes direction, the same initial left or right input need not have the same role at the next cushion. Cushion friction can also alter the remaining rotation. Do not label a whole multi-cushion route from the first impact alone.
Why there is no fixed degree correction
The rebound depends on approach angle, speed and spin still present at impact, including rolling or sliding state. Ball contact and cloth travel change that state. A fuller object-ball hit can remove substantial forward speed while leaving sidespin, so the spin-to-speed ratio at the cushion differs from the initial ratio.
Consequently, neither “half a tip means five degrees” nor “hit harder to get more reverse” is a general calibration. A nearly grazing first cushion may respond little to sidespin while a later, steeper cushion responds more. Check both the immediate exit and the following path rather than treating a curved path as a straight reflection.
A three-condition exercise
Start with a single cue ball away from a corner and choose an oblique route into one long cushion. Record the starting position and a reference arrival; keep cue elevation and a comfortable pace consistent. Compare centre-side contact, a modest amount of running sidespin, and a similarly modest amount of reverse sidespin. Here “centre-side” means no lateral offset, not a promise that the ball reaches the cushion without forward roll.
Repeat each condition several times. Record the actual first-cushion arrival, the crossing point on the opposite side and whether the ball retains enough speed. If the approach changes when you add side, you are not comparing identical cushion impacts. First account for squirt and swerve; do not attribute every difference to the cushion.
Transfer the reference to a carom
Add the first object ball and recheck the cut before adjusting the last target. Separately track its movement and any chance of another collision. If the cue ball finishes short, distinguish insufficient travel from a wrong exit direction. More reverse may shorten the direction while also reducing the available travel; it is not an automatic cure for either failure.
Change one input, reset the layout and compare again. Keep a second record for a different table or cloth condition. The cited technical demonstrations use pool tables; they explain mechanisms but do not supply a measured correction for your carom table.
What to inspect in 3Ball
Use a fixed position, compare lateral-spin inputs and follow the replay through each cushion. Compare arrival locations and whether the route reaches the second ball. A spin control shows an input; it does not certify “reverse at cushion three,” a physical success rate or a universal number of degrees. Keep simulator observations separate from your real-table notes.