What effect does tip contact height (for draw and follow) have on squirt or net cue ball deflection?
Hitting higher on the CB can do two important things related to net CB deflection (AKA squerve or the combined effects of squirt and swerve). Hitting higher can result in the cue being more level if the butt is lowered to help raise the tip. This would actually create less swerve, which would tend to exaggerate the effect of squirt (since less of the squirt is being cancelled by swerve). See squirt cue elevation effects for more info. However, with a higher hit on the ball, squirt actually has two components … one sideways which causes CB deflection (what we normally call “squirt”), and one downward (into the table). The downward component will cause swerve to occur sooner (even before the CB moves forward very much at all). This is sometimes called “immediate swerve.” This effect is more noticeable with highly-elevated-cue shots like massé shots and jump shots with off-center hits (intentional or not) that create a lot more swerve (CB curve) than with typical low-elevation pool shots. The immediate swerve associated with follow shots lessens the effect of sideways squirt (since more of the sideways squirt is being cancelled by the sooner swerve).
A draw shot, on the other hand, has less downward force into the table (from cue elevation) due to an upward component of squirt which reduces the “immediate swerve.” Also, as illustrated in Diagram 1 of “Squirt – Part VIII: squerve effects” (BD, March, 2008), swerve takes longer to complete with a draw shot since the CB slides over a longer distance while the curving (swerve) takes place, before the CB heads in a straight line. Because the swerve occurs later, it doesn’t cancel as much as the squirt effect, so the net or effective CB deflection will typically be larger with draw shots, especially with more speed (as long as the cue isn’t elevated an extra amount, which causes more swerve). For more information, see squerve.