What is different about a jump cue and why does it jump better than a typical playing cue, especially a playing cue with an LD shaft?
Jump cues are shorter, lighter and stiffer, with a hard tip (e.g., phenolic). All of these features make it easier to get more rebound height off the table slate with a legal hit (i.e., not an illegal “scoop” jump shot).
To get good jump action, it helps to have a hard tip (e.g., phenolic), a stiff shaft, and a light cue (resulting in faster cue speed and less forward post-hit cue speed). The hard tip and stiff shaft generally result in a more efficient hit (i.e., more speed will be delivered to the CB for a given cue weight and speed). For more info, see cue efficiency. The hard tip, stiff shaft, and fast speed also help reduce cue tip contact time. For more info, see the cue tip contact time resource page. A shorter tip contact time is important to allow the CB to separate from the tip before the CB interacts too much with the table surface. If the tip is still in contact while the CB is interacting with the slate, the CB won’t jump as well.
Also, if the cue tip does not get out of the way while the CB is bouncing off the slate, a poor jump can result. This can be caused by poor jump shot technique (e.g., hitting the CB too high, or using a grip that is too tight), but having a light jump cue also helps since it will lose more forward speed with the hit.
In general, LD-shaft playing cues do not jump as well as other cues. Compared to a typical good-action jump cue, a playing cue has a softer tip, a less-stiff shaft, poorer hit efficiency, more weight, and less speed during a jump stroke. An LD shaft can be even less stiff and have a poorer hit efficiency. All of those things can hurt when it comes to jumping the CB. Although, LD-shaft playing cues can still be used to jump small amounts reliably, per the following video: