RELATED APPLICATION This application is a Continuation of and claims priority to U.S. Application No. 10/710,631, filed July 26, 2004, the entire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION A billiard cue is basically a tapered shaft with a tip attached to the very front end for making the contact with the cue ball. Billiard cues may have one or more releasable joints along their length. The shaft or shafts that form the body of a billiard cue have been made from a great variety of materials. There are prior billiard cue shafts which include a wood core and a skin of composite material such as glass fiber/epoxy or carbon fiber/epoxy. These prior shafts are made with a maple or other hard and heavy (11-12 g/ci) wood core and coated with a thin skin of low grade composite material. These low strength composite skins may increase stiffness slightly but they also add weight. Because these materials average about 2 Vz times the density of the wood core, the prior composite coated wood shafts are heavier than like sized solid wood shafts which is particularly undesirable for the first few inches of the tip end of a cue; indeed, U.S. Patent No. 6,162,128 describes a way of reducing the mass of the first few inches of a solid maple shaft by boring a hole which removes only a few grams but has proven to improve performance (by reducing "cue ball deflection") and shafts built this way have become quite popular with top players. Another issue is straightness; the kinds of hardwoods used in prior composite coated wood shafts tend to be rather unstable and it is predictable that the wood cores are not perfectly straight to begin with. The coating is likely somewhat unevenly applied and the shaft is then centerless sanded and in the end result these shafts are not any straighter on average than solid wood shafts. One advantage these shafts have is that they do not get dinged up on the surface like pure wood shafts do, but in spite of this advantage they have never become popular with the better players.

SUMMARY OF THE INVENTION One embodiment of the invention is directed to a billiard cue. The cue has a shaft including a wood core and a skin of composite material. The wood of the core has a density less than about 9 grams per cubic inch (g/ci). The composite material may include fibers in a binder. The wood may also have a density less than about 8 g/ci, or may be Sitka spruce. The skin may have a thickness that varies along a length of the shaft, and in particular, may vary from a thinner skin near a front end to a thicker skin near the back end. As well, the billiard cue may include watertight capping material to prevent exposure of the wood core to water.

BRIEF DESCRIPTION OF THE DRAWTNGS The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. FIG. 1 shows the overall configuration of a common two piece billiard cue joined at the middle with a releasable joint. FIG. 2 shows a longitudinal cross section of the back half of a cue made using the present invention. FIG. 3 shows a longitudinal cross section of the front half of a cue using the present invention. FIG. 4 shows a typical lateral cross section of the shaft. The light wood core 17,20 is coated with the composite skin 16,19.

DETAILED DESCRIPTION OF THE INVENTION

A unique and improved billiard cue shaft is disclosed. The billiard cue shaft includes a light wood core and a composite outer skin. Preferably, the wood is light but has a high stiffness and/or strength. FIG. 1 depicts an embodiment of a tapered billiard cue comprising two pieces joined at the middle with a releasable joint. The front half of the cue includes a shaft 12, a tip cap 13, and a tip 14. The back half of the cue includes a shaft 11 and a butt cap 15. Alternatively, the billiard cue may be a one piece construction, or be comprised of three or more pieces that are releasably joined.

FIGS. 2 and 3 depict longitudinal cross sectional views of the front half and back half of a tapered billiard cue of FIG. 1. In FIG. 2, the light wood core 17 is coated with the composite skin 16. The shaft is capped water tight at the front by joint section 18, and at the back by butt cap 15. In FIG. 3, the light wood core 20 is coated with the composite skin 19. The shaft is capped water tight at the front by tip cap 22, and at the back by joint section 21. A tip 23 is attached to the tip cap 22. A lateral cross section of the shaft is depicted in FIG. 4. The light wood core 17,20 is coated with the composite skin 16,19.

The composite outer skin may include fibers in a binder (e.g., glass fiber/epoxy or carbon fiber/epoxy). The wood has a density substantially lower than a wood used in conventional billiard cues (e.g., hard maple or other hard and heavy woods with a density of about 11 to 12 grams per cubic inch (g/ci)). In one embodiment the wood has a density lower than about 9 g/ci. In another embodiment the wood has a density lower than 8 g/ci. In a particular embodiment of the invention, the billiard cue shaft includes a wood core made of Sitka spruce (6-8 g/ci). Sitka spruce has perhaps the highest strength to weight ratio of all woods known.

The shaft is designed in such a way as to take advantage of the best properties of wood and the great strength, durability, and stability of modern composite materials. By forming the core of a light but also quite strong wood, such as Sitka spruce, the composite skin can be thicker in areas where a cue can benefit from being stiffer without becoming too heavy. The skin can be very thin close to the tip end which together with the light wood core allows the first few inches of a cue to be of lower mass than prior composite skinned wood shafts which in turn causes performance changes which many players prefer. The thickness of the skin layer may vary continuously over the entire length of a shaft, or may vary over only a portion of the shaft. For example, the skin thickness varying over the entire front half of a shaft as depicted in FIG. 2, but being the same thickness in the back half. Alternatively, the continuously varying skin thickness may be only over a portion of the front or back half of a shaft.

Another advantage of this design is that the shaft can be manufactured with near perfect straightness and stability. Some light woods such as Sitka spruce are much more stable than the most common and popular hard shaft woods such as maple and are easily machined to a nearly perfectly straight core section. The composite skin can be applied thick enough to allow final machining of the entire outer surface on centers to achieve near perfect final straightness. Both ends of the shaft can be capped water tight and the shaft should remain stable indefinitely.

Other embodiments of the invention include constructing individual portions of a billiard cue in accordance with features previously described herein. For example, the composite skinned, light wood core construction may be applied only to the front end of a billiard cue as depicted in FIG. 2, or only the back end as depicted in FIG. 3. In cues constructed of three or more pieces, any one of the pieces may include the composite skinned, light wood core construction discussed herein.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.