Patent Application
20100240467
1. Field of the Invention
The present invention relates to novel domed tip pads and domed tip combinations for cue sticks. It also relates to cue sticks having such novel domed tip pads and combinations.
2. Description of the Related Art
Players of billiards and pool and similar billiard table games use cue sticks for striking balls during the course of play. A cue stick has a grip end and a striking end. The striking end is typically fitted with a shaft ferrule to which an impact-protection tip pad is attached by an adhesive. A shaft ferrule is often referred to in the art simply as a “ferrule,” but the term “shaft ferrule” is used herein and in the appended claims for greater clarity when reference is being made to the conventional cue stick ferrule. The shaft ferrule absorbs some of the shock during ball striking thereby protecting the cue stick shaft from impact damage, e.g., splitting. Shaft ferrules are typically made of high-impact materials that are resistant to cracking, chipping, and breaking, e.g., brass, ivory, carbon fiber, plastics such as melamine resin, aegis, or phenolic resin.
The tip pad is often referred to in the art simply as the “tip”, but the term “tip pad” is used herein and in the appended claims for greater clarity. The tip pad provides the interface during striking between the ball and the rest of the cue stick. Tip pads typically have the shape of a disc or a short cylinder. One face of the cylinder is typically flat and seats upon the outer face of the shaft ferrule to which it is held in place by a bonding layer of an adhesive. The other cylinder face is the striking face of the tip pad and usually has a convex shape with a desired degree of curvature.
Tip pads come in different hardnesses and with different diameters and striking face curvatures. Hard tip pads are favored for high-impact shots, e.g., breaking shots, and may be made of phenolic resin or leather. Softer tip pads are favored for placement shots, especially when the player desires to put spin on the ball being struck. Softer tip pads are typically made of multiple layers of compressed-together leather, although one-piece leather tip pads are sometimes used. The level of hardness that a leather tip pad has depends on the amount compression pressure that was used in making it, the greater the compression, the greater the hardness.
Tip pad diameters vary within ranges which are related to the type of game for which the cue stick is intended for use and an individual player's preference. Cue sticks which are intended for use in playing pool usually have tip pad diameters of between about 11 to about 14 millimeters, with 13 millimeter being the most common. Cue sticks which are intended for use in playing snooker generally have tip pads of smaller diameters, the most common being 9.5 millimeters.
The radius of curvature that a tip pad has on its striking face is preferably chosen to correspond to the amount of spin that the player desires to put on the struck ball. Lesser degrees of curvature provide for less spin, especially accidental spin, thus yielding straighter shots, e.g., for breaking. Higher degrees of curvature make it easier to impart spin to the struck ball. The degree of curvature varies inversely with the radius of the curvature. The radii of curvature typically used for striking faces are those corresponding to three United States coins, i.e., the dime (8.95 millimeters), the nickel (10.6 millimeters), and the quarter (12.15 millimeters).
The striking face of a tip pad is usually made with a controlled level of surface roughness. Greater roughness provides for better ball gripping during impact, thereby making it easier to impart spin to the struck ball. Smoother tip pads make it less likely that spin will be accidentally imparted to the struck ball.
Repeated ball impact causes wear damage to the tip pad. The shape of the striking face will change, often flattening and becoming distorted. The tip pad may also mushroom out over the side of the shaft ferrule. The striking surface also becomes smoother making it more difficult to control the amount of spin given to the struck ball. High impact shots, such as breaking shots, are particularly damaging. As the tip pad damage accumulates, the player's shooting accuracy is likely to decrease. Cue chalk is typically applied to the striking face of the tip pad before every shot as a means of both decreasing the rate of damage accumulation and compensating for the damage already present. Shaping tools are sometimes used to partially restore the shape and surface roughness of the tip pad by cutting or abrading the tip pad. However, shaping tools are of limited effectiveness and can only be used a finite number of times before too little tip pad remains to be worked upon.
Compounding the problem of tip pad wear damage are rules of play that sometime prevent a player from changing cue sticks during the play of a game.
Conventionally, a damaged tip pad can be removed by breaking or dissolving the adhesive layer that holds the tip pad to the shaft ferrule or by cutting away the tip pad. Once removed, a new tip pad can be glued into place. However, this method of repair is time-consuming and is often inconvenient to conduct, especially during the play of a game.
Over the years, there have been numerous attempts to address the problem of tip pad damage through different schemes for improving the replaceability of the tip pads. Examples of such schemes are disclosed in U.S. Pat. Nos. 7,097,570 B2, 6,719,638 B2, 6,183,371 B1, 5,462,490, 3,580,576, 3,226,119, 2,544,970, 1,614,414, 1,544,696, 1,532,985, 1,476,622, 1,429,752, 1,340,395, 1,257,249, 1,141,587, 1,077,664, 1,013,671, 985,067, 934,162, and 52,128, as well as in U.S. Patent Application Publication Nos. US 2007/0219009 A1, and US 2007/0066411 A1. However, all of these schemes suffer from one or more of the following disadvantages: undue complexity, added heaviness, and proneness to unintended loosening of the component holding the tip pad.
A co-pending patent application of the present inventor, U.S. Ser. No. 12/070,634, which is incorporated herein in its entirety by reference, overcomes many of the above-enumerated disadvantages of the prior art. It does so by providing a replacable tip assembly for the striking end of a cue stick. Its tip assemblies comprise a tip ferrule and a tip pad holder which mate together along a conical surface junction, with the conical surface of one of these components being concave to receive the convex conical surface of the other. That patent application defines the term “tip ferrule” to mean the ferrule component of such a replaceable tip assembly, which is to be distinguished from the shaft ferrules of the then-conventional cues. That definition of tip ferrule is also is used herein and in the appended claims. In replaceable tip assemblies of that patent application, the conical surface junction extends to the outer diameter of the tip pad holder and of the tip ferrule, thus assuring that the impact load from ball striking will be distributed substantially uniformly across the diameter of the tip ferrule, without deflection of the tip pad holder, and thereafter into the cue stick shaft. The conical surface shape of the conical surface junction increases the area of surface contact of the junction and controllably resolves the impact force into lateral and axial components of force to the junction.
Although the replaceable tip assemblies of that patent application represented a great advance in the crowded art of cue tip design, the present inventor later recognized with inventive insight that those tip assemblies did not address a problem that still plagues the prior art. That problem is tip strike location sensitivity and can be variously thought of as relating to a cushioning effect or to a conforming effect of a leather tip pad. As mentioned above, leather tip pads are used on many cue sticks and are currently required under the rules of play of some cue stick sports.
In order to understand the tip pad strike location sensitivity problem, it is first necessary to understand the construction of conventional leather tip pads. Most conventional leather tip pads are made by laminating together several layers of leather with the aid of an adhesive and compressive pressure, circularly punching the laminate to produce a laminated leather cylinder, and then abrasively cutting one end face surface of the cylinder to give the familiar rounded shape with the desired amount of curvature, while allowing the opposite end face surface to remain flat for seating it either directly or indirectly upon the end of a cue stick. This cut-laminate process results in the concentric circle, or “bull's eye,” pattern that a leather tip pad has when viewed on end before it is chalked. Some conventional leather tip pads are made of a thick single layer of leather which is compressed and cut to achieve the desired levels of hardness and curvature.
The compressed leather gives the leather tip pad its preferred level of hardness and its ability, when striking a ball, to resiliently conform to the contour of the struck portion of the ball's surface. This ability to conform is extremely important because it permits the leather tip pad's surface to contact a controlled amount of the ball's surface. Too little conforming results in a nearly point contact between the leather tip pad and the ball, thereby decreasing the ability of the tip pad to impart a spin to the struck ball. Too much conforming results in too much cushioning during striking, thereby decreasing the amount of the striking force that gets imparted to the struck ball and potentially imparting more than the desired amount of spin to the struck ball.
The inventor of the present invention insightfully recognized that it is this cut design of the conventional leather tip pad that causes the tip strike location sensitivity problem. He recognized this cut design causes the thickness of the leather between the point of strike and the flat seating surface of the tip pad to vary from point to point across the arc of the tip pad's axial profile. Ball strikes which are made dead center on the leather tip pad's bull's eye pattern have the maximum amount of leather thickness between the striking point and the seating surface while points lower down the arc have progressively less leather thickness. This variation in leather thickness makes the cushioning or conforming effect of the tip pad for a particular ball strike dependent on where on the arc of the tip pad surface the ball strike occurs. This variability in cushioning or conforming effect is one reason why a shooter who has just made a shot, walks away from the table shaking his head when he misses the same shot on the next try even though he is certain that he made the two shots in exactly the same way using the same cue stick.
The inventor believes that, by way of the present invention, he is the first to directly address the tip strike location sensitivity problem. He recognizes that in the prior art there have been departures from the cut leather tip pad, but those departures have been by way of abandoning leather as the tip pad material either in favor of other materials or by way of using a thin layer of leather of only incidental thickness. For example, U.S. Pat. No. 1,525,910 to Blair teaches the use of a rubber tip pad. U.S. Pat. No. 3,381,960 to Reinhart teaches the use of a tip pad formed of a mixture of polyurethane elastomer and leather flour. U.S. Pat. No. 3,695,611 to Lower et al. teaches the use of a synthetic elastomer, e.g., neoprene as the tip pad material. U.S. Pat. No. 7,452,282 B2 to Gulyassy describes a cue stick a having at its striking end a one piece, hemispherically crowned element that acts as both the ferrule and the tip pad, preferably made of a resilient material such as a phenolic or plastic. Since the main purpose of the cue stick taught by the Gulyassy patent is to transfer as much striking force to the struck ball as possible, e.g., for jump and breaking shots, it expressly restricts the use of leather to a very thin covering of the tip.
It is an object of the present invention to overcome the aforementioned problem of location sensitivity of the cushioning or conforming effect of a tip pad.
It is also an object of the present invention to provide a tip pad that has the beneficial aspects of the cushioning or conforming effect of conventional leather tip pads.
It is also an object of the present invention to provide a tip pad that has the beneficial surface friction of conventional leather tip pads.
It is also an object of the present invention to provide cue sticks meeting all of the foregoing objects.
It is also an object of the present invention to provide a tip pad meeting the foregoing objects as part of a simple replaceable tip assembly for the striking end of a cue stick.
It is also an object of the present invention to provide cue sticks having the replaceable tip assembly described in the immediately previous object.
One aspect of the present invention is a novel cue tip combination comprising a ferrule and a leather tip pad, each of which has a rounded seating face which mates to that of the other. The rounded seating surface is preferably that of a sphere segment surface in the case of a ferrule and that of the negative or underside of such a sphere segment surface in the case of a tip pad. A ferrule having such a rounded seating face is referred to hereinafter and in the appended claims as a “domed tip ferrule.” A tip pad having such a rounded seating face is referred to hereinafter and in the appended claims as a “dome-seated tip pad.” In some embodiments of the present invention the domed tip ferrule is a shaft ferrule which has a rounded tip pad seating face. In some other embodiments of the present invention the domed tip ferrule comprises a tip ferrule and a corresponding tip pad holder which has a rounded tip pad seating face.
In accordance with the present invention, the semi-sphericity of the seating face of a domed tip ferrule and dome-seated tip pad ranges between a minimum and maximum arc segment. Arc segments smaller and larger than these minimum and maximum values provide poor shooting control. The inventor of the present invention has determined the minimum and maximum arc segment values, expressed in terms of their respective curvature angles, are about 15 and about 90 degrees, respectively. In contrast, the hemispherical tip taught by U.S. Pat. No. 7,452,282 B2 has an arc segment value of 180 degrees, which is well outside the range of between about 15 and about 90 degrees of the present invention.
Another aspect of the present invention is a novel replaceable cue tip assembly comprising a tip ferrule and a tip pad holder which mate together along a conical surface junction, with the conical surface of one of these components being concave to receive the convex conical surface of the other, wherein the tip pad holder has a tip pad seating face adapted to receive the seating face of a dome-seated tip pad. Such tip pad holders are referred to herein and in the appended claims as “domed tip pad holders.” In this aspect of the present invention, the replaceable cue tip assembly may also include a domed tip pad. The conical surface junction provided by the present invention extends to the outer cylindrical diameter of the tip pad holder and to the outer radial periphery of the tip ferrule, thus assuring that the impact load from ball striking will be distributed substantially uniformly across the diameter of the tip ferrule, without deflection of the tip pad holder, and thereafter into the cue stick shaft. The shape of the conical surface junction increases the area of surface contact of the junction and controllably resolves the impact force into lateral and axial components of force at the junction. An additional advantage of the conical surface junction of the present invention is that it provides for an automatic concentric alignment of the tip pad and cue stick shaft without the need for a truing operation on a cue lathe. Another advantage of the present invention is that it permits the mass production of cue shafts which allow the user to interchange different tip pads.
Preferably, in the present invention, the apex regions of the respective mating conical surfaces of the tip ferrule and the tip pad holder comprise a complementary mortise and tenon set which mate together without the end face of the tenon contacting the bottom face of the mortise. The mortise and tenon may include complementary threads which reversibly engage to permit the tip ferrule and tip pad holder to screw together and apart. Alternatively, the mortise and tenon may be designed to fit connect together in a bayonet joint fashion or in a cam-lock fashion, e.g., such as with the cam-lock design disclosed in U.S. Pat. No. 4,934,883.
Another aspect of the present invention is to provide dome-seated tip pads.
Another aspect of the present invention provides cue sticks having the aforementioned domed tip ferrules and mating dome-seated tip pads.
Another aspect of the present invention provides cue sticks having the aforementioned novel replaceable tip assemblies comprising the domed tip ferrules and dome-seated tip pads.
The criticality of the features and merits of the present invention will be better understood by reference to the attached drawings. It is to be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the present invention.
In this section, some preferred embodiments of the present invention are described in detail sufficient for one skilled in the art to practice the present invention. It is to be understood, however, that the fact that a limited number of preferred embodiments are described herein does not in any way limit the scope of the present invention as set forth in the appended claims.
Referring to
Referring to
The rounded shapes of the seating face and the striking face of the dome-seated tip pad make the thickness variation from edge to center of the dome-seated tip pad significantly less than it is for the conventional flat-bottomed tip pad. This reduced thickness variation causes the impact cushioning effect of the domed tip pad to be substantially independent of the strike location upon the striking face of the dome-seated tip pad.
For example, referring again to
As mentioned above in the Summary of the Invention section, the curvedness of the seating faces of a domed tip ferrule and dome-seated tip pad ranges between a minimum and maximum arc circle segment for the present invention. This element of the present invention may be understood by reference to
The arc segments 66A and 66B depicted in
The dome-seated tip pad may be designed so that the arc segment of its striking face is the same as that of its seating face. However, it is not necessary for these two arc segments to be the same. However, too much of a difference between the arc segment values of the striking and seating faces results in the flattening of the striking face to a point where shooting control becomes poor. Also, too much of a difference between the arc segment values of these striking and seating faces may an impracticable amount of leather stretching being necessary at one of these faces. Preferably, the arc segment of the striking face is somewhat smaller than that of the seating face as this will reduce the amount of stretching needed for the striking face and will also decrease the amount of edge-to-center thickness variation for the dome-seated tip pad.
It is to be understood that the present invention contemplates that the dome-seated tip pad may consist of a single layer or multiple layers of leather. In either case, it is preferred that the leather be compressed to the conventional levels of density and hardness used for the particular game the dome-seated tip pad is intended to be used in. Also in either case, the thickness of the dome-seated tip pad is to be selected according to the particular game the dome-seated tip pad is intended to be used in, as it is preferred that the thickness of the dome-seated tip pad be in the range of thicknesses used for conventional tip pads, the thickness being measured at the centers of the conventional and dome-seated tip pads. It is also preferred that the density and hardness of the dome-seated tip pad be selected according to the game in which the dome-seated tip pad is intended to be used.
Multi-layer dome-seated tip pads according to the present invention preferably have between two and eight layers, but any number of layers may be used. It is preferred that the thicknesses of each of the layers be the same, although different layer thicknesses may be used.
A dome-seated tip pad according to the present invention is preferably made from a leather cylinder comprising the desired number of layers of compressed leather. The walls of the cylinder may be somewhat slanted to avoid the necessity of stretching the leather of the striking face of the dome-seated tip pad significantly more than that of the seating face. The cylinder thickness is selected to be approximately that of the desired thickness of the dome-seated tip pad. The leather cylinder is soaked at room temperature in a solution for approximately several hours to soften the leather, and, for multilayer leather cylinders, to soften the interlayer adhesive. A solution consisting of three parts (by volume) of household strength ammonia that has been diluted with one part water has been found to be useable for this purpose. After the soaking has been completed, one of the circular faces of the leather cylinder is placed against the convexly domed end of a first rod within a hollow cylinder having an internal diameter approximately equal to the desired outside diameter the resultant dome-seated tip pad. The concave end of a second rod is then fitted against the opposite circular surface of the leather cylinder. Together, the convexly- and concavely-domed ends of the two rods and the walls of the hollow cylinder form a confinement chamber for the leather cylinder. The leather cylinder is then compressed between the two rods within the hollow cylinder for several hours at a sufficiently high pressure to cause the leather cylinder to take the shape of the confinement chamber. Preferably, the confinement chamber is designed to allow fluid that has soaked into the leather cylinder to escape under the pressure. The leather cylinder, now having the shape of the confinement chamber is removed from the confinement chamber. A small amount of relaxation of the stretched leather may occur after the removal, so it is preferred to wait until after this relaxation has occurred before adhesively attaching the dome-seated tip pad to a domed tip ferrule.
Albeit less preferred, another method of making a multilayered dome-seated tip pad according to the present invention is to individually form each leather layer into a domed shape and then bond the layers together under pressure.
The domed tip ferrules of present invention may be made by machining, molding, casting or a combination thereof.
In some embodiments of the present invention, the domed tip ferrule is the same as a conventional shaft ferrule, except of course, for the fact that it has a rounded seating face for the tip pad rather than a flat seating face. Referring again to
More preferred embodiments of the present invention, however, employ the rounded tip pad seating face feature in conjunction with the replaceable tip pad system disclosed in the present inventor's co-pending patent application, U.S. Ser. No. 12/070,634. Some of these preferred embodiments are described below.
Referring to
The dome-seated tip pad holder 72 has an outer cylindrical surface 92 and opposing first and second ends 94, 96. The first end 94 has conical surface 98 which extends to the outer cylindrical surface 92. At the apex of the conical surface 98 is a tenon 100, which has threads 102. These threads 102 and the threads 90 of the mortise 82 of the tip ferrule 70 are complementary so that the tenon 100 of the tip pad holder 72 can be screwed into the mortise 88 to seat the conical surface 98 of the dome-seated tip pad holder 72 on the conical surface 86 of the tip ferrule 70, as is illustrated in
The included angle of the conical surface 98 of the dome-seated tip pad holder 72 is selected to match that of the conical surface 86 of the tip ferrule 70. Preferably the included angle is in the range of about 45 degrees to about 140 degrees, and most preferably it is about 90 degrees. Angles shallower than about 45 degrees lack the requisite amount of lateral force resolution to maintain joint tightness against loosening whereas angles steeper than about 140 degrees tend to unduly elongate the tip pad holder.
Referring to
The tip ferrule 70 is preferably adhesively attached to the cue shaft 8. It is also preferred that the inside cylindrical surface 114 of the mortise 82 of the tip ferrule 70 (see
Although in the embodiment of the present invention shown in
Referring now to
In the embodiments depicted in
The means of connecting the tip ferrule and the domed tip holder are not restricted to the use of threaded mortise/tenon joints such as those described for the embodiments of the present invention shown in
Also, other means of connecting the tip assembly to the cue shaft than those depicted in
Referring to
It should be understood that although in the embodiments of the present invention described with regard to
It is also to be understood that although in the embodiments of the present invention described with regard to
Referring to
The domed tip ferrules, tip ferrules, and domed tip pad holders of the present invention may be made of any suitable material for use in the game in which the cue stick to be played. Characteristics to be taken into consideration in making the material selection are the density of the material (and hence the resulting weight of these components), the material's impact strength, its machinability or formability, and its resistance to impact fatigue fracture. Also important is the material ability to produce an aesthetically pleasing surface. Preferably these items are made from a metal or a plastic. Preferable metals include aluminum alloys and brass. They also may be made of carbon fiber composites.
In embodiments of the present invention which include a removable dome-seated tip pad, various means may be utilized for loosening and tightening the dome-seated tip pad. For example, as shown in
The present invention also includes embodiments comprising domed tip ferrules or tip assemblies of tip ferrules and domed tip pad holders of the types described in the above embodiments of the present invention in combination with a cue stick. In some such embodiments, the domed tip ferrule or tip assembly is attached directly to the cue stick shaft, e.g., as is shown in
While only a few embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as described in the following claims. All United States patents and published United States patent applications referred to herein are incorporated herein by reference as if set forth in full herein.
