Title:
TEN PIN BOWLING BALL
Kind Code:
A1


Abstract:
The present invention concerns a bowling ball having an arrangement of holes for allowing a bowler to grip the ball. The arrangement includes a thumbhole having a profile which is shaped to accommodate the thumb of the bowler in a bent position. The thumbhole can be configured to accommodate the thumb of the bowler in a bent position in which the bowler grips the ball, and provides a clearance fit with the thumb of the bowler when in a substantially straight position. The shaped profile of the thumbhole can be provided by a pad for the thumb or be defined by an insert to the thumbhole.



Inventors:
Thomson, Skene (Dundee, GB)
Application Number:
12/276001
Publication Date:
04/15/2010
Filing Date:
11/21/2008
Primary Class:
Other Classes:
473/128
International Classes:
A63B43/00
View Patent Images:
Related US Applications:



Primary Examiner:
PIERCE, WILLIAM M
Attorney, Agent or Firm:
Studebaker & Brackett PC (One Fountain Square, 11911 Freedom Drive, Suite 750, Reston, VA, 20190, US)
Claims:
1. A bowling ball comprising an arrangement of holes for allowing a bowler to grip the ball, wherein the arrangement comprises a thumbhole having a profile which is shaped to accommodate the thumb of the bowler in a bent position.

2. A bowling ball as claimed in claim 1 wherein the thumbhole is configured to accommodate the thumb of the bowler in a bent position in which the bowler grips the ball, and provides a clearance fit with the thumb of the bowler when in a substantially straight position.

3. A bowling ball as claimed in claim 1 wherein the thumbhole has a longitudinal axis and a cross-section which is variable along the longitudinal axis.

4. A bowling ball as claimed in claim 1 wherein the thumbhole has a longitudinal axis and comprises a contact surface for a pad of a thumb of a bowler, the contact surface being inclined to the longitudinal axis.

5. A bowling ball as claim 1 wherein the thumbhole comprises at least one wall longitudinal to the thumbhole and a formation in the wall configured to be gripped by the thumb of a bowler in a bent position.

6. A bowling ball as claimed in claim 5 wherein the formation is a recess or niche formed in the wall.

7. A bowling ball as claimed claim 1 wherein the thumbhole has a curved profile.

8. A bowling ball as claimed in claim 1, wherein the thumbhole has an angular profile.

9. A bowling ball as claimed in claim 1 wherein the shaped profile is defined by an insert to the thumbhole.

10. A bowling ball as claimed in claim 1 wherein the arrangement of holes comprises a finger hole having a longitudinal axis and a contact surface for a pad of a finger, the contact surface being inclined to the longitudinal axis.

11. An insert for a thumbhole of a bowling ball, the insert comprising a shaped profile which defines a formation in the wall configured, in use, to be gripped by the thumb of a bowler in a bent position.

12. An insert as claimed in claim 11 wherein the insert defines a contact surface, the contact surface configured, in use, to be contacted by a pad of a thumb of a bowler with the thumb in a bent position.

13. An insert as claimed in claim 11 wherein the insert is configured to be located on a longitudinal wall of a thumbhole of a bowling ball and defines a formation upstanding from the wall.

14. An insert as claimed in claim 11 wherein the insert has a throughbore configured to accommodate the thumb of the bowler in a bent position in which the bowler grips the ball, and provides a clearance fit with the thumb of the bowler when the thumb is in a substantially straight position.

15. An insert as claimed in claim 14 wherein the throughbore has a longitudinal axis and a cross-section which is variable along the longitudinal axis.

16. An insert as claimed in claim 11 wherein the throughbore has a longitudinal axis and the contact surface is inclined to the longitudinal axis.

17. An insert as claimed in claim 11 wherein the throughbore comprises at least one wall longitudinal to the throughbore and the formation is a recess or niche formed in the wall.

18. An insert as claimed in claim 11 wherein the insert is asymmetrical and is configured to be located in the thumbhole in a first orientation and a second inverted orientation.

19. An insert as claimed in claim 11 wherein the insert is configured to be located in the thumbhole in a plurality of rotational positions.

Description:

The present invention relates to an improved ball grip and in particular to an improved grip for a ball used in ten-pin bowling.

In the competitive sport of ten-pin bowling, a bowler delivers a bowling ball down a lane towards a rack of pins located at the opposing end of the lane, with the objective of knocking down as many of the pins as possible in order to score points. The bowling ball is made from plastic, urethane or reactive resin materials (or a combination of these materials), has a diameter of 8.5 inches (21.6 cm) and varying weights of up to 16 lbs (7.2 kg). Since the size of regulation bowling balls is the same, balls of different weights have different densities. In addition, the cores of different bowling bowls may vary in their distribution of weight. Some bowling balls are designed to be centre-heavy, so that they are made to spin more easily, whereas some have weight distributed closer to the surface of the ball.

In order to consistently knock down (or “carry”) all ten pins, most bowlers of intermediate or high skill level will deliver a ball with revolutions imparted to the ball so that it does not follow a straight path. For example, a right-handed bowler may impart rotation to the ball such that it slides or skids along an oiled portion of the bowling lane (about 38 feet or 11.58 metres from the release) before hooking from right to left towards the pins in the unoiled portion of the lane. Left-handed players will tend to deliver the ball in the opposing sense.

A bowling ball generally has holes drilled into it to allow the bowler to grip the ball and control the delivery. A bowling ball according to the prior art is shown in FIGS. 1A to 1C, generally depicted at 10. The ball 10 has three holes drilled into it: a thumbhole 12, and holes 14a, 14b for each of the ring finger and the middle finger. The ball 10 has a conventional grip arrangement, in which the ring finger and middle finger are placed into the finger holes 14a, 14b up to the second knuckle joint. FIG. 2 shows a ball, generally shown at 20, having a fingertip grip according to the prior art. In the fingertip grip, the finger holes 24 are configured to accept the fingers of the bowler only up to the first knuckle joint. A semi-finger grip (not shown) allows the bowler to place his fingers in an intermediate position between the conventional and finger tip grips. The type of ball and grip selected by a bowler depends on the bowler's delivery style and strength. Typically, by professional bowling shop (or “pro-shop”) operator will measure the width of span at diameters of the fingers of a bowler in order to determine the required positions and dimensions of the thumbhole and finger holes required for the bowler's preferred grip type.

All of the above-described grips use the same type of thumbhole (12 in FIG. 1; 22 in FIG. 2), which is a straight parallel-sided hole drilled into the ball. The thumbholes are ideally a close fit with the bowlers thumb, but may be of circular or elliptical cross-section to accommodate the bowler's thumb. The thumbhole need not be drilled into the ball in a radial direction (i.e. it may not be normal to the surface of the ball). The thumbhole may be pitched with respect to a plane which bisects the finger holes to suit the hand shape, thumb position and type of release of a particular bowler. FIG. 1C shows the pitched thumbhole 12 in the ball 10.

There are a number of problems with the currently available grips. One such problem is that the thumb of the bowler may stick in the thumbhole due to too much frictional contact between the thumb and the side walls of the hole. Frictional contact between the thumb and the thumbhole may cause the bowler to release the ball later than intended. Even releasing the ball a fraction of a second later than intended can have a significant effect on the direction, trajectory and/or rotation of the ball. Thus the thumbhole may lead to misdirected deliveries and lower scoring.

Secondly, friction between conventional thumbholes and the thumb causes the ball to rub on the thumb during its release. For regular and/or professional bowlers, who may bowl tens of ten frame games in one day, repeated over periods of weeks or months, this can create damage to the thumb. Over periods of months or years, the bowlers thumb can end up being seriously damaged.

In addition, since the release of the ball relies on overcoming a frictional force between the thumb and the thumbhole, in certain conditions the ball can be released earlier than intended. For example, a worn ball may have a reduced co-efficient of friction on the inside of the thumbhole due to repeated use. In addition, moisture due to perspiration can build up in the thumb to reduce the coefficient of friction. In use, the bowler may not anticipate the loss of friction, which can result in the delivery of a ball being mistimed and therefore misdirected.

Thumb tapes are used to increase the frictional contact between the thumbhole and the thumb. The tape is an adhesive tape formed from a plastic and/or natural rubber material. The tape may be applied to the inside surface of the thumbhole. Alternatively, tapes can be used on fingers and/or thumbs to protect fingers and/or thumbs from damage, and change the frictional coefficient. Although the use of tapes does permit an element of control over the coefficient of friction between the thumb and the thumbhole, and allows the fit of the thumb and the thumbhole to be adjusted, it does not address problems of the thumb sticking to or slipping from the hole due to change in bowling conditions.

It would be desirable to provide a bowling ball configuration which offers an improved grip to the bowler, and allows improved consistency and control of delivery.

It is one aim of the invention to provide a thumbhole configuration for a bowling ball which addresses the drawbacks and deficiencies of available bowling ball configurations. It is a further aim of the invention to provide a bowling ball which addresses the drawbacks and deficiencies of the prior art bowling balls. Further aims and objects of the invention will become apparent from the following description.

According to a first aspect of the invention, there is provided a bowling ball comprising an arrangement of holes for allowing a bowler to grip the ball, wherein the arrangement comprises a thumbhole having a profile which is shaped to accommodate the thumb of the bowler in a bent position.

Preferably, the thumbhole is configured to accommodate the thumb of the bowler in a bent position in which the bowler grips the ball, and accommodates the thumb of the bowler in a substantially straight position in which the thumb can easily be removed from or inserted into the thumbhole. Thus the thumbhole may accommodate the thumb in a straight position in which the bowler may release the ball. The bowler may therefore grip the ball with a bent thumb position and release the ball by straightening the thumb in the thumbhole. This provides an improved grip which allows the bowler to hold and manoeuvre the ball more easily compared with previously available grips. In addition, the invention allows the bowler to have greater control over the timing of release of the ball, thereby improving the accuracy and consistency of delivery. Furthermore, the invention reduces damage to the bowlers thumb when compared with the arrangements previously proposed.

The thumbhole may have a longitudinal axis and a cross-section which is variable along the longitudinal axis.

The thumbhole therefore has an internal profile which varies along its length.

The thumbhole may have at least one wall longitudinal to the thumbhole and a formation in the wall configured to be gripped by the thumb of a bowler in a bent position. The formation may be a recess or niche formed in the wall.

According to a second aspect of the invention, there is provided an insert for a thumbhole of a bowling ball, the insert comprising a shaped profile which defines a formation in the wall configured, in use, to be gripped by the thumb of a bowler in a bent position.

According to a third aspect of the invention there is provided a method of configuring a thumbhole in a bowling ball, the method comprising:

obtaining the dimensions of the hand of at least one bowler intended to use the ball; and

providing the thumbhole with a shaped profile to accommodate the thumb of the bowler in a bent position.

According to a fourth aspect of the invention, there is provided a bowling ball comprising an arrangement of holes for allowing a bowler to grip the ball, wherein the arrangement comprises a thumbhole having a longitudinal axis and a cross-section which is variable along the longitudinal axis.

According to a fifth aspect of the invention, there is provided a bowling ball comprising an arrangement of holes for allowing a bowler to grip the ball, wherein the arrangement comprises a thumbhole having at least one wall longitudinal to the thumbhole and a formation in the wall configured to be gripped by the thumb of a bowler in a bent position.

According to a sixth aspect of the invention, there is provided an insert for a bowling ball, the insert comprising a thumbhole configured to receive the thumb of a bowler, wherein the thumbhole has a profile which is shaped to accommodate the thumb of the bowler in a bent position.

According to a seventh aspect of the invention, there is provided an insert for a bowling ball, the insert comprising a thumbhole configured to receive the thumb of a bowler, wherein the thumbhole comprises a longitudinal axis and a cross-section which is variable along the longitudinal axis.

According to an eighth aspect of the invention, there is provided an insert for a bowling ball, the insert comprising a thumbhole configured to receive the thumb of a bowler, wherein the thumbhole at least one wall longitudinal to the thumbhole and a formation in the wall configured to be gripped by the thumb of a bowler in a bent position.

The present invention encompasses a method of configuring a thumbhole in a bowling ball, the method comprising:

obtaining the dimensions of the hand of at least one bowler intended to use the ball; and

providing the thumbhole with a shaped profile to accommodate the thumb of the at least one bowler in a bent position.

The method may further comprise configuring the thumbhole to provide a clearance fit with the thumb of the at least bowler when in a substantially straight position.

In one case, the comprises locating an insert in the thumbhole, the insert defining the shaped profile of the thumbhole.

The method can comprise configuring the insert to accommodate the thumb of the at least one bowler prior to locating the insert in the thumbhole.

In another case, the method comprises forming a recess in a sidewall of the thumbhole in the bowling ball or in a sidewall of the insert.

Embodiments of the first to eighth aspects of the invention may comprise features of other aspects of the invention and their preferred embodiments, and/or may comprise features of the dependent claims.

There will now be described, by way of example only, various example embodiments of the invention with reference to the following drawings, of which:

FIGS. 1A, 1B and 1C are respectively top, first sectional and second sectional representations of a bowling ball according to the prior art having a conventional grip hole orientation;

FIG. 2 is a sectional representation of a bowling ball according to the prior art having a fingertip grip hole configuration;

FIG. 3A is a first longitudinal sectional view of a bowling ball in accordance with an embodiment of the invention;

FIGS. 3B and 3C are cross-sectional views through the thumbhole of the embodiment of FIG. 3A;

FIG. 3D is an alternative longitudinal sectional view of the bowling ball of FIG. 3A;

FIG. 4 shows the bowling ball of FIG. 3A in use being gripped;

FIG. 4B illustrates the same bowling ball at the point of release;

FIG. 5 is a longitudinal section through a bowling ball in accordance with an alternative embodiment of the invention;

FIG. 6 is a longitudinal section through a bowling ball in accordance with an alternative embodiment of the invention;

FIG. 7 is a longitudinal section through a bowling ball in accordance with an alternative embodiment of the invention;

FIG. 8 is a longitudinal section through an insert in accordance with a further alternative embodiment of the invention;

FIG. 9 is a longitudinal section through an insert in accordance with a further alternative embodiment of the invention;

FIG. 10 is a longitudinal section through an insert in accordance with a further alternative embodiment of the invention; and

FIG. 11 is a longitudinal sectional view through an insert in accordance with a further alternative embodiment of the invention; and

FIG. 12 is a longitudinal section through a bowling ball in accordance with a further alternative embodiment of the invention.

Referring now to FIG. 3A, there is shown a bowling ball, generally depicted at 30, shown in sectional view through a thumbhole 32 in the z-y plane. The y-axis is in the direction of delivery of the ball down the lane towards the pins. The z-axis is not necessarily vertical, and instead represents the longitudinal axis of the thumbhole. In this embodiment, the thumbhole does not deviate from a radius of the ball, although it will be appreciated that in other embodiments, the thumbhole could have an angular pitch, for example as shown in FIG. 1C.

The ball 30 is a standard ball, comprising for example plastic, urethane or reactive resin materials (or a combination of the above). The ball 30 comprises a core and a cover, although in this embodiment the detail of the ball material and internal structure is omitted to preserve clarity since it is well known to those skilled in the art.

The thumbhole 32 is formed to a depth to suit the bowler or bowlers intended to use the ball. In this case, the depth is approximately 6 cm. The thumbhole has a cross-section shaped to accommodate the thumb of the bowlers intended to use the ball, and in this case has a substantially elliptical cross-section. The thumbhole is profiled such that the cross-section varies along the longitudinal axis of the thumbhole. The function of the varying cross-section is to accommodate a bend in the thumb of the bowler, as will be described below.

FIG. 3B is a cross-section through line B-B′, which is a depth of the thumbhole having reduced cross-sectional area. Line B-B′ corresponds to a position of a peak 34 of the profiled surface 36 of the thumbhole. FIG. 3C is a cross-section through line C-C′, which is a depth of the thumbhole having increased cross-sectional area. Line C-C′ corresponds to a position of a recess or niche 39 in the profiled surface 36 of the thumbhole. In this embodiment, the variable cross-section and profiled surface of the thumbhole is created by insert 40. The insert 40 has a curved outer surface which corresponds with the wall of the thumbhole 32. The inner surface of the insert 40 defines the surface 36 of the thumbhole. The surface 36 faces the direction of delivery of the ball during use, and an opposing surface 37 is substantially parallel to the longitudinal axis of the thumbhole 32.

FIG. 3D is a longitudinal section through the bowling ball 30 rotated by 90° with respect to the section of FIG. 3A. The figure shows that the side walls 38 are substantially parallel with the longitudinal axis of the hole.

FIG. 4A and 4B show schematically the ball 30 in use. In these drawings, the ball is shown in schematic longitudinal section, with sections through the thumbhole 32 and a finger hole 33. A bowler (who in this example is right-handed) places his right hand 50 into the thumbhole 32 and the finger hole 33. The hand 50 is shown in profile. The front or palm side of the thumb 52 is placed against surface 36, and the backside of the thumb faces wall 37. The finger 53 of the bowler is located in finger hole 33 (not shown), which in this example is configured for a finger tip grip. Although not shown in the drawings, the invention is also applicable to a conventional grip, or any variation in between.

The profile of the thumbhole 32 allows the bowler to place his thumb 52 against the surface 36 in a bent condition. The transitional region between the peak 34 and the recess 39 provides a surface 42 for contact with the pad of the thumb 52. The surface 42 is inclined to the longitudinal axis of the thumbhole 32, and provides a surface against which the pad of the thumb can rest and grip the thumbhole and ball, as shown in FIG. 4A. This provides the bowler with a comfortable grip on the ball, with the hand in a natural, curved position. It increases the ease of handling bowling balls of larger weights, enabling the bowler to select a heavier ball than the prior art ball he would normally choose. The gripping of the ball 30 does not depend on frictional contact provided by a tightly fitting thumbhole. Indeed, the back wall 37 and the side walls 38 may be a clearance fit with the thumb, which reduces the likelihood of damage to the thumb over repeated use.

FIG. 4B schematically shows the ball 30 during the release by the bowler. With the hand in position in the hole arrangement, the bowler straightens the thumb 52, releasing the pressure of the thumb pad on the surface 42. This reduces the forces retaining the grip on the ball considerably. In an ideal release, there will be no contact between the thumb and the thumbhole and thus there will be no friction between the ball and the thumb. Even if there is some contact, there will at most be a light frictional force at the peak 34. This friction is easily overcome by the weight or momentum of the ball, which is released from the bowler's grip and delivered down the lane. In FIG. 4B, the clearance distance between the back of the thumb and the thumb hole wall 37 is exaggerated to improve the clarity of the drawing.

Thus the release of the ball is controlled by the straightening of the thumb of the bowler, and is a controllable, repeatable action. Since the gripping and releasing of the ball is not dependent on frictional contact with a tightly fitting thumbhole, it is affected less by variations in conditions, such as changes in a co-efficient friction due to moisture on the thumb or in the hole. In addition, during release of the ball, the back and side surface need not be in contact with the thumb, which reduces damage to the thumb over periods of repeated use. In this embodiment, the insert 36 is shaped to provide the thumbhole with a larger cross-sectional area towards the entrance of the hole 32. This reduces the likelihood of damage to the front or palm side surface of the thumb and the thumb pad as the ball is released.

FIGS. 5 and 6 are schematic sectional views of balls according to alternative embodiments of the invention, and will be understood from FIGS. 3 and 4. FIG. 5 shows a thumbhole 132 formed in a ball 130. The thumbhole 132 has a cross-sectional profile which varies in a longitudinal direction of the hole. The varying profile is provided by an insert 140 to the hole which extends along part of its length. The insert 140 is similar to insert 40, although it differs in that its comprises a substantially parallel portion 141 extending in the longitudinal direction of the hole 132. A transitional portion of the insert defines a surface 142 for contact with the thumb pad of the bowler. The insert 140 is upstanding from a wall of the thumbhole and defines a corresponding recess or niche 136 to accommodate a bent position of the thumb of the user. Use of the arrangement of FIG. 5 is similar to that described with reference to FIGS. 4A and 4B.

FIG. 6 shows a further alternative ball 230 comprising a thumbhole 232. Similarly to the previous embodiments, the thumbhole comprises an insert 240 which defines a varying cross-section of the thumbhole, to allow it to accommodate a bent position of the thumb. As with the previous embodiments, the insert 240 defines a surface 242 for contact with the thumb pad of the bowler when the thumb is in a bent position, and provides a recess or niche 236 in the wall of the thumbhole. The insert 240 is similar to the insert 40, although instead of the arcuate profile of the insert 40, the insert 240 is angled to a peak 234. The surface 242 is angled between the peak 234 and a lower edge of the insert. Use of the arrangement of FIG. 6 is similar to that described with reference to FIGS. 4A and 4B.

FIG. 7 is a schematic sectional view of a further alternative embodiment of the invention. In this embodiment, the ball 330 comprises a thumbhole 332 which has an inner profile similar to the thumbhole 232 of FIG. 6. However, in this embodiment, the shaped profile is not defined by an insert, but rather is formed by shaping the internal surface of the thumbhole itself. The shaped profile 340 is formed by a drilling and under-reaming process, and provides a recess or niche 336 which allows the thumb to be accommodated in a bent position to grip the ball. Use of the embodiment of FIG. 7 is as described with reference to FIGS. 3 and 4.

FIG. 8 is a schematic sectional view through a further alternative embodiment of the invention, through a thumbhole 432 in a ball 430. In this embodiment, an insert 440 is a substantially tubular member having an outer diameter corresponding to the inner diameter of a bore drilled in the ball. The insert 440 is open-ended and has a throughbore 442 which defines the thumbhole. The bore 442 has an internal cross-sectional profile which varies longitudinally along its length. The profile defines a surface 444 which in use may be gripped by the thumb pad of a bowler with the thumb in a bent position, and provides a recess or niche 436 in the wall of the thumbhole. Use of the embodiment of FIG. 8 is as described with reference to FIGS. 3 and 4.

The embodiment of FIG. 8 has the advantage that the insert may be more easily located in a pre-drilled hole in the ball than the insert 40. No special positioning of the insert 440 or shaping of the drilled hole in the ball is required, because the outer dimensions of the insert 440 may be standardised to the dimensions of a hole drilled in the ball.

For example, this and other embodiments of the invention may be used in conjunction with current techniques for configuring balls used by pro-shop operators. A professional or regular bowler will tend to have several different bowling balls, and will prefer to have the same feel to every ball he or she owns. The thumbhole will be over-drilled to accommodate a thumbhole plug, which is a cylindrical plug typically with a length of around 7 cm (2.75 inches) and a diameter of approximately 3.5 cm (1.375 inches). The thumbhole plug is secured into the hole by a suitable adhesive, bonding agent or cement. The thumbhole of the required dimensions is formed in the thumb plug by drilling a hole along the longitudinal axis of the plug. This allows the bowler to select a preferred thumbhole plug type which can be used regardless of the materials used to construct the ball itself. Rather than using the parallel-sided, tightly-fitting thumbhole of the prior art, the thumbhole plug can used to form the insert 440, or another insert in accordance with the invention. The arrangement of FIG. 8 also allows pre-fitting of the insert to the user, ensuring that the contact surface is at the required depth. For example, the internal profile of the insert 440 may be selected or configured before it is secured into the ball.

FIGS. 9, 10 and 11 show inserts according to further alternative embodiments of the invention, and will be understood from FIG. 8. FIG. 9 shows an insert 540, similar to the insert 440, but having parallel outer sides with no upper lip. As with the previous embodiments, the inner surface of the insert 540 defines a recess 536 and a contact surface 542 for the thumb of a bowler. The insert 540 is asymmetrical along its length. In an inverted configuration, the insert 540 defines a second recess 538, and a second contact surface 544, which provide the same function as the recess 536 and surface 542 but at a deeper position within the thumbhole. In the inverted configuration, the recess and surface of the insert 540 are located at a suitable depth for a bowler with a longer thumb. Thus the insert 540 may be suitable for a greater range of bowlers. Use of the embodiment of FIG. 9 is as described with reference to FIGS. 3 and 4.

FIG. 10 shows an alternative insert 550 formed from a substantially tubular member. The insert is similar to the insert 540, although it is integrally formed from a substantially tubular component 552 and a secondary insert 554 which is located within a throughbore defined by the insert to create the varying cross-sectional profile. The secondary insert is secured to the tubular component by a suitable adhesive, cement or bonding agent. The insert 550 also differs in that it is not constructed from a continuous tubular body. Instead, a portion of the cylinder is absent from the wall opposing the formation, to around half the circumference of the tubular member (shown by the dotted line). The upper and lower ends of the insert define cylindrical rings 558, and the middle section is open to one side. This arrangement uses a reduced amount of material and may also facilitate location and attachment of the secondary insert in an appropriate position on the inner wall of the tubular component 552. Use of the embodiment of FIG. 10 is as described with reference to FIGS. 3 and 4.

FIG. 11 shows an alternative insert 560, which defines a recess 562 by removing the portion of the cylindrical body which makes up the insert. In this embodiment, the varying cross-sectional profile is created by widening a portion of the bore to define a recess 562 which accommodates the thumb in a bent position and a contact surface 564. This is in contrast with the previous embodiments, in which the contact surface is defined by a formation upstanding from a side wall. Use of the embodiment of FIG. 11 is as described with reference to FIGS. 3 and 4.

There is shown in FIG. 12 a further alternative embodiment of the invention. A bowling ball 630 comprises a thumbhole 632 and a finger hole 633. The thumbhole 632 is formed with a cross-section which varies along its longitudinal axis, by the provision of an insert 640. The insert 640 in this embodiment is similar to the insert 140 of FIG. 5. The finger hole 633 is also provided with a cross-sectional profile which varies along its longitudinal axis, with the variation created by insert 642. The insert 642 defines a surface 644 for contact by the pad of the finger 53. Thus the finger hole 633 accommodates the finger 53 in a bent position. This provides the bowler with a comfortable and secure grip on the ball. The ball 630 is configured for a conventional grip, which allows the bowler to curve his palm around the surface of the ball, in contact with the surface of the ball. In other embodiments it may be configured for a fingertip grip or a hybrid grip. Finger hole inserts within the scope of the invention may have any of the variations of the thumbhole inserts in its various different embodiments. This embodiment has the advantage that one hole configuration, with a span of for example of approximately 76 mm (3 inches), may be suitable for a number of different bowlers with mid-range hand sizes. Bowling balls could therefore be configured in a limited number of standard span sizes, for example in the range of 60 mm to 90 mm, which would be suitable for use by the majority of adult bowlers.

The inserts of the present invention may be formed by moulding techniques, such as injection moulding, or other plastic forming techniques such as casting. Alternatively, the shaped profile of the inserts can be formed from a machining process, such as drilling and/or reaming including under-reaming.

Because embodiments of the invention use a loose fitting thumbhole the thumbholes may be used by a wide variety of bowlers having a range of thumb sizes. This facilitates production and sale of inserts in standard sizes, which can be fitted or retrofitted to bowling balls in the orientation required by the bowler. However, the thumbholes and/or inserts of the invention can be custom-fitted to a particular bowler.

In one embodiment of the invention, an internal surface of the thumbhole or insert is provided with a layer soft, uncured, putty-like material. The bowler inserts his thumb into the thumbhole in the required orientation with fingers located in the finger holes. The bowler bends his thumb to form a recess or niche in the side wall of the thumbhole which accommodates the bent thumb position. The bowler therefore deforms the putty material to vary the cross-sectional area of the thumbhole. The bent thumb is then straightened, and the thumb is pulled out of the thumbhole. The soft putty-like material is allowed to cure until it hardens, retaining the shape created by the bowler's bent thumb.

In one embodiment, the soft putty-like material is applied to the inside surface of the bowling ball. In an alternative embodiment, the soft putty-like material is provided on the inside surface of an insert, which is used to form the required shape thumbhole before placing the insert in the ball.

In the above-described embodiments, the contact surfaces are oriented to generally away from the finger holes. The actual final rotary angle of the contact surface may be varied according to where the thumb pad of the particular bowler would normally rest on the inside of a conventional thumbhole. The formation and/or insert may then be oriented in that rotary position, before being permanently formed into the thumbhole (for example by gluing).

The invention relates to a bowling ball comprising an arrangement of holes for allowing a bowler to grip the ball. The arrangement comprises a thumbhole having a profile which is shaped to accommodate the thumb of the bowler in a bent position. In a preferred embodiment, the thumbhole is configured to accommodate the thumb of the bowler in a bent position in which the bowler grips the ball, and provides a clearance fit with the thumb of the bowler when the thumb is in a substantially straight position. The invention also relates to an insert for a bowling ball which defines a formation for gripping by the thumb in a bent position.

The present invention provides a bowling ball configuration which offers an improved grip to the bowler which allows improved consistency and control of delivery. The invention also provides a bowling ball configuration which reduces the likelihood of damage to a user over repeated use. In embodiments of the invention, this is achieved by reducing or substantially eliminating the frictional contact between the thumbhole and the thumb of the bowler during the release. It provides the bowler with a comfortable grip on the ball, with the hand in a natural, curved position. It increases the ease of handling bowling balls of larger weights, enabling the bowler to select a heavier ball than the prior art ball he would normally choose.

This invention allows a natural grip with the thumb, the fingers and the palm of the hand curved to hold, carry and swing the ball before it is released towards the pins. The thumb hole is preferably loose enough to allow clearance at the back and sides of the thumb, to ensure the ball can fall free from the thumb when the bowler straightens the thumb on his decision to release the ball, allowing it to have a substantially friction free, clean release.

Variations to the above-described embodiments are within the scope of the invention, and the invention extends to combinations of features other than those expressly claimed.