Golf putter

A golf putter is shaped and has the shaft thereof connected to the clubhead thereof so that the club has a center of percussion that extends for essentially the entire length of the clubhead. The shaft is attached to the clubhead internally of that clubhead.

TECHNICAL FIELD OF THE INVENTION 
The present invention relates to the general art of amusement devices, and 
to the particular field of golf equipment. 
BACKGROUND OF THE INVENTION 
As every serious golfer understands, putting is at least half of the game 
of golf. Simple arithmetic bears this conclusion out in that since two 
putts are allowed for each hole, a par seventy-two course allows half the 
strokes for putting. Birdies are generally made by using only one of the 
allotted two putts on a hole. 
Among top players, shadings in shot-making ability are faint, and it is the 
putting game which often determines who wins a given tournament. For this 
reason, accomplished golfers spend a great deal of time working on their 
putting game. 
Most secrets of good putting includes admonitions to move the clubhead low 
along the ground, to keep the putter square to the line of flight at 
impact, and to strike the ball on the clubhead's sweet spot. Most golfers 
practice these rules during a putting practice session. 
Many golfer's use different stances for different putts. For example, a 
golfer on any given round may employ a square-to-square stroke, an 
inside-to-outside stroke, and an outside-to-inside stroke. Still further, 
many golfers use different style putters, ranging from a blade putter to a 
barrel-shaped putter. However, during any of these strokes or using any of 
the different putters, the ball should be struck on the club's sweet spot. 
Since putting is such an important part of the game of golf, the art 
contains many examples of putters. While the art contains several 
different style putters, all of the presently available putters have a 
common drawback in that it is somewhat difficult to ensure that the golfer 
will strike the ball with the sweet spot each time he putts a ball. This 
is especially true if the golfer changes stances and strokes during a 
round. Even if the sweet spot is marked, it may still be difficult for a 
golfer to impact a ball with this marked spot. 
The sweet spot of a golf club head is the center of percussion of that 
clubhead. The center of percussion is defined in terms of a rigid body, 
and is defined as the point of application of the resultant of all the 
forces tending to cause the body to rotate about a certain axis. The 
center of percussion is the point at which a suspended body may be struck 
without causing any pressure on the axis passing through the point of 
suspension. Thus, if a rigid body, free to move about a point O, and the 
line of force is perpendicular to the line from O to the center of mass, 
then the initial motion of the body is a rotation about the center of 
percussion relative to O. If a ball is struck at the center of percussion, 
no "sting" is felt if the club is held on the center of oscillation. If 
the ball is struck off of the center of percussion, there may be a 
twisting force exerted on the club. 
As above mentioned, one of the basic tenants of good putting technique is 
to keep the clubhead square to the line of flight at impact. Thus, since 
striking the ball with a club at a location spaced from the sweet spot may 
tend to twist the club, it is important for the putter to permit the 
golfer to strike the sweet spot against the ball, no matter what the 
stroke, the stance or the type of putter is being used. 
While many of the presently-available putters have a marked sweet spot, in 
fact, the sweet spot is so small that it is difficult to hit. Even further 
to this, striking a ball off of the sweet spot may cause the club to twist 
in different ways depending on how and where the ball is struck relative 
to the sweet spot. This rotation of the club may cause a putt to be errant 
for no apparent reason so that a golfer cannot even truly analyze the 
stroke to correct it. 
Thus, it is extremely important for any golf club to permit the ball to be 
impacted at the clubhead's sweet spot. However, due to the precise nature 
and the importance of the putting portion of the game, it is even more 
critical that the putter have a sweet spot that is easy to hit in a 
consistent manner, no matter what stance and swing is used. It is in this 
area that prior art putters fall short. 
Still further, the club shaft of these putters is attached to the clubhead 
in a manner which may even unbalance the putter, especially if the ball is 
struck off of the sweet spot. Often, this connection of the head to the 
shaft is such as to actually interfere with the putting stroke, especially 
if the putt must be made from near the fringe of a green where the grass 
may be of different lengths. Still further, the connection between the 
clubhead and the shaft of many prior art putters can loosen over time 
thereby further vitiating even a proper stroke. 
Therefore, there is a need for a putter which permits a golfer to 
consistently strike the ball on the sweet spot of the clubhead, and which 
has the clubhead connected to the club shaft in a manner which is secure 
and is not likely to disturb or vitiate the golfer's putting stroke. 
OBJECTS OF THE INVENTION 
It is a main object of the present invention to provide a putter which 
permits a golfer to consistently strike the ball on the sweet spot of the 
clubhead. 
It is another object of the present invention to provide a putter which 
permits a golfer to consistently strike the ball on the sweet spot of the 
clubhead, and which has the clubhead connected to the club shaft in a 
manner which is secure and is not likely to disturb or vitiate the 
golfer's putting stroke. 
SUMMARY OF THE INVENTION 
These, and other, objects are achieved by a putter, specifically a putter 
having a barrel-shaped clubhead, which has the center of percussion 
enlarged so as to make it quite easy for a golfer to consistently impact a 
ball with the clubhead's sweet spot no matter what type of stroke or 
stance is being used and no matter what the conditions of the putt. The 
putter is also designed so that the connection of the clubhead to the 
shaft does not interfere with this consistent impact at the sweet spot and 
will, in fact, will make it easier to strike the ball at the proper 
location on the club. 
Specifically, the distance from the axis of suspension of an element to the 
center of percussion is generally given by the relationship q.sub.0 
=I/(mx.sub.0), where I=the moment of inertia of the body about its axis of 
suspension to the center of gravity of the body; m=the mass of the body; 
x.sub.0 =a characteristic dimension of the body; and q.sub.0 =the distance 
from the axis suspension to the center of percussion. The design of the 
putter embodying the present invention sets the value of I/m so the center 
of percussion for the club is quite large without making the club 
cumbersome to handle. In fact, the specific design of the present achieves 
the object of enlarging the center of percussion, it does so in a manner 
which synergistically also achieves the additional objects of affecting 
the attachment of the shaft to the clubhead without having the attachment 
located where it might interfere with the putting stroke, and can be 
located in the most advantageous position on the clubhead. 
Still further, the attachment of the shaft to the clubhead is at two widely 
spaced apart locations so that shaft energy is transferred to the clubhead 
over a wide spacing. The swing energy is thus distributed over a large 
surface area of the clubhead. Such enlargement of attachment area further 
decreases the possibility that the clubhead will twist at impact since 
impact force is almost always at the point of attachment of the clubhead 
to the shaft. This feature of the invention can be visualized by comparing 
the effects of an impact on a cantilever beam versus the effect of the 
same impact at the same location on a simple beam. Referring to FIG. 1A, 
it is seen that impact point IP is spaced from support point S on the 
cantilever beam CB will cause a twisting moment TM about the support point 
S, with a mirror image effect occurring for a support point located at the 
opposite end of the beam. The magnitude of the twisting moment TM varies 
as a function of the moment arm MA as measured between points IP and S. 
However, as shown in FIG. 1B, a simple beam SB is supported at two points 
S.sub.1 and S.sub.2 so impact at point IP will not cause a twisting of the 
beam no matter where the beam is struck. Even if the cantilever beam is 
weighted at its ends, the twisting will occur; whereas, even if the simple 
beam is unweighted, the twisting will not occur. 
In effect, one way of viewing this feature could be that the center of 
percussion covers essentially the entire length of the beam since no 
twisting will occur no matter where the beam is struck. 
Still further, by connecting the shaft to the clubhead at spaced apart 
locations, any pressure waves set up in the clubhead as a result of the 
impact between the clubhead and the ball will be damped and controlled in 
a manner that is specifically set up at the factory. Thus, uncontrolled 
vibrations are not likely to occur in the putter embodying the present 
invention thereby making this putter easier to control and handle as 
compared to prior putters. 
Still further, the clubhead of the present invention is attached to the 
shaft internally of the clubhead. Thus, movement of the clubhead is not 
likely to be affected by contact of attaching elements with the grass or 
the ground beneath the putter. This internal attachment will also not be 
affected by environmental conditions, so it will remain secure and 
consistent throughout the lifetime of the club.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
Shown in FIG. 2 is a putter 10 embodying the present invention. The putter 
10 includes a shaft 12 which is gripped at a top end (not shown) by a 
golfer during a putting stroke, and a barrel-shaped clubhead 14 attached 
to that shaft near a bottom end 16 thereof. 
The clubhead 12 is shown as being barrel-shaped; however, other putter 
clubhead shapes, such as blade and the like, can also be used without 
departing from the scope of the present invention. The barrel-shaped 
clubhead is shown as a preferred embodiment only, and no limitation is to 
be interpreted thereby. 
The shaft 12 has an outer dimension D, which is generally the outer 
diameter of a cylindrical shaft, and a longitudinal axis L. The shaft 12 
is attached to the clubhead at two spaced apart locations A1 and A2, and 
the clubhead is designed so that the center of percussion, or sweet spot, 
extends for essentially the entire area between locations A1 and A2, that 
is, essentially the entire length of the clubhead as measured between 
clubhead toe T and heel H. The shaft is thus connected to the clubhead in 
the manner of a simple beam, with locations A1 and A2 corresponding to the 
simple beam supports S.sub.1 and S.sub.2 respectively. The design of the 
clubhead and the attaching elements are also such that the value I/m in 
the center of percussion relationship is such as to further ensure that 
the center of percussion will be located between locations A1 and A2. 
More specifically, the clubhead 14 includes a sleeve element best shown in 
FIGS. 1 and 3-5. The sleeve element 14 forms the striking surface of the 
clubhead and includes a first end 18 and a second end 20 corresponding to 
the putter toe and heel ends respectively. A wall 22, which in the case of 
a barrel-shaped clubhead is cylindrical, connects the first and second 
ends together, and has a longitudinal axis 24 extending from the first end 
18 to the second end 20. 
The sleeve element 14 also includes a central bore 26 extending from the 
first to the second end thereof, with that bore 26 having an inner 
dimension as measured thereacross on the inner surface of the sleeve 
element adjacent to the bore. In the case of a cylindrical sleeve element, 
this inner dimension is the inner diameter of the element. 
The sleeve element has a golf club shaft-receiving hole 30 defined 
therethrough from the outer surface of the sleeve and intersecting the 
bore 26. The hole 30 extends at a skewed angle with respect to the 
longitudinal centerlines L and 24. The hole has an inner dimension ID, 
such as the inner diameter, which is greater than the outer dimension D of 
the shaft so that shaft 12 fits through the hole 30 in a loose fit. This 
loose fit is such that the shaft 12 can move freely into and out of the 
bore via the hole 30 without significant interference. The purpose of this 
loose fit is so that the shaft 12 will not be connected to the sleeve 
element via the sleeve wall 22. The angle of the hole is such that the 
angle of the shaft 12 with respect to the axis 24 is 68.degree., 
70.degree., 72.degree. or 80.degree. so the clubhead can be at standard 
angles with respect to the shaft. The preferred material for the sleeve 
element is metal, specifically brass. However, other materials can be used 
without departing from the scope of the present disclosure. 
Referring next to FIGS. 2, 6, 7 and 8, it is seen that the clubhead further 
comprises an insert element 36 located in the sleeve element and 
connecting the shaft 12 to the sleeve element. The insert element includes 
a first end 38 and a second end 40 connected together by a body 42. The 
body 42 has an outer dimension OD, which in the case of a cylindrical 
shape corresponds to the outer diameter thereof, which is smaller than the 
inner dimension of the sleeve element so that the body 42 is spaced from 
the sleeve. 
The insert element also includes a first flange element 44 on the first end 
38 and a second flange element 46 on the second end 40. The flange 
elements 44 and 46 can be monolithic with the body 42, but are described 
separately for the sake of convenience. 
Each of the flange elements has an outer dimension, in the case of a 
circular flange, the outer diameter, that matches the inner dimension of 
the sleeve element. The outer dimension of the flange elements is selected 
so that the flanges effect a force fit with the sleeve element inner 
surface so that once set inside the sleeve, the insert element will not 
move with respect to that sleeve element. The force fit can be effected by 
shrinking the sleeve onto the insert element using any of a number of well 
known shrink fit forming methods, such as freezing or the like. Adhesive 
can also be used to effect the attachment of the insert element to the 
sleeve element. 
The insert element also includes two shaft-receiving holes 50 and 52, each 
having an inner dimension, specifically an inner diameter, that matches 
the shaft outer dimension D so that a force fit between the shaft and the 
insert element is effected adjacent to the holes 50 and 52. This force fit 
attaches the shaft to the insert element. As discussed above, the flanges 
44 and 46 are attached to the sleeve element, and the shaft is essentially 
unattached to the sleeve element adjacent to the hole 30. Thus, the shaft 
is attached to the sleeve element via the insert element. 
The holes 50 and 52 are also oriented at a skewed angle with respect to the 
centerlines 24 and L so that the angles of the holes 50 and 52 match the 
angle of the hole 30 whereby an alignment of hole centers is effected when 
the insert element is in place in the sleeve. Such alignment is indicated 
in FIG. 2. The shaft 12 extends through such aligned holes so that the 
shaft lowermost end 54 abuts the inner surface of the sleeve adjacent to 
the hole 52. As above noted, the insert element can be monolithic, and in 
such a case, the holes 50 and 52 represent the ends of a continuous hole 
extending transversely at an angle through the monolithic body. 
The flanges 44 and 46 are located at positions A1 and A2, and thus the 
attachment of the shaft to the sleeve is at positions A1 and A2 which are 
widely spaced apart with the shaft being located between such positions. 
The combination of shapes, masses and connection locations effectively 
locate the club sweet spot at essentially the entire area between 
locations A1 and A2 so that a putt struck with the club 10 will be true 
and essentially always struck at the sweet spot of the club. 
FIG. 9 is a perspective view showing the assembled device. 
It is understood that while certain forms of the present invention have 
been illustrated and described herein, it is not to be limited to the 
specific forms or arrangements of parts described and shown.