US1921068A - Shaft for golf clubs and method of making - Google Patents

Description

1933- D. F. BOYDEN SHAFT FOR GOLF CLUBS AND METHOD OF MAKING 2 Sheets-Sheet 1 Filed March 12, 1929 Patented Aug. 8, 1933 UNITED STATES PATENT OFFICE SHAFT 'FOR GOLF cLUBs AND METHOD OF MAKING 2 Claims.

,Among the important qualities .desired of shafts more particularly intended .for use in golf clubs are that such shafts withstand effectively the stresses of use; that they possess the 5 proper life and ,feel and that they make possible the realization of high driving power.

,It .is :well known that ,different parts of the shaft have to withstand different strains, and that ,a shaft usually ,breaks a short distance above the head, for it ishere that the torsional stress caused by hittingtthe ball off center of the shaftis greatest, andgraduallydecreases toward the grip end of the shaft. It is also well known that the driving ;power of the shaft lies at its .upper portion pr toward its grip end, and that bamboo ,is a resilient material which transmits this driving .power effectively to the head end, but which is not very effective to take torsional stress.

In UnitedStates Letters Patent granted to me .September 13, 1927, I have-disclosed and claimed ashaft comprisingalower section made entirely of woodsuch as hickory up to and below the point where maximum strain occurs and above :this pointhaving. a central longitudinal tapering slot in ,which'is fitted a correspondingly shaped lower end of .an upper section'of material such vas bamboo, this latter seotionpreferably being extended to a pointsufliciently above the lower section to provide a handle portion. More specifically, the upper section comprises a plurality .of strips of bamboo of idiiferentlengths, nested and secured together as by glue, the pith side of onestrip being cut to receive the enamel side .of the strip immediately adjacent thereto. With'such a shaft, it has been found that great driving powermay be realized and the proper resistance to1the stresses of useafforded.

This invention relates toshafts of the general .type disclosed and claimed in ,my hereinbefore identified patent, its general object being to provide an improved shaft, .a more economical method of making the .same, and an improved assembly with ahead.

In accordance with the present invention, ,the cylindrical blank from .Which (the lower section is to be made is longitudinally .kerfedcentrally from one end to -a point short of the other end, .vrhereupon theupper wedge-shaped section ,is inserted in the kerf .to expand it-to longitudinally tapering form, and is bonded as by glue to the side walls of the kerf. The outside expanded or excess portion of the ,lower section istheneut ,away and the rough shaft trimmed -to:shape. .Such a methodis much simpler and more economicalthan that heretofore employed, it being possible to formthe central longitudinal ,kerf inthe lower section in one operation. .It has been found that wood such as hickory is suficiently flexible and resilient to withstand expansion of the kerf to longitudinally tapering form by the upper section, without being split or otherwise injured, and due to its deformation it is under tension, which serves to hold or grip the upper section more firmly in place. Further, in accordance with the present invention, the kerf orslot of the lower section V is formed with a bottom inclined from one to the other side, and the lower end of the upper section is complementally out, the head being mounted on the shaft with its striking face on the same side as the upper end of said inclinedfbottom. With such a construction, a backing .or reinforcement for the lower section is provided, ,so that impact with the driving 7 face of a club with a ball or other object does not tend to separate the sections. Further, in accordance with thepresent invention, the head is mounted on the shaft with its striking face in a plane substantiallyperpendicular to the 0 planes of bonding of said strips of bamboo, these planes .thusbeing parallel to the plane of swing. .Experience-hasshown that if the head is mountedon the shaft with its striking face on the same side as the enamel side of the bamboo 5 strips, the strips flex on each other, which after a time causes the shaft to become soft or slow in action, there being lag in the transmission of driving ,power from the grip end to the head end, especially at the finish of the swing, whenthe head should meet the ball with maximum driving power in order to obtain a good drive. By mounting the head on the shaft in accordance with the present invention, this deterioration of .the shaft is found in practice not to occur and, furthermore, it has been found that the shaft has higher driving power. With the foregoing and other features and objects in view, a better understanding of the resent invention may be gained from the following more complete description thereof when considered with the accompanying drawings,

wherein Figure 1 represents in perspective a plurality of strips of bamboo to be assembled for the construction of the upper section. a

Figure 2 is a side View of the assembled and trimmed strips, the dotted outline showing the strips before they are cut to fit into the lower section. 1 10 Figure 3 is a plan view of the same.

Figures 4 and 5 represent sections on the lines 44 and 55, respectively, of Figure 2.

Figure 6 is a plan view of the lower end of the assembled upper section.

Figure 7 illustrates in front view the shaft assembled with a head.

Figures 8, 9, l0 and 11 represent sections on the lines 8-8, 99, 10-l0and l1-ll, respectively, of Figure 7.

Figure 12 illustrates in perspective a finished golf club.

Figure 13 is a fragmentary section through the shaft, showing the joint formed at the bottom of the slot of the lower section with the lower end of the upper section.

Figures 14 to 18, inclusive, are side views of the shaft at various stages of its making, Figures 14 and 15 respectively showing the lower section before and after it is kerfed, Figure 16 showing the upper section inserted in the kerf to expand it, and Figure 17 showing the rough shaft after the expanded portions of the lower section have been trimmed.

Figures 18 and 19 are side views of the upper portion of the finished shaft, one view showing the shaft turned from the position of the other View.

Figure 20 is a section on the line .2020 of Figure 16. I

Figures 21 and 22 are sections on the lines 2121 and 22--22, respectively, of Figure 17.

Referring first to Figure 14 of the drawings, 1 represents a cylindrical blank of hickory or equivalent wood from which the lower shaft section may be formed. As shown in Figure 15, a longitudinal kerf or slot 2 of, say, about inch in width may be formed therein centrally downwardly to a point somewhat above that at which maximum stress usually occurs, thus leaving a pair of fork members 1 having flat, parallel inner faces or walls and projecting from the unkerfed portion p. The kerf is preferably made in one operation and parallel with the grain of the wood, as by the use of a suitable rotary saw, the bottom d of the kerf being'left sharply inclined by the saw, as best shown in Figure 13. The kerf 2 serves for the reception of a longitudinally wedge-shaped upper section 3, which may be made of bamboo or other material of like characteristics, the lower end 6 of this section being cut complemental to the bottom of the kerf 2, as best shown in Figure 13.

As shown in Figure 1, the section 3 is made up of a plurality of bamboo strips 4, 5, and 6, of different lengths, nested together. Inasmuch as the strongest and most resilient part of bamboo is its outer or enamel portion 0, the upper section is preferably made in such a way as to retain a maximum of this part of the bamboo. To this end, the inner or pith side i of each of the strips is cut to fit against the enamel portion of the immediately adjacent strip, the enamel portion of which latter has been smoothed down The section 3 s fiiciently to make a nice fit. thus comprises the strip 6 extending throughout the entire length of the section, reinforced by the shorter strips 5 and a on its concave side. fhe strips are assembled and glued or cemented together as shown in dotted outline in Figure 2, whereupon the assembly is cut to tapered form, as shown in full lines. Thus, the convex side of the assembled strips is skived off along the plane aa, and the concave side along the plane b-b, to provide fiat sufaces for gluing onto the inner flat faces of the fork members 1. The planes of skiving terminate sufiiciently short of the upper end of the strips to provide a handle portion 72 made entirely of bamboo. The section 3 is inserted in the slot 2 which extends throughout a substantial portion of the lengths of the shaft and intermediate its ends and bonded in place by glue or other cementing material, the fork members ,2 being sprung apart and expanding the narrow kerf of uniform width to longitudinally tapering form, as shown in Fig.- ure 16. .The rough shaft thus produced has a good deal of excess wood on both sides, particularly near the upper end of the lower section, as best shown in Figure 20. This excess may be readily removed by placing the rough shaft in a jig that holds it on center at both ends, and skiving surplus wood from both sides, as by means of a circular saw. This operation leaves the rough shaft approximately square at its'upper end, as shown in Figure 21, andround at the lower end, as shown in Figure 22, the fork members 1" being of gradually diminishing thickness toward their upper ends. The rough;

shaft may then be turned down to size as on By constructing a shaft as hereinbefore described, a minimum of the enamel portion of 1 the bamboo is sacrificed. Furthermore, the bamboo strips are nested to one another substantially in their natural curvature, and, due to the non-homogeneous nature of this ma--- terial, the center of torsional stress or neutral 1 axis is eccentric to the axis of the shaft, which appears to give desirable characteristics to the shaft.

As indicated in Figure 7, a head 10 when as 7 sembled with the shaft is mounted thereon with 1 its striking face 11 on the same side as the upper end Z of theinclined bottom of the kerf in the lower section, and in a plane substantially perpendicular to the planes of bonding b of the; strips of bamboo of the upper section, as best 1 indicated in Figure 8. If desired, the shaft may be wrapped with cord or other suitable reinforcing material 1 at the lower end of the slot 2 and a shortdistance below the grip end.

While I have described an upper section as 1 comprising three strips of bamboo, a greater 'or less number of strips may be used, when desired. Also, if desired, this section may be one-piece when made of a suitable material; or it may be. made up of a plurality of strips of the same or 1 dissimilar woods, or of wood and bamboo. Shafts possessing different characteristics may thus be constructed to suit the demands of dif ferent players. While in the particular shaft described hickory and bamboo are used; other 1 woods may be employed in lieu thereof. For instance, ash, lancewood, ori greenheart maybe used in lieu of hickory, and black palm, Bethabare, and other woods and canes may be used alone or in combination, in lieu of bamboo. 1

Having thus described an embodiment of this invention, it is obvious that it is susceptible of change and modification without departingfrom the spirit or. scope of invention as defined by the appended claims. a 1

What I claim'is: 1

1. In combination with a shaft of the class described comprising a lower sectionprovided witha tapering slotterminating at-a point above the lower end of the shaft, and an upper sec- 1 tion fitted into said lower section and made up of a plurality of strips of bamboo, the pith side of each of which nests onto and is bonded to the enamel side of the strip adjacent thereto, of a head mounted on said shaft with its striking face in a plane substantially perpendicular to the planes of bonding of said strips of bamboo.

scribed, comprising a lower section, provided with a tapering slot terminating withan inclined bottom at a point above the lower end of the shaft, and an upper, wedge-shaped section fitted of the slot, of a head mounted on said shaft withits striking face on the same side as the upper I end of the inclined bottom of said slot. 2. In combination with a shaft of the class der DWIGHT F. BOYDEN.

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