US2097616A - Racket - Google Patents

Description

Nov. 2, 1937.

T. A. DAVIS Filed March 30, 1935 2 sheets-sheet i T. A. DAVIS Nov. 2, 1937.

2 Sheets-Sheet 2 RACKET Filed March 30, 1935 fforrafgf.

Patented Nov. 2, 1937 TES muren srmaar OFFICE- 7 Claims.

This invention relates generallyto tennis rackets and the like, and more particularly to methods of and means for controlling the weight :and

v balance of tennis rackets.`

In the manufacture of rackets, the nal total weight and balance of course is kept constantly in View during the making of the iframe. -It` is well known, however, 'that it 'is impracticable to attempt to control weight and balance 'simply by shaping and selection of wood densities. `Accordingly, it has been Athe `practice in the art that the nal total weight of a racket, as'well as its balance, are controlled by a selected mass placed in a selected and adjustable position `in the handle. Thus, for instance, ithas been common to put a lead plug in thehandle, or to drive into the end ofthe handle asuitable number'of` pins of suitable length and to 'drive them in'toa suitable position. Such methods, however, Vare not entirely effective in compensating ffor theffacv tor of varying handle sizes, and the consequent variation of the total weight and balance.

It is accordingly a primary object of thepresent invention to provide a tennis racket construction in which weight and balance can be controlled with increased effectiveness in the making of rackets of various handle sizes. f A preferred form of vracket to which the invention is particularly adaptable involves a frame and handle made up ofs'everal continuous laminations which extend completely around the head andintothe handle. The outermostla'minations are extended to the butt end ofthe handle, `the interior -larninatins being stopped at a distance vsome s'ixin'ches `from that en'd. The space 'between these'outermost laminations at the butt end or the *handle is filled with a. plug of very light wood, such a'sbalsa wood, with its `grain running transversely, sothat the end grain of the balsa wood is presented to the inner surfacesbf the outside laminations.

The iinaldesired total weight of the frame is controlled Las closely as possible by selection of r wood densities. `Forgexample,batches of wood of relatively light density are employed in making up fra-mes in thelighter weightspand vice versa. Compensation necessary to be made l`to take care of varying handle sizes, and of finalfbalance, are provided for by varying the size of the balsa wood ller. For example, everything else b eing equal, and it being desired to make up aracket having a small size handle,asomewhat smaller balsa filler is putiniandfthe two outside handle laminations pressed in "against it. Accordingly, it being the light balsa filler that is changed in dimension to provide for the smaller handle, rather than` the heavier wood of the Ahandle laminations, the total weight of the handle is not greatly decreased, but is kept upto the'value required for correctracket balance. Onthe other hand, if a large handle is ,desired, a somewhat larger than averagebalsa filler is inserted,` and thusithe total weight of'the nished handle is kept down to the pointrequired toI maintain substantially the same iinishe'd balance. y

For purposes of further adjustment, the length of the light Vbalsayller may bevariedfso `as to provide more or less weight of heavy Vwood. inthe handle. 'l v x 'l `With this preliminary discussion, the' invention will now be more `fully understood by referring to the drawings, and Ato the Lfollowing detailed description'of a `present preferred embodiment of theinvention.

In the drawings; l l Fig. 1 is an elevation of a tennis Aracket of a type to which the present invention may be ap-` Fig.` 2 isa side elevation of the handle ofthe racket shown in Fig. 1; ,i .25

Fig. 3 isa view similar to Fig.'-1,but showing the racket with the'throat laminations removed and with part of the handle broken awayto eX- pose the construction o'f the handle in accordance with the present invention; Fig. 4 is a view similar to a portion of Fig. 3, showing a handle of relatively smaller size in accordance with the invention;

Fig. 5 is a view showing the handleinV alarge size form; l

Fig. 6 is a section taken on line 6-'6 of Fig. 4;

Fig. '7 is a section taken on line 1-1 of Fig. 5;

and

Fig. 8 shows the handle in an intermediate stage of manufacture.

Theracket here shown for illustrative purposes comprises the usual oval head Ill and ,handle Il, the head being formed of a plurality of wood plies in oval Aformation converging at the lower end toward throat I4 and thence, except for certain plies which are cut out to permit insertion of the relatively light Wood filler` (tov be described), continuing downwardly to form the handle. The several :plies are formed tothe desired shape of the frame by placing them in a press, the contacting surfaces of the plies having been previously coated with anadhesive, and the frame is then allowed to remain in the press alength of time suitable for the adhesive to dry `and the plies to become securely glued together to form a rigid frame.

The head portion of the frame includes four relatively thicker plies l5, I8, Il, and I3 which extend around the head, and extend downwardly beyond the throat toform the handle. There are also two relatively thinner plies 20 and 2l placed between the thicker plies as shown. The racket also has, within the triangular space at the throat, a block 25 shaped in accordance with the curvatures of the frame sides at this point, and a pair of laminations 26 and 2l' are glued on the upper side of the block and to the inside of the frame, tapering out as sho-wn.

Added to the four major plies making up the frame and handle is a fth ply 28, which begins with a taper just above the throat and extends downwardly into the handle, as shown in Fig. 3.

To strengthen the frame at the throat, thin plates 35 of` wood veneer are glued to opposite faces of the frame at the throat. These veneer plates extend for a short distance toward the handle and up along each side of the head, as shown vin Fig. l'. In the embodiment here `illustrated, each of these plfates35 is made up of 'two plies 35d and 35h.

The racket as now described issimply typical of Va type of racketlto which the present invention may advantageously be applied; it is tobe understood, however, that the improvements of the present invention are not necessarily limited to certain details fof the racket Yhere; chosen for illustrative purposes. Y Y

Referring now to the handle construction of the racket, itwill be-seen from Fig.3 that the two outermost plies I8 and 28 continue tothe butt end of the handle, while plies I5, I6, I'I, 28and 2| lstop at a point' about midway of the handle, say six to eight inches from its butt" end, as indicated in Figs. 3,4, and 5. The framemembers asso far described are made of relativelydense and heavy'wood, such as ash, walnut, birch, hickory, etc.

The space between outermost handle plies I8 and 28 and below the lower ends ofthe short plies I5, I6, nand I1 is lled'with a plug 38 of some relatively light wood, as balsawood, placed with its grain running transversely, that is, with its end grain presented to the inner surfaces of the two outerside edge: strips I8, 28.

The racket handle is built out at the sides to proper size and weight by means of side slabs or plates 48, which-:are glued to the edges of the Yhandle plies' and to' the side surfacesof Vbalsa wood plug 38, these side members extending upwardly'from the'butt end-of `the handle., and theirv upper ends tapering out at a point several inches below the throat, as illustrated. The outer surfaces ofside plates 48 and exterior handle plies I8 are nally out to the., conventional octagonal tennis racket handle shape, as illustrated in Figs.V 6 and 7. n Y

The butt end of the handle is finished by placing a rubber or leather cap 42 over the end and securing it to the wood. Before this is done, however, it may be found desirable to insert one or two cr more metal pins G3 into the butt end v of the racket to eifect a nal balance adjustment (Fig. 3).

In making up the frame as Vthus described, the properly cut plies are coated with glue and placed in the press, with the balsa plug 38 placed in position, and an extra ply 45, which extends the length of the handle, is placed and glued on the outer surface of each outside ply I8, aS 1 lustrated in Fig. 7. The press is then set up to press the plies tightly together, and the glue allowed to dry and set.

The handle is next sawed to the proper width dimension, which operation may remove all or nearly all of the added plies d5. In the instance of Fig. 3, the plies d5 are shown as having been entirely removed by the sawing operation. In Fig. 5, a thin fragment of the plies 45 is illustrated as remaining. This sawing operation is accurately carried out with Vreference to the center line of the head of the racket, so that the handle will finally be symmetrical with reference to this center line. If in the gluing operation the handle has become offset slightly from this center line, the sawing operation may remove a slight amount of the wood of the handle ply I8 on one side while leaving a corresponding thickness of the extra ply 45 on the other. The use of the added plies 45 and the sawing operation `as described Ythus assures that the nal handle will be accurately symmetrical with reference to the center line of the head of the racket. Where the handle as originally formed lis symmetrical and accurately centered with reference to the center line of thel head, however, the entirety of the plies 45 may be removed, or an equal thickness of these plies may be left on each edge of the frame (Fig. 5). Y

Fig. 3 is illustrative of an average size Yracket handle, in which is used a balsa plug 38 of a thickness t equal to the original dimension between the two outside or edge strips I8, 28. When the freshly glued racket frame is placed in the press and the press is tightened, the inner surfaces of members 28 are tightly pressed against the exposed end grain of the balsa wood block. There is accordingly no tendency for the balsa wood to be crushed. If the grain of the balsa wood were to run longitudinally of the handle, on the other hand, theV pressure of the press would cause this balsa Woodblock to crush and the handle frame to fracture or break down at once. It is therefore essential that the grain of block 38 run at right angles to the inner surfaces of side plies 23, and this constitutes a feature of importance in the present invention.

If Vnow a racket frame is to be made up with handle size smaller than on the racket of Fig. 3,

a balsa wood block of slightly less thickness t' is f lower ends of'plies I5, I 6, I'I becomes squeezed inwardly until they engage the end grain suri faces 38a of block 38', this condition being illustrated clearly in Fig. 4. It will now be evident that when the racket handle as so formed is then subsequently sawed down to the size required, a lesser amount of -heavy wood of the outermost plies I8 will be removed than had the plies not been squeezed inwardly into engagement with the reduced dimensionv block 38'. Thus, a relatively larger amount of the heavy wood of the handle (the outside plies) is preserved than had the handle of the racket of Fig. 3, with a balsa wood block of thickness dimension t, been sawed down to the reduced dimension required. The amount of light wood lost to the handle by reducing the dimension of the balsa block from thickness t to thickness t has an immeasurable effect on the weight of the handle. Thus by this manner of construction, the weight of the handle is kept well up while its width dimension is reduced. y

aoccasio- V Likewise, if a racket handle of `relatively larger size is required, a balsa-.wood block 38" of. in` creased thickness dimension t" (Fig. 5) is chosen, causing plies I8 and 28 to be flexed outwardly a corresponding amount. When the edges of the handleare `then sawed tothe larger dimension :5; tively' heavy wood in the handle remains substantially unchanged.

It will thus be evident that the-total thickness of the four heavy wood. layers made up of plies I8 and 28 remains substantially the same in the three handle sizes, the three handles differing mainly in the differing thicknesses of the balsa wood filler employed. And because of the relative lightness of this balsa wood ller, such variation in thickness from handle to handle causes very little difference in the weight or balance of the three rackets.

The immediately foregoing description is based on theV assumption that the thickness dimension t (distance between plies 28) is constant, as it usually will be in rackets made up of plies of the same thicknesses. However, in the practical manufacture of rackets, different ply-,woods are used, of slightly differing densities; and conse.

quently the plies are a little different in thickness in order 4that the total weights remain about the same. For instance plies of walnut will be a little thicker than those of ash; and in: a`

racket made of the former wood the dimension of ash. To obtain the same size of handle in each instance, a balsa block 38 of the same size is used; resulting in that the walnut handle plies may be bentl inwardly as in Fig. 4, while the ash plies may be bent out as in Figj5., The construction consequently will be seen to take care Yof varying ply thicknesses, while at the same time maintaining desired handle sizes.

A further variable condition is encountered in` Y compensated, however, since the smaller handle relatively lighter weight is therefore usually oiy advantage rather than a disadvantage, tending sizes are usually demanded with the lighter yweight rackets; the fact that the side platesV 40 for such lighter andrelatively small .handled rackets are relatively thinner and therefore of as it does to hold the balance ofV the racket constant rather-than to cause unbalance. A corresponding result in the other direction obtains with the heavier and relatively larger handled rackets.

However, if it is desired to make up a racket of small handle size/ but of relatively heavy weight, then the length of the balsa plug may be reduced, and the relatively heavy plies I5, I6, and I1 extended further down into the handle."

This will have the eiect of increasing the weight This variation is `usually.

of the'handle to compensate the lessened weight dueto-theft thinner` side plates or slabsl that go with the smaller handle. Fig. 4 is illustrative of suchanglad-justment, the plug 38 beingV illustrated as being -somewhat shorter in length than the plug 38`^ofthe racket of Fig. 3.

Correspondingly, aracket handle of Vlarge size (Fig. 5) may be kept down in weight by increasing the length of the balsa plug, and therefore decreasing the quantity of the heavy wood in the handle.

`As ayariational means of compensating for thezincreased weight of the handle due to thicker side` plates 48 in the larger handle sizes, the innerisurfaces of such plates40 may be routed out or grooved, as indicatedv at 48 in Figs. 5 and '7.

Preferably, I construct the rackets to be slightly lighty inthe handle, if anything, so that final adjustment forbalance can bemade by driving one or two short metal pins 43 in the butt end of the handle. This nal adjustment is all that .is` required to balance the racket for the trade after it has been glued together, trimmed, and finished.

, Thus it will be seen that my racket constructien enables the size of the handles to be varied duringl i manufacture without substantial change inthe kquantity of the relatively heavy wood in thev handle, so that rackets of diierent` handle sizes will` all balance about alike'. lighter rackets (constructed usuallyA of lighter samples .of` wood) are usually. provided with the smaller` handle sizes, any lightening of the handle due to use of thinner side plates 4U is a compensatory change as regards racket balance, as is use of thicker side plates on the larger size handles.

But when a racket of large sized handle but lightl weight, or. a racket of small size handle but heavy weight, is. wanted, this may be taken care of by control-of the longitudinal length of the balsa plug, andtherefore of the quantity of relatively heavy wood in the handle, `which varies inversely with the length of the balsa plug. Or, in the instance of the few extremely la-rge size handles, this condition may be taken care of by routing the inner surfaces of the side plates.

It will be evident that the provisions of the present invention are adaptable to rackets of many different types of construction. It is essential, however, that the rackets to which the provisions of the present invention are to be applied include two somewhat` flexible members running down the two opposite edges of the handle, such as are capable of being flexed inwardly or outwardly to conform to thethickness of the balsa plug, to be used. in any'given instance. In thepresent illustrated racket, these side members are made up of` two glued together plies I8 andV 28. l use of two such plies is not limitative onl tlreinventicn, the requirement being simply that two exiblejmeinbers be provided capable of being bentzinwardly or outwardly as the` thickness dimension of ,the light wood plug or filler may be` varied.

MI, claimz.. l. In a tennis racket handle, the combination of two outside substantially ilat flexible edge members of relatively heavy wood extending parallel to one another the length of the handle, relatively heavy wood material between said edge members extending `from the racket throat end of the handle to a point about midway of the length of the handle, a relatively light wood ller block between and abutting the inner surfaces of said Since the v It will be evident, however, that the edge members and 'extending from a point near the lower end of said wood material to the butt end ofthe handle, the grain of said filler block running at right angles to the flexible edge members, the thickness of said block measured in the direction of the grain being less than the distance between the flexibleY edge members at the upper end of the'handle, and said flexible edge membersbeing ilexed inwardly at the upper end of said ller block Yand being glued against its adjacent end grain surfaces.

2. In a tennis racket handle, the combination of Vtwo outside substantially flat exible edge members cf relatively heavy wood extending parallel to one another the length of the handle, relatively heavy wood material between said edge members extending from the racket throat end of the handle to a point about midway of the lengthof the handle, a relatively light wood ller block between and abutting the inner surfaces of said edge membersand extending from a point near the lower end of said wood material to the Ybutt end of the handle, the grain of said iiller block running at right angles to the flexible edge members, the thickness of said block measured in the direction of the grain being greater than the distance between the flexible edge members at the upper end of the handle, and said exible edge members being flexed outwardly at the upper end of said filler block to accommodate the increased thickness thereof.

3. In a tennis racket handle, the combination of two outside substantially ilat flexible edge members of relatively heavy wood extending parallel to one another the length of the handle, relatively heavy wood material between said edge members extending from the racket throat end of the handle to a point about midway of the length of the handle, a relatively light wood ller block between and abutting the inner surfaces of said edge members and extending from a point near the lower end of said wood material to the butt end of the handle, the grain of said filler block running at right angles to the flexible edge members, the thickness of said block measured in the direction of the grain being greater than the distance between the flexible edge members at the upper end of the handle, and said flexible edge members being flexed outwardly at the upper end of said filler block to accommodate the increased thickness thereof, and side plate handle members fastened against the edges of said flexible members and tosaid relatively heavy wood material, said side plate members being grooved on their inner surfaces to reduce their weight.

4. In a tennis racket handle, the combination of two outside substantially flat flexible edge members of relatively heavy wood extending parallelV to Vone another the length'of the handle, interior plies of relatively heavy wood extending Y downwardly in the handle between said edge members to a point about midway of the length of the .handle and a relatively `light wood ller block between and'abutting the inner surfaces of said edge members and extending fromra point near end of the handle, the thickness of said block measured at right angles to the planes of the edge members being slightly less than the total thickness of the interior plies, and said flexible edge members being flexed inwardly at the upper end of said ller block against the adjacent surfaces of said block.

5. In a tennis racket handle, the combination of two outside substantially flat flexible edge members of relatively heavy wood extending parallel to one another the length of the handle, interior plies of relatively heavy wood extending downwardly in the handle between said edge members to a point about midway of the length of the handle,`and a relatively light wood ller block between and abutting the inner surfaces of said edge members and extending from a point near the lower ends of the interior plies to the butt end of the handle, the thickness of said block measured at right angles to the planes of the edge members being slightly greater than the total thickness of the interior plies, and said flexible edge members being flexed outwardly at the upper end of said ller block to accommodate the increased thickness thereof.

6. In a tennis racket handle, the combination of two outside substantially flat flexible edge members of relatively heavy wood extending parallel to one another the length of the handle, relativelyy heavy wood material between said edge members extending from the racket throat end of the handle to a pcint about midway of the length of Ithe handle, a relatively light wood filler block between and abutting the inner surfaces of said edge members and extending from a point near the lower end of said wood material to the butt end of the handle, the grain of said ller block running at right angles to the flexible edge members, the thickness of said block measured in the direction of the grain differing slightly from the distance between the flexible edge membersat the upper end of the handle, and said flexible edge members being exed at the upper end of said filler block tovaccommodate'such dimen-` edge members and extending from a point near f the lower ends of the interior plies to the butt end of the handle, the thickness of said block measured at right angles to the planes of the edge members being slightly different from the total thickness of the interior plies, and said flexible edge members being ilexed at the junction between said interior plies and said filler block to` accommodate such diierence in thickness between the interior plies and the filler block.

THEOPI-IILUS A. DAVIS.

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