US1863059A - Stringing of lawn tennis and like rackets - Google Patents

Description

June 14, 1932. w, JAFFE STRINGING' OF LAWN TENNIS AND LIKE RACKETS Filed Feb. 20, 1930 3 Sheets-Sheet 1 F/GZ.

(I I g I I l INVENTOR WILL/BM EDWHRD BERT/0L0 Til/"FE 5 F) TTORIYYS June 14, 1932. w. E. B. JAFFE 1,863,059

STRINGING OF LAWN TENNIS AND LIKE RACKETS Filed Feb. 20, 1930 3 Sheets-Sheet 2 c c J "WE/Woe MHZ I EDWFIRD BERT/10mm?! 87'. 6 y

HTTOHIYEY$ June 14, 1932. w, JAFFE 1,863,059

STRINGING OF LAWN TENNIS AND LIKE RACKETS Filed Feb. 20, 1930 5 Sheets-Sheet 3 e5 I I 2 ILZ & 2 :2,

e j/ z j 6 b l l n T-rOANEys Patented June 14, 1932 PATENT OFFICE WILLIAM EDWARD BERTHOLD JAFFE, OF CHELSEA, ENGLAND STRINGING OF LAWN TENNIS AND LIKE RACKETS Application filed February 20, 1930, Serial No.

This invention relates to a, method of stringing lawn tennis and other rackets and apparatus for facilitating such stringing.

In ordinary hand stringing of racket frames the frame is held by being clamped by the handle only and is liable to be subjected to a variety of strains and consequent distortion during stringing. First the mains i. e.

the longitudinal strings are strung taut but not under their final tension. Then the racket frame is strutted longitudinally by means ofa screw expanding tool called a billiard.

The mains are then successively drawn through by hand and thus stretched to the requisite tension, the billiard providing support against longitudinal shortening of the frame but not otherwise. Then the cross strings are strung under tension, thereby slightly contracting the frame laterally and in expanding it longitudinally, whereupon the billiard drops out.

It has already been proposed to modify the ordinary hand stringing process, described above, by stretching the longitudinallystrung racket frame longitudinally or, al-

ternatively, by compressing it laterally, prior to the insertion of the cross stringing, by means of mechanically displaced curved segments moveable in' a centrally apertured frame. In connection with such apparatus it was also proposed to. provide rotatable winding spindles around the frame of the apparatus, by means of which the strings could be tensioned mechanically though without means of measuring or automatically regulating the tension to a predetermined amount. It has also been proposed to clamp the frame by its head and handle or alternatively by the two sidesand the handle with a View to prevent distortion of the frame during stringing by means of mechanical appliances which may measure the load but do not provide automatically for a predetermined tension being applied and not exceeded.

In the above described processes the racket frame is purposely distorted during stringing or at any rate it is not positively supported against distortion in all directions, consequently the final shape of the frame 429,929, and in Great Britain April 30, 1929.

and the tension of the strings de nd upon the judgment and skill of the wor an who effects the stringing. By such methods a good racket frame can therefore be easily spoilt by a poorly skilled stringer and, even 66 when all are strung by one and the same highly skilled stringer, the strung rackets arenot all uniform. v a

According to the present invention, the racket frame is positively supported against 60 distortion in all directions while the mains and the cross strings are strung to their final tension, and the strung racket frame is then released.

Further the process can be adapted to obviate the necessity for the exercise of judgment in tensioning the'strings by employing a winding device for that purpose arranged so as to enable a predetermined tension to be applied and to be automatically maintained until the string is fixed.

A jig for holding the racket frame against distortion in all'directions during stringing, and enabling the strung frame to be released, consists, for instance, of a plurality of annular segments, presenting interrupted surfaces located to abut against the head, handle end and sides of the internal profile of the racket frame, said segments being mounted on an annular base plate, with means for displacing the said surfaces into and from firm contact with the internal profile of the racket frame.

Thus, with racket frames approximately uniform in size and shape, a racket frame can be fitted over and embrace the; interrupted surfaces of the jig segments, whereupon on displacing these segments outwardly, not only is the frame securely held, but positive support is provided to resist distortion of the frame durin the operation of stringing the mains and t e cross-strings.

To enable the tension to which the strings are drawn to be precisely determined, a wind ing drum or barrel on which each string is successively wound may be yieldingly mounted but restrained by a load so as to yield, while maintaining the desired tension until the string can be fixed, when the string has been drawn to such predetermined tension.

The ig is adjustable relatively to the yielding load-restrained winding barrel, so that the several stringing holes in the racket frame can be brought into suitable operative positions relatively to the winding barrel.

A constructional embodiment of an apparatus for carrying out the invention is illustrated by way of example on the accompanying drawings, in which Fig. 1 is an elevation of the entire apparatus.

Fig. 2 is a perspective view of one of the interchangeable loading weights.

On a larger scale:

Fig. 3 is a plan of the jig which holds the racket frame against distortion. Fig. 4 is a longitudinal section of the jig I on the line 4-4 of Fig. 3.

Fig. 5 is a transverse section of the jig on the line 5-5 of Fig. 3.

Fig. 6 is a plan of the winder shown in relation to a portion of the jig, and

Fig. 7 is an elevation of the winder.

a, Fig. 1, is a pedestal at the head of which is a bracket arm I) in which an upright spindle 0 is clamped by nuts 0 This spindle 0 provides a journal on which a jig for holding I located relatively to the longitudinal At intervals around a racket frame (1 (shown in dot-dash lines in Figs. 3 and 4) is mounted to be rotatable by hand in a horizontal plane.

The jig, shown in detail in Figs. 3-5 comprises a cross bar a, journalled on the spindle 0,'on which is secured an annular framee. the frame 6 are pivoted on vertical studs P, a plurality of annular segments 7, except at one end where a fixed segment g is provided on the frame '6.

The pivoted vsegments f are symmetrically axis H, Fig. 3, of the annular jig frame e, and to the fixed segment 9.

All the segments 7 and g are provided with upstanding pins 7:. so located as approximately to fit the internal profile of the racket frame d and to come between the usual stringing holes d, Fig. 4., of the racket frame (1.

The pivoted segments f are, by inwardly directed and downwardly cranked arms f at their ends remote from their pivot studs 7, connected to the heads 71 of plungers i guided to slide radially in guides e on the frame cross bar 6 and on an arm 6 thereon. The inner ends of the plungers 11 are located between flanges j j of a collar j ournalled on the spindle 0 and are connected to these flanges 9' by pins 71 which extend into oblique cam slots 9' in the two flanges 7' The collar j is formed with a wormwheel segment 7' end of a spindle is journalled in a bearing 6 on the arm 6 of the frame cross bar e This worm spindle is is adapted to be rotated by a tOIILI IIY bar is.

Rotation of the worm spindle is in one diq'ection angularly displaces the collar j in with which gears a worm k on the such direction that its cam slots i thrust the plungers i radially outwards, which thereby thrust the segments f also outwards to bring their pins 71. into pressure contact with the internal profile of the racket frame d. The latter is thus held against distortion and is then strung by hand all the strings being drawn to their final tension.

After the racket frame has been strung, reverse rotation of the worm spindle is withdraws the pins h from pressure'contact with the strung racket frame (1, which can then be removed from the jig.

e are pivoted clips for initially positioning the racket frame on the jig.

The shape of the profile of the racket frame (1 determined by the profile outlined by the pins h of the jig, is the shape which the racket frame should preserve when completely strung. Consequently it is highly desirable that the individual strings be drawn to such degree of tautness that, when the strung racket frame 03 is removed from the jig, the tensions of the individual strings will be mutually balanced without causing any change of shape of the racket frame. This involves each string being drawn to a given tension, varying with the position of the respective string in the racket frame.

- A mechanical device facilitating stretching the strings, which yields automatically while maintaining a predetermined tension as soon as the respective string has acquired that tension, is therefore provided. Such a device is illustrated on Figs. 1, 2, 6 and 7.

l is a winding drum, provided with cleats Z and mounted on a horizontal spindle in the head m of a post m on a bracket arm m at the head of the pedestal a. The winding drum Z is fast with a wormwheel Z gearing with a hand rotated worm l The head m is pivoted about a horizontal pin m to the post m, on the side of the latter adjacent to the jig above described. The head m also has a lever arm m protruding away from the jig. This arm m is, by a link n connected to one end of a lever n which by its other end is pivoted to the pedestal a. A massive weight 0 is suspended from the lever 12. and by a hand rotated screw 0 can be traversed alongthe lever n in relation to a scale marked on the lever. A small hanger p also depends from the lever 12. on which can be mounted additionel weights, one of which 9 is shown in Fig. 2.

As each string 1', Figs. 6 and 7 is strung through the respective holes in the racket frame d on the jig, it is wrapped around the cleats Z and the winding by the worm Z to stretch the string 1'. As soon as the tension string 7' is suflicient, it causes the head m of the post 'm to tilt towards the racket frame d and jig, by the'tension of the string 1' overcoming the restraining influences of the drum Z is rotated thus imposed upon the will be indicated.

The adjust ability of the position of the weight along the lever n and the ability to employ additional weights 9, enable any desired tension of string, within working limits, to be predetermined to suit both the position of the respective string in the racket and also different classes of rackets.

On the string 1" being stretched to-the desired tension it is secured by plugging the respective string hole in the racket frame, and the string is released from the cleats Z of the winding drum Z, andpassed again through the racket frame to constitute the next string thereof.

During the stringing the'jig is rotated about its spindle c to present towards the winding drum Z, the respective stringing hole from which the string 1' happens to extend.

' 1. In a racket stringing apparatus, means for holding a racket frame against distortion in all directions, a winding drum pivoted adjacent to and tilting towards said racket frame holding means, and loading means restraining tilting of said drum.

2. In a racket stringing apparatus, means .for holding a racket 'frame against distortion in all directions, a winding drum, a mounting of said winding drum pivoted adjacent to and tilting towards said racket frame holding means, and loading means restraining tilting of said winding drum mounting.

3. In a racket stringing apparatus, means for holding a racket frame against distortion -v in all dlrectlons, a winding drum, a mounting of said :drum pivoted adjacent to and tilting towards saidracket frame holding means, an arm fast with sald mounting and protrudingaway from said racket frame holding-means, a lever pivoted beneath'said 1 arm, a link interconnecting said arm and said lever, and a weight adjustable along said lever.

4. In a racket stringing apparatus, means for holding a racket frame against distortion in all directions, a Winding drum pivoted adjacent to and tilting towards said racket frame holding means, and loading means restraining tilting of said drum, said racket frame holding means and said drum being relatively angularly adjustable.

5. In a racket stringing apparatus, a rotatable annular base, relatively displaceable annular segments mounted on said annular base and presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around .said interrupter surfaces, means for relatively displacing said segments into and from firm contact with the internal profile of a 5 racket frame applied around said interrupted surfaces, a winding drum pivoted adjacent to and tilting towards said annular base, and loading means restraining tilting of 'said drum.

6. In a racket stringing apparatus, a rotatable annular base, relatively displaceable annular segments mounted on said base and presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, cam means relatively displacing said segments into and from firm contact with the internal profile of a racket frame applied around said interrupted surfaces, a winding drum pivoted adjacent 'to and tilting towards said annular base, and loading means restraining tilting of said drum.

7. In a racket stringing apparatus, a rotatable annular base, relatively displaceable annular segments mounted on said base and presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, cam means relatively displacing said segments into and from firm contact with the internal profile of a racket frame applied around said interrupted surfaces, means simultaneously displacing all said cam means, a winding drum pivoted adjacent to and tilting towards said annular base, and loading means restraining tilting of said drum.

8. In a racket stringing apparatus, a rotatable annular base, an annular segment fixed on said annular base, annular segments pivoted on said annular base, said fixed and pivoted segments presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, plungers pivotally connected to said pivoted segments, a rotary spindle mounted in said base, collars on said spindle formed with oblique cam slots, pins on said plungers extending through said cam slots, a wormwheel fast with said spindle, a worm gearing with said wormwheel, a spindle of said worm mounted on said base, a winding drum pivoted adjacent to and tilting towards said annular base, and loadingmeans restraining tilting of said drum.

9. In a racket stringing apparatus, a rotatable annular base, relatively displaceable annular segments mounted on said annular base and presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, means for relatively displacing said segments into and from firm contact with the internal profile of a racket frame applied around said interrupted surfaces, a winding drum, a mounting'of said drum pivoted adjacent to and tilting towards said annular base, an arm fast with said mounting and protruding away from said annular base, a lever pivoted beneath said arm, a link interconnecting said arm and said lever, and, a Weight adjustable along said lever- 10; In a racket stringing apparatus, a ro tatable annular base, relatively displaceable annular segments mounted on said base and presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, cam means relatively displacing said se me'nts into and from firm contact with theinfernal profile of a racket frame applied around said interrupted surfaces, a

winding drum, a mounting of said drum pivoted adjacent to and tilting towards said annular base, an arm fast with said mounting and protruding away from said annular base, a lever pivoted beneath said arm, a link interconnecting said arm and said lever, and a Weight adjustable along said lever.

11. In a racket stringing apparatus, a rotatable annular base, relatively displaceable annular segments mounted on said base and presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, cam means relatively displacing-said segments into and from firm contact With the internal profile of a racket frame applied around said interrupted surfaces, means simultaneously displacing all said cam means, a winding drum, a mounting of said drum pivoted adjacent to and tilting towards said annular base, an arm fast with said mounting and protruding away from said annular base, a lever pivoted beneath said arm, a link interconnecting said arm and said lever, and a Weight adjustable along said lever.

12. In a racket stringing apparatus, a rotatable annular base, an annular segment fixed on said annular base, annular segments "5. pivoted on said annular base, said fixed and pivoted segments presenting interrupted surfaces at the internal profile of the head, handle end and sides of a racket frame applied around said interrupted surfaces, plungers pivotally connected to said pivoted segments,

a rotary spindle mounted in said base, collars on said spindle formed with oblique cam slots, pins on said plungers extending through said cam slot-s, a wormwheel fast with said spindle, a worm gearing with said wormwheel, a spindle of said worm mounted on said base, a windlng drum, a mounting of said drum pivoted adjacent to andtilting towards said annular base, an arm fast with said mounting and protruding away from said annular base, a lever pivoted beneath said arm, a link interconnecting said arm and said lever, and a weight adjustable along said lever. 4

13. In a racket stringing apparatus, means for holding a racket frame against distortion in all directions, means for stretching a racket string mounted adjacent to said racket frame holding means, and means automatically preventing said string stretching means stretching said string to above a predeter-

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