US2560697A - Proportional divider - Google Patents

Description

July 17, 1951 PROPORTI F. JOY

oNAL DIVIDER Filed Dec. 1e. 194e amy.

Patented July 17, 1951 UNITED vSTATES PATENT OFFICE vPROPOR'IIONAL DIVIDER Joseph F. Joy, Pittsburgh, Pa., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of *P ennsylvania Application December 16, 1946'Serial No, 116,523

This invention relates to drawing instruments and more particularly to an improved proportional divider having improved means for adjusting the pivotal point between the divider arms or leg members and for iirmly holding the pivotal point in adjusted position, so that measurements taken from a drawing or the like may be increased or decreased according to scale as desired.

Proportional dividers of known makes usually have the V( iivider arms or leg members thereof longitudinally slotted, and passing through the slots is a pivot pin or bolt having clamping means associated therewith to hold the slotted divider arms or leg members intheir different positions of adjustment. Such lknown arrangements are not only relatively complicated and expensive to manufacture but are also subject to inadvertent slippage which hinders proper use of the instru,- ment. The proportional divider of the present invention is provided Ywith solid, non-slotted leg members, andthe pivot and clamp is'arranged externally of the non-slotted divider arms or leg members in a novelmanner so that the pivot may be. nrrnly held in .its positions of adjustment. Furtherfby making the leg members solid and arranging thetpivot and clamp externally thereof,

it is found possible to decrease the cost of manu` facture while, at the saine time, making the instrument more reliable in use.

It is accordingly an object of the present invention to provide an improved drawing instrument whichv has many advantages over known devices. A further object is to provide an improved proportional divider having improved pivot means whereby the possibility ,of the selected adjustment of the divider arms or leg members becoming disturbed during use is substantially avoided. Yet another object is to provide an improved proportional divider` having solid, non-slotted divider arms or leg members and improved clamping means arranged externally of the divider arms or leg members for iirmly holding the pivot point thereof in adjusted position. A further object is to provide an improved proportional divider of a design which eliminates Acostly machining operations, enabling manufacture at less cost. A still further object is to provide an improved proportional .divider which not only has decided advantages over known devices from the standpoint of manufacture and cost, but one which also may be used with greater accuracy and facility. Yet another object is the provision of an instrument of the above character which is extremely simple in construction, requiring but few component parts, thoroughly reliable and efeient irl its purposes,

17 Claims. (Cl. 33-150) and inexpensive to manufacture, as well as strong and durable. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompany-ing drawing there are shown for purposes ofillustration two forms which the invention may assume in practice.

In this drawing;

Fig'. 1 is a front elevational View of a proportional divider constructed in acoordance'with a preferred illustrative embodiment of the invention.

Fig. 2 is a view in central longitudinal section taken substantially on line 2 2 of Fig. 1, with parts shown in full'.

Fig. 3 is an elevational view similar to Fig. 1, with the divider arms in extended position.

Fig. 4 is a detail sectional View taken on line -of Fig. 3, illustrating details of the pivot and clamp.

Fig. 5 is a detail sectional view taken on line 5-5 of Fig. 4, showing the pivot structure.

Fig. 6 is a cross-sectional view taken centrally through the pivot on line 6 6 of Fig. 2,

Figs. '7 and 8 are, respectively, end and side viewsv of the arm seat or bearing element.

Fig. 9 shows, in elevation, the combination spring and pivot disk which is used at the pivot pointbetween the divider arms.

Fig'. 10 vis a cross-sectional view taken on line l-fl of 4Fig. 9.

Fig. 11 is a cross-sectional view taken on line II-ll of Fig. 2, showing the arm seat and slot structure.

Fig. l2 is a fragmentary view in central longitudinalsection, illustrating a modied form of pivot and clamp.

Fig'. 13 is across-sectional view taken on line l3`l3 of Fig. 12. l

Fig. 14 is a cross-sectional view taken on line Ill-'I4 of Fig. 12, showing the arm slot structure.

In b oth illustrative embodiments of the invention, there is shown a proportional divider of novel construction having solid, non-slotted divider' arms or leg members and an improved pivot and clamp structure arranged externally of the divider arms for firmly holding the adjustment of the pivot while freely allowing adjustment of the divider arms when desired. In the use of proportional dividers, it is ofttimes necessary to take a large number of measurements with the dividers set in one proportion, and in doing this, it often happens that the position of the pivot point becomes inadvertently shifted as ya result of frequent handling of the instru.-

ment, thus destroying the setting of the instrument and sometimes causing serious trouble in carrying out the work then in hand. By the use of the improved external pivot and clamp of the present invention, the probability of such disturbance of the adjustment is very slight. Also, by the provision of the improved pivot and clamp structure of the present invention, the pivot of the divider arms may be adjusted through a relatively wide range without the limitations of the longitudinal slots, previously referred to, in the divider arms of conventional dividers, and may be adjusted at any desired point between the extreme limits of the range of adjustment.

In the preferred illustrative construction shown in Figs. 1 to 11 inclusive, the proportional divider has but six component parts, and includes a pair of divider arms or leg members I and 2 which are of a solid, non-Slotted construction and are held together by an external pivot or clamp structure, generally designated 3, of an improved design. The arms or legs are of a sturdy, though light, generally semi-circular cross section having plane inner adjacent surfaces 4 and curved outer surfaces 5. The outer arm surfaces are provided with numbered graduations stamped or otherwise imposed thereon comprising a scale 6, divided into suitable units, so that the divider may be readily set at the desired proportion. lIhe arms or legs are provided at their long sides with points 1, 1 and at their shorter sides with points 8, 8.

The improved pivot or clamp structure 3 includes a generally cylindrical pivot-box or outer casing 9 having a uniform central bore I0, and the casing side walls are cut away or slotted at II to provide a seat I2 for the arm or leg I passing through the casing. Thus the arm I is held against pivotal movement with respect to the pivot-box 9 but is free to slide longitudinally in its seat I2 relative to the pivot-box. Adjoining the seat-slots II are segmental slots I3 extending circumferentially through the casing walls and through which the other leg or arm 2 passes, and the leg 2 is not only free to slide longitudinally with respect to the pivot-box but also to swing relative to the pivot-box within limits determined by the ends of the slots I3. Arranged in the casing-bore I and seated at I4 against a shoulder provided at the bottom of the bore is a circular seat element or pivot bearing I5 for the leg member 2, and the element I5 is slotted or grooved transversely at I6 at its inner side to conform to the contour of the curved outer surface 5 of the leg 2, as shown most clearly in Fig. 6. Thus a snug fit is provided for the pivoted leg 2. The seat or bearing element I5, when the clamp is loosened, is free to turn in the casing-bore, thereby to provide a swivel bearing for the pivoted leg 2 as the latter is swung in the arcuate slots in the casing Walls. A combination spring and pivot disk I'I, herein of dished form as shown in Fig. 10, affording some resiliency, is arranged within the casingbore between the inner plane surfaces 4, 4 of the divider arms, and threaded at I8 within the outer threaded end of the casing-bore is a clamping nut I9 formed with a knurled grasping portion 20. When the nut is tightened, the divider arms are pressed toward one another, compressing the spring disk I'I to the desired tension between the legs and clamping the element I5 tightly against its seat I4, thereby firmly to hold the arm-pivot in adjusted position and to secure ment I5 has a central opening 24 and the end.

wall of the pivot-box 9 is centrally cut away to provide for similar observation of the corresponding indicating numeral on the arm 2.

The instrument is assembled, as shown in Figs. 2 and 5, and, upon assembly, the bearing element I5 is first placed in the bore I0 of the pivot-box against its seat I4. The arm 2 is next placed in the groove I6 through the segmental slots I3, and the combination spring and pivot disk I'I is next inserted in the casing bore II] against the inner plane surface 4 of the arm 2. The arm I is then slid in place in the seat I2 and the clamping nut I9 may then be threaded into the casing-bore and tightened to hold the parts together. When in use, the divider may be set to the desired proportion by sliding both arms or legs I and 2 as a unit, when the arms are held together in closed position, relative to the pivot-box or by sliding the pivot-box bodily relative to the arms, until the desired indicating numerals yare centered within the observation openings 23 and 24. When the desired relation of the pivot arms has thus been made, the clamping nut I9 may be screwed down, compressing the combination spring and pivot disk II to the desired tension between the divider arms. The instrument is thus made ready for use. In operation, the leg I, by reason of its being snugly seated in the slotseat I2 of the pivot-box, becomes firmly held to the box and moves therewith, whereas the leg 2 seated in the bearing seat of the element I5 which is rotatable relative to the pivotbox is free to move through the desired range of the segmental slots I3 in the casing. Obviously, the tension between the divider arms may be adjustedto the desired degree by means of the clamping nut I9, thus regulating the pressure on the spring-disk I'I to the desired amount. By locating the disk between the arms in the manner disclosed, the pivotal action of the arms is improved, thereby facilitating positioning of the arms. By reason of the arm I held against pivotal movement relative to the pivot-casing and the clamping nut I9, possibility of change of adjustment due to inadvertent slippage is substantially eliminated. Adjustment of the instrument from one ratio to another may be quickly accomplished simply by loosening the clamping nut and sliding the arms I and '2 in and out of the pivotbox or sliding the pivot-box bodily relative to the arms until the desired setting of the pivot is obtained.

In the modified embodiment shown in Figs. l2, 13 and 14, the divider arms, the pivot box, the clamping nut and the bearing element I5 for the arm 2 are generally like those of the embodiment above described. In this novel construction, the pivot box or casing 25 is segmentally slotted at 26 and 21 to receive both arms or legs I and 2 so that both arms may swing relative to the casing Within limits determined by the ends of the slots. Arranged in the casingbore is a pivot element 28 similar to the bearing. element I5 and similarly transversely slotted or aseoeafz g-rooved at 29y at its inn-er side to` conform to. the curved outer contour of the,l arm l. A clamping nut ."ill,l similar tothe clamping, nut t9., engages the element 2'8. upon setting of the pivot.. When the clamping nut is tightened, in the manner .0f the preferred embodiment, the combination spring and pivot dislr l1 between the divider arms is compressed to the. desired tension, and the elements are held rmly in position in the casing bore so that the. proper setting .of the pivot is made possible. By the provision of*A the rotat, able bearing elements for each of the divider arms, it is. possible not only to. obtain firm setting of the pivot but also. swinging and sliding adjustment of the ar-ms is facilitated.- If desired, the bottom end wall .of the casing 125;. may be formed with a threaded aperture to receive a suitable annular, openfcentered screw plus s that the bearing element l may be inserted in place or removed through the bottom end wall of the casing Without disturbing the clamping nut. Otherwise, this embodiment of the invention is similar to that above described.

As a result of this invention an. improved draw:

ing instrument is provided which has [many advantages over previous devices, in that the set-1 ting of the pivotal point between the arms is facilitated and the possibility of inadvertent slip1 page of the pivotal point and longitudinal slip-A page .of the arms is substantially reduced. The improved dividers are of a simple and sturdy con: struction, and due to their novel design, may b e cheaply manufactured, since costly machining operations have Vbeen eliminated. By .the prof vision .of the improved pivotal mounting for the arms, eliminating excessive friction between the parts, adjustment of the arms is made relatively easy. These and other advantages vand .the man: ners of use of the improved drawing instrument Iwill be clearly apparent to those skilled in the art.

While there are in this vapplication specincally described two forms which the invention may assume in practice, it will be understood that these forms of the same are shown for purposes of illustration and that the invention may .be fur: ther modied and embodied in various other forms without departing from its spirit or .the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1- .111:3 drawing pfstmml'l -O the. 99341-393381' described, a pair Vof relatively `Yadju(stable arms, an Outer easing .a central .and Openings through the walls thereof through which said arms pass, one of said .openings being in the form of Va. seat `for Aone .of .said arms to hold the` latter against swinging movement relative to said `casingand the .other opening being inthe form of a segmental slot -ior- .permitting limited swinging movement of said other arm relative to said casing, and adjustable clamping means secured Ato said casing for moving one oi said arms toward the other to clamp said arms in adjusted position relative yto said casing.V

2. In a proportional divider, a pair of relatively :adjustable divider arms of solid cross section throughout their length and having pointed ends, and a pivot and clamp device including a pivot box arranged externally of said arms and having openings in its side Walls through which said arms pass and one of said openings being laterally elongated to permit swinging movement of one of said arms relative to the other and to said pivot box, and adjustable clamping means 6. associated with said pivot box f9.1'- .rlloving said :arms toward one another fritionaily to hold said swingable arm against swing-ille lllQYeHlglli. rela; tive tosaid other arm .and seid pivot bols.

s. In a proportional divider, a 'pail of reletively adjustable divider arms having pointed ends, and a pivot and f-rictional clamp device including a .clamp and nii/Ot @9X arranged elle ternally of said arms and ha ing openings in its Side Walls through which said arms page, @Ollipressible .spring and pivot element between .Seid arms, .and a single adjustable means. Secured t0 said pox and adjustable relative thereto .for mov-v ing one of said armsrelative to the other to compress said spring and pivOi 6191.119111? hold both arms lll adjusted position relative to said. box.-

1- In .an instrument or the Character `described, a pair of relatively adilltohle @mls or solid cross section throughout their length, and a pivot and clamp. .device .ingllldirls a unitary casing member arranged externally of said arms and .through which Said .arms estelle Sad device embodying a single adjustable Clamping element adjustably secured to said casing member acting on one of said arms to move the arms toward One another t0 .Clamp both arms .lll adjusted Position with respect msgid ,Casing member- -5- a proportional divider, e nail el leletlvelv adjustable divider arles having pointed ends, a cylindrical outer .casing llavlle clrllmf ferentially extending segmental slo s in the walls thereof through which. Said ailes pas t0 permit limited Swinging movement of the ernl's'rlliive to seid .casina and adjustable .Coaxial @lmplllg element ,Secured .lo said @eine aridr 'ed-lusiable relative thereto .for leg/ills one f' Seid alims toward. the. other l0. 01eme Said' allllsln' adjusted Position relative te .Said easing? 6. va proportional divider, a pair of relatively edelstahl@ divider' arms hal/ille minted ends, an outer casing having .a central portion and segmental yslots in the walls thereof through which said arms pass ytopermit limited swinging movement of said arms relative to' said casing, rotatable bearingelementsv in said casing bore and providing seats for said arms so that said bearing elements turn with said arms relative to .Seid casina and all 'adjustable clamping element secured to said casing `'andacting on one of said arms for .moving the same toward said other .arm to clamp said arms and said bearing elements in adjusted position relative to said casing.

7. zIn a .drawing instrument .o f the character described, a pair .of relatively Iadjustable .arms vof `solid cross section throughout A'their length, and a pivot and clamp device including a pivot box arranged externally of Vsaid arms and -having openings in the side walls thereof through which said arms pass, and a single adjustable element associated with said .pivot box 'for rmoving said arms together vfrictior'ially to hold said arms in adjusted .posi-tion in vstationary .relation with ref spect to said pivot'box.

` instrument of the .character described, a pair `'ofielatively adjustable arms of solid cross section throughout their length, and a pivot and clamp device including a pivot box arranged externally of said arms and having openings in the side walls thereof through which said arms pass, rotatable bearing elements in said pivot box one for each arm, and a single clamping device associated with said pivot box for moving said arms together and holding said bearing elements against rotation thereby frictionally to secure both arms in adjusted position relative to said pivot box.

9. In a drawing instrument of the character described, a pair of relatively :adjustable arms, one of which has graduations on its outer side to provide a scale, and a pivot and clamp device providing a pivot for said arms and iadjustably engaging said arms for effecting setting of the pivot clamp and including a rotatable adjustable element for securing said arms in adjusted position, said rotatable adjustable element having an axial opening therethrough to provide sight of one of said graduations when the same is positioned centrally of said opening.

10. In a drawing instrument of the character described, an arm having graduations along one side thereof, and an external arm clamp including a rotatable adjustable screw element formed with an axial sight opening so that one of said graduations which lies centrally of said opening may be readily observed.

l1. In an instrument of the character described, a pair of divider arms, a pivot and clamp casing having openings through its side walls through which said arms pass, one of said openings being laterally elongated to permit relative swinging adjustment of said arms, and a single clamping element secured to said casing and adjustable frictionally to clamp said arms against axial movement and to resist swinging movement thereof relative to said casing.

12. In an instrument of the character described, a pair of relatively swingable and axially adjustable divider arms of solid cross section, a casing having a central bore, said casing having openings through the side walls thereof through which said arms pass and one of said openings being laterally elongated to permit relative swinging adjustment of said arms, arm-pivot means in said casing-bore, said pivot means turning in said bore with one of said arms during such relative swinging arm adjustment, and a single clamping screw threaded in said bore for frictionally clamping said arms against axial movement and to resist turning movement of said pivot means relative to said casing.

13. In a drawing instrument of thecharacter described, a pair of relatively adjustable arms of solid cross section throughout their length, and pivot and clamping means arranged externallyof said arms and including an outer casing unit having openings through its side walls through which said arms pass, one of said openings being laterally elongated to permit relative swinging adjustment of said arms with said arms in said elongated opening swingable relative to said casing unit.

14. In a drawing instrument of the character described, a pair of relatively adjustable arms of solid cross section throughout their length, and pivot and clamping means arranged externally of said arms and including an outer casing unit having openings through its side walls through which said arms pass, one of said openings being laterally elongated to permit relative swinging adjustment of said arms with the arm in said elongated opening swingable relative to said casing unit, and a single clamping element adjustably secured to said casing for moving one of said arms towards the other to clamp both arms in adjusted position relative to said casing.

15. In a drawing instrument of the character described, a pair of relatively adjustable arms, an outer casing having a central bore and openings through the side walls thereof through which said arms pass, one of said openings being laterally elongated to permit relative swinging adjustment of said arms with the arm in said elongated opening swingable relative to said casing, a bearing element mounted in said bore to rotate relative to said casing and providing a seat for one of said arms, and a clamping nut threaded within the casing bore for moving one of said arms toward the other to clamp both arms and said bearing element in adjusted position relative to said casing.

16. In a drawing instrument of the character described, a pair of relatively adjustable arms, an outer casing having a central bore and openings through the side walls thereof through which said arms pass, one of said openings being laterally elongated to permit relative swinging adjustment of said arms with the arm in said elongated opening swingable relative to said casing, a combination spring and pivot disk arranged in said casing bore between said arms, and a clamping nut threaded in said bore for moving one of said arms toward the other to compress said springdisk to the desired degree thereby to hold both arms in adjusted position relative to said casing.

17. In a drawing instrument of the character described, a pair of relatively adjustable arms, one of Which has graduations along its outer side to provide a scale, and an adjustable pivot providing and clamping device arranged externally of said arms for providing a pivot for said arms and adjustable to prevent relative pivotal movement of said arms, said device including an element adjustable to provide a setting of the arm pivot and provided with a sight opening located centrally of said pivot providing and clamping device so that one of said graduations which lies centrally of said opening may be readily observed.

JOSEPH F. JOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 179,793 HOW July 11, 1876 283,907 Low Aug. 28, 1883 540,809 Bye et al June 11, 1895 FOREIGN PATENTS Number Country Date 8,282 Great Britain Apr. 9, 1902 149,860 Germany Mar. 29, 1904 202,134 Germany Sept. 26, 1908

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