US1768828A - Scaling instrument - Google Patents

Description

July 1, 1930.v 'J'. D. CARTER SCALING' INSTRUMENT Filed Jan. 24, 1927 lllullullwlllllllll Patented July 1, 1930 irtaszs JAMES D. CARTER, OF CHICAGO, ILLINOIS scanne INSTRUMENT Application filed January ze, 1927. serial No. 162,959.

This invention relates to a scaling instrument adapted to reproduce a drawing or other pattern on either an enlarged or a reduced scale, andthe invention has particular reference to the means provided for proportionately Y moving the tracing and marking fingers or pointers in ratio to one another. e

The object of the present invention is to 19 provide positively acting gears and connections for certainly maintaining the ratio of movement of the parts during all positions of adjustment, and the invention is directed primarily to the arrangement of these worlrl ing parts and the housings provided therefor in such a way as to secure precision in adjustment combined with convenience in manipulating the instrument.

Further objects will appear from a de- 20 tailed description of the invention in connection with the accompanying drawings wherein- Figure 1 is a side elevation of the instrument as a whole;

Fig. 2 is an end elevation showing the gear assembly;

Fig. 3 is a modiiied arrangement of thegears and housings;

Fig. 4 is a disassembled detail, partly in C section, showing the preferred method of mounting one of the Vgears on the guide rod with which it is associated:

Fig. 5 is a detail showing the adjustable rider for one of the tracing pointers;

Fig. 6 is a detail showing the mounting for a duplicated form of the instrument; and

Fig. 7 is a cross sectional detail taken on line 7 of Fig. 1.

The instrument is carried on a base head 10 comprising a gear housing 11 which terminates in a reduced neck 12. The neck is provided with an upper bore 13 and a parallel lower bore 14, which constitute journal moimtings Jfor an upper tubular guide rod 15 and a lower tubular guide rod 16'. Thev upper tubular guide rod is bored to receive a rod 17 provided on its exterior with a steep pitched spiral groove 18 which meshes with a fin 19, formed on thi@ interim" 0f' al knurled cap 20, which is threaded on the end of the' tubular guide rod, so that as the feed rod 17 is moved longitudinally, a relatively slow rotation will be imparted to the upper tubular guide rod. The two rods 15 and 17 with the spiral connection between them constitute what will be termed telescoping screw elements.

The lower' tubular guide rod is provided on its exterior with low pitched threads 21, and the interior of the guide rod is bored to receive a lower inner supporting rod 22 which telescopes freely within the interior of the lower guide rod. The ends of the rods 17 and 22 are entered into a head block 23, and the upper spirally grooved rod 17 is preferably clamped in position by means of a set screw 24, which, when screwed down, will clamp the rod against rotation within the head block, but may be unscre'wed to permit such rotation where adjustment of the parts is required.

The rear end 25 of the upper guide rod 15 is reduced and partially threaded on its exterior 26, and also provided with a threadedbore 27. The reduced end carries a driving gear wheel 28 provided with a hub .cap 29, which is formed with an interior recess 30 threaded to screw onto the threaded portion 26 of the reduced end 25. The gear is locked in position by the provision of a centrally disposed headed screw 31 which threads through the gear and onto the threaded bore 27, the threading of the screw being on a diiierent pitch from the threading which engages the hub of the gear, so that when the parts are threaded together 'accidental displacement will be prevented. n

v It `will be noted thaty the reduced endl 2 6 of the upper guide rod is but partially threaded, and the Unthreaded portion journals within the base head 10, so that as the rod 17 is moved longitudinally, a slow rotation will be imparted through the tubularv guide rod 15 to the gear 28.

The gear 28 meshes with a driven gear 32 having a hub 33 which is bored and secured to the reduced end 34 of the lower guide rod 16 in a manner .in all respects similar to Mgg. Y l

that just described. The lower guide rod has mounted thereon a rider 35 provided with an interior thread 36 engaging with the low pitched thread 21 on the exterior of the lower guide rod, and the rider carries a pointer 37 which may serve as a mounting for a lead or stylus 38, depending upon whether the pointer 37 is intended to follow a pattern or trace a line in the reproduction of the pat-tern. The upper side of' the rider 35 is provided with a groove 39 which engages with a thin intermediate guide rod 40, the inner end of which is socketed in the head 10, and the outer end of which is carried by a bridge 41 through which the rods 17 and 22 are entered. rlhis arrangement allows free travel of the rider and, at the same time, maintains the pointer against lateral displacement.

The head 10 is swivelly mounted upon a post 42, the lower end of which is swiveled on a cross pin 43 which is carried by a recassed base or support 44, the arrangement being such as to provide a universal mounting for the instrument to permit either a lateral swinging movement or an up and down tilting movement, or such combinations of the two movements as may be desired.

The outer head block 23 carries a pointer 45, which, like the pointer 37, may serve to socket either a lead or a stylus 46, depending upon the conditions of use. Below the lower guide rod 16 is located an elastic cord or cable 47 upon which is mounted a pointer 48 provided with a tubular supporting head 49, the bore of which is of suitable diameter to permit the elastic cord or cable to be threaded through it when the cable is stretched, but which will be held against longitudinal movement by the thickening of the cable when the tension is released or reduced. The inner end of the cord or cable is preferably anchored within the neek 12 by means of a set screw 50 which permits release of the cable, if desired, and the outer end of the cable is similarly anchored by a set screw 51, although these details ma. be modified as desired.

`n lieu of lthe gear arrangement heretofore described, the gear arrangementshown in Fig. 3 may be employed. A relatively small gear 52 is carried by the upper guide rod 15, and said gear is in train with an intermediate pinion 53 which meshes with an upper pinion 54 in rigid relation with a large gear 55, which in turn meshes with a driven pinion 56 carried by the lower guide rod 16.

In ,this gear arrangement, the head 1()a is upwardly extended to afford a mounting for the more complex gear train indicated, but in other respects the arrangement is essentially the same as that heretofore described. Various gear ratios may be established by a substitution of gears and pinions, which may be easily eiected by a substitution of gears which are preferably mounted in the manner indicated in Fig. 4 to facilitate such substitution.

In relatively large instruments where it is desirable to supplement the manual adjustment of the parts, a pulley or other power element 57 may be provided, which will be acted upon by a weighted cord or cable or other means for acilitatin g the operation of the parts.

Although the instrument has been heretofore described as a single instrument, the operating parts may be duplicated on opposite sides of the head 10, as indicated in Fig. 6, in which case, the tracing and inscribing operations performed by one end of the instrument will be reproduced in inverted relation by the other end of the instrument, but since the method ot transmitting motion is in each case the same, it is not deemed necessary to describe the duplicated arrangement in detail.

In use, if it is desired to produce a drawing on a reduced scale, the outer pointer 45 will serve as the tracer for following the lines of the pattern, and as the outer head block 23 is moved in and out in following the pattern line, or in shading, the endwise movements of the rod 17 will impart a relatively slow rotation to the upper guide rod 15 and to the gear 28 or the train of gears, as the case may be. The rotation thus imparted will be transmitted through the gear ing to the lower exteriorly threaded guide rod 16 which will impart a back and forth movement, in reduced ratio to the inner pointer 37 which, in this instance, will carry the marking lead which serves to draw in the reproduction. The ratio between the movements of the inner and outer markers will be the resulta-nt of the ratio in pitch between the feeding screw threads and the gear ratio.

In order to effect an easy operation of the parts, it is desirable to provide a steep or heavy pitch for the threads on the rod 17, and a low pitch for the threads on the lower guide rod 16, and the ratio of these threads is such as to more than compensate for the difference in speed of rotation between the upper and lower guide rods. That is to say, although the lower guide rod will be rotated, for instance, in the ratio of :tour to one, the screw pitch may be in the ratio, for instance, of eight to one, which will give an ultimate ratio of travel of the pointers of two units of travel for the outer pointer to one unit of travel for the yinner pointer, so that this ultimate ratio will be the one which determines the scale on which the reproduction is made.

It is also necessary to preliminarily adjust the position of the inner marker with relation to the scale adopted, so that its movements in ratio with such scale will be in accord. This adjustment can be easily effected by -unscrewing the set screw 24 which permits the rod 17 to rotate idly with the rotation imparted to the upper guide rod 15, incidental to the longitudinal movement imparted to the inner marker during the adjustment of the latter. After the marker has been properly positioned, however, the rod 17 will be locked against rotation by the tightening of the set screw.

l/Vhere an enlarged reproduction is desired, the inner pointer may serve as the tracer to follow the pattern, and the outer pointer will serve as the inscribing tool, in which case, the parts will be manipulated by moving the head block 23 in and out to maintain the inner pointer in register with the pattern line. A

lVhere quick results are desired without the need for the utmost precision in adjustment, the pointer 48 may be employed, and adjusted 0n the elastic cord or cable 47 to the degree required to establish the proper ratio of movement, in which case the in and out movements of the outer pointer will be reflected in a proportionately diminished ratio of movement bv the pointer 48, theratio in each case being that between the total length of the elastic and the length of the section measured to the position occupied by the marker 48. lt will be understood, however, that the use of the elastically controlled marker is supplemental to the use of the gear controlled markers which particularly form the subject of the present invention.

The device is one which is simple in construction, and, at the same time, the means afforded for mounting and regulating the feed of the markers insure ease and precision in manipulation, and a general rigidity in structure which isessential in securing intended results, the telescoping arrangement of the parts affording the required rigidity to the structure as a whole.

Although the invention has been described with considerable detail, it will be understood that variations in the method of forming and mounting the respective portions of the instrument may be made without departing from the spirit of the invention. Furthermore, although the pointers have been referred to as tracing or inscribing tools, it is obvious that they might take the form of carving tools where it is so desired to use the mechanism of the present invention.

I claim:

l. In a scaling instrument, the combination of a pair of pointers, telescoping screw elements one of which is connected with one of the pointers, means for connecting said elements whereby one of said elements pointer and adapted to be moved longitudinally by therotation of the last mentioned screw element, and gear connections between the Lrotatable screw elements, substantially as described.

2. ln a scaling instrument, the combination of a pair of pointers, telescoping screw elements one of which is connected with one of the pointers, one of said elements receiving rotation from a longitudinal movement of the other, a rotatably mounted screw element and a rider mounted thereon, said rider carrying the other pointer and adapted to be moved longitudinally by the rotation of the last mentioned screw element, gear connections between the rotatable screw elements, and an interior guide rod upon which the last named screw element telescopes said guide rod being connected with and .longitudinally movable with the first named telescoping element which carries the pointer, substantially 'asdescribed.

3. inV a scaling instrument, the combina'- tion of a pair of pointers, telescoping screw elements one of which is connected with one of the pointers, one of said elements receiving rotation from a longitudinal movement of the other, a rotatably mounted screw element and a rider mounted thereon, said rider carrying the other pointerl and adapted to be moved longitudinally of the rotation of the last mentioned screw element, gear connections between the rotatable screwelements, an interior guide rod upon which the last named screw element telescopes said guide rod being `connected with and longitudinally movable with the first named telescoping element which carries the pointer, and a mounting for the instrument vadapted to permit lateral and vertical movements to one end of the instrument, substantially as described.

4. In a scaling instrument, the combinationof a mounting, a pairl of guide rods journaled at their inner ends within the mounting, an inner guide rod telescoped within each of the guide rods and projecting outwardly therefrom, a head block into which the projecting ends of the inner rods are mounted, one of the inner rods and its associated guide rod having screw threaded engagement with, one another, and the other guide rod havingexterior threads, a riderv threaded onto the last mentioned guide rod, a pointer carried by the rider, and a second pointer carried by the head block, and intermeshing gears journaled within the mounting and. carried respectively by the exterior guide rods, substantially as described.

lll() 5. In a scalin instrument, the combination of upper an lower exterior guides rods, inner rods telescoping respectively thereinto, a head block connecting the ends of the inner rods, a mounting within which the opposite ends of the guide rods are journaled, meshing gears on the journaled ends of the exterior guide rods, the upper guide rod and its associated interior rod having steeply threaded engagement with one another, a

low pitched thread on the exterior of the lower guide rod, a rider mounted on the lower guide rod and having threaded engagement therewith, an intermediate rod with which the rider engages to prevent its rotation, a point-er carried by the head block, and a pointer carried by the rider, substantially as described.

6. In a scaling instrument, the combination of upper and lower exterior guide rods and inner rods telescoping respectively thereinto, a head block connecting the ends of the interior rods, a mounting within which the opposite ends of the guide rods are journaled, meshing gears on the journaled ends of the exterior guide rods, the upper guide rod and its associated interior rod having steeply threaded engagement with one another, a low pitched thread on the exterior -of the lower guide rod, a rider mounted on the lower guide rod and having threaded engagement therewith, an intermediate rod with which the rider engages to prevent its rotation, a pointer carried by the head block, a pointer carried by the rider, an elastic cable secured at one end to the head block and at the other end to the mounting, and a supplemental pointer carried thereby, substantially as described.

In a scaling instrument, the combination of a pair of pointers, telescoping screw elements one of which is connected with one of the pointers, means connecting said elements whereby one of said elements receives rotation from a longitudinal movement of the other, a rotatably mounted screw element and a rider threadedly engaging the element, said rider carrying the other point er and adapted to be moved longitudinally by the rotation of the last mentioned screw element, and connections between the rotatable screw elements adapted to impart rotation from one to the other, substantially as described.

JAMES D. CARTER.

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