US2771706A - Drafting board - Google Patents

Description

Nov. 27, 1956 H. E. JoHNsoN DRAFTING BOARD- INVENTOR 2 Sheets-Sheet 1 Filed Sept. 30, 1952 all. .2|

ORNEYS' Nov. 27, 1956 Filed Sept. 30, 1952 H. E. JOHNSON DRAFTING BOARD 2 Sheets-Sheet 2 :jk/5313313111:1:1112 :e

Figli ORNEYS United States Patent DRAFTING BOARD Henry Elmer Johnson, San Leandro, Calif. Application September 30, 1952, Serial No. 312,263

2 Claims. (Cl. 45-129) The present invention relates to an improved drafting machine and in particular to apparatus adapted to hold a drafting board or the like in adjustable vertical position.

While there are commonly employed a variety of devices to hold and support drafting or other work requiring the use of instruments or extended surfaces upon which pictures or drawings are to be made, these devices generally present a horizontal or tilted surface upon which the work may be disposed. Where large surfaces are employed this disposition of the surface requires a large amount of oor space thereby increasing the overhead cost of the work and requiring very large Hoor areas for even medium sized projects. Also with large drawings requiring a large board to hold same the draftsman or artist is disadvantageously positioned to work upon much of the surface thereof as he must lean across the board to reach far corners or alternatively must continually remount his work on the board to place it in proper position.

Although this problem has been apparent to many, diculty in overcoming it has resulted from the fact that in engineering drafting at least a very precise alignment of the work is necessary. Also the Work must be held quite rigid so that many types of adjusting mechanisms are quite inapplicable for any more than mere sketching.

In addition to the above noted requirements and limitations there is the further criteria that particularly in precise drafting practice the maximum accuracy is possible when the eye and the immediate work is aligned. Further, such an alignment, which clearly can only be provided by suitable adjusting mechanism, materially reduces eyestrain and fatigue with a corresponding benefit not only to the draftsman but also in the resulting work which is thereby much more likely to be free from errors resulting from fatigue-produced laxness on the part of the draftsman.

Accordingly it is an object of the present invention to provide an improved drafting machine.

It is another object of the present invention to provide an improved drafting machine capable of maintaining drafting or the like in adjustable vertical position.

It is a further object of the present invention to provide a device for maintaining a drafting board in vertical position with positive-acting, precisely-controllable adjusting means for disposing any portion thereof at eye level.

A still further object of the present invention is to provide an improved drafting machine having a drafting board carriage that is vertically adjustable by gear means and including locking means therefor.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

The accompanying drawings illustrate two preferred embodiments of the invention and include a variety of gures as follows:

Figure l showing a first embodiment in front elevation and broken section as indicated.

Figure 2 showing a plan view of the embodiment of Figure l.

Figure 3 showing a sectional View of Figure 1 taken at 3 3 thereon.

Figure 4 showing the locking mechanism adapted for use with both illustrated embodiments.

Figure 5 showing a second embodiment in front elevation with portions removed as indicated.

Figure 6 showing a sectional view of Figure 5 taken at 6 6 thereon, and

Figure 7 showing a plan view of the second embodiment.

Figure 8 is a portional elevational view of a third embodiment of my invention.

Considering the elements and embodying the invention and referring first to the form thereof illustrated in Figures 1-3 it will be seen that there are provided a pair of vertical standards 11 and 12. These standards 11 and 12 are maintained in vertical position by attachment to a support frame 13 that may have a box construction, as illustrated, with the number and size of bracing members being dictated by the size of standards 11 and 12 and the elements to be carried thereby. Standards 11 and 12 are disposed in spaced parallel relationship and may be formed of angle iron although generally a light-weight metal angle is preferable. A pair of rails 14 and 16 are attached one to each of standards 11 and 12 and extend substantially the length thereof. Rails 14 and 16 preferably are of the retaining type and as such are formed with a U-shaped cross section, as shown in Figure 2, to receive a movable member and restrain same from lateral motion. Rails 14 and 16 may be aixed to standards 11 and 12 in any suitable manner such as welding or bolting with flush head connectors and are disposed in the interior angles of standards 11 and 12 with the open sides thereof facing each other.

A drafting board carriage member 17 slidably engages rails 14 and 16 and for this purpose may have straight end pieces 18 of added cross section. Carriage 17 extends between rails 14 and 16 so that it snugly ts into rails 14 and 16 in slidable relation thereto and may have a solid construction, as shown. Carriage 17 may be adapted to hold a drafting board or the like upon which suitable paper may be disposed for drafting or art Work, or alternatively carriage 17 may be employed directly as a drafting board for mounting paper or the like and in such instance is preferably formed of a soft wood. In this latter instance carriage end pieces 18 are preferably made of a hard material such as metal so as to withstand wear in rails 14 and 16 and also to better engage same for sliding therealong; While in the former instance all of carriage 17 including end pieces 18 may be formed of metal and further carriage 17 may have an open construction.

In order to provide for positive controlled movement of carriage 17 along rails 14 and 16 there is provided a worm gear 19 having journals 21 and 22 at opposite ends thereof, which may of course be alternatively considered a shaft having threads 23 thereon corresponding to the gear threads. Worm gear 19 is carried in bearings 24 and 26 which engage journals 21 and 22 respectively. Bearing 24 is mounted upon a transverse structural member 27 which extends across the back of standards 11 and 12 adjacent the top thereof and which is in turn mounted by end plates 28 secured thereto and to standards 11 and 12. End plates 28 extend some distance behind standards 11 and 12 so that member 27 is disconstruction of apparatus posed at a distance behind the standards and bearings 24 is mounted on the front of member 27 at the center thereof so that worm gear 19 is disposed between standards 11 and 12 intermediate the depth of member 27. Bearing 24 may be bolted upon member 27 .while the rigid connection of member 27, end plates 2 8 and standards 11 and 12 may be accomplished in any suitable manner such as welding.

At the lower end of gear 19 there is provided .a similar mounting structure including a structural element comprising a lower bearing support member 29 extending between standards 11 and 12 and disposed at a distance in back thereof by end plates 31 rigidly joined to standards 11 and `1 2 and to the ends of member 29. Bearing 26 is mounted as by bolts upon `the front of member 29 in alignment with upper bearing 24 so that with journals 21 and 22 of gear `19- engagingbearings 24 and 26 respectively, gear 19 is vertically mounted parallel to rails 14 and 16 and equidistant therebetween. Worm gear 19 is attached to carriage 17 by drive means such as screw block or worm block 32 which hasV a threaded aperture therethrough engaging worm gear 19 and which is rigidly secured to the back of carriage 17 Thus, with Worm block 32 threadably engaging worm gear 1 9, rotation of worm gear 19 positively drives worm block 32 therealong with a consequent movement of attached carriage 17.

Convenient means for rotating worm gear 19 is provided by a shaft 33 extending horizontally between standards 11 and 12 at the bottom of worm gear 19 and rotatably mounted in end pieces 31 which also mount lower bearing support member 29. Handwheels 34 may b e attached to the ends of shaft 33 to facilitate rotation thereof and a bearing 36 may be provided in engagement with shaft 33 near the center thereof and mounted on lower bearing support member 29. Translation of rotation from shaft 33 to worm gear 19 is provided by engaging bevel gears 37, of which one is mounted upon shaft 33 and the other upon the lower end of worm gear 19, as by keying. Bevel gears 37 are mounted in engagement so that rotation of shaft 33, as by handwheel 34, drives Worm gear 19 around so that the threads thereon rotate. This acts upon engaging worm block 32 as a jack screw inasmuch as worm block 32 is restrained from rotation by connection to carriage 17 and consequently worm block 32 and attached carriage 17 are driven in a vertical direction depending upon the direction of rotation of handwheel 34.

inasmuch as carriage 17 is vertically mounted it is advantageous to provide means for operating thereon which is not subject to falling or displacement. In this respect there is` provided a parallelogram 38 which includes a base plate. 39 extending horizontally between standards 11 and 1 2 and rigidly secured thereto, as by screws as shown. Base plate 39 is preferably mounted with its upper edge slightly below eye level of a'person using the drafting machine and provision may be lmade for securing lower plate 39 at various vertical positions upon standards 11 and 12 to accommodate persons of diiferent height using the machine. Disposed directly above lower plate 39 is an upper plate comprising a straight edge 41 and being joined to lower plate 39 by a plurality of links 42 that are each pivotally mounted at each end `to base plate 39 and at the other end to straight edge 41. Links 42 are identical and are mounted in horizontal alignment with sufficient length that when vertically disposed, straight edge 41 is raised some distance above base plate 39. Thus straight edge 41 is mounted for vertical displacement by rotation of links 42 in their mountings and provision is thereby made kfor making parallel lines upon drafting on carriage 17 by mere movement of straight edge 41 and a latitude of vertical adjustment is provided by links 42. A trough 43 may be mounted between standards 11 and 12 below parallelogram 38 for receiving drafting; instruments or the like and Containing Same in `c,C, .I1vs*r.1.it-,.1.1i pagina isis ready'use. i

Although a characteristic and advantage of worm gear drives is the stability thereof in respect to reflected motion there is further provided as insurance against inadvertant motion of carriage 17 a locking mechanism 44 which is adapted to engage handwheel 34 to prevent rotation thereof. inasmuch as carriage 17 must be maintained precisely stationary during any particular drafting operation such asthe making of a line upon a drawing when its immobility is required, this locking feature is 'very important, especially in reference to the possibility; of inadvertant touching of handwheel 34 by the draftsman. To this end there is provided a locking arm 46 which is pivotally mounted upon end piece 31, or an extension 43 thereof as shown, adjacent handwheel 34. Arm 46 has a handle formed at one end thereof and the other end extending from the pivotal mounting toward handwheel 34-'is apertured to receive a resilient member suchuas arubber nose 47. Preferably the handle end of. locking arm '46 is' formed shorter than the other end or at least lighterlthan the end on the other side of the pivotal mounting so that' with arm 4.6 mounted in alignment or slightly above thel center of handwheel 34, arm 46 naturally pivots out Vof, engagement With handwheel 34. Locking of'handwheel 34 may be easily accomplished by grasping the handle end of arm 46 and pivoting arm 46 into engagement with the adjacent edge of handwheel34 so that the rubber nose 47 is crushed against the handwheel. This effectively prevents any motion of handwheel 34 and thus carriage 17 is securely locked in position.

There has been described above a particularly advantageous and practical embodiment of the present invention, however,v the invention is not limited to the details thereof and in this respect attention is invited to-Figures 5, 6 and 7 wherein there is illustrated a further embodiment also having the same advantages and capabilities. All elements common to the two illustrated embodiments are similarly numbered andv thus carriage 17 is slidably mounted in vertically disposed rails 14 and 16 at either end thereof. Rails 14 and 16 are secured to standards 11 andV 12 which may extend upward from feet or basemembers 51 that extend some distance on front and back of standards 11 and 12. Base members 51 may consist of channels that are inverted to provide a fiat upper sur face upon which standards 11 and 12 rest andare secured as by welding thereto. The choice of steadying means employed with the invention is dependent upon a variety t of factors suchas the position of the drafting machine in a room and the type of work to be done thereonand-for many purposes the simplied base member 51 will be found to be assatisfactory as the more extensive support frame 13 of Figure l.

In order to provide drive means for carriage 17 a bearing support member 53 is mounted horizontally-between standards '11 and 12 by end' pieces extending rearward therefrom and which may convenientlyl be formedv integral with member S3, as shown in Figure 7. Member 53 is analogous to member 29 of Figure 3 andl like member 29 is mounted slightly below the bottom end of the carriage travel. A gear wheel 54 is rotatablymounted upon support member 53 parallel to carriage 17 and an elongated arxn 56 is pivotally mounted adjacent the outer edge of gear wheel S4. Arm 56 is preferably mounted on the face of gear Wheel 54 adjacent car-riage 17 and at its opposite end is rigidly connected to one end-of a short link 57 extending substantially normal theretoythe other end of link 57 being pivotally mounted upon the back of carriage 17 adjacent the top thereof. There is thus produced an eccentric drive arrangement whereby rotation of gear wheel 54 drives arm 56 eccentrically connected thereto and this motion is translated through link 57 to carriage 17. Becauseof the -rail mounting of carriage 1 7 it is free to move only inl a vertical direction Vandthilsfas geartwheel54 turns thetranslationlimparted to arm' S6 thereby is transmitted through link 57 to carriage 17 to drive it along rails 14 and 16. Link 57 is connected to carriage 17 on the center line thereof equidistant from rails 14 and 16 and arm 56 extends from gear wheel 54, mounted adjacent standard 12 for example, past the centerline of carriage 17 toward standard 11 so that link 57 is always inclined from its connection on carriage toward standard 11. It will be appreciated that one half turn of gear wheel 54 raises carriage 17 to its maximum height and a further half turn lowers carriage 17 its maximum travel so that gear wheel 54 need only be turned in one direction to effectuate raising and subsequent lowering; it being noted that a relatively large gear wheel is necessary to etectuate a large movement of carriage 17.

Rotation of gear wheel 54 and consequent drive of carriage 17 is accomplished by the provision of a worm gear 58 engaging gear wheel 54 mounted upon a shaft 59 extending through member 53 and having a handwheel 34 or other means secured to the end thereof. Shaft 59 is mounted for rotation as by a bearing 61 secured to member 53 and thus gear wheel 54 is driven by turning handwheel 34 which is attached by shaft 59 to worm gear 58 engaging gear wheel 54.

In view of the somewhat different structure of this embodiment it is preferable `to provide stitfening bars 62 which extend between standards 11 and 12 at least at the top and bottom thereof to impart rigidity thereto and to insure a parallel relationship thereof. It may also be advantageous to extend the end pieces 18 of carriage 17 about the entire perimeter thereof to impart maximum rigidity thereto, particularly when carriage 17 is formed of wood or the like. The embodiment of Figure 5 is also provided with a parallelogram 38 which may be constituted as set out above and also a trough 43 for containing drafting instruments. Also the locking mechanism 44 is adapted to be used with this embodiment.

It will be appreciated from the foregoing description that the embodiment of Figure 5, like that of Figure 1 provides a positive movement of the drafting board carriage and disposes said carriage in vertical position for maximum accessibili-ty and accuracy of work. Further, the drafting board carriage is at all times aside from actual Iadjustment thereof maintained in a rigidly fixed position with the adjusting mechanism in no way reducing this rigidity.

Figure 8 discloses another modification which is arranged to be utilized with the drive mechanisms of Figure 1 or Figure 5. As hereinabove mentioned, the structural arrangement is such as to provide a drafting board which will maintain itself in proper alignment as it vertically moves so that the fixed straight edge will always be disposed at right angles to the opposed vertical edges of the board. To preolude the possibility of any tilting of the board in a generally vertical plane, auxiliary guide means may be utilized whereby the said opposed edges of the board will be required to move in unison. Such means preferably includes a rack gear 71 extending adjacent each of the vertically disposed edges of the carriage 17. The teeth of the racks are engageable with a pair of horizontally spaced pinion gears 72 which are xed to a shaft 73 journalled in a pair of end bearings 74. It will be understood that as the pinions are capable only of simultaneous rotation, the opposed edges of the carriage will also lbe moved in synchronism Without 1the danger of either of the edges preceding the other and throwing off the proper setting of the carriage.

I claim:

1. An improved drafting machine co-mprising a pair of rails, support means connected to said rails and maintaining same parallel in vertical position, a vertically disposed drafting board carriage extending between said rails in slidable relation thereto and adapted to carry drafting, a worm gear, means rotatably mounting said worm gear upon one of said rails, a gear wheel rotatably mounted in engagement with said worm gear, an arm pivorally secured at one end toy said gear wheel adjacent the edge thereof, and a link rigidly secured to the other end of said arm and pivotally mounted upon said carriage whereby rotation of worm gear turns said gear wheel to slide said carriage along said rails through said eccentric.

2. Apparatus as set forth in claim 1 including a pair of horizontally spaced members disposed adpacent each of the vertically extending edges of said board, said members being engageable with portions `of said board for maintaining the latter in fixed vertical relationship during vertical movement of said board,

References Cited in the file of this patent UNITED STATES PATENTS 1,810,575 Quiring June 16, 1931 FOREIGN PATENTS 2,093 Great Britain 1862 16,779 Great Britain 1905 28,411 Great Britain Dec. 6, 1909 110,776 Sweden May 30, 1944 168,911 Germany Mar. 17, 1906

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