US2459216A - Drafting machine - Google Patents

Description

Jan. 18, 1949. EAR. BOOTH 2,459,216

DRAFTING MACHINE Filed May 30, 1945 2 Shets-Sheet l lNvENToR EUST'A'CE RUSSELL BOOTH ATTORNEYS Jan. 18, 1949. E, R, BOOTH 2,459,216

DRAFTING MACHINE4 INVENToR EUSTACE RUSSELL'BOOTH BY dEAA/111i, Panmw ATTORNEYS Patented Jan. 18, 1949 DRAFTING MACHINE Eustace Russell Booth, Staines, England, assigner of one-half to Sydney Marks, Feltham, England Application May 30, 1945, Serial No. 596,658 In Great Britain June 6, 1944 1 claim. 1

This invention relates to drafting machines and more particularly to drafting machines in which the drawing board is rotatable relatively to its support and is adapted to be locked in various angular positions. The invention has for its object an improved and simplified construction of drafting machine of this kind. f

In accordance with the invention there is pivoted to the support, which may be a pedestal, and which is provided with a socket or a spindle to receive a spindle, or a socket on the lower side of the drawing board, a pair oi pivoted arms provided at their inner ends with toothed quadrants or the like adapted to mesh and carrying at their outer ends upstanding pins engaging in slots in a straight edge extending across the drawing board. The straight edge is thus guided parallel to itself over the board. The drawing board which is suitably provided on its periphery with angular graduations is tted on its lower side with a disc or plate having angularly spaced notches or holes corresponding to the angular graduations on the periphery and adapted to be engaged by a spring-pressed pin supported on the pedestal. The pin is provided with a collar engaged by one end of a lever pivoted on one of the arms, the other end of the lever being located conveniently below and near the edge of the board. The pin is pressed normally by the spring into engagement with one of these notches or holes and holds the drawing board locked. To rotate the drawing board to a new angular position it is merely necessary to raise the outer end of the lever in order to depress the pin out of engagement with the notch or hole and when the drawing board has reached its new position to release the lever when the pin again engages one of the notches or holes on the disc and again holds the drawing board locked.

The invention is illustrated in the accompanying drawing in which Fig. 1 is a plan view of the improved drafting machine, Fig. 2 an elevation, Fig. 3 is a detail view of the releasing lever. Fig. 4 is a detail showing an adjustment for the drawing board and Fig. 5 la detail view of an auxiliary locking mechanism.

Referring to the drawings, I indicates a circular drawing board which is provided on its lower side with a tapered spindle 2 to engage a central socket on a support which is shown as a spider or tripod 3. Two of the legs 4 of the spider are provided with bearings 4a to receive pivot members 5 by which a pair of arms B are mounted for lateral movement, these arms being provided at their inner ends with toothed quadrants 'I adapted to mesh. The arms 6 carry at their outer ends upstanding pins 8 engaging in slots 9 in a straight edge Ill which is supported by these pins slightly clear of the surface of the drawing board. Due to the meshing of the quadrants the arms 6 move together and the straight edge I0 is thus guided parallel to itself over the board. The swing or pivoting of the arms 5 is limited by Pins 'la mounted in sockets in the legs 4 carrying the arms 6. The pins 'Ia extend through slots 'Ib in the respective webs of the quadrants l. IIhe drawing board is suitably provided on its periph eral edge with a metal rim II graduated in degrees and is tted in its lower side with a centrally disposed disc or plate I2 having angularly spaced holes I3 corresponding to the angular graduations on the periphery and adapted to be engaged by a spring pressed pin I4 supported in one of the pivot members 5. The pin I4 is provided with a collar I5 engaged by one end of a lever I 6 pivoted at I'I on one of the arms G as indicated in Figs. 2 and 3, the other end of the lever I6 being located conveniently near the edge of the board. The pin I4 is pressed normally by means of a spring I8 into engagement with one of the holes I3 and thus holds the drawing board locked. To rotate the drawing board to a new angular position it is merely necessary to raise the outer end of the lever I6 in order to depress the pin I4 out of engagement with the hole and when the drawing board is rotated to its new position to release the lever I6 whereupon the pin engages one of the holes in the disc I2 and again holds the drawing board locked.

In order to lock the drawing board in any intermediate position we may provide one of the legs 4 with an extension I9, as shown in Fig. 5, to which is secured a blade spring 20 provided at its outer end with a brake block 2I. The blade spring is engageable by a screw 22. On rotation of the screw in one direction the brake block is pressed against the action of the blade spring 20 against the rim of the drawing board thus holding it in any desired position. The outer end of the blade spring 20 is inwardly bent as indicated in Fig. 5 to provide a pointer pointing to the graduations on the outer rim of the drawing board.

In order to tilt the board slightly the foot of one of the l-egs 4 of the pedestal may be screwthreaded and engaged by a screw 23. By turning the screw so that it projects beyond the foot, this leg 4, and with it the drawing board may be tilted.

On the pedestal may be xed an annular rim suitably marked which in conjunction with the to said last-mentioned arm and arranged to'd'e-y rim on the drawing board can be used as a cirpress said pin. i cular slide rule with the straight edg-e employed EUSTACE RUSSELL BOOTH.

as a cursor.

Iclaim; 5 REFERENCES CITED v In a drafting machine, the Combination With a The following references. are of record inthe drawing board having a support, of a pair oi outme of mis patent; wardly extending arms pivoted for lateral move- I ment to the support below the board, each arm UNITED STATES PATENTS.' including a toothed quadrant at its inner end 10 Number Name Date beyond its pivot point, the quadrants of the arms 139,507 Hitchcock June 3, 1873 being meshed with each other so that the arms 434,690 Wardon Aug. 19, 1890 pivot about their pivot points simultaneously and 6821061 Bustanoby Dec. 3, 1901 to the same extent, a straight edge mounted over 753,463 Austin' Mar. 1, 1904 the board and connected tothe outer ends of the 15 837,112 Perkins Nov, 27; 1906 pair of arms at points equdistant from the le- 1,395,200 Moore Oct. 25, 1921 spective pivot points of the arms, the `drawing e* 210715331A Ronnqujst Mar, 15,1937 board being rotatable with respect to the support, a spring-pressed pin carried by said support lat FOREIGN .PATENTS f the pivot point of one of said arms and adapted 20 Number Country Date to engage the drawing board, and a lever pivoted 545,155 Germany Feb. 26, 1932

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