US2257529A

US2257529A - Drawing instrument

Info

Publication number: US2257529A
Application number: US336034A
Authority: US
Inventors: George E Mattos
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-05-18
Filing date: 1940-05-18
Publication date: 1941-09-30
Anticipated expiration: 1958-09-30

Description

Sept. 30, 1941. G. E. MATTOS DRAWING INSTRUMENT Filed May 18, 1940 J Z a J 5 6 f 2 WW 4 W3 j w J Inventor A ttorneys Patented Sept. 30, 1941 I UNITED STATE-S PATENT OFFICE 2,257,529 I a I DRAWING INSTRUMENT George E. Mattos, Oakland, Calif. Application May 18, 1940,'Serial No. 336,034

'2 Claims. (01. 120-19) 7 My invention relates to improvements in drawing instruments such as drafting pencils, knifeedged pencils, carpenters pencils, and steel workerssoap-stone pencils, and the like, and in the writing media used'therein, and an important object of the invention is to provide arrange- .ments of this character involving simplified and superior means for holding, positioning, and feeding a relatively thin, flat writing medium relative to the holder.

Other important objects and advantages of my invention will be apparent from a reading of the following description and the appended drawing, wherein a preferred embodiment of the invention is shown.

In the drawing:

Figure 1 is a perspective view of the embodiment.

Figure 2 is an enlarged vertical transverse sectional view therethrough.

Figure 3 isa plan view of the slide.

Figure 4 is a horizontal sectional view taken through Figure 1 approximately on the line 4-4 and looking downwardly in the direction of the arrows.

Figure 5 is a perspective view of the relatively thin flat writing medium.

Figure 6 is a transverse sectional view taken through Figure 5.

Referring in detail to the drawing, the numeral 5 generally designates the holder which comprises a metal or other suitable material plate or sheet bent or pressed along longitudinal lines to provide a C-shaped cross section providing laterally inwardly directed flanges 6 and I, respectively, which have laterally inward edges spaced to define a slot 8 in which the slider I'I works.

Slidable in the space between the flanges 6 and I and the Web ID of the holder is the relatively thin flat writing medium II which is shorter than the holder so as to be topped by the slide in a manner to be described. The writing medium I I is in the form of a thin relatively wide flat plate of suitable material to provide the type of marks desired, the same being substantially uniform in width and thickness throughout the length thereof as clearly indicated in Figures 5 and 6.

The lower end portion of the holder is smaller than the writing medium I I and provided with vertical expansion slots I2 and I3 in the flanges 6 and I, and I4 and I5, respectively, in the flanges and the web, with the material of the holder bent inwardly at these points to make strong frictional engagement with the writing medium and thereby assist inholdihg the writing medium in the desired adjusted position in the holder. The upper portion of the holder is large enough to easily and freely admit the writing medium so that'the same is freely slidable in this portion of the holder. The web of the holder is equipped with an exterior clip I5 which is attached to the upper part thereof for convenient carrying connection of the device in the pocket of the user.

The slide or slider I1 is formed from a blank of spring material of the shape shown in Figure 3, and comprises the transversely elongated rectangular part I8, the longitudinally elongated narrow connecting part I9, and the substantially square larger part 20, the latter having rounded corners 2I and 22 on one end thereof and the rectangular centralized tab 23 on the opposite end thereof.

The material of the blank I! is of substantially the same thickness and width as the writing medium II so that the part I8 slides freely in the holder 5 with the side portions thereof behind the

flanges

6 and 1, and with the connecting portion I9 extending outwardly through the slot 8 with its edges in close proximity to the edges of this slot. The connecting part I9 is bent downwardly approximately on the dotted line 24, and the lower portion of the part 20 is bent upwardly approximately on the dotted line 25. In this arrangement the then upper end of the tab 23 engages the bight portion of the bend 24, as shown in Figure 2. In this arrangement the side portions of the inturned portion of the part 20 bear frictionally against the outer surfaces of the flanges 6 and I, in opposition to the pressure exerted by the part I8 on the web I0 and on the backs of the flanges 6 and I, the

bends

24 and 25 being sufiiciently spread to provide this action. In this way, considerable pressure is required to be exerted in an inward direction upon the portion 20 of the slide to release the slide to enable adjusting its position along the holder. In the absence of such manual pressure, the edge 26 of the slide, when abutted with the upper end of the writing medium II, acts to hold the writing medium against shifting under writing pressure on the lower end thereof. The slide I1 also acts to project the writing medium so as to feed the same from the lower end of the holder as required, when the slide is pushed downwardly relative to the holder proper.

Soapstone and commercial pencil graphite for writing and drawing are conveniently commercially obtainable in five-inch lengths. I may utilize in the present holder graphite and soapstones of this length trimmed to widths of between one-quarter to one-half inch and to thicknesses of between twenty-thousandths (20/1000) of an inch and iorty-thousandths (40/ 1000) of an inch.

In writing media having a thickness of between 20/1000 and 30/1000, the ratio of width as compared to thickness is structurally and functionally critical in ,full line work on wood or metal, and the width must'be not less than one-quarter inch with a 20/1000 writing medium. Needed strength is absent on narrower and/or thinner sections. The most practical thickness for general use and desirable strength are between 25/1000 and 30/1000.

Although I have shown and to be definitely understood that I do notwishto limit the application of my invention to"the precise structural details set 1 forth, except-as may be; required by thescopeof theksubjoined claims.

Having described the invention; whatis claimed,

as new is:

V 1. A- device. of? the character described,said device comprisingias-tube formed-in oneside; with described herein a preferred embodiment of theinventibn; itiisi' a longitudinal slot defining spaced flanges, a frictional slide having a first part extending through and movable along said slot, a second part connected to said first part and sliding behind said flanges and engageable with the upper end of said rod, and a third part connected to said first part and frictionally bearing against the outer side of said flanges, said first, second, and third parts being integral portions of a single piece of flat spring material.

2 A device ofthe character described, said device compris'ing' a tube formed in one side with a longitudinal slot defining spaced flanges, a frictional slide having a first part extending through and movable along said slot, a second part connected. to said first part and sliding behind said flanges and engageable with the upper end of said rod, and athir-d part connected to said first part and frictionally bearing against the outer side of said flanges, said third part comprising a convolutionunder spring: tension to engage the outer side oiesaid flanges in opposition to the engagernentof saidsecond partwith the inner sides of said flanges,

' GEORGE E. MATTOS.