US2790245A

US2790245A - Drafting spline

Info

Publication number: US2790245A
Application number: US556934A
Authority: US
Inventors: Wilkes Reuben
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-01-03
Filing date: 1956-01-03
Publication date: 1957-04-30
Anticipated expiration: 1974-04-30

Description

April 30, 1957 R. WILKES DRAFTING SPLINE Filed Jan. 5, 1956 11v REUBEN ILKES b/QM United States Patent ice 2,790,245 DRAFTING SPLlNE Reuben Wilkes, Seattle, Wash. Application January 3, 1956, Serial No. 556,934

2 Claims. (Cl. 33-177) This invention relates to drafting splines to be used by draftsmen in the ruling of irregularly curved lines, for example, in the ruling of railway curves, ships lines and other curved lines; it being the principal object of the invention to provide a spline that is exceptionally flexible; that can be easily held in place upon the drafting surface; which is of such resiliency that it can be easily flexed to the desired curvature and which will immediately assume a normal straight condition when released from any curved formation.

It is a further object of the present invention to provide a spline of the above stated kind wherein a thin, flexible, flat strip of resilient material forms a ruling member and to which strip a relatively thick backing strip of sponge rubber is attached; this latter strip providing a member that is adapted to rest upon the drafting surface to hold the ruling strip on edge and against which slight downward pressure may be applied to cause it to frictionally adhere to the surface and thus to hold the ruling strip in any curved formation to which it has been bent.

It is a further object of the invention to give the foam rubber backing strip such cross-sectional form that when the spline is bent to a sharp curve it will not form a bulge at the bend that will cause the metal strip to be tilted to a degree that would make its use for ruling difiicult.

Further objects of the invention reside in the details of construction of parts and in their combination and use, as will hereinafter be fully described.

In accomplishing the above mentioned and other objects of the present invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. l is a perspective view illustrating the present spline in use; showing one way of holding it in place while a line is being ruled.

Fig. 2 is a top view of the spline in its normal straight form as laid upon a drafting surface and illustrating in broken lines, the manner in which it can be flexed for the ruling of various irregular curves.

Fig. 3 is a cross-sectional view of the spline, particularly illustrating the beveling of its under surface relative to the plane of the metal strip.

Fig. 4 is a perspective view illustratingthe use of weights or ducks for holding a position of the spline on a drafting surface.

Referring more in detail to the drawings:

The present spline comprises a single straight strip of thin, flexible resilient material such as, for example, a strip of spring steel. The length of the strip is optional, but I have found that a practical length for such devices, as provided for use by mechanical draftsmen, is from ten to twenty inches. For ruling ships curves or railway curves, it may be made in greater lengths. The width of the metal strip 10 may be varied but it has been found most practical, especially if the spline is short, to keep 2,790,245 Patented Apr. 30, 1957 inch. The strip of spring steel is of such resiliencythat,

-if -'bent -from its normally straight form and then resleasedfi it will-instantly spring back to a normally straight condition.

A: sponge rubbens'trip 1 2 is vuleanized,- glued or otherwise fixed to what will be referred to as the back side of the metal strip 10. This strip 12 being coextensive with the metal strip 10 and of the same height. Its thickness is approximately equal to the vertical width or height of the metal strip towhich it is applied so that in crosssection it is substantially square, except for a slight beveling of its lower surface as shown in Fig. 3, the purpose of which will now be explained.

It will be observed by reference to Fig. 3, that the top surface of the sponge rubber strip 12 is flush with the top edge of the metal strip 10 and at a right angle to the vertical plane of the metal strip. Also, it will be observed that the under surface of the rubber strip 12 is beveled at an angle of approximately 5 relative to the horizontal plane of the surface on which the spline rests. In view of the fact that the rubber strip, when bent sharply for the ruling of an outside curve, will be compressed at the bend, and a downward bulge will be formed in accordance with the extent of the bending, this downward bulging without the beveling of the rubber strip, would cause the ruling strip 10 of the spline to be tilted forwardly, thus making its use for ruling difllcult. The bending of the spline to any curved form, for example, to the reverse curve as shown in Fig. 4, will cause the metal strip to be held in a vertical position on the drafting surface regardless of the beveling of its under surface. It is only when it is perfectly straight that it will rest on its beveled surface.

In Fig. I, I have shown the usual way in which a draftsman holds the spline on a drafting surface with one hand while ruling a line with the other, using the metal strip 10 as the ruling guide. In Fig. 4, I have shown the spline as held in place by ducks 15, these being lead weights adapted to rest on the drafting surface, and which have fingers 15f extending therefrom, formed with downturned points 15p at their, outer ends adapted to be holdingly engaged with the top surface of the rubber strip 15 to hold the spline in a set position.

It is not my intention that the spline shall be restricted as to materials used in its making, or to its length or cross-sectional dimensions. A plastic strip might be used in lieu of the spring steel strip 10 described, and the two strips might be adhesively or otherwise joined. Furthermore, while it is desirable and advantageous to bevel the under surface of the rubber strip, the device can be used with a certain degree of success without such beveling and therefore it is not desired to confine the invention to the beveled strip.

Such splines are easy to use, practical and relatively inexpensive.

Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is:

1. A drafting spline comprising a thin, flexible and resilient strip of metal, or the like, of uniform dimensions throughout its full length, serving as a ruling edge, and a resilient relatively thick strip. of sponge rubber fixed'to said metal strip along the back face thereof and extending to its full length; said sponge rubber strip, having uniform cross-sectional dimensions throughout its length andhaving a top surface that is flush with the top surface of the metal strip and at a right angle thereto, and having a fiat bottom surface that is flush with the bottom surface of the metal strip and adapted to be pressed into frictional holding contact with the surface the under surface thereof is beveled at a slight angle.up- 10 wardly and rearwardly from the lower edge of the metal strip. 7 7

References Cited in the file of this patent UNITED STATES PATENTS Fisher Apr. 27, 1858 Davenport May 20, 1884 Williams July 23, 1889 Moses Apr. 18, 1939 FOREIGN PATENTS Italy June 8, 1935