US772622A - Instrument for drawing curves. - Google Patents

Description

No; 772,622. PATENTED OCT. 18, 1904.

I E. J. LORING. v

INSTRUMENT FOR DRAWING CURVES.

APPLICATION FILED FEBJZ. 1904.

-N0 MODEL.

" WITNESSES UNITED STATES Patented October 18, 1904.

P TENT OFFICE.

ERNEST J. LORING, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR OF LORING, or

INSTRUMENT FOR DRAWING CURVES.

SPECIFICATION forming part of Letters Patent No. 772,622, dated October 18, 1904.

' Application filed February 8, 19(14. Serial No. 192,515. (No model.)

To all whom, it may concern;

Be it known that I, ERNns'r J. LORING, of Somervill'e, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Instruments for Drawing Curves, of which the following is a specification.

This invention has for itsobject to provide an instrument adapted for a drafting instru ment to generate or test tangential curves, &c., or adapted for-use as a testing or working templet for any constructional or mechanical work requiring the generation or transference of relatively flat curves.

To this end it embodies a resilient ruling guide or edge of adjustable curvature which hasa characteristic or predetermined law of curvature and is mounted and adjusted in a novel manner, as will be fully explained.

Of the accompanying drawings, Figure 1 represents a plan view of a drafting-board and T-square and an instrument embodying my invention. Fig. '2 represents a perspective view of the instrument, showing the top plate separated from the rest of the instrument. Fig. 3 represents an enlarged plan view of one end of the instrument. Figs. 1 and 5 represent detail perspective views illustrating twomodified forms of mechanism for adjusting the rulingguide.

The same reference characters indicate the same parts in all the figures.

The instrument comprises a frame composed of parallel flat side plates 10 10, separated by a thin back strip 11 and shallow posts 12 12 and connected by screws 13,whose heads are flush with or below the plate-surface. .The back edge 1 1 of the instrument is a straight edge, and the front edge is a rulingguide 15, of adjustable curvature, fixed in its intermediate portion at16 at a point-about one-third of the distance from one end of the instrument and having free end portions or extremities, one of which is thus made about twice the length of the other. These extremities are engaged by pivoted levers 17 in the form of the invention shown in Figs. 1,2,

hereinafter more 7 and 3, having projections 18 occupying curved cam-slots 19 in the frame-plates, the

.pivots of the levers being eccentric to the 2, and the ends of the projections 18 indexmarked, whereby different predetermined adjustments may be effected.

The ruling-guide 15 is flexible and resilient between its fixed portion 16 'and its two free extremities, so that according to the degree of pressure exerted by the levers 17 in their different positions the extremities or end portio'ns of said ruling-guide will assume differ-- ent degrees of curvature. The curvature of each end varies according to a characteristic or predetermined law-that is to say, the ruling-guide is so regulated in dimensions and material between its fixed point and free extremities as to invariably assume the same curvature for any given position of either extremity. The rate of curvature of the par-' ticular curve for which the instrument may be arranged can be expressed as a continuous or progressive function of the length of arc, andtheinstrumentwill generate such a curve with closest accuracy. .It may also be used to transfer any curve from workto drawa ing if said curve is of the samecha'racteristic of curvature as that for which the particular instrument is fitted. I

It is obvious that by properly constructing the instrument its working edge will bend to a curve which may be of uniform curvature or one whose curvature either increases or decreases from the tangential point, this increase or decrease progressing at any predetermmed rate.

The manner of using the instrument is illustrated in Fig. 1, in which 2O is a draftingboard, and 21 a T-square. of the instrument is placed against the edge of the T-square, as shown, and the opposite ruling edge employed to plot the desired curves on the drawing-surface, the ruling edge, as will be evident, being continuous and forming the outermost edge of the. instrument, so that continuous curves may be drawn.

Preferably the ends 22 of the frame are at right angles with the back edge 14 and the projecting handle portions of levers 1'7 arranged entirely within the rectangular limits of said back and end edges, so that the instrument may be used in any position in cooperation with T-squares, triangles, straight-edges, &c. By making one of the two independently-adjustable portions of the ruling-guide longer than the other the ends are differentiated and the instrument adapted to a large variety of curved forms. Opposite the fixed point 16 the ruling edge of the guide 15 is always parallel to the straight rear edge 14 and perpendicular to the end edges 22. Hence the instrument is readily placed to its work. It is one of the features of the instrument that there are no projections beyond the planes of the parallel fiat surfaces of the frame, thus making the instrument perfectly reversible.

It will be seen, particularly in Fig. 3, that the front edge of the frame at the shorter end recedes from the straight line of the rest of the edge, as shown at 23, beginning in the vicinity of the fixed point 16. The shorter end portion of the ruling-guide 15 is adapted to take either a convex line, as shown in full lines in said figure, or a concave line, as shown in dotted lines, or astraight line between the two. It is obvious that this might also apply to the longer portion of the ruling edge, although not so shown.

The construction of the instrument renders it compact, and the location of the centers of gravity of the several parts all in the same plane conduces to strength and tends to prevent twisting of the instrument.

Various types of operating mechanism may be employed. Fig. at shows a modification in which a pivoted cam plate or lever 24 engages the ruling-guide 15. In Fig. 5 an eccentric 25, journaled in the frame-plates 10, has a strap 26, whose head rocks in a socket in the ruling-guide, whereby motion is imparted in both directions, as in Figs. 1, E2, and 3.

Various other modifications may be made without departing from the spirit of the invention.

The instrumentmay be made in various The back edge 1 L for drawing the entasis of a column a similar instrument of greater size may be used as a templet in the production of the column itself.

I elaim 1. A drafting instrument comprising a frame having a straight back edge, a rulingguide of variable curvature having a point fixed with respect to the said back edge and tangent to a line parallel with the back edge, said guide having a free working edge continuous across said point of tangency and a shiftable extremity, and means for shifting said extremity in a direction transverse to said back edge.

2. A drafting instrument con'iprising a frame having a straight back edge, a rulingguide of variable curvature having a point fixed with respect to the said back edge and tangent to a line parallel with the latter, said guide having a free working edge continuous across said point of tangency and shiftable extremities on both sides of said point, and means for shifting said extremities in a direction transverse to said back edge.

3. A drafting instrument comprising a frame having a straight back edge, a resilient ruling-guide having a fixed point of attachment to said frame and a shiftable extremity, said guide being free between said fixed point and extremity and so constructed as to assume predetermined curvatures varying according to the degree of pressure exerted on said extremity, and means interposed between the frame and said extremity for shifting said extremity transversely of said back edge to impart varying flexure to the guide.

1. A drafting instrument comprisim a frame, a resilient ruling-guide having a fixed point of attachment thereto and a shiftable extremity, and a pivotally-movable adjusti nglever interposed between said frame and extremity and so arranged as to act with mechanical advantage on said extremity.

5. A drafting instrument comprising a ruling-guide having a continuous ruling edge provided with independently-shiftable end portions possessing characteristic laws of ourvature, means for holding said ruling edge immovable at a point intermediate of its ends, and means to independently adjust the end portions of said ruling edge to different degrees.

6. A drafting instrument comprising a frame, a ruling-guide having a point fixed on said frame and a shiftable extremity and possessing a characteristic law of curvature, and means acting on said extremity to adjust said guide to convex and concave curves or a straight line.

7. A drafting instrument comprising a frame, a ruling-guide having a fixed point of attachment thereto and shiftable end portions of different lengths and characteristic laws of curvature on opposite sides of said fixed point, and means interposed between said frame and edge, and means for independently adjusting.

the curvature of the end portions of said guide.

10. A drafting instrument comprising a frame composed of side plates separated by a space, a ruling-guide of adjustable curvature filling said space and having one edge protruding beyond said plates, and means for varying the curvature of said guide.

11. A drafting instrument comprising'parallel fiat frame-plates, an adjustable rulingguide mounted between said plates, and means mounted between the plates to adjust the curvature of said guide, the planes of the two sides of the instrument being formed by the outer surfaces of the plates and being free from outward projections. v

12. A drafting instrument comprising a frame having straight back and end edges in rectangular relation, a ruling-guide of adjustable curvature carried by said frame, and adjusting means for saidguide arranged entirely within the rectangular limitsof said back and end edges. Y

. I. In testimony whereof I have aflixed my signature in presence ,of two witnesses.

ERNEST J. LQRING. Witnesses:

R. M. PIERSON, A. C. RATIGAN.

Images