US2671967A - Drafting spline holder - Google Patents

Description

3i" FFICE are UNITED STAT DRAFTING SPLINE Herman- Frankel. Del Giudice, Seattle, Wash.,assignor to Boeing. Airplane Company, Seattle, Wash, a corporation of Delaware Application January5, 1953,. SerialN'o. 329,715

5 Claims. (Ole 33l77)1 l 2 This invention relates to a drafting implement, thefiex-ible spline 2 of known type isfitted. In and particularly to a device for engaging andv order to hold the spline in this fixed curvature; holding a le p e at -fi d rv ur n the several elements of the present invention order that it may beused asa guide foramarking cooperate. The implement as a whole includes tool, such as a pen or pencil. Such splines are a plurality of blocks 3, supported in alignment very frequently used in aeronautical drafting, for transversely of the board, to which end they may p aldevice for the p p indicated be provided with retaining flanges 4, received 11111511136v capable f holding p i s W e y O in the undercut groove 5 of a guide bar 6. This of t y V y Curvature, of ppreciable bar may be supported upon a base strip 1 which lateral extent, cndwithal fi mly. and yet m it may be an independent straight-edge; or which be readily adjustable f y one p t t nylike the straight edge of a drafting machine may other whenthatis desired. be supported at the opposite edgesof the draft- In particular it is. desirable that therestraining board 5, and maybe moved up and down the ing force by which: the. flexible. spline is held board, The particular. nature of the supporting to its u ure e pp along 11116 Which l5 and guidingv elements, if any, other than the is su tan al y p p di ula t a tangent blocks a, is not material to the principles of; this throughthe point of v engagement of the holding invention device. with the-spline. Unless. thisprinciple is Each block 3 is rather broad; and stands up Observed, e: -device tends to be pulled somewhat above the drafting surface of the askew, by the inherent resistance ofthespline te 0 board 1, although. not to such an extent as to h e of u u With the: r u t t t e constitute a-seriousobstruction to the draftsrnan. splineitself departsfromthe desired curvature. H r, th b1 c-ks upper surface at all points Illt principal object f e p t v nstands appreciably above the height of the spline On to provide a device of the n tu -and o e 2; Preferably, in the form illustrated in Figures use indicated above. Among. more specific ob- 35 l and 2, the upper surface of the block isridged jectsi it s desirable, a150, 1301' Provide a device in the direction. of the alignment of the blocks, this naturez'which will be simple in construction, such a id being. indicat d at a, From this itself readily. adjustable to accommodate various ridge th block slopes gently, at least toward that conditions of. use,,never so positively held that edge as which, is nearer the spline 2, and aswill it cannot be shifted slightly in any of various shgrtly a ar, the ridge 3- and this near edge dir t s, t v ly p i a a d v as constitutealternate fulcra. A. similar result Such as W l ot p oj d y above. the may be achieved in the-form shown in Figure 3 ac of the. fting board nd t u interfere by gently rounding the entire upper surface, as with the draftsman. shown at 812 in Figure 3. I

With these and: other obiectsin mind, as will A clevis, generally indicated, by the numeral 9, be apparent hereinafter, the present invention is pivotally mounted at IU upon. the block. The comprises the novel drafting spline holder, and pivot axis generally parallels the ridge 8 and the novel combination and arrangement of the the edge to. These clevises may be of wire, several parts thereof with relation to one anand preferably each is of appreciable breadth other and for use with known types of splines, corresponding to the breadth of the block to all as shown in the accompanying drawings in which it is pivotally mounted. Preferably the a Preferred f and as Will be hereinafter re transverse portion Ea of each clevis is straight, fully plained and defined. and parallels the edge 8a and the ridge 8, but

Figure 1 is a perspective view of such a spline is located some distance outwardly of each, at holder in the side of its block which is nearer the spline 2.

Figure 2 is in the nature of a side elevation, Means are employed to urge the clevis 9, and being in fact a vertical sectional view from top particularly its transverse portion 9a, strongly to bottom of the drafting board, viewing in downwardly toward the board, although the clevis side elevation the spline holder applied thereto. can be pulled upwardly in opposition to this Figure 3 is a view similar to Figure 2, showing 50 force. The simplest construction to these ends a somewhat modified construction. is provided by spring means such as are indicated The drafting board may be of any desired at 91), these being a continuation of the wire of form, and upon its surface, or upon a drafting which the clevis 8 may be constructed, reacting sheet resting upon that surface, it is assumed from the block itself to urge the transverse portion to be the intention to draft a curved line to which 55 9a downwardly toward the board.

Associated with each such block and its clevis, at least each that is to be employed in a given situation, is a narrow, rigid stick II. Each stick is of some appreciable length, and is provided at its outer end with a pointed retainer I2, or similar holding means, whereby it will engage and hold down the spline 2. Each such stick II is passed beneath the transverse portion 9a of its block, and rests also either upon the ridge 8, as is shown in the dotted line position in Figure 2, or upon the edge 8a, as in the full line showing of that figure, either such edge constituting a fulcrum, and the transverse portion 9a of the clevis constituting a point of application of force whereby the outer retaining member I2 is pressed strongly downwardly.

It will be observed that if the extension of a stick I I beyond its block is rather appreciable, the gentle slope of the upper surface of the block 3 causes the stick to fulcrum at the ridge 8, and thus to attain maximum leverage to the point of application at 9a of the downwardly directed force. If, however, the projection of the stick is short, as, for example, at the left in Figure 1, then the fulcrum of the stick is at 8a, and the leverage to the point of application of the force at 9a is less. By such means the sticks are caused to exert roughly equal forces at the spline. This effect is heightened, and an infinite variation in force is achieved, by the rounded alternative construction illustrated at 8b in Figure 3.

It has heretofore been noted that the blocks are quite broad with relation to the width of the sticks, and the transverse portion 9a of the clevis is similarly broad. The advantage of this lies in the possibility that notwithstanding the straight-line guide 6 for the blocks, and the impositiveness of the engagement of the sticks, any given stick may be canted or inclined laterally to an extent that permits its outer end at I2 to extend approximately perpendicular to a tangent at that point of curvature. This breadth of the blocks and clevises affords very considerable freedom of adjustment of the splines to various positions to achieve the end just indicated. Also it will be noted that each block may be slid lengthwise of the guide bar 6 to whatever position best suits it for the holding of a spline in a given position.

The base strip I with its blocks 3 may be left set up ready for use when required, and the entire assembly may, if desired, be detached from the drafting machine or from the board, and readily replaced when required.

I claim as my invention:

1. A device for use in retaining a flexible drafting spline at a fixed curvature upon a drafting board, which device comprises a plurality of blocks disposed in side-by-side alignment transversely of the board, means for supporting said blocks in such alignment and in spaced relationship, close to but upstanding above the board, a clevis pivotally mounted upon each block, to swing about an axis directed generally in the direction of their alignment, and all clevises having their transverse portions projected beyond that side of their respective blocks which is nearest the spline, means reacting between each clevis and its block to urge said transverse portion downwardly towards the board, and a plurality of rigid sticks, one for each block, bearing at one point upon the top of the block as a fulcrum, received beneath and urged downwardly by the transverse portion of its clevis, and at its distant end extending to a distance to bear downwardly upon the spline, whereby to retain the latter fixed in the vicinity of the point of contact.

2. A spline-holding device as in claim 1, wherein each block is crowned along a line generally parallel to the direction of their alignment, and intermediate the blocks edges which are parallel to such direction, to afford an elevated fulcrum point distant from the transverse portion of the clevis for a less inclined, farther projecting stick, and an alternative fulcrum point located nearer the transverse portion of the clevis for a more steeply inclined, lesser projecting stick.

3. A spline-holding device as in claim 1, wherein the upper surface of each block is sloped gently from a ridge directed generally parallel to the direction of their alignment to the edge of the block which is nearest the spline, said ridge and said edge being higher above the board than the spline-engaging end of its stick, in any operative disposition.

4. A spline-holding device as in claim 1, characterized in that each block and its clevis are materially broader than the width of a stick, whereby a stick may be inclined at a transverse angle to meet the curvature of the spline approximately at right angles to a tangent at the point where the stick will bear upon the spline.

5. A spline-holding device as in claim 1, wherein the block-supporting means comprises an undercut guide, and the several blocks are complementally shaped to slide along and be held by said undercut guide.

FRANK J. DEL GIUDICE.

No references cited.

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