USRE626E - Improvement in wood-screws - Google Patents

Description

IUNITEDI4 STATES,

PATENT" OFFICE.

THE EAGLE scREW MANUFACTURING coMFANY,oF PRov1nENcE, RnonE y ISLAND, AssIGNEE oF THOMAS J. sLoAN.

IMPROVEMENT IN wooo-'SCREWs Specification forming part of Letters Patent No.'4,704, dated August 20,1846; Reissue No. 107, dated I' February 22, 184e; Reissue No.

626, dated November 23, 1858.

To all whom it may concern:

Be it known that TIOMAS J. SLOAN, of the city, county, and State of New York, did invent Certain new and useful Improvements in Wood-Screws; and Ldo hereby declare that the following is a full, clear, andexact description thereof, reference being hadl to.` the accompanying drawings, making part of ,this specification, in which- Figure l represe ts a wood-screw of theimproved forni; and Fig. 2 the form of the corethat is to say, what the form would be if the thread was stripped ori'.

The same letters indicate figures. l

Prior to the said invention of the said THOMAS J. SLoAN woodscrews were usually made with the whole length of the threaded part of the same diameter, slightly tapering from end to end, but screws so formed were objectionable for the reason that they could not be inserted in any kind of wood without iirst boring ahole like parts in` both l, as large as the core, or nearly so, and even then it was difficult to start them in the proper place on account of the long lip-like projections presented at the end bythe thread,which was then of fuller nearly tull depth. In some instances the extreme end was'made of a slightlyreduced diameter, such as would be vobtained by simply causing the chaser to ap' j proach the axis of the screw in cuttingthe last convolution, so that in a section taken in the planegof the axis of the screw the core between the several convolutions' of Vthe thread would approach the axis like a series-of steps, each parallel with the axis or nearly so; and although this `somewhat avoided the objection above stated, it was still objectionable for the reasons that they could not b brought to a point, and the last convolutir, however reduced in diameter, nevertheless till presented a blunt end, with the thread of full or nearly full depth projecting on one side of the core,

and because such a screw could not be inserted without first boring a hole, and even then the lip-likcgprojection had a tendency to cut into and follow the grain lof the wood and as the diameterof the core wa's reduced at each convolution toward the end, and the surface of the core was parallel, or nearly so, with the axis, the under surface of the thread surface, thereby reducing the strength of the thread, for the greater the projection of thc thread from the core the moreeasily it will be projection of the upper surface of the'thread from the core the greater the' hold on the wood. and the less the projection of the under surface from the core the greater the strength of the thread to resist any force which tends to draw or pull the screw out of the wood. Screws so formed were'objeetionable foranother reason In chasing the thread on the point the metal is severely strained, and the core of the last convolutions, being of a greatly reduced diameter, would-be torn or twisted oli' very liable to be broken oit' when encountering a knot or' other hard obstruction when applying the screw. Screws were also Inadc,in some instances, pointed conical along the entire threaded part, in the manner of a 'gimletpoint, the convolutions of the thread being representedby one spiral. line, and the bottom of the groove betweenthe threads by another s piralfline, and with the depth of thread gradually diminishing toward the point or apex of the core; but in such screws, known as gimlet-pointed screws, the convolutions ot' the thread along the entire length were of gradui ally less pitch toward the apex of the corethat is, eachl turn in succession toward the formed the point could be made to enter the wood readily and at any\givcn point, such screws failed to accomplish the desired purpose, because the travel of a screw when turned depends upon the pitch ofthe thread, and as the pitch of the thread in .i such screws was gradually shorter toward the point, it was evident that after the first entrance' into the pitch, in taking eiect, instead of being aided by the preceding convolutions, would be re sisted by them, and in consequence the threads of greatest pitch were lrequired to force those of less pitch through the wood.

v'represents a woodscrew formed according to the said invention; and Fig. Zrepresents the projected from the core more than thefupper i broken, as'it is the upper surface of the thread g whichholds in the wood, andl the greater the by the cutter; and if not so broken ofi', it was, p

point was shorter, and although when so wood, each succeeding convolution of greater In theA accompanying drawings, Figure 1- form of the core, or, rather, what would be the form after the threads of the screw, Fig. 1, were cut oli.

In the said drawings, a represents the thread, formed on` the shank b in the usual manner.-

The core is made of a conical form for a short' the'other, presenting in section a slightly curved line. The threads on the conical point is graduali y reduced until it is finally lst in the conical point, but the same distances between the several convolntions of the thread is maintained along the entire length from where it begins at the shank-to whereit ends at the apex of the conical point, so that for every turn of the screw each convolution of the thread along the entire length will tend to advance the screw through the same distance. A screw thus formed will present the following advantages.: ,First, as the power for inserting a screw is applied at the head and the resistance is presented to the threaded part, and the resistance graduallyincreases, as must 4 also the power applied in proportion as the threaded part advances into the wood, it follows that the'greatest strength to resistance is required Where the thread begins on the shank, and by making the core a gradual curve for some distance with the thread developed thereon of a gradually increasing depth, the

core ywill present -more strength than it'ithe` corel is cut down between the several convolutions to a parallel line with the axis.; and in addition to the better disp 'sition'of the metal for strength, the conical f m-ot' the corel will be more readily drawn into the wood by the thread than if the core be made in eiehelomv -and',8ecofnd, the 'point being composed cfa' yconica-1v core with the thread on it in the form Vof aspiral graduallyA convolutions of the decreasing in depth l apex of theconical core,' but"'fwith the convie:-

and iina-lly merged: in thef lutions atequal distances apart, and the same distance apart as on the body of thescrew, thevpoint of the screw wherever applied and turned will at once enter and travel in the line of its axis, each convolution in succession, as it takes into the wood, giving aid to force the core into the wood, the conica-l point acting wedge-like to spread apart the wood grad-` ually for the cylindrical core; and this form of point also presents the metal in the best condition to resist the action of the cutter in cutting the thread and-forming the pointed core.

It is not intended by the foregoing to limit the claim of invention to a precise geometrical form, as that would be too diieult to attain in the practicedv manufacture of wood-screws.

What is claimed as the invention of the said` THOMAS J, SLOAN, inthe manufacture-of i 1. Making thecore with a conical jpoint,

substantially as described, 'incombination with the body of a cylindrical form, or nearly so, substantially as an d for the purpose'specifled l 2. Making'the core with "av conical point, substantially as describedin combination with the thread formed on such conical point of a gradually less depth as it approaches the apex.V of the core, and with vthe several convolutions on the conical point and on the body at equal distances apart, substantially as and for the purpose specified. 3. Making wood screws with begins on the shank to -where it becomes of full.depthrsnbstantially as and for'the pur i pose specilied.

body-that is, with all the convoluti'ons at equal distances apart and of gradnallyj less depth from the 'substantially' as described. y f Baena s onnw co1l1r ANr,{L,-s l. PerWM. G. ANGELL,

Agent Witnesses@ WM, H. BISHOP,

'ANDREW DE LACY..

Athe core of a conical'shape along that-part of the length f ofthe screw extending from where the thread i base to the apex of the core,

Images