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Publication numberUSRE6730 E
Publication typeGrant
Publication dateNov 9, 1875
Filing dateAug 4, 1875
Publication numberUS RE6730 E, US RE6730E, US-E-RE6730, USRE6730 E, USRE6730E
InventorsAllan Oummings
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Improvement in wood-screws
US RE6730 E
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

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`Parn1vfr OFFICE.


Speeication forming part of Letters Patent No. 161,390, dated March 30, 1875; reissue No. 6,730, dated November 9, 1875; application tiled August 4, 1875. l

'. invented an Improvement in Screws, of which driveri'rom the slotvor nick in the head of the l In order to fully and satisfactorily accomf plish this object, I form in the center of the head of a screw, in addition to the usual slot or nick, a deep cavity or hole, of suitable shape, into which `cavity and slot a properlyl shaped `screw-driver or :tool is inserted, and

furnishes the leverage for driving or withdrawing the'screw. The form` of this driving tool is that of an ordinary screw-driver, the blade of which, at 'the base, is provided with a projecting spur, coinciding in shape with the cavity in the head ofthe screw, so that it will fit both the'slot or nick /and cavity at thesame time, thus giving great strength andvastly increased power.

In carrying out my invention I have made this cavity, in the center of the screw-head, angular in shape, this form being the best adapted for the purpose by reason of its furnishing the greater amount of increased power,

. as well as forthe additionahreason that it is the most readily formed in the screw-head. Any angular-shaped cavity other than square will fully answer the purposes of my inven-V tion.

n In the following description I have carefully pointed out and described the various modes and forms to which my improvement may be applied and adapted.

In the drawings, which form apart of this specification, Figure 1 is an elevation, partially in section, of an ordinary wood-screw, the rounded head of which is provided with a 4DrvIsIoN B.

deep angular cavity, in addition to the usual slot, in accordance with my invention. Fig. 2 shows my improvement as applied to an ordinary screw, the usual slot being omitted. Fig. 3 is a vplan view of an ordinary screw, inthe head of which the cavity is shown -as square in shape, and combined with the usual slot. lFig. 4 is a plan 'View of the head ofthe screw illustrated by Fig. 2.- Fig. 5 is a moditication, in which the cavity is shown as triangular in shape.

Similar letters of reference will indicate correspondingv parts. y

'It is a well-known and fully-established fact that the ordinary screw-head, which is provided only with a narrow,.shallow slot or nick milled across its face, in which slot the screwdriver is applied, is very susceptible to injury, 'caused mainly by the frequent slipping ofthe 4screw-driver from the slot or nich when the screw is being set home?7 in' either wood or metal, or being'withdrawn fromthe saine.. It is also not an unusual occurrence to have one. half of the screw-head split oft Whenever am extra amount of power is applied through the` ordinary screw-driver. These mishaps are so common as to benotorious amongthe manufacturers and mechanics who use large numbers of screws, and the loss resulting from such damaged screws annually amounts to large sums ot' money.

It is to entirely obviate all of these diiiiculties, to gain additional strength in the screw-head, and an increased driving-power, also to render it absolutely impossible to injure the screw-head in any manner,l that I have inademy present invention. A

Large quantities of what are known as capped screws for ornamental purposes are now made, and extensively usedin fitting and nishin g up the interior ofcars, stages, coaches, in furniture, billiard-tables, pianos, and for other similar purposes. The heads ot' these screws, either ator rounded, are covered with a thin metallic cap, which is plated with gold, silver, or nickel, as may be desired. 1n the process of capping, the plate is cut away from that portion of the head of the screw in which the'slot or nickis formed. Thismetallic cap or vcover being very thin, the utmost neety'in the use of these-capped screwsl is called for.A In driving them with the ordinary screw-driver, it is very com mon for the driver to slip from `the slot or nick, tearing up the cap,and thus spoilingits appearance, and necessitating its being thrown aside.

It will be readily seen that by`combining' with the usual slot or lnick in this vclass -of `screws a cavity of angular shape formed in the' center ofthe screw-head, and using as the driving-tool'a"screwdriver provided with an angular projecting spur, so that it will tit the cavity and Vslot at the same time, perfect safety is insured to the metallic capas well as to the screw-head itself.` Perfect Work also is thus insured, and no loss yof screws absolutely guaranteed.- The process of capping is also sim-` plitie'd.`J Y

Large quantities of soft-.metal screws irl-brass or similar composition metals are also much used, and the same difticulties are met with. In such classes ofscrews all trouble is obviated by my improvement. -v v It is in the relnovalor withdrawing of screws that my invention, combined with the l improved form of screw-driver, proves its great utility and advantages.

from the slot, repeating the same until it is utterlyimpossible to start the screw from its bed, or to obtain any hold in the then damaged slot or nick. The screw has then to be Y removed by cutting it out, to the great damage of thework in'which it was located. My improvement completely eradicates all this trouble, as a screw having a cavity in its head is readily and surely withdrawn at the first' f Screws that have been long embedded and, .rusted in are diiicult to remove with an ordinary screwdriver, as it will invariably vslip screws, in both instances,`are also provided with vthe usual slot or nick, 'an d may also 'ei- The' slot'or nick is of therbe capped or not. the usual size, no changein that respect being called for in the addition of my improvement. shape and depth as may in practice be found- Pto he best adapted to fully accomplish the pur-A poses of my invention. It may be made usually the same size from top to bottom, or, if preferred, made tapering.

In Fig. 4, which is a plan view of the head of the screw shown in Fig.2, the-cavity a is shown f' as square in shape.` This shape seemsto be the best adaptedV for the purpose; but other angular forms may be used," as shown in Fig. 5, in lwhich a triangular .shaped cavity is given.

It is obvlous that any one of these or other angular shapes will answer. I therefore do not confine or limit myself to any designated one ofthem.

'These cayities may be formed in the screwhead by proper tools attached-to the screwmachine, at the same time the screw is being formed, or they-may be made in a distinct machine, as a separate process `from the for^ Vmation ofthe screw itself. These operations.'

are well-known mechanical processes, and. as

they'form'no part of my present invention, require no detailed description herewith.

Itis obvious. that my improvement is readily applied to all ofthe known forms of screws, both machine and wood. l A

Having thus fullydescribed myfinvention, what I claim as new, and desire to secure by Letters Patent, is-

A screw the head of which, at itscenter,

is provided with au angular cavity, inA addition to the usual slot or nick, substantiallyas and for the purposes as herein shown and described.

ALLAN UUMMINGs. Signed in presence ot'- y A. L. MUNsoN, R. I. GRIFFITH.

The cav-ity or hole a, is formed of such