US179695A - John feeaesqn - Google Patents

Description

J'. FREARSON. SCREW-DRIVER.

No.179,695. Patented J'u1y11,187-6.

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Specification forming part. or Lam-re uest. 179,606, July 11, 1816; appllostion filed i March 23, 1876. p

provements in screw-drivers is applicable.

My invention in screw-drivers consists of the improvements hereinafter described, and illustrated in the accompanying drawings.

Beforedescribing my said invention it] screwdrivers I may remark, by way oi'contrast, that the termination erecting end of the. ordinary "screwdriver is of a rectangular-figure, so as to fit the rectangular groove or nick which extends across the head of the ordinary screw.

To this kind of screw and-screwdriver there are many well-known objections, some of which -I. will-mention. For instance. when the screwdriver properly fits the width and whole length of the said groove or nick in the hea. of one size of the ordinary screw it will not properly fit any other size, because the blade of the screw-driverwill not extend to the whole 7 length of the grooves of screws of a larger size,

and therefore there will be a loss of the requisite power to drive such larger-sized screws,

and the said screw-driver will extend beyond.

the heads of screws of smaller size, so that the two edges of the acting end of the driver, protruding beyond the heads of smaller screws, come in contaet'with the countersunk material, so as to disfigure the work, and the protruding edges of the screw-driver prevent the screw from being driven to its required position. When the said screw-driver is ground taper on its two flat sides, for the purpose of driving screws of different sizes, there is a tendency for the driver to slip out of the groove or nick in the act of driving the screw, and also to deface the finished work. As the ordinary screw-heads are upset by a flat-faced die or punch, the heads are generally fractured, and,

when the nick happens to be in one of these is in the center of the head of the screw.

lractures the tendency is to burst the head. asunder. V a

Now, the object of my invention in screws: and screw-drivers is to remove or diminish all the before-mentioned objections, and I effectually remove or diminish the said objections in the following manner:

By reference to the specification of my petcavity isot' a'combined V shape-that is, its

sides and its: ends all inclinemr converge to or toward one point; thereforeits greatest depfh n another head of a screw there are two V cavities or nicks crossing each other at right angles at the center of the screw-head, thus forming four radial grooves or nicks' and in another head of a screw there are three V-nicks crossing each other at the center of the screwhead, thus forming six radial grooves or nicks, each making, with the adjacent one, an angle of about sixty degrees. Each crossing nick in the two last-mentioned screws are of precisely the same angles as the single one first described.

My invention of improvements in screwdrivers is applicable to the said screws.

The screw-driver, which is applicable to the said single nick in the head of my screw, or to any one of the combined V-nicks, has a flat blade, its acting end being of a combined V shape.

The other screw-drivers, which are applicable to those of the screws which contain sev-' eral V-nicks, have several radial V-branches, all converging to or toward one point. In making these screw-drivers I first make that part which is to enter the cavity in the head of the screw ot' a conical shape, and then, by means of cutting-tools or other means, I make three or more flutes or grooves in the said conical part, thus leaving a corresponding number of radial V-branches, the three sides .of each branch from the base'to the apex of the cone converging to or toward one point.

I will now describe my invention with reference to the accompanying drawings.

A, Figure 1. represents in elevation the broad side, and A, Fig. 2, reprcsentsiu elevation the narrow side, and A, Fig.3, represents in plan the acting end, of a screw-driver according to my invention. Fig. i represents, in elevation, the acting end of a screw-driver which has three radial V- branches, each marked B, and all the said branches, from the base to the apex of the fluted cone, converge to or toward one point; and Fig. 5 is a plan of the same. This screw-driver is applicable to a screw-head having three or six radial V- grooves therein. Fig. 6 represents, in elevation, the acting end of a screwdriver which has four radial V-branches, which are at right' angles to each other, and each marked B, and

' all the said branches, which form the fluted cone, incline or converge to ortoward one point; and Fig. 7 is aplan of the same. This screw-driver is applicable to the cavities in the heads of screws having two V-nicks crossing each other in the center of the heads.

By preference I make the screw-driver of the last description as illustrated, Figs.6 and 7; and as the cavities in the heads of my screws will be made to correspond with the acting ends of the said screw-drivers, the angles being the same in all sizes of screws and screw-drivers, every size of screw can be driven by one screwdriver, each sizeof screw possessing a cavity exactly proportionate to its size and the power required to driveit. As the cavities in the heads of my patent screws are deepest in the center, and of great depth,

the screw-driver takes a firmer gripe of the screw than the ordinary driver takes in the nicks of the ordinary kinds. The screw-driver, according to my invention, at once takes its axial position, and when pressed in the cavity as the ordinary driver is pressed it cannot slip out of the cavity so as to deface the work; and as the cavities do not extend to the sides of the screw-head, the screw-head is much stronger than that of the ordinary kind, and from the construction of the driver and the cavity the driver can never come in contact with the countersunk portion of the work.

I make, by preference, the angle marked A, Fig. 1, of about thirty degrees, and the angle marked A, Fig. 2, of about ten or twelve degrees. 7

Having describedmy invention, and the manner it may be performed, I wish it to be understood that I do not confine myself to the precise details herein described and illustrated, as the same'may be varied without departing from the;nature of myinvention; but

I claim as my invention of improvementsin screw-drivers- A screw-driver having two or more radial branches extending from the centeror axis,

and describinga cone in revolving, all the acts i'ng'sides of the said radial branches converging toward an axial point, substantially as and for the purposes described, and as illustrated in the accompanying drawings.

JOHN FREARSON. Witnesses: 7

.J 01am B. GOULD, J. FRANCIS BRAME.

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