Lee Valley Tools Woodworking Newsletter
Vol. 1, Issue 5
July 2007
Featured Patents

Patented May 23, 1933
United States Patent Office
Peter L. Robertson, of Milton, Ontario, Canada
Slotted Socket Screw
Application filed October 18, 1930. Serial No. 489,607.

The principal objects of this invention are to provide a screw which will be readily driven either by the ordinary flat blade screw driver or by the tapered squared end screw driver used for socket screws.

A still further object is to provide a screw which may be readily adjusted by either type of screw driver, thus obviating the inconvenience and annoyance due to either form of screw driver not being available.

A still further object is to provide a screw, the head of which will very securely grip the end of the socket screw driver and which will also facilitate the entrance of the screw driver into operating engagement.

A further and important object is to enable the production of a combined slot and socket screw with the minimum displacement or removal of material, effecting a reduction of wear and strain on the forming tools and a resultant reduction in cost of the finished article.

The principal feature of the invention consists in the novel construction of a screw head with a rectangular socket having slightly tapering sides and chamfered edges leading thereto, together with a tapered end to receive the pyramidal end of the screw driver and which is diagonally intersected by a deep slot cut across the recess.

In the accompanying drawing, Figure 1 is a plan view of my improved form of screw head as applied to a countersunk head screw.

Figure 2 is a vertical mid-sectional view of the screw shown in Figure 1.

Figure 3 is a plan view of a modified form in the form of a round head screw.

In the invention herein shown, the screw head 1 is formed with a central squared socket which is punched into the material of the screw and has the very slightly tapering side walls 2 which are formed with the chamfered edge 3 at the outer side and lead to the pyramidal converging surfaces 4.

A slot 5 is cut transversely of the head 1, preferably across the diameter of the squared socket.

The provision of this slot does not in any manner interfere with the action of the tapered end and pyramidal pointed screw driver which is directed into the recess by the chamfered edges 3 and securely grips the tapered surfaces 4, the pyramidal point guiding it into place.

In the form of the invention shown in Figure 3 a round-headed screw is shown with the transverse slot 6 extending across the diagonals of the tapered rectangular orifice 7, into which the pyramidal-shaped end of the socket screw driver is inserted.

The transverse slot does not in any manner detract from the use of the rectangular socket but it does enable the use of the screw or the adjustment thereof where a socket screw driver is not available and a flat bladed screw driver may be used.


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