A screw having a head and a threaded shank and, in the head, a cruciform shaped recess comprising a central cavity and four grooves radiating from the central cavity at 90 DEG angular spacings, the bases of the grooves lying on a conical (or pyramidal) surface and wherein the included angle at the vertex of such cone (or pyramid) has a value within the range of 40 DEG - 45 DEG , the preferred value being 40 DEG .

Title
Threaded fastener
Application Number
GB19750030366 19750719
Publication Number
1521141 (A)
Application Date
July 19, 1975
Publication Date
August 16, 1978
Assignee
Gkn Fasteners
IPC
B25B 15/00
F16B 23/00
F16B 23/00
B25B 15/00
B21K 01/00
B21J 13/02
B25B 23/02
F16B 23/00
B25B 15/00
B21K 01/46
B21J 13/02
B25B 23/10
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