A hex key can turn only what the socket can hold. ASME B18.3 sets the hex size and a minimum key engagement for every screw: a 1/2 in. socket head cap screw takes a 3/8 in. key with at least 0.245 in. of full hex. ASTM F912 and F880 torque-test set screw sockets with the key at full depth: the socket must not ream and the screw must not burst. We press sockets on a hydraulic press, which is how we make socket screws in stainless, nickel alloys and sizes that are rarely stocked.
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model dataScrew drawn to ASME B18.3-2012: 1/2-13 socket head cap screw at the maximum head, 0.750 in. across by 0.500 in. high, with a 3/8 in. socket and 0.245 in. minimum key engagement; 1/2-13 set screw with a 1/4 in. socket. Head and socket machined, as ASTM F837 allows for stainless; set screws machined, as F912 allows. Pilot drawn 1.0066 times the across-flats size (20% of each flat left drilled), with a 118° point and a 90° countersink larger than the broach; push and rotary broaching after published shop practice; the chips the broach packs below the socket are drilled out with a drill smaller than the hex across flats. Socket gauging after ASME B18.3; hardness from ASTM A574 and F912; the torque test from F912 and F880, with no figures given. Broach teeth, depths and speeds are illustrative; spinning tools are shown slowed down. The press, drilling machine, lathe (a slant-bed turning centre with a round disc turret) and gauges are generic.
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