Thread spec by measuring a sample:
Size #8 USA standard self tapping screw
Standard USAS B18.6.4-1966
Type AB:
18 threads per inch, right hand thread
Major/minor diameters .163 OD/.119 root (inches)
standard 60 degree thread form (there exist designed for plastic custom metal screws with a more acute angle but these are not that kind)
Point type B
Nominal length of shank: .625 inches
If you inadvertently substitute the common Type A self tapping screw with nearly the same major and minor diameters but 15 threads per inch some serious cross threading and thread destruction in the housing could result .
Size #8 USA standard self tapping screw
Standard USAS B18.6.4-1966
Type AB:
18 threads per inch, right hand thread
Major/minor diameters .163 OD/.119 root (inches)
standard 60 degree thread form (there exist designed for plastic custom metal screws with a more acute angle but these are not that kind)
Point type B
Nominal length of shank: .625 inches
If you inadvertently substitute the common Type A self tapping screw with nearly the same major and minor diameters but 15 threads per inch some serious cross threading and thread destruction in the housing could result .