Keo 3/8 in 82° Cobalt HSS Single-Flute Countersink

This Keo 3/8 in, 82° single-flute countersink is manufactured from cobalt high-speed steel (HSS-Co), as clearly marked "3/8" X 82° Co" on the shank — cobalt content (typically M35/8% Co) provides superior heat and wear resistance compared to standard M2 HSS, making it well-suited for countersinking stainless steel, high-temperature alloys, and other difficult-to-machine ferrous materials. The 82° included angle conforms to the standard for imperial flat-head fasteners (ASME B18.6.3), producing properly seated #4 through #12 flat-head screws. The tool features a single-flute (zero-flute chatterless) geometry visible in the photos — this design virtually eliminates chatter and produces a smooth, accurate countersink in both hand-held and machine applications. The round straight shank is compatible with standard drill chucks; the large-body fluted version (first photo) and slender single-flute version (third photo) represent the same size/angle specification packaged with a protective red plastic storage cap (S3511-GEE label visible on cap). Offered new in uncoated bright finish.

Product Specifications