HTC HSS Countersinks

A countersink cuts the cone that lets a flat-head screw finish flush with the surface. The whole job is decided by one number: the included angle, which has to match the fastener, not the drawing’s idea of a chamfer.

Pick the angle first

  • 82° — the standard for inch flat-head machine screws and wood screws in the US.
  • 90° — the metric equivalent, and the usual choice for deburring and for chamfering a hole before tapping.
  • 60° — center-drilling work, lathe centers, and lead chamfers where a shallower cone would leave too wide a mouth.

One flute or three

The single-flute countersink has one cutting edge through a cross hole. It has nowhere for a chip to stack up and it does not chatter the way a multi-flute tool does on a thin sheet or an interrupted entry, which is why it is the deburring tool of choice. The three-flute version cuts more evenly and leaves a better finish on a seat that has to bear a fastener head squarely, and it holds the angle better over a production run.

What is in this range

  • Included angles: 60°, 82° and 90°
  • Flutes: 1 and 3
  • Material: high-speed steel
  • Finishes: bright (uncoated), TiN-V, TiCN-PG and TiAlN-HC
  • Origin: made in the USA by HTC Mfg.

Also available: HTC Countersinks and Countersink Sets.

Not sure which size or geometry you need? Email our technical team with the fastener you are seating — FM Carbide helps you machine better!