• Counterbore end mill - HSS 4 flute pilot counterbore for M3 to M20 socket head cap screws
  • HSS pilot counterbore for flat-bottom recesses that seat cap screw heads
  • High-speed steel counterbore for steel, aluminum, cast iron, plastics and wood
  • Pilot counterbore sizes M3 to M20 with matching pilot and cutter diameters
  • Counterbore for socket head cap screws in fixture plates and jigs
  • 4 flute counterbore end mill with fixed pilot for drill press and milling machine
  • M4 HSS counterbore end mill, 4.2mm pilot x 8mm cutter, for M4 socket head cap screws
  • M3 HSS counterbore end mill, 3.2mm pilot x 6.5mm cutter, for M3 socket head cap screws
  • M12 HSS counterbore end mill, 12.4mm pilot x 20mm cutter, for M12 socket head cap screws
  • M10 HSS counterbore end mill, 10.3mm pilot x 17.5mm cutter, for M10 socket head cap screws
  • M8 HSS counterbore end mill, 8.2mm pilot x 14mm cutter, for M8 socket head cap screws
  • M6 HSS counterbore end mill, 6.2mm pilot x 11mm cutter, for M6 socket head cap screws
  • M20 HSS counterbore end mill, 21mm pilot x 30mm cutter, for M20 socket head cap screws
  • M18 HSS counterbore end mill, 18.5mm pilot x 28mm cutter, for M18 socket head cap screws
  • M16 HSS counterbore end mill, 16.5mm pilot x 26mm cutter, for M16 socket head cap screws
  • M14 HSS counterbore end mill, 14.4mm pilot x 24mm cutter, for M14 socket head cap screws
  • M5 HSS counterbore end mill, 5.2mm pilot x 9.5mm cutter, for M5 socket head cap screws

Counterbore End Mill - HSS 4 Flute Pilot Counterbore for Socket Head Cap Screws, M3 to M20

Counterbore End Mill - HSS 4 Flute Pilot Counterbore for Socket Head Cap Screws, M3 to M20

$24.99
$24.99
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Counterbore end mill - HSS 4 flute pilot counterbore for M3 to M20 socket head cap screws

Counterbore End Mill - HSS 4 Flute Pilot Counterbore for Socket Head Cap Screws, M3 to M20

$24.99
$24.99
SAVE Sold out
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This counterbore end mill cuts a flat-bottom counterbore around an existing hole so socket head cap screws sit flush with or below the surface. The fixed pilot rides in the drilled hole and keeps the cut centered.

Drill the clearance hole first, then run the counterbore at low speed in a drill press, milling machine or CNC center. Each size is matched to a metric cap screw from M3 to M20.

Specifications

  • Type: 4 flute pilot counterbore, high-speed steel (HSS)
  • Sizes (pilot x cutter): M3 3.2 x 6.5mm, M4 4.2 x 8mm, M5 5.2 x 9.5mm, M6 6.2 x 11mm, M8 8.2 x 14mm, M10 10.3 x 17.5mm, M12 12.4 x 20mm
  • Large sizes: M14 14.4 x 24mm, M16 16.5 x 26mm, M18 18.5 x 28mm, M20 21 x 30mm
  • Overall length: 45-110mm depending on size
  • Workpiece materials: copper, aluminum, tool steel, cast iron, plastics and wood
  • Package: 1 counterbore in the size you select

Best for

Fixture plates, jigs, machine guards and enclosures where cap screw heads must sit below the surface.

FAQ

What size counterbore for an M6 cap screw?
Choose the M6 size: 6.2mm pilot for the clearance hole and an 11mm cutter for the screw head.

Can I use a counterbore in a hand drill?
It works best in a drill press or mill, where the spindle stays square to the part and the floor of the counterbore comes out flat.

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