RUKO FLS-DIN373-HSS-TiN-M-4x Countersink Bit, M4, HSS, TiN Coated, DIN 373

The RUKO FLS-DIN373-HSS-TiN-M-4x countersink bit stands out with its three-flute design ground from solid HSS, offering clean, chatter-free countersinking in a compact pilot-guided tool. The TiN coating reduces friction and improves chip flow, making it a dependable choice for repetitive work in steel, cast iron, non-ferrous metals, and plastics.

Highlights

• DIN 373 countersink with pilot for M4 screw threads
• Solid HSS body with titanium nitride (TiN) coating for longer life
• Three cutting edges provide smooth, vibration-free countersinking
• Cylindrical shank fits standard drill chucks
• Right-hand cutting direction for conventional drilling

In daily use

This countersink creates flat-bottomed seats for M4 flat-head screws and is equally useful for deburring drilled holes. The 4.3 mm pilot guides the tool concentrically, while the 8.0 mm head diameter matches common M4 countersunk screw heads. Use it with or without coolant depending on the material and setup.

Full specifications

• Standard: DIN 373
• Tool type: Countersink / Spot Facer
• Material: High-Speed Steel (HSS)
• Coating: Titanium Nitride (TiN)
• Thread size: M4
• Pilot diameter (d1): 4.3 mm
• Countersink head diameter (d2): 8.0 mm
• Shank diameter (d3): 6.0 mm
• Overall length (l1): 45 mm
• Pilot length (l2): 12 mm
• Number of cutting edges: 3
• Shank type: Cylindrical
• Cutting direction: Right-hand
• Manufacturing method: Ground from solid
• Coolant compatibility: Yes
• Packaging unit: 1 piece

Final note

A precise, pilot-guided countersink for M4 applications, built to DIN 373 and finished with TiN for durability.