RUKO STB-HSS-3S-Gr,0/9-4-12mm Step Drill Bit 4-12 mm, 9 Steps, 3-Flat Shank

Sheet metal workers and electricians rely on the RUKO STB-HSS-3S-Gr,0/9-4-12mm step drill bit for fast, clean holes in thin materials. With a 9-step profile from 4 to 12 mm in 1 mm increments, it drills, deburrs, and reams in one operation. The 3-flat shank prevents slipping in the chuck, and the self-centering point starts holes accurately without a pilot drill.

Key specifications

• Material: High-Speed Steel (HSS)
• Drilling diameter range: 4 - 12 mm
• Number of steps: 9
• Step increment: 1 mm
• Shank type: 3-flat shank
• Shank diameter: 6.5 mm
• Overall length: 67 mm
• Maximum material thickness: 4 mm
• Point angle: 118°
• Surface finish: Bright (uncoated)
• Tool type: Step drill bit
• Application: Sheet metal, non-ferrous metals, plastics, thin materials
• Cutting direction: Right-hand cutting
• Standard: DIN 1412 C
• Coolant recommendation: Yes, for optimal performance
• Suitable for: Drilling, deburring, reaming
• Material hardness compatibility: Up to 900 N/mm²
• Manufacturing process: Ground from solid
• Self-centering point: Yes
• Prevents slipping: Yes (due to 3-flat shank)

Why choose it

The 3-flat shank ensures a secure grip, eliminating bit slippage even under high torque. Ground from solid HSS, the bit withstands material hardness up to 900 N/mm², making it durable for professional use. The bright finish reduces friction and heat buildup, extending tool life.

Ideal use cases

• Enlarging existing holes in sheet metal
• Creating clean, burr-free holes in plastic enclosures
• Drilling and deburring in non-ferrous metals like aluminum
• Preparing holes for cable glands or conduit fittings

Good to know

Use a cutting fluid or coolant for optimal performance and longer bit life. The self-centering point allows drilling without a center punch, saving time on the job. The bit is designed for materials up to 4 mm thick.