EZARC 4–12mm M35 Cobalt Step Drill Bit / Unibit – 9 Steps, AlTiN Coated, Spiral Flute, 1/4" Hex Shank, For Metal, Stainless Steel & Aluminium

9 Steps. M35 Cobalt. AlTiN Coated. One Bit for Every Hole Size.

Sheet metal, stainless steel, aluminium, brass, copper, cast iron — the EZARC 4–12mm M35 Cobalt Step Drill Bit (also known as a unibit or cone drill bit) cuts clean, precise holes in a single pass without needing to swap bits. Nine steps from 4mm to 12mm in 1mm increments, M35 cobalt high-speed steel for superior hardness and toughness, and an AlTiN coating rated at 89 HRC that withstands temperatures up to 900°C. The triple-flute C-profile cutting edge delivers 2× the cutting speed of standard step drills with enhanced stability and reduced deviation. Fits any drill with a 1/4" hex chuck.

Key Features

• 9 Step Sizes: 4, 5, 6, 7, 8, 9, 10, 11, 12mm — one bit replaces nine; no swapping required
• M35 Cobalt HSS — superior hardness, toughness and bending strength vs standard HSS; ideal for harder materials
• AlTiN Coating (89 HRC) — aluminium titanium nitride; resists heat up to 900°C, wear and corrosion; outlasts black oxide coatings
• Triple-Flute Spiral Design — enhanced stability; reduces deviation during cutting
• C-Profile Cutting Edge — smoother cutting; 2× faster than standard step drills
• 1/4" Hex Shank — fits standard drill chucks and quick-release hex chuck systems
• 145mm Overall Length

Compatible Materials

• Mild steel and medium hardness steel (plate up to 3mm)
• Stainless steel (plate up to 1mm)
• Aluminium, brass, copper and cast iron
• Galvanised pipe and low-carbon steel
• Plastic

Usage Tips

• Use low speed and light pressure until reaching the desired depth
• Apply cutting oil or water-soluble lubricant to reduce friction, heat and debris
• Start-up speed may be slower due to the larger cutting angle — this is normal