1-1/2 in Cobalt Drill Bit 1.5in M35 HSSCO - Heavy-Duty Stainless Drill

In this review the 1-1/2 in Cobalt Drill Bit (M35 HSSCO) is evaluated as a heavy-duty option for metalworkers who need a durable, sharp drill for tough materials. The bottom line: it is best for machinists and contractors who drill cast iron, copper, zinc alloy and particularly stainless steel because the M35 HSSCO composition and the 135-degree split point improve wear resistance and centering. The black and gold polished treatment also helps coolant cling to the cutting edge, reducing heat during longer holes and supporting reliable cutting when used properly.

Key Features

• M35 HSSCO construction: delivers a balance of hardness and toughness for wear resistance in demanding metal drilling applications.
• Black and gold polished surface: adds lubricity and creates small pockets that hold coolant near the cutting edge to reduce heat buildup.
• 135-degree split point: provides accurate centering and faster penetration so holes start cleanly without excessive wandering.
• Spiral flutes (right-hand cut): evacuate chips up and out of the cut to reduce clogging and improve cutting stability.
• Round reduced shank: 1/2 in reduced shank allows use in a variety of chucks and toolholding systems while keeping a larger cutting diameter.
• Material versatility: suitable for cast iron, zinc alloy, copper and stainless steel, making it useful across common shop tasks.

Who It's For

The drill bit is aimed at professional machinists, metal fabrication shops and serious DIYers who regularly drill hardened or abrasive metals and need a bit that stays sharp and resists wear. Its size and reduced shank make it a practical choice when a larger diameter is required but the available chuck cannot accept a full 1-1/2 in shank.

It is less suited to casual users who only drill wood or soft plastics, or to applications that require specialized coatings or carbide tips for extreme production speeds. Buyers who need guaranteed perfect accuracy every time should consider pairing this bit with a good drill press and proper setup, since some users reported mixed results on centering in difficult setups.

Pros & Cons

Pros

• Excellent wear resistance from M35 HSSCO material for tougher metals.
• Polished black and gold finish holds coolant and reduces friction for longer runs.
• 135-degree split point improves centering and reduces walking at the start of the hole.
• Round reduced shank fits a wide range of toolholders, increasing versatility.

Cons

• Some users report mixed drilling accuracy depending on setup, so precise work demands a stable jig or press.
• Durability varied in reports, with occasional breakage when pushed beyond recommended feeds or without proper pecking/cooling.

Specifications

Diameter	1-1/2 in (1.5in)
Material	M35 HSSCO high-speed steel
Shank	1/2 in reduced round shank
Overall length	6 in OAL
Point angle	135-degree split point
Flute	Spiral fluted, right-hand cut
Surface finish	Black and gold polished

Our Verdict

The 1-1/2 in M35 HSSCO cobalt drill bit is a solid choice for metalworkers who need a durable, high-performance bit for stainless steel and other metals. It offers good value for those who use proper setups and cooling; it performs best in a drill press or secure jig where the split point and polished surfaces can be used to their full advantage.

Frequently Asked Questions

Is this bit suitable for stainless steel?
Yes, the M35 HSSCO composition and the polished surface make it appropriate for drilling stainless steel when used with proper coolant and moderate feed rates.

Can it be used in a hand drill?
It can, but for best accuracy and to reduce breakage risk the bit performs better in a drill press or with a secure jig and steady feed.

What does the reduced shank mean?
The 1/2 in reduced round shank lets the larger 1-1/2 in diameter bit fit into chucks that cannot accept the full diameter shank, increasing compatibility with common toolholders.