Cobalt M42 Stubby Drill Bits for Screw Machine Work

Quick answer

For screw machine work, 1/8" Cobalt M42 stubby drill bits are the right choice: their short length reduces flex and breakage, while the 135° split point prevents walking on metal.

Why stubby length matters in screw machines

Screw machines and CNC lathes operate at high speeds and feed rates. Standard-length drill bits flex under these forces, causing wandering holes and premature breakage. Stubby drill bits are much shorter, so they are stiffer and less prone to deflection.

The shorter flute length also means less chip buildup and easier chip evacuation in confined spaces. This makes them ideal for repetitive, precision drilling in production environments.

Cobalt M42 vs. standard HSS

Cobalt M42 steel contains more cobalt than standard HSS, which lets the bit withstand higher temperatures without losing hardness. This is critical when drilling stainless steel or other hard metals at production speeds.

While standard HSS bits are cheaper, they dull faster on tough materials. Cobalt M42 bits hold an edge longer, reducing tool changes and downtime. The tradeoff is higher upfront cost, but for frequent metal drilling, the durability pays off.

Split point prevents walking

A 135° split point is a common feature on quality drill bits. The split point geometry creates a self-centering effect, so the bit doesn't 'walk' across the workpiece when you start drilling. This is especially useful on curved or uneven surfaces.

Without a split point, you often need a center punch to start the hole accurately. With a split point, you can start drilling directly, saving time and improving hole placement.

Diagnosis: Is your drill bit the problem?

• Symptom: Your drill bit wanders off center or breaks frequently when drilling metal in a screw machine.
• Likely cause: Standard-length HSS bits flex under high feed rates and lack a split point, causing walking and breakage.
• Corrective action: Switch to 1/8" Cobalt M42 stubby drill bits. Their short length adds rigidity, and the 135° split point keeps the bit centered. Check that the shank fits your machine's collet before ordering.
• Stop or choose another option: If you're drilling shallow holes in soft materials like wood or plastic, standard HSS bits are sufficient and more economical. For deep holes, consider a longer bit or a peck drilling cycle.

Product facts

• 1/8" Stubby Cobalt M42 Drill Bits Stub Drill Length Machine Screw 10 Pcs Drill Hog®: Drill Hog's 1/8" Cobalt M42 Stubby Drill Bits are made from premium solid cobalt M42 steel and feature a 135° split point. The solid cobalt construction withstands high heat, and the split point prevents walking, so you get accurate holes and longer bit life in screw machines.