Drill Bit Sets for Metal: Cobalt, Titanium, and Point Angles Explained

A good drill bit set for metal uses high-speed steel, cobalt, or a hard coating, includes the sizes you actually use, and has a split-point tip that starts without wandering. Cobalt bits handle stainless and hard steel best, while coated HSS bits are a solid general-purpose choice.

Know Your Metal Before You Choose

The material you drill decides the bit. Mild steel, aluminum, and brass are forgiving, so standard high-speed steel (HSS) bits work well. Stainless steel, hardened alloys, and cast iron generate more heat and wear, so they call for cobalt bits or other premium alloys. Using a cheap bit on tough metal leads to a dull tip, burned edges, and a ruined bit in a few holes.

Thickness matters too. Thin sheet metal needs a different technique from thick plate, and step bits are often better for sheet. If you work mostly with thin sheet, a step bit complements a standard set.

Bit Materials and Coatings

• Plain HSS: inexpensive, fine for soft metals and light use.
• Black oxide: reduces friction and rust, a good budget upgrade.
• Titanium nitride (TiN) coating: adds surface hardness and extends life on steel.
• Cobalt (M35 or M42 alloys): holds an edge under heat, best for stainless and hard steel.
• Carbide-tipped: very hard, for specialized work, but brittle.

Keep in mind that coatings wear off after sharpening, but cobalt bits remain hard throughout. If you need to drill stainless regularly, a cobalt drill bit set for stainless steel is a sensible investment.

Tip Geometry: Point Angle and Split Point

The tip determines how the bit starts a hole. A 135-degree split-point tip is the common choice for metal because it self-centers without a center punch, reducing walking. A 118-degree point is the traditional general-purpose angle and works well in softer metals. Sharper angles cut aggressively in soft materials, while flatter ones resist wandering in hard material.

Look for precision-ground flutes and consistent diameters. Cheap sets often have uneven tips that drill off-center. Even with the best bit, mark the spot with a center punch to guide the start.

Set Contents and Sizing

Check that the case labels each size clearly and that the bits sit securely. A quality index case saves time and prevents damage. Pick a set that includes small sizes for pilot holes, since good metal drilling often starts with a small bit and steps up.

Technique: Speed, Pressure, and Lubricant

Slower speeds are better for metal. Large bits and hard materials need low RPM, while small bits can spin faster. Apply steady pressure and let the bit cut chips rather than rubbing. Smoking or blue chips are signs of too much speed or dull bits. Use cutting oil to reduce heat and extend bit life, especially on steel and stainless. A small bottle of cutting oil for drilling metal goes a long way.

Clamp the workpiece securely. A spinning metal piece can cause serious injury. Wear safety glasses and avoid loose clothing or gloves around the drill. Back the work with scrap wood when going through thin sheet to reduce burrs. Deburr holes afterward with a larger bit or deburring tool.

Sharpening and Care

Dull bits can be resharpened with a bit-sharpening jig or a bench grinder if you have the skill. Otherwise, replace them. Store bits in their case and keep them dry. Do not drop them on concrete, since the tips chip easily. Wipe off oil and chips after use, and check for wear before each project.

Think about the drill you will use. Cordless drills with a clutch can drive bits well, but hard metals benefit from a corded or high-torque drill with variable speed. A drill press gives more control, especially for precise holes and thicker plates. Match the shank type too: round shanks fit standard chucks, while hex or reduced-shank designs help with impact drivers, though impact drivers are generally not ideal for drilling hard metals unless the bits are specifically rated.

Budget wisely. A large set with many sizes may include bits you never use. Often, buying a quality set of common sizes plus individual replacements for the sizes you use most is cheaper over time. Keep cutting fluid, a center punch, a vise or clamps, and a deburring tool in the same drawer so the whole process stays tidy and repeatable. Pre-drilling pilot holes reduces the load on larger bits and improves accuracy. For deep holes, withdraw the bit periodically to clear chips and add oil. These small habits extend bit life more than any single feature of the set.

Finally, keep a few spare sizes of the bits you use most, such as 1/8, 3/16, and 1/4 inch. Small bits break easily when pressed too hard, and having replacements nearby keeps a project moving instead of sending you to the store midway through a job.

Frequently Asked Questions

Is cobalt worth the extra cost?

For stainless steel and hard alloys, yes. For mild steel and aluminum, coated HSS is usually enough.

Why does my bit walk across the metal?

The tip lacks a starting point. Use a center punch and a split-point bit, and start slowly.

Can I use wood bits in metal?

Not well. They are designed differently, dull quickly, and can bind in metal.