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A high-quality drill bit set is defined by four things you can check before buying: the steel grade (M2 high-speed steel at minimum, M35 cobalt for hard metals), a precision-ground rather than roll-forged flute, a 135-degree split-point tip, and consistent sizing in a sensible range. Coatings and piece counts get the marketing space, but steel and grinding decide how long a bit lasts and how accurately it cuts.
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What we cover
Steel Grade: The Foundation of Quality
“High speed drill bit set” is a common search, and it refers to HSS, high-speed steel. HSS keeps its hardness at the temperatures generated by drilling, which carbon steel cannot. But HSS is a family, not a single material.
| Material | Typical alloy content | Relative hardness at heat | Best use | Typical 29-piece set price |
|---|---|---|---|---|
| Carbon steel / unmarked “HSS” | Low or unspecified | Low | Softwood, plastic, occasional use | $10-$25 |
| M2 HSS | About 6% tungsten, 5% molybdenum | Good | Wood, mild steel, aluminum, general use | $30-$70 |
| M35 cobalt (HSS-Co5) | M2 plus about 5% cobalt | Very good | Stainless, hard steels, heavy use | $60-$150 |
| M42 cobalt (HSS-Co8) | About 8% cobalt | Excellent | Production metalwork, tough alloys | $120-$250+ |
| Solid carbide | Tungsten carbide | Highest, but brittle | Machines and drill presses, not hand drills | Usually bought individually |
Cobalt bits are an alloy through their full body, so resharpening does not remove the benefit. That is the key difference from coated bits, covered below.
Grinding: Fully Ground vs Roll-Forged
Cheap bits are usually roll-forged: the flutes are hot-pressed into shape, then the tip is ground. They tend to be black and slightly rough. Better bits are fully ground from hardened stock, giving sharper cutting lips, more accurate diameters and better concentricity. In practice, a fully ground bit drills a rounder, closer-to-size hole and wanders less.
How to tell at a glance
- Fully ground bits often have a bright or uniform finish along the flutes, sometimes with a brown steam-oxide or gold tint.
- Many European makers mark bits to the DIN 338 standard, which specifies dimensions for jobber-length twist drills.
- Look for a ground clearance behind the cutting edge; roll-forged tips often show a rougher, less precise grind.
Tip Geometry: 118 vs 135 Degrees
A 118-degree point is the traditional general-purpose angle, suited to softer materials, and is easy to resharpen. A 135-degree split point is flatter and has a split web that starts cutting immediately without walking, which matters with a handheld drill on metal. For a mixed-use set, 135-degree split point is the better default.
Coatings: What They Do and Do Not Do
| Finish | What it adds | Limitation |
|---|---|---|
| Black oxide | Mild corrosion resistance, reduced friction | Little hardness gain |
| Bright finish | Clean, uncoated cutting edge | Can rust if stored damp |
| Titanium nitride (TiN, gold) | Hard surface, less heat and friction | Lost from the tip after resharpening |
| Steam oxide / bronze | Common on cobalt; corrosion resistance | Cosmetic beyond that |
| Black-and-gold | Oxide body with ground tip | Depends on underlying steel |
A TiN coating on poor steel is still poor steel. Judge the base material first.
Sizes and Set Composition
The classic quality set is the 29-piece fractional index from 1/16 inch to 1/2 inch in 1/64-inch steps. It covers tap drill sizes, clearance holes and almost every common job. Metric sets typically run 1 to 13 mm in 0.5 mm steps (25 pieces). Big “200-piece” kits often pad the count with duplicates of small sizes and driver bits.
- Reduced-shank bits: sizes above 3/8 inch on 3/8-inch shanks fit smaller chucks but reduce stiffness.
- Three-flat shanks: prevent slipping in keyless chucks.
- Hex shanks: fit impact drivers and quick-change holders, but add a little runout.
- Index case: a labeled metal or rigid case keeps bits sorted and stops edges chipping against each other.
Brands Known for Quality Sets
Across the market, recognized names for good twist-drill sets include Drill America and Norseman in the US, Chicago-Latrobe and Triumph for machine-shop grade bits, Guhring, Ruko and Dormer from Europe, and the professional lines from Bosch, DeWalt, Milwaukee and Irwin. Within each brand there are tiers; look for the cobalt or fully ground version rather than assuming the name alone guarantees quality.
Choose by Your Work
| You mostly drill | Recommended set |
|---|---|
| Wood and plastic, occasional metal | M2 HSS, 29-piece, 135-degree split point |
| Mild steel, aluminum, automotive | M2 or M35 fully ground, 29-piece index |
| Stainless and hard alloys | M35 or M42 cobalt with cutting fluid |
| Furniture making, fine woodwork | Separate brad-point set alongside HSS |
| Impact driver use | Impact-rated hex-shank set, then HSS set for precision |
Red Flags in Low-Quality Sets
- No steel grade stated anywhere, just “HSS” or “titanium” on the packaging.
- Very high piece counts at very low prices, padded with screwdriver bits and duplicate small sizes.
- Visible burrs, uneven cutting lips or off-center points when you look straight at the tip.
- Soft plastic cases with loose slots that let bits rattle together.
- Bits that wobble visibly when spun in a well-tightened chuck, a sign of bent or poorly ground shanks.
Making a Good Set Last
- Match speed to size and material: large bits and hard metals need lower RPM; a 1/2-inch bit in steel runs at a few hundred RPM, while a 1/8-inch bit can run much faster.
- Use cutting fluid on metal: it reduces heat, the main killer of edges.
- Clear chips: peck drill deeper holes to avoid packing the flutes.
- Do not overheat: blue-tinted tips mean the temper is gone; regrind past the damaged section.
- Resharpen: quality HSS and cobalt bits are worth resharpening; cheap bits often are not.
Bottom Line
A high-quality drill bit set is M2 HSS or better, fully ground, with a 135-degree split point and a sensible 1/64-inch progression in a protective index. Spend on steel and grinding before coatings or piece count, and add a cobalt set only if you regularly drill stainless or hard steel.