Choosing a Drill Bit Set: Coatings, Split Points, and Size Coverage

A drill bit set is one of the first purchases a new crew makes and one of the last things anyone wants to think about. The difference between a well-chosen set and a cheap assortment shows up within the first few holes: bits that wander on slick metal, shanks that slip in the chuck, and sizes that skip the ones you need most. The deciding factors are easy to check on the package once you know what they mean.

Manufacturers sell dozens of sets with the same piece count at wildly different prices, and a few of those differences are marketing. The same sizing logic that applies to impact-rated bit systems applies to drill bits. This article walks through what the specs actually mean: coatings, point geometry, shank design, and size coverage, plus how the set fits into the cordless tool platform you already own.

Start With the Cordless Platform You Already Own

Drill bits do not exist in a vacuum. They spin in the chucks of cordless drills that belong to a larger system: batteries, chargers, and a family of tools that share them. Before you spend on bits, know what platform you are on and how the lineup compares, because the drill decides what the bits can do. A compact 12-volt drill drives small bits efficiently, while an 18 or 20-volt class drill has the torque for spade bits, hole saws, and large twist drills. Platform decisions extend beyond drills; the same battery system runs saws and outdoor equipment, and cordless chainsaw comparisons show how far a single platform stretches.

Match bit size to drill capacity

• Keyless chucks on most cordless drills grip 1/16 to 1/2 inch shanks.
• Bits larger than 5/8 inch usually need a chuck that opens wider, often on a corded drill.
• Quarter-inch hex shank bits fit impact drivers, which changes how you shop for sets.

One platform, one battery system

Sticking to a single battery platform means one charger, one set of spares, and one learning curve. That ecosystem argument is why crews compare whole lineups before switching brands, and why a bit set purchase usually follows the drill, not the other way around.

What a Quality Drill Bit Set Should Include

Look for three things on the package: the coating, the point geometry, and the size spread. Black oxide is the coating on most mid-priced sets. It is a surface conversion finish that adds corrosion resistance, wear resistance, and lubricity compared to bright or unfinished bits, which helps the bit cut longer and resist rust on humid job sites. Point geometry matters just as much: a 135-degree split point starts on hard, slippery surfaces without walking, while a standard 118-degree point drifts more on metal. Shank design matters because you will be changing a drill bit dozens of times a day, and bits with three flats on the shank grip the chuck better and resist spinning under load.

Coating options at a glance

• Bright or unfinished: cheapest, rusts fastest, fine for wood and occasional use.
• Black oxide: corrosion resistance and lubricity, the standard for general purpose sets.
• Titanium nitride: a harder gold-colored surface that stays sharp longer and costs more.
• Cobalt: the choice for stainless steel and hard alloys, with the best heat resistance.

The split point difference

A split point has a notched tip that creates its own starting divot, so the bit bites instead of skating across the surface. On a 135-degree grind the effect is strongest on hard, slippery materials like stainless trim and painted steel. For wood-only work a plain point is fine, but a mixed trade set should be split point across the board.

Size coverage decides whether the set is useful. A 14-piece set that runs from 1/16 to 3/8 inch covers most drilling, but two sets with the same piece count can cover different sizes. One popular configuration trades a 1/2 inch bit and a 5/64 inch bit for duplicate 3/16 and 1/4 inch bits, which pads the count without adding range. Duplicates help when you break the common sizes, but a set that skips 1/2 inch entirely forces a separate purchase later.

The table shows how two 14-piece sets differ. Set A covers 13 distinct sizes and includes the 1/2 inch bit that crews reach for constantly. Set B covers 12 sizes and adds spares in the middle. A 1/2 inch bit bought by itself can run $14 or more, so a set that omits it is not really a bargain at the same price.

How Voltage Ratings Shape Drilling Performance

Cordless drills are sold by voltage class, and the number on the box describes the work the bit can do as much as the drill itself. Twelve-volt drills are compact and fine for 1/4 inch and smaller bits. Eighteen and 20-volt class drills deliver the torque that spins larger bits, spade bits, and hole saws without stalling. The marketing voltage is not the whole story: battery chemistry and motor design matter as much as the label. The history behind cordless power tool voltage ratings explains why two drills with similar labels can feel so different.

Choosing bits for your drill’s power

• 12-volt class: 1/16 to 1/4 inch twist bits and small pilot holes.
• 18 and 20-volt class: the full range through 1/2 inch, plus spade bits and hole saws.
• SDS and rotary hammers: masonry bits, core bits, and concrete anchors.

Torque settings and bit protection

Run the clutch at a setting that matches the fastener and the material. Too much torque twists small bits and snaps them at the flute; too little stalls the cut. Newer drills pair torque settings with electronic braking that stops the chuck before the bit grabs and binds.

Recalls and Safety Notices: Check Before You Stock Up

Tools and accessories occasionally get pulled from shelves for defects, and the pattern is common enough that a quick check belongs in any large purchase. Power saws, chargers, and cutting accessories have all been subject to recall notices in recent years, sometimes for blade or guard failures that cause injury. Recent recall notices on sliding miter saws show how quickly a popular model can be flagged, and the same diligence applies to drill bits: a batch with bad heat treatment can snap in use, and a bent shank can damage a chuck.

Where to check

1. The manufacturer’s recall page for the brand you buy.
2. The consumer product safety agency database.
3. The retailer’s product page for safety notices.
4. The serial number lookup on the tool itself.

What a recall means for your purchase

A recall usually means the manufacturer offers a free repair or replacement, and the fix is worth taking even if the tool has worked fine. Registering a purchase makes it easier to receive notices. For accessories like bits, confirm the set you are buying is the current revision rather than old stock that sat in a warehouse.

Battery Power Is Moving Beyond the Drill

The cordless revolution that started with drills now reaches nearly every trade. The same batteries that spin a 1/2 inch bit now power saws, grinders, work lights, and increasingly heavy equipment. On concrete job sites, battery power and robotics are changing how crews mix, place, and finish material, cutting the cord on machines that used to need generators. The practical effect for a buyer is that accessory purchases now outnumber tool purchases on most sites. Every new battery tool adds a set of consumables, and planning the accessory budget around the platform keeps the drawer organized and the work moving.

What this means for your bit box

A bigger battery platform means more tools share your spares, and bit selection expands beyond twist drills. Impact drivers, oscillating tools, and rotary tools each take their own accessories, so the same buying discipline, coating, geometry, and size coverage, applies across the box.

Extending the Life of Your Drill Bits

A quality set lasts for years when bits are used and stored properly. Dull bits are the most common failure: a bit that no longer cuts cleanly burns wood, work-hardens metal, and chews up the drill’s torque. Purpose-built sharpeners make drill bit sharpening a five-minute job instead of a bench-grinder art form, and the skill pays for itself quickly on a busy site.

Five habits that protect bits

1. Use cutting fluid or wax on metal to reduce heat.
2. Drill pilot holes before stepping up to large diameters.
3. Ease off the pressure when the bit starts to bind.
4. Keep bits in the case instead of loose in a pouch.
5. Separate masonry bits from steel bits in storage.

When to sharpen and when to replace

Sharpen twist bits when the corners round or the cut starts to smoke. Replace bits that are bent, cracked, or worn past the flute. The same logic applies to the whole set: once the common sizes are gone or damaged, a fresh set at sale price beats a drawer full of survivors.