The best drill bits for aluminum depend on the hole size, the thickness of the workpiece and the other materials you drill. Our shortlist is the DEWALT DWA1184 for a general-purpose twist-bit set, IRWIN Unibit 10231 for several hole sizes in thin aluminum, and Bosch CO14B for a workshop that also drills tougher metals. Pick the bit shape and actual sizes you need before choosing a coating or a larger set.
These are feature-based buying recommendations, not results from hands-on testing. We checked manufacturer information and the exact linked packages. We do not rank cutting speed, hole finish or service life, and we do not assume that a higher price or a cobalt label guarantees a better result in your particular aluminum alloy.
Quick comparison
| Product and exact package | Best fit | Size coverage | Main limitation |
|---|---|---|---|
| DEWALT DWA1184, one 14-bit HSS set | General workshop and mixed-material tasks | Selected fractional sizes from 1/16 to 1/2 inch; two 1/8-inch bits | 13 distinct diameters, with gaps between some larger sizes |
| IRWIN Unibit 10231, one HSS step bit | Making different-size holes in thin aluminum | 13 diameters, 1/8 to 1/2 inch in 1/32-inch steps | Thin material only; check the usable step depth |
| Bosch CO14B, one 14-bit M42 cobalt set with case | Aluminum plus stainless-steel and other metal projects | Selected sizes from 1/16 to 1/2 inch; two 1/8-inch bits | Same 13 distinct diameters as the DEWALT set |
1. DEWALT DWA1184: a practical general-purpose starter set
The DWA1184 is a sensible starting point when your aluminum project is part of broader work with wood, plastic and metal. DEWALT specifies high-speed-steel construction and a 135-degree split point. Our recommendation for routine aluminum work is an application of that general metal-drilling design, rather than an aluminum-specific performance claim. For a specified alloy or demanding production job, get cutting recommendations for that material and setup.
The manufacturer lists 14 bits covering 13 diameters: 1/16, 5/64, 3/32, 7/64, 1/8, 9/64, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8 and 1/2 inch. The extra bit is another 1/8-inch. This is useful everyday coverage, but the larger diameters are not a complete consecutive series. Check a project’s required hole or tap-drill size against the actual list.
Pros: Broad everyday size coverage, a spare 1/8-inch bit and a split-point design intended to reduce walking. Cons: No metric, numbered or lettered sizes, and the manufacturer’s application description is general metal drilling rather than a specific aluminum-alloy recommendation. Do not buy it expecting 14 different diameters.
Use it with a suitable drill chuck and within your drill’s capacity. DEWALT classifies the set as standard, so an impact driver should not be assumed compatible. The selected retailer description limits the three-flat shank feature to sizes larger than 3/16 inch; do not expect the smallest bits to have the same shank shape.
DEWALT DWA1184 14-piece HSS drill bit set
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2. IRWIN Unibit 10231: best for multiple hole sizes in thin sheet
Choose the IRWIN Unibit #1, model 10231, for thin aluminum panels when you want several diameters from one tool. IRWIN explicitly lists thin aluminum among its applications. This is one high-speed-steel bit, not a 13-piece set: its stepped cutting profile covers 1/8 to 1/2 inch in 1/32-inch increments. The linked listing specifies a 1/4-inch shank.
A stepped design lets you enlarge a hole through successive sizes without swapping twist bits at each increment. The single flute and etched size markings help you identify the required step. Stop at the intended diameter: continuing farther can engage the next step and enlarge the opening. Practice on a clamped offcut of the same material before drilling the finished panel.
Pros: One tool covers 13 diameters, the sizes are marked on the flute, and the manufacturer names aluminum as an intended thin-material application. Cons: It tops out at 1/2 inch and is unsuitable as a general replacement for a twist drill through thick stock. The material must fit within the usable cutting depth of the selected step if you want a consistent diameter.
Buy the 10231 HSS #1 configuration shown here. Similar Unibit names can refer to different size ranges, coatings and materials. The linked package contains one bit. Neither a multiple-pack nor a different Unibit number should be assumed to provide the same steps.
3. Bosch CO14B: best for a mixed-metal workshop
The Bosch CO14B makes the most sense when aluminum is only part of your metalworking. Bosch lists its M42 cobalt family for aluminum as well as stainless steel, cast iron, titanium and light-gauge metal. The alloy contains 8% cobalt. That broader material brief is the reason to consider it; we would not pay extra solely on the assumption that cobalt must drill aluminum better.
Choose CO14B, the 14-bit M42 set with a case. Bosch’s exact contents list covers the same 13 fractional diameters listed for the DEWALT set, including a duplicate 1/8-inch bit. The 21-piece version and the similarly named CO14 are separate configurations. Bosch specifies three-flat shanks on bits 3/16 inch and larger.
Pros: An explicitly documented aluminum application, coverage for other demanding metals and a case for organizing the 14 bits. Cons: It does not add missing diameters compared with the DEWALT set, and its mixed-metal strengths may be unnecessary if you only need one aluminum hole size. Check the price difference against the work you actually do.
How to choose drill bits for aluminum
Match the bit shape to the material thickness
For thin sheet, a step bit is worth considering when its diameter range and step depth fit the work. For a deeper hole of one constant diameter, choose an appropriate twist bit and check its usable flute length. IRWIN’s 10231 application guidance is specifically for thin materials; it is not a thickness rating for every aluminum plate.
Buy the required diameters, not the largest piece count
The two 14-bit sets here each provide 13 distinct diameters. If you drill the same size repeatedly, compare the cost of replacing that individual bit with buying a complete set. For tapped holes, use the specified drill diameter for the thread and application. Neither a nearby fractional size nor a large piece count automatically meets that requirement.
Check the chuck and the tool’s limits
Match the shank to the chuck, and check your drill’s permitted hole capacity for metal. Do not assume an ordinary drill bit is impact-rated. CCOHS advises choosing a bit appropriate to the material, work and drill capacity, with the bit properly seated and tightened. Those checks matter more than whether the tool and bit share a brand.
Plan cutting fluid and chip removal
Use a cutting fluid suitable for aluminum and follow its instructions along with the drill and bit guidance. BLACK+DECKER’s lubrication chart lists cutting fluid for aluminum. On a drill press, CCOHS advises lubricating when drilling metal and clearing deep holes frequently. Stop the machine before removing accumulated chips; use a brush or another suitable tool rather than your fingers.
A safer drilling setup
Follow the powered hand-drill guidance and, if applicable, the drill-press precautions. In particular:
- Clamp the work securely. Never hold a small piece in one hand while drilling with the other; the stock can twist or spin.
- Wear suitable safety glasses or goggles. Remove the chuck key and disconnect power before changing or adjusting bits.
- At a drill press, keep guards in place, tie back long hair and keep loose clothing away. Do not wear gloves, rings, watches or bracelets near its rotating parts.
- Use the speed recommended for the bit, material and hole size. Do not force the cut; reduce feed pressure as the bit breaks through. Stop if a bit jams instead of repeatedly cycling the trigger.
Frequently asked questions
Do I need cobalt drill bits for aluminum?
Cobalt is not the first decision to make. Check the bit’s material application, size, geometry and your drilling setup. The Bosch M42 set explicitly includes aluminum in its intended applications; its broader mixed-metal role is our reason to recommend it. A cobalt label alone does not demonstrate a better result than a suitable HSS bit.
Is a step bit better than a twist bit?
For several diameters in thin sheet, the Unibit’s stepped design is convenient. For a deeper, constant-diameter hole, an appropriate twist drill is the more relevant tool. A step bit’s maximum hole diameter does not tell you the thickness of material it can drill at that diameter.
What RPM should I use?
There is no single RPM for every bit diameter and aluminum workpiece. Use the bit and tool manufacturer’s guidance for the material and operation, and stay within the drill’s capacity. An unexplained fixed speed from a generic shopping list is not a substitute for that information.
Does a 14-piece set contain 14 different sizes?
Not in these two sets. Both the DEWALT DWA1184 and Bosch CO14B contain two 1/8-inch bits, giving 13 distinct diameters across 14 bits. The IRWIN 10231 is the reverse kind of count: one bit produces 13 stepped diameters.
Should I drill a pilot hole first?
CCOHS recommends a small pilot hole before large holes with a hand drill. Follow the selected bit’s instructions for your operation: the Unibit is described as self-starting and its successive steps enlarge the hole. Do not treat either approach as a universal rule for every tool, material thickness or hole size.
Which should you buy?
Choose the DEWALT DWA1184 for a general-purpose set when its size list matches your workshop jobs. Choose the IRWIN 10231 for different hole sizes in thin aluminum. Choose the Bosch CO14B when you want an aluminum-capable set that also targets tougher metals. If a project specifies an exact diameter, alloy or tolerance, make that requirement the deciding factor.
