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Aluminum and brass are soft enough to drill quickly, but that does not make every bit set suitable. A dull edge can push the workpiece around, grab as it breaks through, or leave a ragged hole. For clean results, look for sharp, conventional twist drills in useful sizes, and match the set to the holes you actually make. Coatings and large bit counts matter less than geometry, sharpness, and secure workholding.
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What to look for in a set
High-speed steel (HSS) bits are the practical choice for most home and shop drilling in aluminum and brass. They are affordable, widely available, and easy to replace. A well-made HSS bit drills these materials without needing the extra heat resistance of cobalt or carbide. Cobalt bits cost more and are useful if you also drill stainless steel regularly, but they are not an automatic upgrade for soft nonferrous metals.
Choose a set with standard 118-degree points unless you have a specific reason to prefer another geometry. A sharper split point can start more reliably in steel, but it is not a substitute for a center punch or careful layout. For larger holes, a shorter bit is often easier to control and less likely to wander than a long bit of the same diameter.
Check the range and increments before buying. A fractional set covering 1/16 to 1/2 inch is useful for general work, while a metric set with 1 mm increments suits parts specified in metric sizes. If you frequently need close-fitting holes for pins or fasteners, a set with finer increments or individual bits may be more useful than a large assortment with gaps.
How the common set types compare
| Set type | Best for | Trade-off |
|---|---|---|
| HSS fractional or metric set | General drilling and low-cost replacement | May lack fine size increments |
| HSS set with a broad size range | One kit for varied repair and fabrication jobs | More pieces do not guarantee better edges or organization |
| Cobalt HSS set | Shops that also drill tougher steels | Higher price brings little benefit for aluminum and brass alone |
| Individual short or stub-length bits | Accurate starts and better control in a drill press | Must be selected and stored by size |
For most users, a reputable HSS fractional drill bit set is the sensible starting point. A cheaper set is fine for occasional holes in thin sheet or hobby projects if the bits arrive sharp, sizes are clearly marked, and replacements are easy to find. Skip sets that advertise an unusually high piece count but provide few commonly used sizes.
Aluminum and brass need different attention
Aluminum can form long, sticky chips that pack into the flutes. If the bit rubs instead of cutting, heat and built-up material can dull the edge or mar the hole. Use a steady feed, withdraw the bit periodically on deeper holes to clear chips, and apply a small amount of cutting fluid made for nonferrous metals. For a shallow hole in thin stock, lubrication may be unnecessary; keep the bit sharp and avoid lingering in the cut.
Brass is more prone to grabbing, especially when a bit’s cutting edge is aggressive or the work is thin. This can pull the drill into the material at breakthrough. Clamp the work firmly, support thin sheet with a wood backer, and ease off the feed as the point exits. A drill press gives better control, but a cordless drill works for ordinary holes if the work cannot spin or lift.
Do not hold small stock by hand. Even a modest cordless drill can rotate a piece violently when a bit catches. Secure it in a vise or clamp, keep the part close to the support, and wear eye protection. Avoid loose gloves near a rotating bit.
A reliable drilling routine
Mark the location, then use a center punch lightly to keep the bit from skating. On thin sheet, a punch can distort the material, so use a backing board and a gentle mark. Start with a smaller pilot hole when the final diameter is large—roughly 1/8 inch for a hole around 1/2 inch is a useful starting point, though the right pilot depends on the material thickness and the bit.
Set the drill to low gear for larger bits and maintain enough pressure for the edges to cut. Excessive speed can overheat the bit; too little feed can make it rub. There is no single speed for every alloy, bit, and machine, so begin conservatively and check the chips. Clean chips indicate cutting; squealing, smoke, or a polished hole wall suggests rubbing or a dull edge. Stop, clear the flutes, and reduce speed or replace the bit.
For holes larger than about 3/8 inch, a drill press is easier to control than a handheld drill. A step drill can be convenient for thin sheet, especially when several diameters are needed, but it is not the best choice for a precise hole in thick stock. A stub-length HSS bit set can be a better buy when accuracy and reduced flex matter more than having every length.
What to buy for your work
For occasional repairs, a basic HSS set with the sizes you use most often is enough. Buy a better-organized set or replace frequently used sizes individually if the cheap bits lose their edge quickly. If you drill aluminum or brass every week, prioritize sharp, consistent bits and a case that keeps sizes identifiable; a mixed set of random coatings is not a meaningful advantage.
Choose cobalt only if your work also includes frequent drilling in harder steels. Choose a drill press or a clamping setup before spending extra on exotic bit material: in soft metals, poor workholding and a rushed breakthrough cause more bad holes than a lack of premium coating. A clean hole starts with a sharp bit, a stable part, and a controlled feed.