What a bit set really is
A bit set is a group of bits stored in a case, often called an index. The appeal is convenience: a range of sizes in one place, each with a labeled slot. The risk is paying for pieces you never touch or accepting a case that falls apart. Looking at the contents and construction is more useful than looking at the piece count on the front of the box.
What is in a typical index
The most common general-purpose index holds twist bits in fractional sizes. One familiar layout runs from 1/16 inch to 1/2 inch in steps of 1/64 inch, which works out to 29 bits. Smaller sets skip sizes: for example, 1/16 to 1/4 inch in 1/16-inch steps holds just four bits. Metric sets generally step in 0.5 mm or 1 mm increments over a similar range.
Some sets mix categories:
- Wood sets with brad-point bits, sometimes with a countersink.
- Combination sets with twist bits, a few spade bits, masonry bits and driver bits.
- Masonry sets of carbide-tipped bits in a handful of common sizes.
- Metal sets of HSS, black oxide, titanium nitride or cobalt twist bits.
A set that mixes many kinds in a single case can be a decent starter, but each part is usually of ordinary quality. If you work mostly in one material, a set built for that material is typically the better buy.
Material and finish
Since most sets are inexpensive twist bits, check the base steel and any coating listed. High-speed steel is the usual standard for metal, while a bare carbon-steel set is aimed at wood. Coatings like black oxide or titanium nitride add some wear resistance. Cobalt sets are intended for hard metals and tend to cost more. The details of what each material suits are covered in the discussion of bit material.
The case matters more than it seems
A weak case is a daily annoyance and a hidden cost. When you look at a set, consider:
- Labeling. Are sizes stamped on the case, and can you read them? Sizes etched on the shank can wear off.
- Slot fit. Bits should drop in and stay in without rattling, with no loose bits sliding into others.
- Hinges and latches. Thin plastic hinges are often the first thing to fail.
- Layout. Bits in ascending order make it quick to find the one you want and to notice a missing one.
- Size and portability. A case that is too large or too fragile may stay on the shelf.
A case with metal or sturdy plastic and a clear index is more likely to survive years in a toolbox. Good storage also protects the cutting edges, which supports basic tool upkeep.
Shank types
The shank is the end that goes into the drill. It has to match your chuck.
- Round shank. The standard for twist bits, held by three-jaw chucks. Many tools handle them well, but they can slip under heavy load.
- Hex shank. Common on quick-change bits and driver bits, held by a hex-ready chuck or an impact driver. Make sure the bit is rated for the tool, since impact use is harder on a bit.
- Reduced shank. Large-diameter bits sometimes use a smaller shank so they fit a common chuck.
- SDS shanks. Used with rotary hammers and certain drills for masonry. They are a different system, and the options are covered in the guide to drill chucks.
Match the shank to the tool before you buy, and keep keyed or keyless chuck type in mind.
Which pieces get used most
In most sets, a few sizes are used far more than the rest. Small and medium bits, in the range used for pilot holes and common fasteners, tend to be worn down first. The largest sizes in a set may rarely leave the case. Other points:
- If you drill mostly for screws, the sizes around typical pilot and clearance holes matter most.
- Metal work consumes the small sizes quickly, so sharp replacements help.
- Masonry bits are often used only a few times a year, so a small set may be enough.
When a favorite bit breaks, replace that size individually rather than buying a second full set.
Practical buying advice
- Prefer a smaller set of decent bits to a huge set of poor ones.
- Check whether the set includes the materials you actually drill.
- Look for clear markings, sturdy hinges and a case that holds bits securely.
- Confirm the shank suits your drill or impact driver.
- Avoid assuming that a higher piece count means better value, since some counts include driver bits and accessories.
Wear safety glasses when drilling, and unplug the tool or remove the battery before changing a bit. Specifications vary by maker, so check the packaging and the tool’s manual for what is supported.