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Twist Drill Bit

Twist Drill Bit Buying Guide

Twist drills (also commonly referred to as twist bits) are the most widely used of all drill bit types; they will cut anything from wood and plastic to steel and concrete. They are most frequently used for metal cutting, so they are generally made from M2 high-speed steel. At diameters up to about 1/2", twist drills are not only the cheapest of all bits a woodworker could use, they offer the widest selection of sizes. Although they are designed for cutting metal, they will work quite well in wood, if sharp. This generally means that they have not been used to cut hard materials such as steel.

  • Twist drill bits can be used on light metal, wood, plastic, metal, ceramic and masonry.
  • Useful for home repairs, maintenance and building projects with metal, wood or ceramics.
  • General-purpose rotary drilling; most common drill bits for home use.

Costing and Types

  • Titanium: High speed steel bits which have been coated with titanium nitride. This special coating gives the bits a very high surface hardness to help penetrate tough materials, makes the bits highly corrosion resistant and significantly reduces friction between bit and workpiece. Titanium coated bits last up to 6X longer than standard high speed steel bits.
  • Cobalt: Cobalt bits are a special formulation of high speed steel with cobalt added in to withstand very high drilling temperatures. Cobalt bits are specifically designed for drilling very hard, abrasive materials such as treated stainless steel, titanium and cast iron. Cobalt bits are not designed for general purpose use.
  • Black Oxide: High speed steel bits with an added heat treatment that reduces friction between bit and workpiece. Black oxide bits have 50% longer life than standard high speed steel bits.
  • Gold Oxide: Offers added speed and durability for general purpose drilling applications in wood, metal and plastic and drills 3x faster with speed helix.
  • High Speed Steel (HSS): Standard general purpose bits with a polished finish with silver appearance.

Tips for Twist Drill Bit Maintenance:

Most drill bit sets are sold in a case with space to hold each bit in place. This keeps the drill bits from being nicked or scratched and also provides excellent organization. Each spot is marked for the bit's size and type, making it easy to quickly find the right bit for the project you are completing. If your set didn't come with a case or you've been buying individual drill bits, add a storage box with dividers to your tool set. Don't store more than two bits together and use a permanent marker to mark each space with the size and type of drill bit stored there.

  • Let the drill bit cool off after you have finished your project.
  • Wipe the drill and drill bit with a clean, dry towel or cleaning cloth.
  • Use a clean, dry toothbrush to brush off any shavings or other debris that may cling to the tool.
  • Apply machine oil lightly with a paper towel or microfiber cloth. Let it sit for a few minutes, then wipe up any excess oil with a new paper towel.
  • Inspect drill bits for any extensive damage and remove damaged drill bits from the set so they can be replaced.
  • Place drill bits back into their case and store in a cool, dry place.

What Bit Sizes Do You Need?

For simple projects, you don’t need a lot of drill bit sizes. Drill bit with an extensive set cost a lot of money.

Unless you’ll end up using them, there’s no need to waste your money. If you do different projects that vary, you will need bits of various sizes.

If you have been in shopping for a drill, you will notice the manufacturer use the term “jobber” offers.  Well, it implies the bits have a particular flute length.

  • Flute- the spiral part
  • Jobber- a drill bit with a flute length of between 9 to 14 times.

For most home projects, twist or Countersink Drill Bits are usually the most useful types of drill bits. You can always add other sizes and specialty drill bits as you need them as well. Choosing the correct drill bit size may seem like a challenge at first, but it gets easier the more you use your drill.