How to Select the Proper Drill Bit Tool

Important Note: This write up covers only the very basic details concerning the subject. Please contact us for more detailed information, especially if it concerns your production, or other high volume drilling needs.

Metal drill tooling, often called “drill bits” are the most common you will encounter when searching for drilling tools – we will just call them drill bits from here forward since that seems to be the acceptable term for most.

The design of a drill bit for metal drilling depends on various factors such as:

  • The material you need to drill a hole in
  • The volume of drilled holes
  • The speed in which you must drill the hole
  • How deep the hole is or how thick the material is
  • What direction you will be drilling in (horizontal, vertical, some combination of both, etc.)
  • The finish you want to create, such as a screw head either exposed or hidden beneath the surface

Choosing the right drill bit becomes easy once you are experienced at drilling a wide range of materials. We hope that this basic write-up will help you to set up a very efficient and profitable scenario for your business.


Check that the drill bit is the proper type for the job. AutoDrill suggests talking to your tooling supplier to choose the right drill bit type. Here are some very basic guidelines…

  1. Standard steel drill bits are good for most simple drilling jobs such as most plastics, most woods, aluminum, brass, bronze, cast iron, etc.
    HSS or High Speed Steel drill bits are good for some of the more difficult applications where you are drilling structural steel, slightly hardened steel, stainless steel, etc.
  2. Cobalt, TiN coated or even carbide or diamond drill bits are sometimes needed for materials such as tool steel, stainless steel, stone or ceramics, or even woods such as ipe that have silica nodules within the material, etc.
  3. High helix drills can be useful when drilling deep holes where removal of the chips or debris can be difficult.
  4. Reduced tip or pilot drills are useful when drilling into surfaces that are rounded or when you need the drill to stay “on target” better. This also helps when you have less than adequate horse power on your drilling machine.
  5. Split point drill bits are useful for rounded surfaces, drilling at a slight angle, etc. They start much more easily than a standard web tip drill and lower the thrust required to start and maintain a drilling process.
  6. End mill-type drills are used when you can not use a drill bit with a tapered tip.
  7. A spur-point bit is useful for most jobs around the home, its design ensuring a straight hole.
  8. A tile bit, as the name suggests, is best for drilling ceramics.
  9. A flat wood bit creates a large hole, but requires a powerful drill.
  10. Masonry bits are suitable for drilling through stone.

Pick a size of drill bit. This obviously depends on your job and desired hole size when you are done. Drill bits are still measured in fractions of an inch for most of the USA although metric sized tooling has become much more common. Typically, they come in 1/32″ increments although tooling can be acquired in 0.001″ increments or smaller when necessary. The four most common drill size options are:

  1. Fractional (Generally starting at 1/64″)
  2. Metric (Generally starting at 1mm)
  3. Number drills (1 to 60 typically but others do exist)
  4. Letter drills (A to Z)

Select the design of drill bit that will work best for your specific application. We strongly suggest speaking to a tooling expert if this choice is difficult to make or the application is critical.

If drilling into wood or any material where a common fastener will be used, decide if you want the fastener head exposed above the surface of the material. If you want it recessed or hidden (on a wooden cabinet, for example) select a step drill bit or one with a countersink or counter bore attachment / provision. The drill bit widens the hole at the end so the fastener’s head is hidden below the surface a bit.

BONUS SUGGESTION #1: If you are looking to drill a very large number of holes in a manufacturing or production drilling environment, we suggest you experiment with different drill bits from different suppliers during your initial set-up process. Determine which create the highest quality hole, last the longest, throw the chips or curl best for your fixture, provide optimal drilling stability, etc. Using the right drill bit for the right material is always important.

BONUS SUGGESTION #2: If you are about to purchase a production drilling machine for an application, keep in mind that they are often highly efficient versions of manual drilling machines. You can often test your process on a drill press or a Bridgeport type milling machine before spending your hard earned cash on a selffeeder unit.

Please CONTACT US to discuss your application and receive prompt product cost, literature and technical help.

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