A Drill Bit Rundown

Posted by Tomboy Supply on

An essential for every tool box - Drill bits are designed for specific tasks and come in an assortment of coatings and materials. They are also made in many different types of shapes and sizes. Do your drill justice by having the proper drill bits for the job! 

Here at Tomboy, we have made an overview of these types.


Always make sure the drill bits you are using are compatible with the drill you are using.

Drill bit sizing is based on by their diameter. (for example 1/16-inch to ¼-inch). The shank is the end of the drill bit that is secured into the chuck of the drill. There are round and square chucks – square is more secure whereas round is easier to center.  When choosing a drill - consider the tool and work piece material, drill style, performance level, and the drill point angle.

Kinds of Drill Bits

Cobalt Drill Bits – Use for soft metals. Resist high temperatures and abrasion.

Wood Drill Bits – Have a pointed tip called a Brad point and W point to make a cleaner hole that doesn’t snag.

Auger Drill Bits – Use for hard wood, the spiral removes chip debris as you drill. The pointed tip minimizes need for pushing.

Reduced Shank Drill Bits – Used for wood, plastics, and metals. Makes a larger hole with a common chuck.

An example of a Reduced Shank Drill: Drillco 1000EF164

Masonry Drill Bits – Use for stone, concrete and brick. Has a carbide tip.

Step Drill Bit – Use for any surface that is not too thick. Good for thin and soft materials.

An example of a step drill bit: Dewalt DWA1790IR

Spade Drill Bits – Used for making large holes in wood.

An example of spade drill bits: Irwin 88894 13 Piece Speedbor Spade Bit Set

Spear Point Drill Bits – Used for porcelain, glass, and ceramic. Diamond carbide tip


Tile Drill Bit – Made specifically to not create cracks or chips in tile.


Other hole making tools include Hole Saws and Annular cutters.


Drill Bit Material

Carb, Carbide – for hard and brittle work. Requires higher quality equipment. Not recommended for use in drill presses or hand drills. For the most demanding and hardest materials, the carbide is recommended.

HSS, High Speed Steel – for fiberglass, PVC, wood and as well as soft steels. Most practical for basic work.

HSCO, Cobalt – High speed steel with 5-8% cobalt added. This is an upgrade from the high speed steel and is used for drilling into harder steel and stainless steel.

Carbide Tipped – masonry, tile and concrete. Maintain sharpness over extended periods of use.

Drill Point Lengths

A shorter drill bit is preferred – it has less chances of breaking and is more precise. They also help for more confined spaces.  

Stub Length – Lessens deflection and breakage and gives most accuracy. For hand and machine drilling.

Jobbers Length – Most common and used for heavy duty or general drilling.

Taper Length – Longer then the Jobbers length, best used for deep holes.


Drill Point Angles 

Affect tool performance. Flatter have better tool performance and the less flat they are then you will have more torque.

118° (standard) - The most common and best for soft metals.

135° (Self-Centering) – good for hardened materials such as stainless steel. This angle is flatter than the 118°


Flute Design

The flutes are grooves formed in the body of the bit to make the cutting edge at the point. They also assist in the removal of chip debris and help fluid reach the cutting edges. Drill bits can have 0 flutes to 4 flutes.

Standard Flute – Most common with 30° angles

Parabolic – used for deep hole drilling. Good for soft materials like aluminum and plastics.



Surface treatments offer better tool performance and lengthen tool life.

Bright – Untreated and used for general purpose drilling. Used for most woods, plastics and metals.

Black Oxide – an inexpensive black coating. Provides heat resistance and lubricity, as well as corrosion resistance. Not for nonferrous metals. An example of one of our products would be Dewalt DWA1185.

Black and Bronze Oxide Coated – Decreases friction and tolerates higher speeds. 

TiN – Long life Titanium Nitride. Bright gold. Run faster then uncoated drills.

TiCN – Extra life Titanium Carbonitride.  Blue-gray. Good for aluminum, stainless steel and cast iron. Wear resistant.

TiALN – Titanium Aluminum Nitride. Violet. Use with high-alloy steels. Titanium and Nickel based materials.

Tomboy sells many drills for a specific need. If your looking to do some basic work, Norseman has you covered. We also sell a variety of Hole saws and Annular cutters. We also sell hundreds of Kreg products that offer simple solutions for wood joinery as well.

Drill bit types, makes, models, sizes and functions are seemingly never-ending. Manufacturers have made drills for every occasion and this article is a very basic and common list of examples. Feel free to send questions our way and we will gladly help you out with the best tool for your job!