Tips for Picking Out the Drill Bit You Need
April 1, 2021
By Dan Gernes | Sales Development Manager - Metalworking & Safety
By Dan Gernes | Sales Development Manager - Metalworking & Safety
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Here’s a metric for you: cost per hole drilled. For work that requires lots of holes, it helps to know how to get the best cost per hole. Consider these areas while selecting a drill bit: geometry, material, and finish.
ANATOMY OF A DRILL BIT Understanding the distinguishing features of a drill bit is the first step toward identifying the proper products to use. A drill bit consists of four basic parts: the diameter, the shank, the flutes, and the point. 
DRILL BIT ANGLES EXPLAINED
The 118° point angle is a smaller point angle and is ideal for drilling softer materials such as aluminum alloys. However, the 118° point may walk, requiring a center punch to spot drill the hole. The blunt point angle of a 135° split point drill bit produces smaller chips and can be used for harder and stronger materials. A split point is used to keep the bit centered without a pilot hole, preventing the point from walking. 
DIFFERENT MATERIALS & USES
THE IMPORTANCE OF FINISHES
Finishes offer a layer of strength and protection to a drill bit’s surface. The two most common drill bit finishes Fastenal offers are black & gold and black oxide.
Know Your Options
SCREW MACHINE
Sometimes referred to as a “stubby,” the screw machine drill bit is most commonly used in machine drilling applications where a short reach is required or space is a concern. These bits can also be used to drill out spot welds in auto body applications. 
MECHANICS
Mostly used in hand-held drilling applications, it is usually only fluted about two-thirds to accommodate flats on the shank that prevent the drill bit from twisting in the chuck. Mechanics length drill bits are mostly used with air drills. LONGER SHANK 
JOBBER
Jobber drill bits are the most commonly sold and used drill bits because of their ability to be used for many applications. Compared to screw machine and mechanics bits, the jobber has longer flutes and a shorter shank for deeper drilling. LONGER FLUTES 
EXTRA LENGTH
Also known as a “longboy,” extra length bits are used for drilling longer, deeper holes that other drill bits can’t reach. These bits are most commonly supplied in 12" or 18" lengths and are used in machine drilling because lateral motion from hand drilling causes them to shatter and break. 
AIRCRAFT EXTENSION
Aircraft extension drill bits are used primarily for drilling in areas that are difficult to access. These bits have an extra long shank compared to the fluted length. Most aircraft extension drill bits are manufactured to aerospace specifications. These bits are available in 6" or 12" lengths. |
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Customer Story: Drilling through concrete is no easy task. E-Z Drill works to make it, well, easier. Since 1987, they’ve been finding ways to make the tasks of drilling and doweling simpler, safer, and faster. How impressed has the E-Z Drill team been with Fastenal’s service? Check it out here!
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