Metal Working

Best Drill Bit Set for Home Use

A Complete Guide to Help You Select the Best Drill Bit Set for Use Around Your Home!

Home ownership requires ongoing maintenance and the necessity for drilling various size holes is a task frequently encountered. Additionally, projects such as building a set of bookshelves or even hanging a picture usually requires the use of some type of drill bit. Consequently there are almost endless applications for a set of drill bits around the house. That’s why it makes sense to have the best drill bit set for home use available to meet any challenge that presents itself.

Unfortunately, choosing the best set for use around the house can be downright confusing, even for an experienced do-it-yourselfer. There are so many different types of drill bit sets available with unfamiliar, technical-sounding names. To make the task more confusing, certainhome project drilling hole through plywood sets contain shiny black bits while others have attractive gold-colored ones. This raises the obvious question “is one color drill bit actually better than the other?”

Another important consideration when choosing a drill bit set is the type of material the drill bits are made from. Some drill bit sets are constructed from high carbon steel while others are made from high speed steel (HSS). You don’t need to be a metallurgist but it’s helpful to understand the difference.

The purpose of this article is to help you sort through the most important information so you can make the right choice. Drawing on my years of experience as a precision machinist and avid do-it-yourselfer I’ll point you toward the drill bit sets that work best around the house.

What is the Best Drill Bit Set for Home Use?


Small Projects and Occasional Use

A set of drill bits for use around the house are typically only used occasionally for projects such as assembling a piece of furniture or installing a light fixture.  Or, for building that set of book shelves you have been putting off.  For that type of use a small set of drill bits will do the job.  They need to be suited for drilling thin metal and soft materials such as wood and plastic.  Bits made from High Carbon Steel work just fine for those applications.

Large Home Projects and Extensive Use

Perhaps you are planning more extensive projects such as building a deck or maybe even that bonus room you  promised your spouse a few years ago.  Projects that size involve drilling hundreds of holes of various sizes in wood and sometimes metal.  For that kind of use the drill bits need to be stronger and made from HSS (High Speed Steel) for greater wear resistance.
SEE: What is the Best Material for Drill Bits?

No. of Bits & Series
Made from
Recommend Use
Complete Info
DEWALT Titanium Drill Bit Set, 21-Piece (DW1342)
#1 DEWALT (DW1342)
21-Piece FractionalHigh Carbon Steel, TiN CoatedGeneral purpose occasional drilling of sheet metal, aluminum, brass, copper, wood, plastic, and compositesRead More
Bosch 91-Piece Drilling and Driving Mixed Set MS4091
#2 Bosch (MS4091)
91-Piece Mixed w/ Driving bitsHigh Carbon, Chrome and TiN CoatedGeneral purpose occasional drilling of sheet metal, aluminum, brass, copper, wood, plastic, composites, and masonryRead More
Bosch TI21A Titanium Drill Bit Set (21 Piece)
#3 Bosch (TI21A)
21-Piece FractionalHigh Carbon Steel, TiN CoatedGeneral purpose occasional drilling of sheet metal, aluminum, brass, copper, wood, plastic, and compositesRead More
Hitachi 728173 14-Piece Titanium Drill Bit Set
#4 Hitachi (728173)
14-Piece FractionalHigh Carbon Steel, TiN CoatedGeneral household drilling of sheet metal, soft metals, composites, plastics, and woodRead More
Drill America 15 Piece Heavy Duty HSS Drill Bit Set
#5 Drill America (KFD Series)
15-Piece Fractional High Speed Steel (HSS), TiN and Black Oxide CoatedExtensive, heavy use on low and high carbon steel, sheet metal, composites, plastics, and woodRead More
Drill America 115 Piece HSS Black and Gold Finish Drill Bit Set
#6 Drill America (115 COMBO)
115-Piece Fractional, Wire Gauge, and LetterHigh Speed Steel (HSS), TiN and Black Oxide CoatedExtensive general purpose drilling of low and high carbon steel, sheet metal, non-ferrous metals, and soft materialsRead More



#1   DEWALT Titanium Drill Bit Set, 21-Piece (DW1342)


DEWALT Titanium Drill Bit Set, 21-Piece (DW1342)

  • Series: Fractional
  • Type: Twist Drill
  • Sizes: 1/16″ to 1/2″
  • Material: High Carbon Steel
  • Coating: TiN (Titanium Nitride)
  • Recommended for: metal, wood, and plastics
  • Special Features: No-Spin Shanks
  • Case: Yes, plastic

DEWALT is a highly recognized name when it comes to quality tools used by both tradesman and for around the house DIY tasks.

The DEWALT Titanium 21-Piece Drill Bit Set, (DW1342) consists of bits made from high carbon tool steel, coated with TiN (Titanium Nitride) which enables it to cut through most metal objects found around the house.

This set has a good range of bits that should allow the user to take on any drilling challenge. An important feature is the No-Spin Shanks on the larger sizes. This feature amounts to (3) flats on the shank of the larger size bits that allow the chuck jaws to grip without slipping.


  • TiN coated for longer life
  • Wide range of sizes
  • No-Spin shanks prevent slipping


  • No cons
check price of DEWALT Titanium Drill Bit Set, 21-Piece (DW1342) at amazon



#2   Bosch 91-Piece Drilling and Driving Mixed Set MS4091


Bosch 91-Piece Drilling and Driving Mixed Set MS4091

  • Series: Fractional
  • Type: Twist, Pilot Point, Masonry
  • Sizes: (30) Titanium Coated Twist Drills: (2) 1/16″, 7/64″, (2) 1/8″, 9/64″, (2) 5/32″, (2) 3/16″, 1/4″; (8) Pilot Point Drill Bits: (1) 1/8”, (2) 3/16”, (2) ¼”, (2) 5/16”, (1) 3/8”; (11) Masonry Bits: (2) 1/8″, (2) 5/32″, (2) 3/16″, (2) 1/4″, (2) 5/16″, 3/8″
  • Material: High Carbon Steel
  • Coating: TiN and Non coated
  • Recommended for: Metal, wood, plastic, masonry
  • Special Features: (34) 1″ Insert screw bits, PH: (2) 0, (2) 1, (2) 2, (2) 3 PZ: (2) 0, (2) 1, (2) 2, (2) 3 SL: 3; (2) 5,7 T: (2) 10, (2) 15, (2) 20, (2) 25, 30, 40 H: 3, (2) 5, and 6; (15) 2″ Insert screw bits, PH: 0, 1, 2, 3 PZ: 0, 1, 2, 3 SL: 6, T: 10, 15, 20, 25 H: 5 and 6; (8) Nut Setters: 3/16″, (2) 1/4″, 9/32″, 5/16″, 11/32″, 3/8″, 7/16″, (1) Countersink, (1) Bit holder, (1) Ratchet screwdriver, (1) 25 1/2″ Magnetic extension pen
  • Case: Plastic w/ tilt out indexes

The Bosch 91-Piece Drilling and Driving Mixed Set MS4091 is ideal for the person who is confident to take on any DIY challenge around the house that involves drilling holes.

BOSCH is a familiar brand name to those of us who frequent the big box stores.  They are known for producing quality power tools and other products for the do-it-yourself-er and tradesman.

Not only does the Bosch MS4091 set contain a huge assortment of drills, it also has just about all the driving bits you will ever need for your domestic projects. Also included is a Ratchet Screwdriver and a Magnetic Extension Pen.

The Pilot Point bits are excellent for drilling wood because they won’t walk on you and they are easy to start.  Another benefit of Pilot Point drill bits is they tend to make a cleaner exit hole when they cut through the opposite side of the wood piece.  This is a common problem with conventional point twist drills that tend to splinter the wood when exiting.

With the Bosch 91-Piece Drilling and Driving Mixed Set MS4091 you will be able to drill most household metal items, wood, sheet rock, plastic, acrylics, plastics, composites, and masonry.  The only thing this set is missing is a good quality cordless drill.    Also available in 65, 41, and 34 Piece sets.


  • Wide variety of drill bits
  • Includes driver bits
  • Budget priced
  • TiN Coating increases life


  • Limited number of drill sizes
check price of Bosch 91-Piece Drilling and Driving Mixed Set MS4091 at amazon



#3   Bosch TI21A Titanium Home Drill Set (21 Piece)


Bosch TI21A Titanium Drill Bit Set (21 Piece)

  • Series: Fractional
  • Type: Twist, Split-Point
  • Sizes: (2) 1/16″, (2) 5/64″, (1) 3/32″, (1) 7/64″, (2) 1/8″, (1) 9/64″, (1) 5/32″, (1) 11/64″, (2) 3/16″, (1) 13/64″, (1) 7/32″, (1) 15/64″, (2) 1/4″, (1) 5/16″, (1) 3/8″, (1) 1/2″
  • Material: High Carbon Tool Steel
  • Coating: TiN (titanium nitride)
  • Recommended for: General purpose drilling of steel, sheet metal, wood, and plastics
  • Special Features: No-Walk Split Point and No-Slip flats
  • Case: Yes, plastic

The Bosch TI21A Titanium Home Drill Set (21 Piece) is an excellent choice for home use or for professional use with certain limitations.  The TiN coating enables these bits withstand the wear and tear of drilling mild steel and softer metals.

One of the features I really like is the Split-Point which eliminates skating and cuts easier than standard bits. Another important feature is the three-flat shank design on the 3/16″ and larger bits that prevents the drill bit from slipping in the chuck.

I recommend this set for general applications around the house and for service use. Its a good set to keep in your service vehicle tool box for those occasional on-the-job drilling tasks.


  • Good size range
  • TiN Coating increases life
  • No-Slop Flats prevent slipping in chuck
  • Split-Point eliminates skating


  • Plastic case is subject to breakage
check price of Bosch TI21A Titanium Home Drill Set (21 Piece) at amazon



#4   Hitachi 728173 14-Piece Titanium Drill Set


Hitachi 728173 14-Piece Titanium Drill Bit Set

  • Series: Fractional
  • Type: Twist, w/ Split-Point
  • Sizes: (2)ea. 1/16″, (1) ea. 5/65″, 3/32″, 7/64″, 1/8″, 9/64″, 5/32″, 3/16″, 7/32″, 1/4″, 5/16″, and 3/8″
  • Material: High Carbon Steel
  • Coating: TiN (Titanium Nitride)
  • Recommended for: General household drilling of steel, sheet metal, composites, plastics, and wood
  • Special Features: 3-Flat No Spin Shank 7/32″ and up
  • Case:Yes, plastic

I have always had good service with Hitachi tools. The Hitachi 728173 14-Piece Titanium Drill Set is a good option for home use or for occasional service applications.

One of features I like is the Split-Point which makes it easier to start the drill in hard materials such as steel. It also cuts faster and eliminates Skating. The other feature that makes this set a good choice is the No-Slip flats on the shank of the 7/32″ and larger bits.  These flats allow the chuck jaws to grip the bit securely to keep it from slipping.

An extra 1/16″ bit is included to give you a second chance if you break the first one. The removable indexes provide easy access to the plastic case.

Keep this set in your kitchen drawer for those small home projects that come up or toss it in your tool box at work.


  • Good size range
  • Split-Point for easy starting
  • No-Slip flats prevent slipping
  • TiN Coating for longer life


  • Smallest bits are easy to break
check price of Hitachi 728173 14-Piece Titanium Drill Set at amazon



#5   Drill America 15 Piece Heavy Duty HSS Drill Set


Drill America 15 Piece Heavy Duty HSS Drill Bit Set

  • Series: Fractional
  • Type: Mechanic’s Length w/ Split-Point
  • Sizes: 1/16″ to 1/2″ by 1/32 Increments
  • Material: M2 premium grade HSS (high speed steel)
  • Coating: TiN and Black Oxide
  • Recommended for: Mild to high carbon steels, stainless, cast iron, laminates, plastics, and wood
  • Case: Metal

This Drill America 15 Piece Heavy Duty HSS Drill Set is one of the best for use at home or at work. The HSS construction will withstand the high heat generated when drilling steel and gritty materials like stainless or cast iron.

For drilling the types of metal around the house these bits will last for many years. They work just as well on plastics, composites, and wood.

A Split-Point enables the bits to start easily without center punching first and will cut faster with less heat build up.

TiN coating on the flights and Black Oxide finish on the flutes add to the cutting performance.

The bits in this set will stay sharp for large projects such as building a deck or bonus room.

Although the metal case isn’t pretty, it is functional.

One of the best features of this drill bit set is the price which is roughly the amount you would pay for a set made from High Carbon Steel that won’t last as long.

This set of drills is good enough for machine shop use as well as small to large projects around the house.


  • HSS construction for drilling steel
  • Split-Point for easy starting & feeding
  • TiN + Black Oxide for better performance


  • Case can come open
check price of Drill America 15 Piece Heavy Duty HSS Drill Set at amazon



#6   Drill America 115 Piece HSS Black and Gold Finish Drill Bit Set


Drill America 115 Piece HSS Black and Gold Finish Drill Bit Set

  • Series: Number (wire gauge), Fractional, and Letter
  • Type Bits: Jobber Length, Twist
  • Sizes: 1-#60, 1/16” – ½”, A-Z
  • Material: HSS (High Speed Steel)
  • Coating: Black and Gold Finish
  • Recommended for: General Purpose use on metals and soft materials
  • Special Features: 135° Split-Point
  • Case: Metal

Drill America is a USA-based importer of drills and other  tools.  This 115 Piece set is ideal for the well-equipped home workshop where all types of DIY projects are done.

Each bit is made from high quality high speed steel (HSS) that can drill metals including low and high carbon steels, aluminum, brass, copper.  These bits can be used for drill plastics and wood.

If you have the occasion to tap holes, this set as all the bit sizes to accommodate up to 1/2″ threaded holes.  These bits are excellent for use in a drill press as well as a cordless drill.  Or, they can also be used in an auto repair garage, fab shop, general maintenance, or small machine shop.

Don’t let the low price deceive you, these are good quality bits that are much better than what you will find at your local “big box” store or H. Freight outlet.  The metal case is decent but there are customer complaints of the tilt-out indexes coming loose in shipping and spilling bits in box.  Keep in mind, this set is approximately HALF the price you would pay for a Contractor Grade set, but with similar quality.

Also Available in Individual:  Number, Fractional, and Letter series sets.


  • Includes all Size Series
  • Premium HSS construction
  • Split-Point eliminates skating


  • Low quality case

check price of Drill America 115 Piece HSS Black and Gold Finish Drill Bit Set at amazon


Also SEE:  Best HSS Drill Bit Set for Professional Use


drill bit geometry and terminology

The Anatomy of a Twist Drill

It’s easy for me to forget that to most people who don’t drill holes on an almost daily basis like I do, drill bits pretty much all look the same.

But the truth is that there’s a whole lot of different factors that determine how efficient a drill bit performs in a certain type of material.   The geometry, material, hardness, and coating all are important factors to consider when selecting a set of drills.

And since there are so many different types of materials we like to drill holes in there are different types of drill bits that are designed to work best in those different materials and for different applications.


The most obvious feature of a drill bit is the Twist or Helix.  This twist serves two important purposes.  It conveys the chips up and out of the hole as the bit turns.  The twist also determines the Rake Angle at the point of the bit.

A bit with only one or two complete “twists” over the flute length is said to have a Fast Twist.  It moves the chips along the flutes a greater distance with each revolution.  A drill bit with a Fast Twist forms only a slightly positive Rake Angle at the cutting lip which works better for harder materials including ferrous metals.

A bit with several complete “twists” is said to have a Slow Twist.  A slow twist moves chips along the flutes at a slower rate as the drill turns and it forms a more positive Rake Angle at the cutting lip which works best on softer materials including aluminum, plastic, and wood.

Rake Angle:

The rake angle is the angle as it relates to the material as the drill bit turns.   A Neutral rake angle would be like holding the blade of a shovel vertical and pushing it across the ground.  That would produce a scraping effect.  It would plow up some dirt and push it along.  A Positive rake angle would be like holding a shovel blade at an angle with the handle tilted toward you and pushing it along.  It would bite in to the dirt, scooping it and digging down into the dirt.

A Practical Compromise!

So its plain to see from this example that there needs to be a compromise when it comes to the rake angle of a drill bit.  Too much rake and the drill lip digs into the material causing the drill to jam.  Too little rake and it just scrapes the material and creates a lot of heat from the friction.

The optimum rake angle will allow the sharp lip of the bit to dig in to the material just enough to get under the surface without jamming the drill.

From decades of experience and testing the SAE (Society of Automotive Engineers) has determined that a Rake Angle of 30° enables the best drilling performance in most metals including low and high carbon steel, aluminum, and brass.

Drill Point Angle:

drill point anglesThe Drill Point Angle is another important factor to consider when selecting the best drill bit for a particular job.

Harder materials drill more efficiently with a shallow angle approximately 135° while softer materials favor a sharper angle.

Most drill bits for metal working or general purpose are ground to 118° which is an excellent compromise.

Although a 90° is the optimum angle for drilling wood or plastic, there are specialized drill bits that utilize specialized geometry especially for those materials.

For the vast majority of drilling applications a Drill Point Angle of 115° to 118° will deliver excellent performance in a wide variety of materials.

Standard Point VS Split Point:

Drill bits are generally considered to be the fastest tool to use to remove the most amount of metal in the shortest period of time.  While that is probably true, a drill bit is also a highly inefficient tool and here is the reason why:

Most of us understand that as a shaft or drill bit turns at a particular rpm (revolutions per minute) the SFPM (surface feet per minute) increases the further out from the center.  The opposite is also true that the closersplit point drill bit vs common drill bit to the center the slower the SFPM.

Theory vs Reality

So theoretically the exact center of a spinning drill is static or not moving.  In reality we know that isn’t actually the case but what it does mean is that a drill bit when its adjusted to the optimum speed (SFPM) its only the outermost area of the cutting lip that is cutting efficiently.

Getting Negative!

And, to make matters worse, when the end of a drill bit is ground to the correct shape to create the point and relief angles it also creates a negative rake angle at the web of the bit.  This negative rake angle scrapes the metal creating a lot of friction and heat which eventually breaks down the point.

This negative rake angle at the drill bit Web can cause the bit to “walk off center,” especially if it is fed too aggressively.  This is common when drilling steel or when drilling softer materials.

An Effective Solution!

Tool designers have effectively dealt with this issue by creating what is called a “Split Point.”  By machining a neutral cutting edge into the web the chisel point is eliminated, turning it into a cutting surface instead.

This added feature dramatically increases the cutting performance at the web and greatly reduces the tendency to “walk off center” plus it also cuts faster.  A split point has the most advantage when drilling steel.

Standard point drill bits work well for most applications where maximum efficiency isn’t an issue.  They are easier to re-sharpen that bits with split points.  Most sets come with standard points bits but the slightly higher price for a split point is worth the difference

Drill bits with split points are the best choice for machinists and toolmakers or other tradesman where maximum efficiency is important.  The only unfavorable aspect is they are more difficult to re-sharpen.

What is the Best Material for Drill Bits?

High Carbon Steel:

High Carbon Steel when properly heat treated is capable of drilling through low carbon or mild steel.  Most bits intended for use around the home or occasional use are made from high carbon steel.  For that purpose they work just fine.  They will easily drill through most any common metal item found around the house.  They work just fine for softer materials including aluminum, copper, brass, composites, sheet rock, and wood.  These cutting tools cannot withstand sustained cutting of steel because of their limited heat and wear resistance.

The better products will have a TiN (titanium Nitride) coating which greatly increases the hardness and wear resistance.

High Speed Steel:

The majority of twist drill bits are made from a HSS (high speed steel) alloy.  This is the ideal alloy for the most common powered cutting tools.  HSS withstands heat up to 2000° f without the cutting edges breaking down.  HSS  is also very wear resistant and has good tensile strength.

Drill bits made from HSS are well suited for drilling annealed low carbon steel, most annealed high carbon steel alloys, stainless, cast iron, aluminum, brass, copper as well as most soft materials including wood and plastic.

HSS is the best all-around material for drills that are intended for commercial use including metal machining, construction, auto repair, mill wright, rigging, HVAC, and maintenance.


A Cobalt Alloy is another alloy that drill bits are made from.  These bits are usually referred to as Cobalt drill bits although only 5% to 8% of the element is actually used in the alloy.

Cobalt Drill bits are often designated as M35 for the 5% grade and M42 for the 8% grade.  By adding Cobalt to the alloy it increases the strength of the drill bit as well as increasing the heat resistance.  This makes Cobalt drill bits well suited for drilling tough materials such as tool steel and stainless steel.

Cobalt bits are an excellent choice for drilling for production machining of annealed high carbon steels or for drilling through tough car frames.  These bits also work well on mild steel and soft materials but the additional cost won’t yield significant benefits for those application.  Sets are available with drills made from Cobalt.

Tungsten Carbide:

Tungsten carbide is an extremely dense material with unique characteristics that make it desirable for certain tools and machining applications.  Carbide is much harder than HSS at 68-71 HRC compared to 60 Rc.  It is highly wear and heat resistant which enables a carbide bit to drill the toughest materials such as masonry and heat-treated tool steels.

Full Body Carbide Bits are typically used in machine shops for machining tough or hard materials.   These bits are very brittle and prone to breakage, especially if fed too aggressively.  They are also very expensive and are usually only used for special applications.

Masonry Carbide Bits have a piece of carbide silver soldered on the lip of a steel fluted shaft and are typically used  for drilling masonry.  They are available in sets.

Spade Carbide Bits have a pointed carbide blade silver soldered in the center of a steel shaft.  They are typically used for drilling ceramic or porcelain tile and glass and can also be purchased in sets.

Indexable Carbide Insert Drill Bits are made up of a precisely machined steel shank with removable carbide inserts that fit into the cutting area.  Indexable carbide bits have helped revolutionized the machining industry because of their efficiency.  When the cutting edge becomes dull the insert is easily replaced (indexed) without tearing down a machining set up.  Indexable carbide drill bits are not typically available in sets.  They can be purchased from industrial supply companies such as McMaster-Carr .

Finishes and Coatings

A spinning drill bit creates a lot of friction so the surface finish of the tool is an important factor to consider.  HSS is a dense alloy and the machining processes used to produce drills bits usually leave a smooth finish.  A smoother finish is preferable because it reduces the friction as the chips move along the surfaces.

Most materials used to manufacture drills contain iron which is prone to rusting and corrosion so a protective coating is desirable.

Black Oxide:

Black Oxide is a chemical conversion coating that once absorbed into the micro pores of the drill bit it improves its resistance to rust and gives it a deep black appearance.

In addition to protecting the metal, it also enhances wear resistance and reduces chip welding and galling.  Perhaps the greatest benefit is it increases the ability of the bit to retain lubrication which is a critical benefit when drilling.

Titanium Nitride (TiN):

Since industrial grade bits are ground to shape the finish is good as is.  But to improve the frictional coefficient coatings such as Titanium Nitride (TiN) are applied.  This high tech metal finish dramatically increases the hardness of a HSS bit from 60 Rc to 80 Rc. which enables it to cut harder materials without damaging the cutting edges.

Although HSS has a relatively low iron content it is still susceptible to rusting and corrosion; TiN coating protects it.

Never Judge a Drill  by It’s Color!

A superficial benefit of TiN coating is the attractive Gold color which implies added value.  It does add value to a cutting tool but it is also used by some unscrupulous manufactures to dress up a cheep set of drill bits made from inferior materials.  So just because the product you are looking at might look pretty doesn’t mean it is good quality.

Another issue with TiN is that when the cutting edge of a drill bit does finally break down and has to be sharpened the benefits of the TiN coating is lost.  But, in my opinion a drill bit set with TiN coating is worth the small additional cost.

Understanding Drill Size Series!

Brief History

Just to make things more confusing in the early 20th century the SAE (Society of Automotive Engineers) established three different series of drill bit sizes – Number (Wire Gauge), Fractional, and Letter.

In the late 1960’s there was pressure for the US to adapt a “simpler” decimal-based system based on the meter and kilogram which was developed by France in 1799.  This system, based on powers of 10, added to the confusion of the existing screw thread systems.

Industry Resistance

There was a lot of resistance by manufactures to embrace the Metric System for multiple reasons:  The enormous cost associated with re-vamping established industries with familiar standardized parts based on the old system.  Replacing or retrofitting expensive machinery was a huge deterrent.  The prospect of retraining engineers, toolmakers, and machinist to think in terms of Metric values was a serious concern. And, the considerable expense of a tradesman having to replace their expensive measuring tools all added to the resistance.

The Metric System is now arguably the dominant measuring system, even though it has never been fully embraced in the US.  The metric measuring system does offer many advantages, but the old SAE systems are still used extensively in certain industries.

Number or Wire Gauge Series:

Number drill bits range in size from from size #80, the smallest @ 0.0135″ or 0.3429 mm to size #1, the largest @ 0.228″ or 5.791 mm.  A drill bit set of Number drills is a good choice if most of the holes you intend to drill are relatively small.  You will also need number drill sizes for tapping holes ranging in size from #4 to #12.

If you are a toolmaker/machinist, auto repair mechanic, auto restorer, mill wright, metal fabricator, maintenance person, or HVAC technician you need a set of Number Series drill bits.  A Hobbyist will also find number size drill set to be very handy to have around.

Fractional Series:

Fractional drill sizes that are commonly available in drill sets ranging in size from 1/16″ up to 1/2″.  A Fractional Series drill set is ideal for general applications around the house, garage, or shop.  There are enough different sizes to take care of most hole-drilling tasks you will typically encounter.

If you are a trades-person associated with machining, maintenance, auto repair, metal fabrication, mill wright, or commercial HVAC you need a set of fractional series drill bits.

Letter Series:

The Letter Series was developed to fill the gap between fractional drill sizes.  Drill bits in the Letter Series range from “A” @ .234″ to “Z” @ .413″.  These bits are most commonly used for drilling holes for tapping or for drilling hole sizes in between fractional increments.

A Letter Series drill bit set is necessary investment if you are a machinist, toolmaker, auto mechanic, mill wright, maintenance person, metal fabricator, or commercial HVAC technician.

Metric Series:

There tends to be more options with Metric Series drill sets.  Set sizes typically available range from 1 mm up to 10 mm in one milometer increments.  Some sets are also available ranging ranging in sizes from 1 mm up to 6.0 mm in .1 mm increments.

A Metric drill bit set can also be used to fill the gaps found in the Number, Fractional, and Letter series sizes.  These bits are a necessary tool for auto mechanics, machinists/toolmakers, mill wrights, HVAC, maintenance, and metal fabricators.

Silver and Deming:

Silver and Deming is a style of drill bit characterized by a straight shank that is smaller than the diameter of the bit. Typically Silver and Deming drill bits are 6 inches long with ½” diameter shanks. Some bits have straight shanks and some have 3 flats to eliminate slipping in the chuck.

Silver and Deming bits were developed to fill the demand for bits larger than ½” that can be used in drill presses that typically have chucks that will only accommodate up to ½” diameter.

Silver and Deming drill bits range in sizes from 33/64” diameter up to 1 ½” diameter. Most Silver and Deming Drill Sets come with bits from ½” up to 1” diameter.

Length Designations

Twist drill are made in a variety of Length designations.

  • Jobber Length:  These bits offer a compromise between short and long and have enough length and rigidity for the majority of applications.  The majority of drill bit sets come in Jobber Length.
  • Short Length:  Also known as “Stub Length,” these bits provide the maximum rigidity to prevent the drill from flexing and can be used in some machining applications to start the hole without spotting it first.
  • Extended Length:  These long drill bits feature flutes almost the full length and are used for drill deep holes or holes in difficult to reach areas.  Light feeding pressure is necessary to prevent from flexing.

Drill bits are also available in other lengths and styles but are used primarily for special applications encountered in machine shops or manufacturing venues.