Every homeowner knows that there are tools you should always have in the toolbox. Power drills are one of such tools. As their name implies, power drills are power driven – it could be mechanical or electrical power.
For power drills, bits are what makes them click. Just like you can’t drive a car without keys, you can’t use a power drill without a drill bit.
There are various types of drill bits for different applications. In this article, we will let you know how the different types of drill bits suit different applications.
Drill bits are made of carbide or steel- different types of steels are used depending on the application. Drill bits are coated with black oxide, bronze oxide, or titanium nitride. The bits are coated to relieve stress and reduce corrosion caused by friction.
Drill bits are classified into twist drills, counterbore, countersink, flat bottom boring and specialty among others. We will describe these bits and their uses in the subsequent paragraph.
Table of Contents
The Ultimate Guide about Drill Bit Types
#1 Twist Drills
If you want a drill bit that serves all, you should go for twist drills. You will find these most common drill bit types. They are used to drill all types of materials. Twist drills come in various lengths, size and tip styles. The drill bits are usually made of steel or carbide tip and are coated with TiN, black oxide, bronze oxide or a mixture of both.
A twist drill’s length will tell you how rigid it is. The short ones are stronger and less likely to break than the long ones. Twist drills that find use in automated machines have a specified length. Other twist drill bit types are graduated in length and indicate different length ranges using different names:
- Jobber length for drills with flute length of 9-14 times the cutting diameter
- Mechanics length which is shorter than jobber drills
- Screw machine length which is the shortest drill bit type and is designed for screw machines
- Extra length drills which are fragile with flute length up to 18’’
- Aircraft extension drills which are similar in length to extra length drills but are stronger with shorter flute length
- Silver and Deming which are 6’’ long with 3-inch long flutes and a 0.5-inch diameter shank. These bits were originally designed for use in a drill press. They are used in other applications now.
Another feature of Twist Drills
The size of the twist drill is another feature that makes it different from the other bit types. You can find twist drills in a fractional inch, wire sizes, letter sizes, and metric decimal millimeters. You can use the common twist drills for common applications.
The twist drills for larger applications like automated machines are only available in fractional inch and metric decimal millimeters. The tip style for twist drill bits varies depending on the application. Some of the tips are V-point, conventional drill point, spill drill point, brad point, fishtail point, and tapered point.
#2 Counterbore Drill Bits
Counterbore drill bits are made for wood and plastics only. They are used to enlarge the top portion of an already existing hole. This forms a flat or angle bottomed cylindrical opening that allows the head of a screw to rest properly. Counterbore drill bit tips are made of cutting blades that may or may not contain spurs (teeth) on the outer diameter.
Spurs will allow for a fine finish and prevent chipping or splinting on the wood surface. The shank types available are the straight shank, fixed diameter shank, the threaded shank, and specialty shank for various uses. Counterbore drill bits are made of steel or carbide tipped and are usually coated with TiN.
#3 Countersink Drill Bits
Countersink drill bits are used to create a tapered surface hole at the top of a pilot hole. The sizes vary from 13.5mm, 165/8mm to 193/4mm. There are different styles of countersink bits that can drill for metal and wood. The cutting tip has two or more flat blades made at angles of 60 to 120 degrees.
Countersink Drill bits have different types of shanks available for use. Fixed diameter shanks, straight shanks, and specialty shanks among others are the shank types available. They are usually made of steel or carbide tipped and coated with the bronze oxide or Tin.
#4 Self Centering Bits
These drill bits are specially designed for drilling accurate pilot holes in hinges and other hard materials. The drill’s end sits in the countersunk hole of the material to be drilled and aligns automatically to the center of the hole.
Applied pressure will drive the bit in to give a perfectly centered hole. The self-centering bits can be identified by the screw size, which they are meant to drill.
#5 Masonry Drill Bits
These drilling bits are used specifically for building and repairs. They are used on hammer drills to drill holes in bricks and concrete walls. Masonry bits have a hexagonal shank to prevent the bits from sinking into the chuck and a carbide tip.
Masonry drill bits heat up quickly when being used. The heat produced can melt the tungsten brazing on the drill. However, you can reduce the heat by stopping regularly to clean the bit flutes.
#6 Flat Bottom Boring Bits
Flat bottom drill bits are similar to Counterbore bits only that they do not include a center drill. They are used for drilling blind holes in European style hinges.
The regular types are Common types of Flat Bottom Boring Bits include forstner Bits, three wing Drills, door hinge bits, mortising bits and spade bits. They have a fixed size hexagonal shank and they are made of steel and carbide tipped.
Drill bits are as important as they are powerful. You should treat them with care to ensure that they last longer and to prevent the frequency of home accidents.
The drill bit types are an inexhaustible number and we have only treated a small representative fraction of drill bits. This could help you out when you are in a fix. However, we recommend that you study further to get more in-depth knowledge about drill bit types.