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All about Drills

Mechanical Skills: Chapter 6

Introduction to Drills

After this module you will be able to:

- Explain what a drill is,

- Identify the parts on a drill, and

- Use a drill safely Skip to quiz!


A drill is a power tool designed to quickly screw or unscrew fasteners. Drills can also be used to make a hole in some materials.

A drill has several parts:

  • The bit,

  • The chuck,

  • The handle,

  • The trigger,

  • The forward/reverse switch, and

  • The battery

The bit is a thin piece of metal that extends out from the drill. The bit can look like a screwdriver head when you are loosening or tightening screws. Bits can also look like long spiral pieces of metal if you are drilling holes through objects.

The chuck is just behind the drill bit. The chuck holds the bit in place. You can rotate the chuck to secure or loosen bits. Inside of the chuck are three jaws which grip the drill bit. When we tighten or loosen the chuck, we are moving the jaws within the chuck.

The handle is where we hold the drill. The handle will run across your palm, and in between your thumb and pointer finger. The trigger is in front of the handle. Pressing the trigger will cause the bit to start rotating.

There is a switch above the trigger that determines the direction of the drill bit. The switch determines if the bit rotates clockwise for tightening a screw or counterclockwise for loosening a screw.

On most drills, the battery sits at the bottom of the drill handle. The battery provides power to the drill. The battery on a drill is rechargeable.

Drill Bits

Recall that drills have a bit that can cut through various types of material.

There are several types of drill bits including:

  • Wood bits, and

  • Sheet metal bits

It is important to use the correct bit for the material you are drilling. You can break drill bits by using the wrong bit for the job. If a bit breaks the metal shatters and flies at high speeds. Breaking a bit can be dangerous. Always use the correct bit for the material.

The first type of bit we will cover is a wood drill bit. Wood drill bits have flat metal sides that help the bit cut into wood.

There are two types of wood drill bits:

  • Brad point bits, and

  • Spade bits

Brad point bits are used to drill small holes. Spade bits are used to drill large holes.

The brad point bit has smooth sides and a smaller diameter than a spade bit. The smooth sides help the bit easily enter and exit material.

Spade bits are used for drilling larger holes. The design of spade bits lets the bit carve out large amount of material as the bit rotates into the wood.

Sheet metal drill bits are a type of brad point bit. Sheet metal bits have sharp, spiraling, metal sides that help cut through hard metals. The spiral sides help remove the drilled metal as the bit drills deeper into the material.

The thickness of a drill bit can also vary from 1/16th of an inch to inches. The thickness of the bit determines the size of the hole you will make.

When you are drilling a large hole, you must gradually increase the size of the bit. Start by making a hole with a smaller bit. Replace the small bit with a larger one. Repeat the process. Starting with a large bit can break the bit.

The bits we have covered so far are used to drill holes into material. There are also bits used to tighten or loosen fasteners. For example, some bits can loosen or tighten fasteners like nuts, screws, or bolts.

Nut drivers are another type of bit that can be inserted into drills. The nut driver looks similar to the socket on a socket wrench. Nut drivers allow you to quickly loosen or tighten hex head bolts or nuts.

There are also drill bits for all common type of screw heads. You can find bits with heads that should be used on:

  • Philips screws,

  • Slotted screws,

  • Torx screws, and

  • All other common types of screws

Drill Safety

Make sure to wear proper PPE when using a drill. This includes:

  • Safety glasses or face shield

  • Safety shoes

  • Protective gloves

While drilling, objects can fall or shatter. PPE reduces the chance you will be injured.

When using a drill make sure the vents on the drill are clear. This prevents the drill from overheating. Keep drill bits sharp. Sharp drill bits reduce the chance of a bit breaking. Keep all chords away from the cutting area. Chords can be easily tripped on.

Disconnect the power supply when changing bits. This reduces the chance of an accident. Secure the object being drilled to prevent movement while you are drilling.

Always know what object you are drilling into. Drilling through the incorrect material can damage the drill or bit. Look behind what you are drilling. If you drill through an object, you can damage what is behind it.

Drills provide a fast way to create holes and attach and remove fasteners. Being able to use a drill effectively makes completing a job much faster. Always wear proper PPE when handling a drill.


Cordless Drill

After this module you will be able to

- Identify a cordless drill, and

- Safely use a cordless drill Skip to quiz!

Cordless Drill

The most common type of drill is a cordless drill. A cordless drill is a drill that is powered by a battery. The drill does not need to be plugged into an outlet. Cordless drills are easy to move around, powerful, and avoid tripping hazards with chords.

Cordless drills can be used to quickly tighten or loosen screws, nuts, or bolts. Cordless drills can also be used to drill holes into material like wood.

Recall that a cordless drill has the following parts:

  • The bit,

  • The chuck,

  • The handle,

  • The trigger,

  • The forward/reverse switch, and

  • The battery

We covered how each of these parts work in the earlier slides.

Recall that the drill has a forward/reverse button. This button determines if the bit rotates clockwise or counterclockwise. To switch the direction, change the button to the second setting. Press the trigger to confirm the bit is rotating in the direction you want.

Depending on what we are using a drill for, we will need to change the drill bit. For example, if we are loosening a philips head screw then we need a philips head bit.

To remove the drill bit from the drill, we need to loosen the chuck. Recall, the chuck is the part of the drill that holds the bit in place.

To loosen the chuck, set the drill to rotate counter clockwise. Hold the chuck with your non dominant hand, and gently press the trigger. After a second, the drill bit will become loose and you can easily remove the bit from the chuck.

To secure a new drill bit, place the bit into the chuck. Set the drill bit to rotate clockwise. Make sure the drill bit is centered in the three jaws of the chuck.

With your non dominant hand, hold the drill bit inside the chuck. Gently hold the chuck. Keep your fingers away from the jaws of the chuck. While holding the bit and chuck, gently squeeze the trigger. The chuck will tighten around the bit.

Once the bit is tight in the chuck, make sure the the bit is centered in the three jaws. Pull the bit to ensure it has a good connection. You should not be able to move the bit out of the chuck.

Behind the chuck, drills will have a dial that determines the torque on the bit. If the drill does not have enough torque, then it will stop spinning before the hole is complete. If the drill has too much torque, you can drill a screw too deep into the material.

The drill will stop rotating when it experiences the torque you set it to. Setting the torque is helpful if you don’t want to over tighten a screw or bolt. To change the torque, rotate the dial shown in the picture. The higher the number, the more torque the drill generates.

You can also change the speed on a drill by changing the gear. You can change the gear by toggling the switch at the top of the drill. Most cordless drills will have three gear settings. The higher the gear, the faster the bit will rotate but the less torque you will have.

Gear one has the lowest speed and the highest torque. Gear one is great for drilling large holes. Gear one is also great for driving larger screws.

Gear two has medium speed and medium torque. Gear two is a great all around gear. It can be used for most applications.

Gear three has fast speed and low torque. Gear three is best used for drilling small holes. It is also good for drilling smaller screws.

Cordless drills rely on a rechargeable battery to power the drill. After you are done using the drill, you will place the battery into a charging station.

Remove the dead battery by pressing the release buttons on the side of the battery. Pull the battery out of the cordless drill. Insert the dead battery into the slot of the charger.

To start using a cordless drill, identify what bit type you need for the job. Confirm that the correct bit is in the chuck. Check that the bit is securely clamped.

Press the drill bit with a moderate amount of force into the material or screw. You want to press straight into the material or screw. You do not want to drill at an angle. Continue holding downward pressure on the drill and slowly squeeze the trigger.

Gradually pull the trigger back farther to increase the bit speed. You should see the bit or screw entering the material. Continue holding the trigger and pressing down. Release the trigger when you are done.

In this module, you learned how to:

  • Identify a cordless drill, and

  • Safely use a cordless drill

The cordless drill is versatile and mobile. For most job sites, a cordless drill will be your primary drill.


Other Types of Drills

After this module you will be able to:

- Identify types of drills, and

- Safely use each type of drill Skip to quiz!

Types of Drill

There are several types of drills including:

  • Cordless drills,

  • Impact drills, and

  • Hammer drills

Most drills function in a similar way, but impact and hammer drills have some additional features.

Impact Drill

An impact drill is a cordless drill that is used to drive large fasteners. Impact drills have much higher torque values than a standard cordless drills. An impact drill looks like a cordless drill, but it has no clutch. The nose of the drill is much shorter.

Impact drills are used to drive large fasteners that are above 3” long. An impact drill stores the rotational energy of the drill. It releases the energy twice per rotation onto the screw. This happens hundreds of times in a second.

The increased torque of an impact drill allows you to efficiently drill without stripping the fastener. Impact drills should not be used on tough material like concrete.

Recall that impact drills do not have a chuck. Instead of a chuck, you will find a collet. A collet is a mechanism on the end of a drill that secures the bit.

Pull on the collet to release the drills grip on the bit. Pull the bit out. To Insert a new drill bit, pull the collet out. Insert the drill bit into the collet and then release the collet.

Hammer Drill

A hammer drill is a more powerful cordless drill. Hammer drills are used when drilling through tough materials like concrete. The hammer drill connects to a wall outlet and has a second handle to provide additional control.

Hammer drills can create holes in very tough materials. The hammering mechanism slightly pushes the drill bit in and out of the chuck. The in and out motion of the bit creates an action as if the bit is hammering the material.

This hammering action is produced hundreds of times per second. These strong taps help the hammer drill break through concrete.

Like a cordless drill, a hammer drill has a chuck that holds the bit. Follow the same process as the cordless drill to add or remove bits from the chuck.

On a hammer drill, you will find a dial behind the torque dial. This dial has several symbols, one of them is a hammer. To use the hammer mechanism on the drill, you must set the dial to the hammer position.

To use a hammer drill, confirm that you are using the correct bit. Set the dial on the drill to the hammer setting. Place the drill bit on the part of the material where you wish to drill.

Press into the material with a moderate amount of force. Too much force can damage the bit. Slowly press the trigger while maintaining pressure into the material. Stop once you have drilled through the material.

In this module, you learned how to use an:

  • Impact drill, and

  • Hammer drill

Impact drills are used when you need more torque to turn a fastener. Hammer drills are used to drill through tough material like concrete.


Question #1: Which drill bits are used to drill large holes into wood?

  1. Brad point bits

  2. Spade bits

  3. Sheet metal bits

  4. Phillips bits

Scroll down for the answer...

Answer: Spade bits

Spade bits have wide blades to drill large holes into wood.

Question #2: Which is a good drill safety technique?

  1. Keeping electrical cords near the drilling area.

  2. Not securing the drilled material.

  3. Keeping the chuck key in the drill while drilling.

  4. Keeping the drill bits sharp.

Scroll down for the answer...

Answer: Keeping the drill bits sharp.

Having sharp drill bits prevents unneeded force which could cause injury.

Question #3: Before drilling, what should you do?

  1. Remove the drill bit.

  2. Flip the forward/reverse switch.

  3. Check what is behind what you are drilling.

  4. Remove the battery.Scroll down for the answer...

Answer: Check what is behind what you are drilling.

Always check behind what you are drilling so you don’t damage your drill. This also prevents damaging any material behind what you are drilling.

Question #4: What scenario would call for a cordless drill rather than a corded drill?

  1. You need more power

  2. You will be moving around a lot.

  3. You want to have enough electrical power to power your drill all day.

  4. You will be working in one small area.

Scroll down for the answer...

Answer: You will be moving around a lot.

Cordless drills allow you to drill in multiple areas without being slowed down by a power cable.

Question #5: What do you adjust to change the speed of the drill?

  1. Gear shift lever

  2. The clutch

  3. The forward/reverse switch

  4. The chuck

Scroll down for the answer...

Answer: Gear shift lever

The gear shift lever adjust the speed of the drill.

Question #6: Why would you use an impact drill over a regular drill?

  1. To drill through soft woods.

  2. To screw in 1” screws.

  3. To drill through concrete.

  4. To screw in 3” lag bolts.

Scroll down for the answer...

Answer: To screw in 3” lag bolts.

Impact drills are great for installing longer bolts that are over 3”. Impact drill should not be used on lighter jobs as they can be too much power for the job.

Question #7: When is the best time to use a hammer drill?

  1. To install multiple screws.

  2. To drill through soft woods.

  3. To drill through concrete.

  4. To screw in 3” lag bolts.

Scroll down for the answer...

Answer: To drill through concrete.

Hammer drills add a tapping force behind the drill bit that helps go through tough materials like concrete.

Question #8: How do you remove a drill bit on a cordless drill?

  1. Flip the forward/reverse switch.

  2. Cover the vents of the drill.

  3. Hold the chuck while it rotates counterclockwise.

  4. Flip the gear switch

Scroll down for the answer...

Answer: Hold the chuck while it rotates counterclockwise.

To remove a bit, turn the chuck counterclockwise to loosen the jaws of the drill. Turn the chuck clockwise to tighten the jaws of the drill back onto the bit.


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