Click above to watch the video
If you’ve never picked up a drill in your entire life, the above video and this article will show you everything you need to know. If you’ve been using a drill for decades, and think you’ve got it all figured out, stick around, there’s probably still some things you don’t know.
Types of Drills
On a basic level, drill/drivers drill holes and drive screws – say that five times fast. Impact drivers focus on driving screws and do it better than a standard drill by using higher torque and a rotational strike which we’ll talk about a little later.
The hammer drill is a drill/driver does with an optional hammer feature that delivers a downward strike on the spindle. We’ll also get into that more a little later.
Parts of a Drill and Driver
The parts of the drill are pretty straight-forward and there are a couple of things that all of these have in common. The power trigger is located on the handle and variable speed, so it will choose a faster speed depending on how far you pull it back. It’s not fully analog – the speeds are enabled at certain points on the trigger.
The directional switch is directly above the trigger. Pushing in on the left side puts the drill in reverse and pushing in on the right puts it in forward. When the switch is in the middle it locks the trigger.
Most drill/drivers have multiple gears that are some variable of high speed/low torque and low speed/ high torque. Speed and torque have an inverse relationship, so increasing one must decrease the other.
We generally use lower speed/ higher torque to drive a screw and higher speed/lower torque to drill a hole. Slow down the speed to drill into harder surfaces like metal.
The gear selector on this drill/driver and hammer drill is right on top. This impact driver doesn’t have a gear selection feature, but some impacts have different modes that make certain situations easier. For example, it might have a speed that starts at a higher speed, but slows down once the screw is close to tight. Use that setting to drive self-drilling screws.
The speed is generally printed on the side of the tool in RPM (Revolutions Per Minute). Impact drivers and hammer drills also have IPM (Impacts per minute) or BPM (Blows per minute) printed along side RPM.
In first gear the hammer drill has a no load max RPM of 500. In the faster second gear the maximum is 1750 RPM. It delivers 29750 blows per minute when the hammer mode is engaged.
The impact driver has much more speed at a max of 2800 RPM. It also deliver much more torque when the 3200 rotational strikes per minute kick in.
The drills have a torque selection collar that sets the amount of torque allowed before the motor and spindle disengage. This will help you avoid driving your screws into oblivion and then stripping them out. “1” is the lowest amount of torque and 15 is the most, while still engaging the clutch. Turn the collar to the drill bit icon to allow full torque for the drill when drilling holes.
The drills have a 1/2”, 3 jaw, keyless chuck. Drill chucks are meant to be hand tightened instead of holding the chuck and pulling the trigger. My drills have ratcheting chucks and you can hear the clicks as they are tightened.
If you have a problem with bits slipping out or the chuck coming loose when the brakes kick in, it might be because you aren’t hand tightening.
The impact driver has a 1/4” chuck with a quick-release collar that makes it easy to load up 1/4” shank drill bits and drive guides.
There are plenty of keyed chucks out there, so I’ll show you the only one I have – on my drill press. Keyed chucks have gear teeth along the bottom and a key that fits those teeth. The key is pressed into one of three holes and when interlocked, the key has the leverage to tighten and loosen the chuck.
I like to tighten from one side and then tighten from the hole on the opposite side to make sure it’s secure.
How They Work
These tools deliver a rotational force called torque to turn a drill bit or screw. It takes more or less torque depending on the size of screw, depth it needs to be driven, and the hardness of the material you’re driving or drilling into.
As the screw or drill bit is turned the wood resists and is an opposing force to the torque of the drill. This is why a cheap drywall screw can easily break off in harder woods – the wood and the drill are strong enough to make the shank of the screw the weak point.
A couple of things will help avoid this – use stronger screws and drill a pilot hole before driving the screw, especially with hardwoods. When drilling a hole you’re removing material that the screw doesn’t have to remove, there’s less friction and resistance and the screw is easier to drive.
Any of these tools can drill a hole, but they will drill different size holes in different materials better than others.
The drill/driver is an all around light to mid duty tool. The impact driver is more focused on driving most screws in wood and doing it well. The hammer drill does everything the drill/driver does with an added feature can drill and drive into light masonry
How They Work: Drill/Driver
Drill/drivers have less max torque than an impact driver but they are more flexible.
To drill a pilot hole, load the bit into the chuck and hand-tighten the jaws. Seat the bit correctly or it will wobble when it turns.
As I mentioned before most drills have multiple speeds – there can be two or more and the number that corresponds to the setting is different for different drills. But, there’s always a low speed, high torque setting that is best suited for driving screws or drilling into materials like metal and then a high speed, low torque setting that makes drilling holes in wood much faster.
Torque and speed have an inverse relationship, so you’ll always have to decrease one to increase the other.
Turn the torque collar on the drill/driver to the drill bit icon for drilling. This mode turns off the clutch and the drill operates at max torque without disengaging. Push the button in on the right side to put it in forward and drill the hole.
The drill bit is using its sharp head to cut the wood and its flutes move the wood shavings (also called swarf) out of the hole.
We don’t want to drive the screw in too far or strip it out, so we use the torque collar to set the amount of torque the drill applies before the spindle is disengaged. Start low and increase it to get the desired depth. You’ll hear a loud, repeated noise (it’s terrible, honestly) and the spindle will slow down and eventually stop turning.
If the screw isn’t driven as far as it needs to be, turn to a higher torque setting.
How They Work: Impact Driver
A lot of impact drivers are limited to one speed and one drive size, these are 1/4”, but 1/2” are also pretty widely available.
There are drivers on the market with different modes that do things like start out slow or start out fast. They are digitally controlled to make a specific scenario easier.
Impacts spin at higher speeds than a drill/driver and once it reaches a certain threshold, it delivers a rotational strike. This drill spins at 2800 RPM and then delivers 3200 impacts per minute – it can also be described as blows per minute.
When the rotational strikes are engaged, the spindle is solely driven by the rotational strikes of the hammer. The spindle sits still until the hammer strikes the anvil and turns it at about 3200 times per minute. If you’d like to see how the hammer and anvil system works check out this video. It shows the shell cutaway on an impact attachment and filmed in slow motion and illustrates how this mechanism works.
You can drill holes with an impact driver with bits that are “impact ready”. These are special because they’re hex shank bits that are 1 piece of metal and not 2 pieces like typical hex shank bits. The holes will also likely not be quite as accurate. Drills deliver consistent power and impact drivers deliver a violent collision. Great for driving, not so great for accurate drilling.
How They Work: Hammer Drill
The hammer drill is great for drilling and driving into light masonry like some concrete and brick. The mechanism is made up two metal discs and I’ve seen two different configurations. One is both discs with wavy ridges on opposing ends and the other is one disc with a series of balls that ride in ridges on the other disc. Once the discs are engaged they turn against each other and the rising and falling cause the chuck to slam forward.
A rotary hammer is another tool with a similar function. It is superior to the hammer drill for drilling into hard masonry. A rotary hammer has an actual piston mechanism that delivers a downward blow onto the spindle.
The hammer drill pictured also has a brushless motor. Brushes in a motor are pieces of carbon spring loaded to stay in contact with the motor’s rotor. Power is delivered to the motor through them. They wear out, heat up due to friction, create dust, and lower the voltage resulting in less power.
Will you notice the difference between a brushless and brushed drill? It depends how you use it and how often. Someone that just needs a drill around the house for the occasional project will have a hard time comparing the two. To an active hobbyist woodworker always building projects up to a full-time professional carpenter – a brushless motor can be a great investment. More current is getting from the battery to the motor in a brushless motor and the drill is electronically managing the output to match the task – which also conserves battery life. You don’t worry about replacing brushes, and they’re lighter and more compact. Brushless drills last longer and are more powerful than their brushed counterparts.
Types of Drill Bits
A drill bit is sized according to the diameter of its shank or cutting head. Let’s quickly talk about some of the drill bits available and when you might use them. This is by no means exhaustive list, but the most commonly used:
Twist bits are the most commonly used bit and easiest to find in all sizes. Their flatter head can be used in about any situation from wood to light metal. They have channels called flutes that twist around the shank and remove wood or metal shavings. They also tend to wander or skate when you start to drill with them, necessitating a slow start until it bites.
Named for its sharp point (FIG 24) that is great to start a hole in an accurate location. Because of their sharp point and wide flutes this is a wood drilling bit that works great for softer lumber.
My favorite bit because it’s easy to aim, can drill overlapping holes, and makes a clean flat-bottomed hole. When you aren’t drilling a thru-hole, these tend to cut unevenly if not held straight up and down with even, centered pressure.
Spade or paddle
When sharp and kept straight spade bits can make a clean hole. They tend to have long shanks to cut deep holes.
The auger bit has been around for hundreds of years. It was meant to be used with a brace with a slow, methodical turn. It has a screw at the top that pulls the bit through the wood – it’s very aggressive with wide flutes. You won’t be using an auger bit with a drill for casual holes – only deep holes in thick and/or hard woods.
This bit creates a tapered hole so that a flat head screw can sit under the surface of wood or metal. You can find these as a countersink only or a countersink bit that has a twist bit embedded inside to drill a pilot hole and countersink in one motion.
A hole saw cuts holes in just about anything depending on the type of teeth it has. They use a bore that has a twist bit in the center to drill a pilot hole and keep the hole saw straight and accurate. The hole saw cuts a plug that can be removed from the side and are used for large and long holes like for a doorknob or to run wire.
This bit are used with a hammer drill for concrete and brick. It looks like a twist bit but has an extremely hard tip made from tungsten carbide or a similarly hard material.
This attachment loads up in the drill just like a bit and allows you to sand curves.
Right angle drive guide
Used for those tough situations when a screw needs to be driven but the drill won’t fit.
Tips & Tricks
- For those flatter head bits that like to wander or skate, use an awl to get an indentation. The indentation keeps the bit still until it bites.
- Sometimes you need to drill a straight hole and that can be difficult without a drill press. Take two pieces of wood that are square at the ends, offset them, and place the bit in the corner to keep it straight up and down.
- Drilling a hole all the way through wood blows out the fibers on the back side because there’s nothing to support them. There are a few ways to do this, but my preferred way is to mark the depth of the hole on the forstner bit, drill until to that tape until just the point pops through, and then flip the drill around to finish the hole.
- Drill bits are designed to not only cut through the wood but to evacuate wood shavings from the hole. If the flutes get compacted with wood shavings and aren’t able to evacuate the hole, it can become compacted and hard for the drill bit to continue cutting. There’s a simple fix for this – move the drill bit back out of the hole allowing all the shavings to fall out and then go back in and continue drilling.
- To choose the right sized drill bit for a screw, hold them up together with the bit in front of the screw. The drill bit should be the same size as the shank of the screw while the threads from the screw still stick out.
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