Deciding between an impact driver versus hammer drill is not as straightforward as it may seem. After all, both feature some sort of hammering action, and both of them can drill holes.
With the right attachment and settings, you can drive screws and fasteners using either of these tools, too. In practice, though, each of these tools has very specific uses in the workshop or the job site. If you are looking to buy one of these tools, it’s always a good idea to consider if their strengths will fit in nicely with the tasks you need to do.
Of course, you may find that you will eventually own both of these tools – they are simply that effective at the things they are good at. When it comes to features, weight, applications, and cost, both the impact driver and the hammer drill offer compelling advantages depending on the situation and the materials you are working with.
Impact Driver Features
Impact drivers are compact and lightweight tools that look like a smaller and stubbier drill or drill driver at first glance. Make no mistake, though – the impact driver will easily outstrip both the regular drill and the hammer drill when it comes to sheer torque.
The large amount of torque they produce lets you easily drive long screws into hardwood in a matter of seconds, where these same screws will stall out a regular drill or hammer drill or take much longer to drive them with a little more effort.
Impact drivers deliver a hammering action, just like a hammer drill. There is a big difference in the way they use this hammering action, though. An impact driver has a weight inside the tool that stores rotational energy, then quickly releases it in a split second as it impacts the drive shaft along the axis of rotation.
You can think of this hammering action in the same way that you can use a hammer to hit the shaft of a wrench as it holds on to a bolt – each hit goes towards helping the wrench and the bolt turn.
Impact drivers use 1/4 inch hex bit adapters. These can be screwdriver bits, or hex head screws themselves. There are also adapters that let you use sockets with your 1/4 inch hex driver, so you can use your impact driver as a smaller version of your impact wrench.
Take note, though, that you are better off using impact rated hex bits with your impact driver – these ones come with a special coating (black oxide, for example) and will not crack, chip or break as easily even when subjected to all that hammering and vibration.
Impact drivers also come with all the bells and whistles you would expect from many of the newer generations of power tools today. That means they can use the same lithium-ion battery packs as your other tools if you get the same brand. Some of the more expensive models may also come with brushless motors, too.
One of the best features of the impact driver is what is called non-reactionary torque. Since all the impact of the hammering action is directed at the drive shaft, the user hardly feels the vibrations at all. This, as well as the fact that impact drivers are such small and lightweight tools, makes them easy to use for long periods of time.
Hammer Drill Features
A hammer drill is essentially a bigger, beefier drill or drill driver that comes with a hammer feature. In most models, you can turn the hammer mode on or off – when you switch it to off, you can then use a hammer drill just like a regular drill or driver.
When this feature is turned on, they can efficiently drill into concrete, masonry, and other hard materials that a regular drill may have trouble dealing with.
Hammer drills come with a spring-loaded ridged disc the rapidly rises and falls with every turn. These discs have a lot of weight behind them, and it is this action that produces the fast-paced hammering action.
Unlike impact drivers, though, this hammering action is directed at the rear of the drive shaft – the tool hammers the drill bit into the material, as well as turning it. This also means that you, the user, can feel every hit as the hammer drill does its work.
Just like regular drill drivers, a hammer drill often comes with ways to control the speed and torque output. A speed selector in a hammer drill lets you pick a slower speed with more torque, which makes the tool more ideal for driving screws. A high-speed setting, on the other hand, means the drill hammer will produce less torque but can drill faster.
Hammer drills, again just like regular drills, use a three jawed chuck to accommodate a wide variety of bits. Where impact drivers can only use hex bits, hammer drills and regular drills can use both round shaft and hex shaft bits.
Hammer drills may also come with an adjustable clutch for further torque control. With the right clutch setting, you can set the maximum torque to match the fastener you are using as well as the material you are driving them into. This helps you avoid damaging the work piece, as well as cut down on the chance that you strip a screw.
Impact Driver Weight and Size
Regular sized impact drivers are short, lightweight, and very easy to carry around. All the more so for the compact variants – many of these weigh under 3 pounds, and are stubby enough that you might just be able to fit one in your pocket. This lets you use an impact driver in the tightest of spaces, a fact that many HVAC installers and machinery maintenance workers appreciate.
Most impact drivers also come with a belt clip, which lets you wear the tool on you as you navigate ladders and scaffolding. The light weight, small size, and non-reactionary torque of impact drivers also make it a very comfortable tool to use even for long periods of time.
If you are working on a deck, putting up a steel frame, working on some HVAC ducts, or any task that requires you to bend over or use the tool overhead, you will surely appreciate the weight and size advantage that impact drivers bring to the table.
Hammer Drill Weight and Size
Hammer drills are somewhere on the other end of the weight spectrum, compared to impact drivers. The hammer mechanism, plus the larger motor needed to run them, all add up to a big and heavy tool.
Where regular drills are designed to be used with one hand, hammer drills are designed to be used with two hands. You can see that in the fact that many of them come with a secondary removable handle that goes over the chuck. They also tend to be larger and longer than regular drills and are decidedly bulky if you compare them to impact drivers.
Aside from the added weight and size, hammer drills can also be a bit uncomfortable to use. The hammer impacts that hit the rear of the drive shaft are also transmitted to the handle, which can cause discomfort if you use the tool over an extended length of time. It almost feels like working with a mini-jackhammer in your hands.
Impact Driver Applications
Impact drivers are very well suited for driving screws, nuts and bolts. The high torque they deliver is perfect for driving long screws into seasoned lumber or hardwood.
The slower rotational speed they operate with also means that there is less chance for you to strip a screw head, too. Where a regular drill or drill hammer might stall when a long screw gets stuck in a particularly thick piece of hardwood, an impact driver will have little trouble dealing with long fasteners.
Aside from screws, impact drivers are also well suited for driving nuts and bolts efficiently. With the kind of torque they can put out, they can also extract screws and bolts that are stuck, as well. If you have a hex adapter that ends with a 1/2 inch square drive on the other end, you can also use sockets with an impact driver to loosen or tighten lag bolts, nuts, and other large fasteners as well.
Since an impact driver uses non-reactionary torque, there is a less chance that it will seize and twist in the user’s hand. This makes them safe to use even on top of ladders, roofs, or in other places where a user may not have a secure enough footing.
Impact drivers are common in workshops that often deal with hardwood and screws. They are also found in garage shops, where they provide an efficient way to deal with the numerous nuts and bolts you will encounter with automotive projects. Finally, they are a tool of choice for installers and contractors that use a lot of screws in their line of work – HVAC professionals, roofing installers, steel framers, deck builders, and many more.
Impact drivers may also be used for drilling holes. With the right attachment, an impact driver actually makes for a very effective hole saw – the torque they put out can drive even the larger hole saw attachments through thicker pieces of wood.
They do, however, lack the speed to efficiently drill holes using drill bits, and will have trouble putting out enough RPMs to work their way through harder materials. For those applications, you should consider getting a hammer drill.
Hammer Drill Applications
Hammer drills are ideal for drilling holes, and can do so in a wider variety of materials compared to regular drills. Where a drill with no hammer action might struggle with concrete or masonry, a hammer drill has the impact action to make the job go faster.
The difference is even more pronounced when using drill bits with larger diameters – for drilling deep, large holes in harder materials, the hammering action that this tool provides really make a lot of difference.
A hammer drill is the best tool of choice for drilling into brick, concrete, and similar materials. Using a regular drill on these will not only slow you down, but you also run the risk of overusing your tool. Aside from working with hard materials, you can also drill into just about any other material that a regular drill can handle, as well. If you turn the hammer feature off, a hammer drill works just like a regular drill or drill driver for driving screws and other fasteners, too.
Just like a regular drill, a hammer drill will often have features that let you control the speed and torque you can deliver to a screw or drill bit. Many hammer drills come with an adjustable clutch, just behind the chuck, that lets you limit the torque delivered to a fastener.
This prevents you from over torquing or striping your screws and screwdriver bits, and this also lets you work with smaller, thinner screws and bits safely.
Impact Driver Torque
Impact drivers lead the pack in terms of generating torque – in this regard, they are only behind impact wrenches. The hammering action greatly improves the torque they can produce since almost all of the force of the impact goes towards helping the drive shaft turn.
Even the smaller compact impact drivers, short, ultra-portable tools that weigh less than 3 pounds that they are, will easily put out more than 1,000 inch pounds of torque.
Compact impact drivers from good brands will actually give you somewhere between 1,200 to 1,600 inch-pounds of torque, which is more than enough to drive even the longest of screws into wood.
When you start to get into the regular impact drivers, the numbers only get better from them. Even the cordless models can put out over 2,000 inch-pounds of torque. Corded models can produce even more, and especially so for the air powered impact drivers.
Hammer Drill Torque
Hammer drills focus more on rotational speed and beats-per-minute, or BPM, to do their job. That’s not to say that they don’t produce significant torque – some of the higher-end models of hammer drills are now capable of doing over 1,000 inch-pounds of maximum torque with the right gear setting.
