What is an Impact Driver Used For?

Knowing when to use an impact driver and when to use a combi drill is an important factor for any handyman or DIY enthusiast. These two tools might seem similar at a glance but when it comes to doing the job right, they have very different purposes and excel in different areas of home maintenance and renovation projects. I often use both my combi drill and impact driver side by side as they both tackle the jobs required for a perfect finish , but what are the key differences? In this article, I’d like to highlight what an impact driver is and what it should be used for. How it can be used along side a combi drill and why it’s worth having one.

What is the Primary Purpose of an Impact Driver?

An impact driver’s primary function is to fasten screws, nuts or bolts into materials on a large scale. For example, building a decking area will require securing a large number of screws into wood. This is where an impact driver would excel. Its speed and torque allow the operator to secure a large number of screws in a short period of time.

Whilst large-scale driving is at the forefront of the impact driver’s purpose, I also find it useful as a standard screwdriver. It has a great response level on the trigger, allowing users to carefully control the speed and accuracy of driving screws into materials. It also has a great level of torque and power when required for those tougher jobs. Driving screws into tough wood or masonry is no problem for a tool like this.

What the Impact Driver isn’t Good for

Impact drivers are not ideal for precision tasks, such as fastening small screws into delicate or thin materials. Their high torque can easily strip small screws or damage fragile workpieces. Additionally, they are not effective with very short screws, as the impact action can cause slipping or misalignment. Impact drivers are also unsuitable for use with soft materials like softwood, where the force they exert can cause the material to split or the screws to be overdriven. Impact drivers are not designed for drilling holes, as their primary function is to drive screws and bolts rather than bore through materials. For drilling, a standard drill or a drill/driver combo is a more appropriate tool.

Power Ratings Explained

Impact drivers are versatile tools powered by rechargeable batteries, with their power typically measured in volts. The voltage rating is crucial when selecting an impact driver because a higher voltage generally indicates more power, enabling the tool to handle more demanding tasks with greater efficiency. Most impact drivers will come with 18v as standard but you can find higher-rated drivers for professional levels.

In addition to voltage, another critical factor to consider is torque, which is the twisting force an impact driver can apply. Torque is measured in newton meters (Nm), and a higher torque rating means the impact driver can deliver more force, making it more effective for driving large screws and bolts into tough materials.

My Dewalt DCF885 is only an entry-level impact driver but it does everything I need it to. Here is a quick look at it’s specifications. We can then take a look at a few other examples.

Dewalt DCF885

• Voltage: 18v
• Max Torque: 155Nm
• Top Speed: 2800 RPM (revolutions per minute)
• Impact Rate: 3200 IPM (impacts per minute)
• Weight: 971g

Examples of Some More Powerful Impact Drivers:

• DeWalt 20V Max Atomic Impact Driver DCF850
  • Voltage: 20V
  • Max Torque: 207 Nm
  • Top Speed: 3250 RPM
  • Impact Rate: 3800 IPM
  • Weight: 2.1kg
• Milwaukee M18 Fuel Impact Driver 2953
  • Voltage: 18V
  • Max Torque: 226 Nm
  • Top Speed: 3900 RPM
  • Impact Rate: 4400 IPM
  • Weight: 2kg
• Makita Impact Driver LXT DTD156
  • Voltage: 18V
  • Max Torque: 155Nm
  • Top Speed: 2500 RPM
  • Impact Rate: 3000 IPM
  • Weight: 1.6kg

These examples show some of the differences in power ratings and specifications among various models. The DeWalt DCF850, with its 20V battery and 207 Nm of torque, offers substantial power for heavy-duty applications. Similarly, the Milwaukee 2953, though slightly lower in voltage at 18V, provides even higher torque at 226 Nm, making it a robust option for demanding tasks. Understanding these specifications helps in choosing the right impact driver for your specific needs, ensuring you have the power and capability required for your projects.

How an Impact Driver Works

An impact driver is a specialized power tool designed to drive screws and bolts with high efficiency and minimal effort. It accomplishes this through a combination of rotational force (torque) and concussive blows (impacts) that help drive fasteners into tough materials. Here’s a detailed look at how an impact driver works:

Key Components

1. Motor: The electric motor powers the tool, converting electrical energy from the battery into mechanical energy.
2. Anvil: The anvil is a critical part of the impact mechanism that receives and transfers the concussive blows to the bit.
3. Hammer: The hammer is part of the internal mechanism that strikes the anvil to create the impact force.
4. Hex Chuck: This is where the bit is inserted. The hex chuck is designed to hold hex-shank driver bits securely.

Operating Mechanism

1. Rotational Force (Torque): When the trigger is pressed, the motor starts to rotate the drive shaft, which in turn rotates the bit. This rotational force is what initially drives the screw or bolt into the material.
2. Impact Action:
   • As the resistance increases (for example, when the screw encounters dense material), the impact driver senses the need for more force.
   • Inside the tool, the hammer mechanism is engaged. The hammer begins to spin separately from the drive shaft, building up energy.
   • Once the hammer reaches a critical speed, it strikes the anvil. This delivers a concussive blow that translates into a sudden, high-torque burst.
   • This process repeats rapidly, with the hammer striking the anvil multiple times per second, generating a series of impacts. This allows the tool to drive the screw or bolt with much greater force than a regular drill.

This video explains it better than I ever could.

Advantages of Impact Drivers

1. High Torque: The impact mechanism provides a significant amount of torque, making it easier to drive long screws and bolts into tough materials without the tool stalling or the user needing to apply excessive force.
2. Reduced User Fatigue: The concussive blows reduce the amount of rotational force that is transferred to the user’s wrist and arm, making it more comfortable to use over extended periods.
3. Efficiency: Impact drivers can drive fasteners more quickly and efficiently than traditional drills, thanks to their high torque and impact action.

Whats the difference between an Impact Drive and an Impact Wrench?

The primary difference between an impact wrench and an impact driver lies in their power, design and intended applications. While both tools operate on a similar principle—using rotational force and concussive blows to drive fasteners— their specific uses and capabilities differ significantly.

Impact Driver

An impact driver is a lightweight, compact tool primarily used for driving screws and bolts into various materials. It is equipped with a hex chuck that accepts hex bits, making it ideal for tasks that involve fastening screws, such as:

• Woodworking: Driving long screws into hardwoods or softwoods.
• Deck Building: Securing deck boards and railings.
• DIY Projects: General home improvement tasks like assembling furniture or mounting shelves.

Impact Wrench

An impact wrench, on the other hand, is a more powerful, heavier, and bulkier tool designed for high-torque applications. It uses square drive sockets to loosen and fasten nuts and bolts, making it essential for jobs that require significant force, such as:

• Automotive Work: Removing and installing lug nuts on tires, as well as other heavy-duty fastening tasks on vehicles.
• Heavy Equipment Maintenance: Servicing construction equipment, agricultural machinery, and industrial machines.
• Construction: Assembling steel frameworks, scaffolding, and other structural components.
• Mechanical Work: Tasks that involve large, stubborn bolts, such as engine disassembly and assembly.

Key Differences

• Power and Torque: Impact wrenches provide significantly more torque than impact drivers, making them suitable for heavy-duty applications.
• Size and Weight: Impact wrenches are generally larger and heavier than impact drivers, which can be a consideration for prolonged use.
• Bit Type: Impact drivers use hex bits, while impact wrenches use square drive sockets, each suited to their respective tasks.

Conclusion

I use my impact driver and drill/driver on a daily basis and knowing when to use either is essential for any handyman or DIY enthusiast. Despite their similar appearances, these tools serve very different purposes and excel in different areas of home maintenance and renovation projects. An impact driver is a powerful tool ideal for driving screws and bolts, particularly for large-scale tasks and tough materials. It offers speed, torque, and efficiency, making it invaluable for jobs like building decks, assembling cabinets, and general DIY projects.

On the other hand, a combi drill is more versatile, suited for both drilling and driving, making it indispensable for drilling holes and handling more precise tasks. Having both tools in your arsenal allows you to tackle a wide range of projects with the appropriate tool for each task.

By understanding the primary purposes, power ratings, and appropriate applications of each tool, you can ensure you achieve a perfect finish in your projects. Whether you are working on a detailed woodworking project or a heavy-duty automotive repair, using the right tool will make your work easier, more efficient, and more professional.