DEWALT 20V MAX Cordless Impact Wrench DCF891B User Manual

1. Introduction

This manual provides essential information for the safe and effective operation, maintenance, and troubleshooting of your DEWALT 20V MAX Cordless Impact Wrench, model DCF891B. Please read this manual thoroughly before using the tool and retain it for future reference.

1.1 Intended Use

The DEWALT DCF891B Cordless Impact Wrench is designed for professional fastening applications requiring high torque. It is suitable for tasks such as:

• Pipe flange assembly
• Grooved coupling installation
• Tilt wall brace adjustments
• Automotive wheel lug removal and installation
• Setting concrete anchors
• Other applications requiring high torque in compact spaces.

This tool is sold as a bare tool only. A compatible DEWALT 20V MAX battery and charger are required for operation and are sold separately.

1.2 Key Features

• High Torque Output: Delivers up to 600 ft-lbs of max fastening torque and 800 ft-lbs of max breakaway torque.
• 4-Mode Push Button Switch: Allows for easy selection of speed settings to match application requirements.
• Precision Wrench Setting: Helps prevent overtightening in forward and fastener run-off in reverse.
• Integrated LED Work Light: Illuminates dark workspaces for improved visibility.
• Compact and Lightweight Design: Enhances user comfort and maneuverability in tight spaces.
• 1/2" Hog Ring Anvil: Facilitates quick and easy socket changes.

2. General Safety Instructions

Always follow basic safety precautions when using power tools to reduce the risk of fire, electric shock, and personal injury. Read all instructions before operating this tool.

2.1 Work Area Safety

• Keep the work area clean and well-lit. Cluttered or dark areas invite accidents.
• Do not operate power tools in explosive atmospheres, such as in the presence of flammable liquids, gases, or dust. Power tools create sparks which may ignite the dust or fumes.
• Keep children and bystanders away while operating a power tool. Distractions can cause you to lose control.

2.2 Electrical Safety

• Avoid body contact with earthed or grounded surfaces such as pipes, radiators, ranges, and refrigerators. There is an increased risk of electric shock if your body is earthed or grounded.
• Do not expose power tools to rain or wet conditions. Water entering a power tool will increase the risk of electric shock.

2.3 Personal Safety

• Always wear eye protection. Use safety glasses or goggles.
• Wear appropriate personal protective equipment (PPE) such as hearing protection, gloves, and non-skid safety shoes.
• Stay alert, watch what you are doing, and use common sense when operating a power tool. Do not use a power tool while you are tired or under the influence of drugs, alcohol, or medication.
• Prevent unintentional starting. Ensure the switch is in the off-position before connecting to a battery pack, picking up or carrying the tool.
• Do not overreach. Keep proper footing and balance at all times. This enables better control of the power tool in unexpected situations.
• Dress properly. Do not wear loose clothing or jewelry. Keep your hair and clothing away from moving parts.

2.4 Power Tool Use and Care

• Do not force the power tool. Use the correct power tool for your application.
• Do not use the power tool if the switch does not turn it on and off. Any power tool that cannot be controlled with the switch is dangerous and must be repaired.
• Disconnect the battery pack from the power tool before making any adjustments, changing accessories, or storing power tools.
• Store idle power tools out of the reach of children and do not allow persons unfamiliar with the power tool or these instructions to operate the power tool.
• Maintain power tools and accessories. Check for misalignment or binding of moving parts, breakage of parts, and any other condition that may affect the power tool’s operation. If damaged, have the power tool repaired before use.
• Use the power tool, accessories, and tool bits in accordance with these instructions, taking into account the working conditions and the work to be performed.

2.5 Battery Tool Use and Care

• Recharge only with the charger specified by the manufacturer. A charger that is suitable for one type of battery pack may create a risk of fire when used with another battery pack.
• Use power tools only with specifically designated battery packs. Use of any other battery packs may create a risk of injury and fire.
• When battery pack is not in use, keep it away from other metal objects, like paper clips, coins, keys, nails, screws or other small metal objects, that can make a connection from one terminal to another. Shorting the battery terminals together may cause burns or a fire.
• Under abusive conditions, liquid may be ejected from the battery; avoid contact. If contact accidentally occurs, flush with water. If liquid contacts eyes, additionally seek medical help. Liquid ejected from the battery may cause irritation or burns.

3. Components and Features

Familiarize yourself with the various parts of your DEWALT DCF891B Impact Wrench.

Figure 1: The DEWALT DCF891B 20V MAX Cordless Impact Wrench, featuring a 1/2-inch hog ring anvil, LED work light, and belt clip.

Figure 2: An annotated diagram illustrating the key features of the DCF891B impact wrench, including the 1/2-inch anvil, variable speed trigger, LED light, and 4 speed modes.

• 1/2" Hog Ring Anvil: For quick socket attachment and removal.
• LED Work Light: Provides illumination for the work area.
• Belt Clip: For convenient carrying and temporary storage.
• Variable Speed Trigger: Allows for precise control over fastening speed.
• 4-Mode Push Button Switch: Selects between different speed and torque settings, including the Precision Wrench mode.
• Battery Release Button: Used to detach the battery pack.
• Forward/Reverse Selector: Changes the direction of rotation.

Figure 3: Detail view of the control panel on the DCF891B, highlighting the 4-mode push button switch and LED work light control.

4. Setup

4.1 Battery Installation and Removal

The DCF891B operates with DEWALT 20V MAX Lithium-Ion battery packs (sold separately).

1. To Install: Align the battery pack with the tool's battery port. Slide the battery pack into the tool until it clicks into place. Ensure it is securely latched.
2. To Remove: Press the battery release button (usually located at the front of the battery pack) and pull the battery pack out of the tool.

NOTE: Ensure the battery is fully charged before first use. Refer to your battery charger's instruction manual for proper charging procedures.

Figure 4: The DCF891B impact wrench shown with a compatible DEWALT 20V MAX battery (sold separately) installed.

4.2 Attaching the Belt Clip

The belt clip can be attached to either side of the tool for user convenience.

1. Locate the screw hole on the side of the tool handle.
2. Position the belt clip over the hole.
3. Secure the belt clip with the provided screw using a screwdriver.

4.3 Attaching Sockets to the Hog Ring Anvil

The 1/2" hog ring anvil allows for quick and secure attachment of impact-rated sockets.

1. Ensure the tool is off and the battery is removed before attaching or removing sockets.
2. Push the desired 1/2" square drive impact socket firmly onto the anvil. The hog ring will compress and then expand to hold the socket securely.
3. To remove, simply pull the socket firmly off the anvil.

CAUTION: Only use impact-rated sockets with this tool. Non-impact sockets may shatter and cause injury.

5. Operation

5.1 Powering On/Off and Variable Speed Trigger

The tool is activated by pressing the variable speed trigger. The speed is controlled by the amount of trigger depression.

• To start the tool, depress the trigger.
• To stop the tool, release the trigger.
• For variable speed, apply more pressure to the trigger for higher speeds and less pressure for lower speeds.

5.2 Forward/Reverse Control

The direction of rotation is controlled by the forward/reverse selector switch, located above the trigger.

• For forward rotation (fastening), push the selector to the left.
• For reverse rotation (loosening), push the selector to the right.
• For locking the trigger (preventing accidental start-up), position the selector in the center.

5.3 4-Mode Push Button Switch and Precision Wrench Setting

The 4-mode push button switch allows you to select different speed and torque settings, optimizing performance for various applications.

Figure 5: The DCF891B impact wrench demonstrating its 600 ft-lbs max fastening torque capability in an application.

Figure 6: The DCF891B impact wrench showcasing its 800 ft-lbs max breakaway torque for stubborn fasteners.

• Press the mode selection button to cycle through the available modes (1, 2, 3, and Precision Wrench). An indicator light will show the currently selected mode.
• Modes 1, 2, 3: Provide increasing levels of speed and torque for general fastening and loosening tasks.
• Precision Wrench Mode:
  • In Forward (Fastening): The tool will fasten at a controlled speed and then pause briefly before impacting, helping to prevent overtightening. This allows the user to finish tightening manually if desired.
  • In Reverse (Loosening): The tool will impact at full speed to break loose a stubborn fastener, then reduce speed to help prevent fastener run-off once the fastener is loose.

Figure 7: The Precision Wrench feature of the DCF891B in action, designed to prevent overtightening and fastener run-off.

5.4 LED Work Light

The integrated LED work light illuminates the work area. It activates when the trigger is depressed and remains on for a short period after the trigger is released.

• The LED light can be adjusted for brightness or turned off using the dedicated light button on the control panel.

6. Maintenance

Your DEWALT power tool is designed to operate over a long period with a minimum of maintenance. Continuous satisfactory operation depends upon proper tool care and regular cleaning.

6.1 Cleaning

• Tool Housing: Wipe the tool housing with a damp cloth. Do not use solvents or harsh chemicals.
• Ventilation Slots: Keep the ventilation slots clear of dust and debris to prevent overheating. Use compressed air if necessary.
• Anvil: Periodically inspect the hog ring anvil for wear or damage. Replace if necessary.

6.2 Lubrication

This power tool is factory lubricated and requires no additional lubrication.

6.3 Storage

• Store the tool in a cool, dry place, out of reach of children.
• Remove the battery pack from the tool before storage.
• Store battery packs in a cool, dry place, away from direct sunlight and extreme temperatures.

7. Troubleshooting

If your DEWALT DCF891B Impact Wrench is not functioning correctly, consult the following table for common issues and solutions.

If the problem persists after attempting these solutions, contact DEWALT customer service or an authorized service center.

8. Specifications

9. Warranty Information

DEWALT offers a comprehensive warranty for its products. For detailed warranty terms and conditions, please refer to the official DEWALT website or the warranty card included with your product. Keep your proof of purchase for warranty claims.

Typically, DEWALT power tools are covered by a 3-year limited warranty, 1-year free service contract, and 90-day money-back guarantee. Specific terms may vary by region and product.

10. Customer Support

For technical assistance, service, or to locate an authorized service center, please contact DEWALT customer support.

• Website: Visit the official DEWALT website for support resources, FAQs, and service center locators.
• Phone: Refer to your product packaging or the DEWALT website for regional customer service contact numbers.

When contacting support, please have your tool's model number (DCF891B) and serial number available.