Introduction
This manual provides essential information for the safe operation, maintenance, and troubleshooting of your CRAFTSMAN V20* Small 4-1/2-inch Cordless Angle Grinder (CMCG400B). This tool is designed for grinding applications, offering powerful performance and user-friendly features. Please read this manual thoroughly before initial use to ensure proper handling and to maximize the lifespan of your tool.

Figure 1: CRAFTSMAN V20* Small 4-1/2-inch Cordless Angle Grinder (CMCG400B).
Safety Information
Always adhere to general power tool safety warnings and instructions to reduce the risk of electric shock, fire, and serious injury. Keep your work area clean and well-lit. Do not operate power tools in explosive atmospheres, such as in the presence of flammable liquids, gases, or dust. Always wear appropriate personal protective equipment, including safety glasses, hearing protection, and gloves. Ensure the tool is switched off and the battery is removed before making any adjustments or changing accessories.
Components Overview
The CRAFTSMAN CMCG400B Angle Grinder includes the following components:
- (1) CMCG400 Small Angle Grinder
- (1) Grinding Guard
- (1) Grinding Wheel
- (1) Spanner Wrench
Note: Battery and charger are sold separately.

Figure 2: Included components of the CRAFTSMAN V20* Angle Grinder.

Figure 3: Key features of the angle grinder, including the 3-position handle, spindle lock, tool-free guard, and powerful motor.
Setup
1. Battery Installation
- Ensure the grinder's power switch is in the OFF position.
- Align the battery pack with the battery port on the tool.
- Slide the battery pack into the tool until it clicks securely into place.
2. Handle Installation
The grinder features a 3-position handle for enhanced control and versatility.
- Screw the auxiliary handle into one of the three threaded holes on the grinder's gear housing.
- Tighten the handle firmly by hand.

Figure 4: The 3-position handle provides added control and comfort during use.
3. Guard Adjustment
The tool-free guard allows for quick and easy adjustments.
- Loosen the guard clamp lever.
- Rotate the guard to the desired position for optimal protection.
- Tighten the guard clamp lever to secure the guard in place.

Figure 5: Quick adjustments can be made with the tool-free guard.
4. Grinding Wheel Installation
- Press and hold the spindle lock button to prevent the spindle from rotating.
- Place the inner flange onto the spindle.
- Position the grinding wheel onto the inner flange, ensuring it sits flat.
- Thread the outer flange onto the spindle and tighten it securely using the spanner wrench.
- Release the spindle lock button.
Operating Instructions
Powering On/Off
To turn the grinder ON, slide the switch forward. To turn it OFF, slide the switch backward. Always ensure a firm grip on the tool before starting.
Grinding Techniques
The V20* Angle Grinder is powered by 8,500 RPM for aggressive applications. When grinding, maintain a consistent angle and pressure. Allow the tool to do the work; excessive force can lead to kickback or damage to the tool/workpiece. Always direct sparks away from yourself and others.

Figure 6: The high-performance motor enables up to 8,500 RPM for demanding tasks.
Heat Dissipation
The cast metal gear housing is designed to dissipate heat during extended use, contributing to the tool's durability and consistent performance.

Figure 7: The cast metal gear housing helps dissipate heat during prolonged operation.
Maintenance
Cleaning
Regularly clean the ventilation openings of the tool to prevent overheating. Use a soft brush or compressed air to remove dust and debris. Do not use water or chemical cleaners.
Wheel Replacement
Replace grinding wheels when they become worn or damaged. Always use wheels that are rated for the grinder's maximum RPM and are appropriate for the material being worked on. Follow the wheel installation steps outlined in the Setup section.
Storage
Store the grinder in a dry, secure location out of reach of children. Remove the battery pack before storing for extended periods.
Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Tool does not start | Battery not charged or improperly installed | Ensure battery is fully charged and correctly inserted. |
| Reduced power/performance | Low battery charge; Worn grinding wheel | Recharge battery; Replace grinding wheel. |
| Excessive vibration | Damaged or improperly installed grinding wheel | Inspect wheel for damage and ensure it is correctly mounted and tightened. |
| Overheating | Blocked ventilation openings; Prolonged heavy use | Clean ventilation openings; Allow tool to cool down. |
Specifications
| Feature | Detail |
|---|---|
| Brand | CRAFTSMAN |
| Model | CMCG400B |
| Power Source | Battery Powered (V20*) |
| Voltage | 20 Volts |
| Wattage | 800 watts |
| Maximum Rotational Speed | 9000 RPM |
| Product Dimensions (L x W x H) | 7.01" x 2.87" x 8.66" |
| Item Weight | 5.7 pounds (2.59 Kilograms) |
| Wheel Size | 4-1/2-inch |
| Handle Positions | 3-Position |
| Guard Adjustment | Tool-free |
| Material | Metal |
Warranty & Support
This CRAFTSMAN V20* Angle Grinder is covered by a Limited Lifetime Warranty. For full details regarding warranty coverage, claims, and support, please refer to the official CRAFTSMAN website or contact their customer service directly. Keep your purchase receipt as proof of purchase.





