Makita 9903 3" x 21" Belt Sander Instruction Manual

Introduction

The Makita 9903 3" x 21" Belt Sander is a powerful and efficient tool designed for fast stock removal and smooth finishing. It features a variable speed control dial, an auto-tracking belt system, and a design that allows for sanding flush to walls. This manual provides essential information for the safe and effective operation, maintenance, and troubleshooting of your belt sander.

Figure 1: The Makita 9903 Belt Sander, showcasing its compact design and attached dust bag.

Setup

1. Unpacking and Inspection

Carefully remove the belt sander and all accessories from the packaging. Inspect the tool for any signs of damage that may have occurred during shipping. Ensure all included components are present: the belt sander, one #80 abrasive belt, and the dust bag.

2. Installing/Changing the Abrasive Belt

1. Ensure the sander is unplugged from the power source before attempting any adjustments or belt changes.
2. Locate the belt release lever on the side of the sander. Push or pull the lever to release tension on the belt.
3. Remove the old abrasive belt (if present) by sliding it off the rollers.
4. Place the new 3" x 21" abrasive belt onto the rollers, ensuring the directional arrow on the inside of the belt matches the arrow on the sander's housing.
5. Return the belt release lever to its original position to tension the new belt.
6. Verify the belt is centered on the rollers. The auto-tracking system will fine-tune this during operation, but a rough alignment is helpful.

Figure 2: Detail view of the belt area, highlighting the belt and the adjustment screw for tracking.

3. Attaching the Dust Bag

The dust bag helps maintain a cleaner work environment. Attach the dust bag to the dust port located on the side of the sander. Ensure it is securely fastened to prevent dust leakage during operation.

Operating Instructions

1. Power Connection

Connect the 16.4 ft. power cord to a standard 120V power outlet. The long cord provides ample reach for various applications.

2. Variable Speed Control

The Makita 9903 features a variable speed control dial, allowing you to adjust the belt speed from 690 to 1,440 feet per minute (ft./min.). Rotate the dial to select the appropriate speed for your specific application and material. Lower speeds are suitable for fine finishing, while higher speeds are ideal for rapid stock removal.

3. Sanding Technique

• Hold the sander firmly with both hands using the main handle and the front grip for comfortable operation and control.
• Place the sander flat on the workpiece before turning it on.
• Move the sander smoothly and evenly across the surface. Avoid applying excessive pressure, as the tool's weight and power are sufficient for effective sanding.
• The innovative design allows for sanding flush to walls with both the nose and side of the sander, making it versatile for various projects.
• The auto-tracking belt system automatically adjusts the belt to keep it centered, reducing the need for manual adjustments during use.

Figure 3: Proper two-hand grip for operating the belt sander on a workpiece.

Figure 4: Demonstrating the ergonomic design and ease of use during sanding.

Maintenance

1. Dust Bag Emptying

Regularly empty the dust bag to maintain optimal dust collection efficiency and prevent clogging. Disconnect the sander from the power source before removing the dust bag. Shake out accumulated dust and reattach securely.

2. General Cleaning

Keep the sander's ventilation openings clean to ensure proper motor cooling. Use a soft cloth to wipe down the exterior of the tool. Avoid using harsh chemicals or abrasive cleaners.

3. Belt Tracking Adjustment (if needed)

While the auto-tracking system minimizes manual intervention, if the belt consistently runs off-center, a minor adjustment may be required. Use the balancing screw (refer to Figure 2) to fine-tune the belt's position on the rollers. Make small adjustments and test the sander on a scrap piece of material.

Troubleshooting

Specifications

• Model: 9903
• Belt Size: 3" x 21" (76 x 533 mm)
• Power Source: Corded Electric
• Voltage: 120V
• Amperage: 8.8 Amps
• Wattage: 1010 watts
• Belt Speed: 690 - 1,440 ft./min. (Variable)
• Noise Level: 85dB
• Item Weight: 9.5 lbs
• Product Dimensions: 11.63 x 5.63 x 6.19 inches
• Power Cord Length: 16.4 ft.
• Included Components: Belt Sander, 1 Abrasive Belt (#80 grit), Dust Bag

Figure 5: Dimensions of the Makita 9903 Belt Sander for reference.

Warranty and Support

Warranty Information

Every Makita tool is thoroughly inspected and tested before leaving the factory. The Makita 9903 Belt Sander is warranted to be free of defects from workmanship and materials for a period of ONE YEAR from the date of original purchase. If you are not satisfied with any Makita tool within 30 days of purchase, you may return it for a replacement or refund.

Should any trouble develop during this one-year period, return the COMPLETE tool, freight prepaid, to one of Makita's Factory or Authorized Service Centers. For complete details, please visit the official Makita website.

Customer Support

For further assistance, technical support, or to locate an authorized service center, please contact Makita customer service. You can also refer to the official User Manual (PDF) for additional details.