Starrett 458MBXRS Automotive Disc Brake Micrometer User Manual

1. Introduction

This manual provides comprehensive instructions for the proper use, setup, operation, maintenance, and troubleshooting of the Starrett 458MBXRS Automotive Disc Brake Micrometer. Please read this manual thoroughly before using the instrument to ensure accurate measurements and safe operation.

Figure 1: Starrett 458MBXRS Automotive Disc Brake Micrometer with included 25mm gage block.

2. Product Overview

The Starrett 458MBXRS is a precision measuring instrument designed specifically for automotive applications, particularly for measuring wear groove depth in disc brakes. Its unique design features a deep-throated frame and a pointed anvil to facilitate accurate measurements in challenging areas.

Key Features:

• Deep-throated frame and pointed anvil: Optimized for measuring wear groove depth in disc brakes.
• Vernier scale in metric units: Provides precise outside diameter (OD) measurements with 0.01mm graduation.
• Ratchet-stop mechanism: Ensures uniform pressure for consistent and repeatable measurements.
• Tapered frame: Allows access to narrow slots and tight spaces.
• Satin chrome finish: Applied to the thimble and sleeve for rust resistance and reduced glare.
• Carbide-tipped spindle and anvil: Enhances durability and wear resistance.
• Lightweight yet rigid steel frame: Perforated design for optimal balance and stability.

Figure 2: Detailed view of the micrometer's measuring surfaces and scale.

3. Setup

Unpacking and Inspection:

1. Carefully remove the micrometer and its accessories from the packaging.
2. Inspect the instrument for any signs of damage during transit. If damage is observed, contact your supplier immediately.
3. Ensure all components listed in the packing list are present, including the 25mm gage block standard.

Calibration (Zero Setting):

Before first use and periodically thereafter, the micrometer should be calibrated to ensure accuracy. This model includes a 25mm gage block for calibration.

1. Clean the measuring faces of the spindle and anvil with a lint-free cloth.
2. Hold the micrometer firmly and carefully bring the spindle into contact with the anvil using the ratchet stop until it clicks 2-3 times.
3. Check the zero line on the thimble against the datum line on the sleeve. They should align perfectly.
4. If misalignment occurs, use the included spanner wrench (if applicable, not explicitly mentioned but common for micrometers) to adjust the sleeve until the lines align. Refer to the specific adjustment procedure for Starrett micrometers if a significant adjustment is needed.
5. For the 25-50mm range, use the 25mm gage block. Place the gage block between the anvil and spindle. Close the micrometer using the ratchet stop until it clicks 2-3 times. The reading should be exactly 25.00mm. Adjust if necessary.

4. Operating Instructions

Measuring Disc Brake Wear Groove Depth:

1. Ensure the disc brake surface is clean and free of debris.
2. Open the micrometer sufficiently to clear the disc brake.
3. Position the deep-throated frame over the disc brake, aligning the pointed anvil with the wear groove.
4. Slowly close the micrometer using the thimble until the spindle makes initial contact with the opposite side of the disc.
5. Engage the ratchet stop and turn it until it clicks 2-3 times. This ensures consistent measuring pressure.
6. Read the measurement from the vernier scale on the sleeve and thimble.
7. Record the measurement. Take multiple readings at different points on the disc for accuracy.

Reading the Micrometer (Metric 0.01mm Graduation):

The micrometer has a main scale on the sleeve and a vernier scale on the thimble.

• Sleeve Scale: The top line indicates millimeters (mm), with each numbered mark representing 5mm (e.g., 0, 5, 10, 15...). The bottom line indicates half-millimeters (0.5mm).
• Thimble Scale: The thimble is divided into 50 divisions, with each division representing 0.01mm. One full rotation of the thimble moves the spindle 0.5mm.
• Reading Procedure:
  1. Read the largest whole millimeter value visible on the sleeve scale.
  2. Check if the 0.5mm mark below the datum line on the sleeve is visible. If yes, add 0.5mm to your reading.
  3. Read the division on the thimble scale that aligns with the datum line on the sleeve. Multiply this number by 0.01mm.
  4. Add all three values together for the total measurement.

5. Maintenance

Cleaning:

• After each use, wipe down the micrometer with a clean, lint-free cloth to remove any dust, oil, or debris.
• For more thorough cleaning, use a soft cloth lightly dampened with instrument cleaning fluid or isopropyl alcohol. Avoid harsh solvents.
• Ensure the measuring faces are always clean to prevent inaccurate readings.

Lubrication:

• Periodically apply a thin film of light machine oil to the spindle screw threads to ensure smooth operation and prevent corrosion.
• Do not over-lubricate, as excess oil can attract dust and debris.

Storage:

• Store the micrometer in its protective case when not in use.
• Store in a clean, dry environment, away from direct sunlight, extreme temperatures, and high humidity.
• Avoid storing the micrometer with the spindle fully closed against the anvil, as this can put undue stress on the instrument. Leave a small gap.

6. Troubleshooting

7. Specifications

8. Warranty and Support

Starrett products are manufactured to the highest standards and are backed by a commitment to quality. For specific warranty information regarding your Starrett 458MBXRS Automotive Disc Brake Micrometer, please refer to the warranty card included with your product or visit the official Starrett website.

Customer Support:

If you require technical assistance, calibration services, or repair, please contact Starrett customer support:

• Website: www.starrett.com (Check for contact information, FAQs, and service centers)
• Phone: Refer to the Starrett website for regional contact numbers.
• Service Centers: Information on authorized service centers can be found on the Starrett website.

When contacting support, please have your product model number (458MBXRS) and purchase details ready.