Introduction: As indicated in the text, error is the enemy of measurement. To reduce the chance of error, we measure the measurement instrument to insure the readings given are as accurate as possible. Since each instrument exhibits its own metrological features, it would be too time consuming to focus on the calibration process on more than one instrument. Therefore, in this lab, we focus on calibrating a one-inch micrometer and provide insight on the process of calibration and how it works. Items needed: One-inch micrometer Full set of gage blocks Any specific adjustment tool required to set the zero point of the micrometer Any necessary tools to assist in the disassembly and reassembly of the instrument Cleaning solvents and lubricants Demonstration: Confirm students are fully capable of reliably reading a one-inch micrometer with accuracy and precision to the fourth decimal point. Disassemble a one-inch micrometer and discuss the function of each piece, as well as the sources of error for the instrument.

27

28 LAB 7

Name: Date: EXERCISE 1 Observation: Visually inspect the instrument. Using the classification of measurement errors guide (Figure 95) identify and record any potential error attributes that may impact the calibration of a one-inch micrometer. Complete the pre-calibration checklist (Figure 97).

EXERCISE 2 Calibration: Confirm the zero setting of the instrument. Utilizing the supplied tool, adjust the instrument (if necessary) to achieve a zero setting. Start a calibration process by using quarter-inch increments in both directions. Take instrument readings against the appropriate gage block and record the findings to full scale. Use one-tenth-inch increments in both directions against the appropriate gage block and record those findings.

EXERCISE 3 Measurement confirmation: Create a graph similar to those shown in Figure 99, graphing both results on the same chart. Is the instrument linear? Is there any uncertainty? Is the instrument accurate?

LAB 7 29

REPORT Have students report their findings for Exercises 1-3. Use the following sections to create your report.

Objective:

Instrument(s) and items used:

Environmental concerns:

Data:

Conclusion: