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Measurement Instruments &Tools. Accurate Measurement. Objectives. What is an ‘accurate’ measurement Review different types of measuring instruments and their application Learn how to calibrate instruments Care and maintenance of instruments Advanced diagnostic session .
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Measurement Instruments &Tools Accurate Measurement
Objectives • What is an ‘accurate’ measurement • Review different types of measuring instruments and their application • Learn how to calibrate instruments • Care and maintenance of instruments • Advanced diagnostic session
Why are these measuring devices called ‘instruments’
Definition of Accurate(from dictionary) • free from error especially as the result ofcare • able to give an accurate result What happens if you do not measure accurately?
Measuring Instruments • Micrometers • Vernier Calipers • Dial Indicators • Telescopic Gauges • Small Hole Gauges • Thickness Gauges • Straight Edge
Outside Micrometer Instrument for making precise linear measurements of dimensions such as diameters, thicknesses, and lengths of solid bodies. It consists of a C-shaped frame with a movable jaw operated by a screw. The accuracy of the measurements depends on the accuracy of the screw-nut combination.
Outside Micrometer Inside Micrometer Depth Micrometer Can you identify the metric micrometer ?
Combination Digital Metric or Imperial at the push of a button
Micrometer Don’ts • Do not drop • Do not run over • Do not over tighten (it is not a vice) • Do not drop in chemicals • Do not leave it covered in grease • Do not let anyone borrow it • Do not leave lying around
Micrometer Do’s • Keep clean • Keep calibrated • Keep in storage box • Keep locked up • Keep away from everyone • Keep in practice reading it !
Brake Drum Micrometer Essentially it is a heavy duty Inside Micrometer
Measuring a brake rotor What is the name of the micrometer in the picture?
Steps to reading a micrometer • Calibrate unit • Identify scale (metric or imperial) • Identify range of micrometer (size) • Read Sleeve first number you see • Read Sleeve for second number (graduation) • Read Thimble Note-if it is a 4 digit mic, read last number on Sleeve (will discuss later)
Step # 1 Calibrate Micrometer Before using any measuring instrument you must check to ensure it is calibrated (accurate) TGB Computing & Publishing YouTube - measuring the thickness of a block using a micrometer www.tgbcomputing.com
Where to find range Imperial equivalent would be a 0-1”
Step # 4 Reading the Sleeve and Thimble Example shows 0.341 1 3 Number on Sleeve Number on Thimble Imperial Micrometer 2 Graduation on Sleeve Thimble numbers go from 0 to 20
Sample Reading Example using a 0-1” Outside Micrometer First number is the size of the Mic 0.000 Second number is the first number on Sleeve .000 Third number is .025 graduations you see onSleeve .025 x 2 = .050 Fourth number is read on the Thimble .016
Recording Measurement from Sample Reading • First reading – Range of Mic. 0 – 1” so the first number would be 0.000 • Second reading – number on Sleeve Number you see is Zero so it would be .000 • Third reading – graduation on Sleeve Two graduations exposed so number is .050 • Final number is number on the Thimble Final number is .016
Total Readings • First reading – Range of Mic. 0.000 • Second reading – number on Sleeve 0.000 • Third reading – graduation on Sleeve 0.050 • Final number is number on the Thimble 0.016 • ______ 0.066 Total is ?
Reading an Imperial MicrometerExercise # 1 (2-3” mic) Answer : 2.550
Reading an Imperial MicrometerExercise # 2 (0-1” mic) Answer: 0.802
Reading an Imperial MicrometerExercise # 3 (1-2” mic) Answer: 1.645
Reading a Metric Micrometer Notice that Thimble numbers are higher than the Imperial Mic ? That’s how you know it is Metric scale. Thimble numbers go from 0 to 45
Reading a Metric MicrometerExercise # 1 (0-25mm Range) Answer : 12. 69
Reading a Metric MicrometerExercise # 2 (0-25mm Range) Answer : 23.99
Telescopic Gauges • Spring loaded • Measure large inside dia.