Basic Measurement 110

This class introduces the basic measuring devices used in the shop to ensure part quality. Includes an Interactive Lab.


Class Name:
Basic Measurement 110
This class introduces the basic measuring devices used in the shop to ensure part quality. Includes an Interactive Lab.
Number of Lessons:
Additional Language:
Spanish, Chinese

Class Outline

  • Objectives
  • The Importance of Measurements
  • Gaging vs. Inspection
  • Accuracy and Precision
  • Sensitivity
  • The Machinist’s Rule
  • Calipers
  • Micrometers
  • Vernier Scale
  • Reading a Micrometer
  • Types of Micrometers
  • Gage Blocks
  • Plug Gages
  • Ring, Thread, and Snap Gages
  • Optical Comparators
  • Coordinate Measuring Machines
  • Instrument Calibration
  • Summary


  • Define standardization.
  • Distinguish between gaging and inspection.
  • Distinguish between accuracy and precision.
  • Define sensitivity for measuring devices.
  • Identify the uses for the steel rule.
  • Identify the uses for the caliper.
  • Describe the micrometer.
  • Explain the vernier scale.
  • Read a manual micrometer.
  • Identify common micrometers.
  • Describe the uses for gage blocks.
  • Describe the use of plug gages.
  • Identify other common gages.
  • Identify the uses for the optical comparator.
  • Describe the uses for the coordinate measuring machine.
  • Identify the role of calibration.

Job Roles


  • CNC Lathe Operations
  • CNC Milling Operations
  • Drill Press I
  • Grinding I
  • Job Planning, Benchwork, & Layout I
  • Measurement, Materials, & Safety I
  • Milling I
  • MSSC Manufacturing Processes and Production
  • MSSC Quality Practices and Measurement


Vocabulary Term Definition
accuracy The difference between a measurement reading and the true value of that measurement.
alloy steel Steel that contains added materials that change the property of the metal. Common alloy elements include chromium, manganese, molybdenum, and nickel.
axes Imaginary lines perpendicular to one another that are used to define the position of objects in three-dimensional space.
blade micrometer A type of micrometer with flattened tips on the anvil and spindle. It is primarily used to measure narrow external grooves.
calibration The comparison of a device with unknown accuracy to a device with a known, accurate standard to eliminate any variation in the device being checked.
caliper A measuring instrument with two pairs of jaws on one end and a long beam containing a marked scale of unit divisions. One pair of jaws measures external features; the other pair measures internal features.
carbide A compound developed by the combination of carbon with usually chromium, tungsten, or titanium. Carbide materials are very hard and wear resistant.
chromium A shiny, hard, steel-gray metal used to add hardness and wear resistance to steel. Many gages are plated with chromium.
contour A curved surface or feature of a workpiece.
coordinate measuring machine A sophisticated measuring instrument with a flat polished table and a suspended probe that measures parts in three-dimensional space.
depth micrometer A type of micrometer with a spindle perpendicular to a flat base. It is primarily used to measure the depth of holes.
English measurements A standard system of measurements based on the inch, second, pound, and Fahrenheit degrees. English measurements are primarily used in the United States and England.
gage block A hardened steel block that is manufactured with highly accurate dimensions. Gage blocks are available in a set of standardized lengths.
gaging The physical inspection of part features using a device with an established standard size. Gaging results in a pass/fail decision.
go/no-go gaging The use of a gage to determine whether a part feature simply passes or fails inspection. No effort is made to determine the exact degree of error.
granite A dense, hard type of rock that exhibits excellent wear resistance and stability. Granite tables are used for various measuring applications.
groove micrometer A type of micrometer with a long stem and two small discs at the end. It is primarily used to measure the width and position of internal grooves.
inspection The examination of a part during or after its creation to confirm that it adheres to specifications.
lapped Polished with an abrasive paste to remove the last bit of unwanted material.
metric measurements A standard system of measurements based on the meter, second, kilogram, and Celsius degrees. The metric system is internationally recognized.
micrometer A U-shaped measuring instrument with a threaded spindle that slowly advances toward a small anvil. Micrometers are available in numerous types for measuring assorted dimensions and features.
optical comparator A sophisticated measuring instrument that projects an image of a part onto a screen to compare the shape, size, and location of its features.
plug gage A hardened, cylindrical gage used to inspect the size of a hole. Plug gages are available in standardized diameters.
precision The degree to which an instrument will repeat the same measurement over a period of time.
ring gage A hardened, round gage with a hole used to inspect the size of cylindrical parts or features.
rule of ten The inspection guideline stating that a measuring instrument must be ten times more precise than the acceptable tolerance of the inspected part feature.
sensitivity The smallest change in a measurement that an instrument is capable of detecting.
snap gage A U-shaped gage with hardened, adjustable anvils on opposite ends used to inspect the length of part features.
standardization The development of universally recognized units of measurement. Standardization ensures that parts of the same size are interchangeable.
steel rule A simple measuring instrument consisting of a long, thin metal strip with a marked scale of unit divisions.
stock Raw material that is used to make manufactured parts. Stock is available in standard shapes such as long bars, plates, or sheet.
thread gage A hardened, threaded gage used to inspect the internal threads of a part.
tolerance The unwanted but acceptable deviation from a desired dimension.
variable inspection The inspection of part features using an instrument calibrated in standard measurement units. Variable inspection reveals the degree of variation from a given standard.
vernier scale A type of scale consisting of two opposing line markings with different divisions. Vernier scales appear on both manual calipers and micrometers.
wear allowance The slight amount of material intentionally remaining on a gage to prevent the passing of defective parts over time.
wring To twist and rub together so that the two surfaces cling to one another.