Instructor:

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Unit 1GDT

• Instructor
• James Thornburgh

Agenda Objectives What is GDT? Why its
Important Measuring Break
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Objectives

• Identify and draw GDT Symbols
• Correctly use GDT symbols
• Describe Maximum and Minimum material conditions
• Describe and correctly apply Datums
• Identify various inspection tools
• Demonstrate the use of measuring devices.

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What is GDT?

• GDT is a way of dimensioning that takes into
  account function and fit with related parts.

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Why GDT is important

• Are Parts Made exactly to the drawings?
• GDT allow drawing to be more accurately
  dimensioned, with looser tolerances.

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Why GDT is important
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Measuring Inspection Devices

• Help you to determine if a part is to spec.
• Open
• You measure the piece by its self
• Functional
• You put the piece in a fixture to determine if
  its good
• Go, No-Go Gauges

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Calipers

• Vernier

• Dial

• Digital

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Reading Vernier Caliper
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Reading Vernier Caliper
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Micrometers

• Vernier

• Digital

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Reading Vernier Micrometer
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Surface Plate
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Height Gauge
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Dial Indicator
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CMM
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Material Conditions

• MMC
• Maximum Material Condition
• When a Feature Weighs the Most
• Small Hole, Large Object
• LMC
• Least Material Condition
• When a Feature Weighs the Least
• Large Hole, Small Object

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Material Conditions

• RFS
• Material size doesn't matter for Tolerance

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GDT Symbols
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Control Types

• Form Controls
• Orientation Controls
• Location Controls

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Form Controls

• Straightness
• Flatness
• Circularity
• Cylindricity

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Form Controls
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Flatness

• Microscopic View of surface

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Flatness
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Orientation Controls

• Parallelism
• Perpendicularity
• Angularity
• Profile

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Orientation Controls
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Angularity
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Profile
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Location Controls

• Position
• Concentricity
• Runout

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Position

• What is the shape of a normal Tolerance Zone?

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Position

• What is the Max it can be out of position?

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Position

• The Position Tolerance sets a round Tolerance
  Zone
• Use Basic Dimensions that have Zero Tolerance
• Symbolized by drawing a Rectangle around Dim

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Position
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Runout
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(No Transcript)
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Defining Datums
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Defining Datums
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Feature Control Frame

• Houses GDT Symbols

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Datums for Plane
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Datums for Axis Centerline
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What do They all Mean?
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What do They all Mean?
  Datum B Datum B
Feature 11.9 12
38.6 0.4 0.5
38.5 0.5 0.6
38.4 0.6 0.7
38.3 0.7 0.8
38.2 0.8 0.9
38.1 0.9 1.0
38.0 1.0 1.1
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Lab Assignments Homework

• Lab
• Measuring Handout
• Workbook 16.1-16.3
• Homework
• Read Ch 16
• Do Review Questions 1-10