Unit 1 GD&T Instructor: James Thornburgh Agenda: Objectives What is GDT? Why it’s Important Measuring Break Objectives Identify and draw GD&T Symbols Correctly use GD&T symbols Describe Maximum and Minimum material conditions Describe and correctly apply Datums Identify various inspection tools Demonstrate the use of measuring devices. What is GD&T? GD&T is a way of dimensioning that takes into account function and fit with related parts. Why GD&T is important Are Parts Made exactly to the drawings? GD&T allow drawing to be more accurately dimensioned, with looser tolerances. Why GD&T is important Measuring & Inspection Devices Help you to determine if a part is to spec. Open You measure the piece by it’s self Functional You put the piece in a fixture to determine if it’s good Go, No-Go Gauges Calipers Vernier Dial Digital Reading Vernier Caliper Reading Vernier Caliper Micrometers Vernier Digital Reading Vernier Micrometer Surface Plate Height Gauge Dial Indicator CMM 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 Material Conditions RFS Material size doesn't matter for Tolerance GD&T Symbols Control Types Form Controls Orientation Controls Location Controls Form Controls Straightness Flatness Circularity Cylindricity Form Controls Flatness Microscopic View of surface Flatness Orientation Controls Parallelism Perpendicularity Angularity Profile Orientation Controls Angularity Profile Location Controls Position Concentricity Runout Position What is the shape of a normal Tolerance Zone? . 02 . 02 2.00±.02 . 02 .75±.02 . 02 Position What is the Max it can be out of position? . 02 . 02 . 03 . 02 . 02 Position The Position Tolerance sets a round Tolerance Zone Use Basic Dimensions that have Zero Tolerance Symbolized by drawing a Rectangle around Dim Position 2.00 Ø2.00 Ø.02 .75 Runout Defining Datums Defining Datums Feature Control Frame Houses GD&T Symbols Datums for Plane Datums for Axis & Centerline What do They all Mean? What do They all Mean? 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 Lab Assignments & Homework Lab Measuring Handout Workbook 16.1-16.3 Homework Read Ch 16 Do Review Questions 1-10