# GD&T Basics

### Intended Audience

Front-line operators and quality professionals who use engineering drawings and blueprints.

### Time To Complete

2 hours (0.2 CEUs)

Print Course Info

## Why is GD&T Training Needed?

Precision parts require precision measurements and that starts with knowing how to read blueprints and engineering drawings so that the proper measurements can be taken.

## GD&T Basics Online Training

In this course, learners will be introduced to key terms used in metrology and GD&T and how to read and interpret basic engineering drawing and GD&T symbols.

## This Training Enables Learners To…

• Define key metrology terms.
• Read and interpret basic engineering drawing symbols.
• Understand GD&T terminology and symbols.

## Recommended Prerequisites

• Basic math skills.

## You May Also Be Interested In…

• Measurement Systems Analysis – Comprehensive training in how to statistically measure the accuracy and reliability of measurement systems.
• Gage Training – Focused on how to use precision hand gages to measure parts against blueprint specifications.

## Gage Training Course Outline

### Unit 1 – Gage Primer

#### Lesson 1 – Why Measure?

• Understand the three main reasons why parts are measured.
• Explain the five critical aspects of measuring.

#### Lesson 2 – Language of Measurement

• Use the language of dimensional measurement.
• Convert English to SI (metric) units of measure and SI to English units.
• Understand basic terminology used on drawings and blueprint.

#### Lesson 3 – Measurement Standards

• Explain the role of standards in the dimensional measurement field.
• Follow the traceability trail of calibration standards.

#### Lesson 4 – Precision and Accuracy

• Explain common sources of measurement error.
• Understand the impact of the five categories of measurement error: accuracy, repeatability, reproducibility, stability, and linearity.

#### Lesson 5 – Datums

• Use a datum to locate the position of part features.
• Identify datum planes, datum points, and datum axis.

#### Lesson 6 – Introduction to GD&T

• Explain the differences between coordinate tolerancing and geometric dimensioning and tolerancing.
• Interpret feature control frames.
• Use the 14 geometric characteristic controls.
• Identify GD&T modifying symbols.

#### Lesson 7 – Surface Finishes

• Characterize the finish of a surface.
• Identify the five most common types of surface deviations.
• Use surface symbols to communicate machining instructions.

#### Lesson 8 – Math for Measuring

• Convert fractions to decimals.
• Calculate the perimeter and area of rectangular shapes and the circumference and area of circular shapes.

#### Unit Test Challenge

• An assessment of the learner’s progress in this unit.

### Unit 2 – Using Gages

#### Lesson 1 – Types of Gages

• Explain the differences between direct and transfer measurement gages.
• Identify the line of measurement.
• Apply the 10-times rule of measurement.

#### Lesson 2 – Calipers

• Use a vernier scale.
• Use a caliper to take measurements.
• Explain the pros and cons of vernier, dial, and digital calipers.

#### Lesson 3 – Micrometers

• Use a micrometer to take measurements.
• Identify applications for inside and outside micrometers.

#### Lesson 4 – Height and Depth Gages

• Use height gages with a surface plate to take direct or comparative measurements.
• Identify height gage accessories used for specialty measuring applications.
• Use depth gages to measure the depth of features.

#### Lesson 5 – Fixed Gages

• Explain the pros and cons of fixed and variable gages.
• Identify measurement applications for fixed gages.

#### Lesson 6 – Test Indicators and Dial Indicators

• Use both test indicators and dial/digital indicator for comparative length measurements.
• Select indicator contact points types and test stands to specific measurement applications.

#### Lesson 7 – Gage Blocks and Surface Plates

• Wring and stack gage blocks.
• Use gage blocks to calibrate variable gages, check the validity of fixed limit ages, and to set comparative-length indicators.
• Use gage blocks with surface plates to make comparative measurements.

#### Unit Test Challenge

• An assessment of the learner’s progress in this unit.

### Unit 3 – Gaging Applications

#### Lesson 1 – Application Overview

• Understand that some dimensional instruments are appropriate and some are not for a specific measuring application.
• Realize that there are common errors and misapplications in measuring and that they can be avoided.

#### Lesson 2 – Linear Measurements

• Select the appropriate type of gages for common linear measurement applications.
• Measure the position of a hole.
• Measure the differential height between two lands.

#### Lesson 3 – Roundness and Circularity

• Use two-point contact gages to measure out-of-roundness.
• Recognize limitations of two-point contact gages for shapes that are oval, egg-shaped, irregular or lobed.
• Be exposed to three-point contact gages and sophisticated gages to measure out-of-roundness.

#### Lesson 4 – Common Misapplications

• 12 common measuring mistakes and misapplications.
• What to look out for and how to prevent these mistakes from happening.

#### Lesson 5 – Measuring Complications

• 10 systemic problems that can lead to measuring complications.
• An exploration of why each complication may occur with suggested remedies to combat the complication and make the system more robust.

#### Lesson 6 – Care of Gages

• Apply universal practices to take care of gages.
• Review tips for cleaning and caring for specific instruments.

#### Unit Test Challenge

• An assessment of the learner’s progress in this unit.

## Gage Training Course Objectives

#### Unit 1 | Gage Primer

The purpose of this unit is to develop a fundamental understanding of basic gaging concepts. The rest of the training program builds on these concepts. Upon completion of this unit you will be able to:

• Describe the purpose of measuring and the importance of precise and accurate measurements.
• Define key metrology terms.
• Explain the source of measurement standards and why they are so important.
• Read and interpret basic engineering drawing symbols.
• Understand GD&T terminology and symbols.
• Identify and classify flaws in the finish of a surface.
• Use basic geometry to describe part dimensions.

#### Unit 2 | Using Gages

In this unit you will learn the proper way to use a variety of dimensional measurement instruments. Upon completion of this unit you will be able to:

• Use calipers, vernier calipers, micrometers, and vernier micrometers and interpret readings taken with those instruments.
• Measure parts with both height and depth gages.
• Use fixed limit gages and describe the advantages and disadvantages of them.
• Perform measurements with comparative length devices such as test indicators and dial indicators.
• Use gage blocks for establishing dimensional standards as well as describe their qualities and grades.
• Explain the purpose and qualities of surface plates.

#### Unit 3 | Gaging Applications

In this unit you will learn how to select the best gage to use for particular measuring situations. Upon completion of this unit you will be able to:

• Specify the best gage to use for a variety of different measuring applications.
• Identify the best way to measure linearity, roundness, and circularity.
• Make sure you don’t make any of the most common measuring mistakes.
• Design a measurement process that eliminates or reduces potential measuring complications.
• Properly care for and maintain gages and measuring instruments.