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# GD&T Basics

Your Best Resource to Learn GD&T

## Sitemaps

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## Posts

- [Free GD&T Training Blog](https://www.gdandtbasics.com/gdt-advice/) - Get access to GD&T training, free online resources, tips, advice and answers from experienced engineers on the GD&T Basics blog.
- [Collecting Dots vs. Connecting Dots: Why Most GD&T Learning Doesn’t Stick](https://www.gdandtbasics.com/collecting-dots-vs-connecting-dots/) - If GD&T has felt frustrating or hard to apply—even after GD&T training—were you being taught the dots, or being taught how to connect them?
- [Common Thread Information: Diameters, Pitch, and Threads per Inch](https://www.gdandtbasics.com/common-thread-information-diameters-pitch-and-threads-per-inch/) - To understand the thread requirements on your drawing, you need to know common standard thread information: thread diameters, threads per inch and thread pitch.
- [Our experience at IMTS 2022](https://www.gdandtbasics.com/our-experience-at-imts-2022/) - We attended IMTS 2022 for the first time as an exhibitor, and it was an amazing experience!
- [Common GD&T Student Questions: A Single Point as a Secondary Datum](https://www.gdandtbasics.com/single-point-as-secondary-datum/) - In this video, Jason discusses whether a single point (without clocking) can be used as a secondary datum in a feature control frame.
- [Common GD&T Student Questions: Identical Virtual Conditions for Mating Boss and Bore Features](https://www.gdandtbasics.com/identical-virtual-conditions-for-mating-boss-and-bore-features/) - Is it allowable to have identical Virtual Conditions for mating boss and bore features? Watch this video to learn how to calculate and compare Virtual Conditions of mating features.
- [Common GD&T Student Questions: Perpendicular Datums from Imperfect Features](https://www.gdandtbasics.com/perpendicular-datums-from-imperfect-features/) - In this video, Jason explains how perpendicular datums can be derived from imperfect datum features.
- [Technologist vs. Senior-Level GDTP Exam – Our Experience](https://www.gdandtbasics.com/technologist-vs-senior-level-gdtp-exam/) - Preparing for the ASME GDTP exam? Our GD&T instructors share tips and experience for both Technologist and Senior-level certifications.
- [Reviewing and Redlining a Bad Drawing](https://www.gdandtbasics.com/reviewing-a-bad-drawing/) - Jason reviews a bad drawing and explains each error, showing how it conflicts with ASME Y14.5 requirements.
- [Control on Multiple Profiles](https://www.gdandtbasics.com/control-on-multiple-profiles/) - Jason reviews a drawing with two identical cutouts to show whether multiple profiles can be controlled by including a multiplier with the feature control frame.
- [ISO vs ASME Position Tolerance](https://www.gdandtbasics.com/iso-vs-asme-position-tolerance/) - In this Question Line Video, Jason reviews a drawing example and compares the ASME and ISO standards for controlling a hole with position tolerance.
- [Designing to MMC and LMC](https://www.gdandtbasics.com/designing-to-mmc-and-lmc/) - Jason answers a student’s question regarding whether a feature of size can be designed to both MMC and LMC boundary constraints.
- [Metric vs Inch Dimensions and Tolerances](https://www.gdandtbasics.com/metric-vs-inch-dimensions-tolerances/) - Jason walks through drawing examples to explain how to tell at a glance whether a drawing is using inch or metric dimensions.
- [Flatness on a Per Unit Basis](https://www.gdandtbasics.com/flatness-per-unit-basis/) - Jason discusses form controls on a per unit basis using the example of controlling flatness on a large surface in this Question Line Video.
- [Inner or Outer Diameter as Datum Feature](https://www.gdandtbasics.com/inner-or-outer-diameter-datum-feature/) - Jason discusses how to select the appropriate datum feature when designing a hollow cylindrical part where both the ID and OD are mating features.
- [Go/No-Go Gaging and Rule #1](https://www.gdandtbasics.com/go-no-go-gaging-and-rule-1/) - In this Question Line video, Brandon explains how a go gage and no-go gage are used to verify that Rule #1 of GD&T is met for a feature of size.
- [Bridging the Skills Gap: Empowering the Manufacturing Industry through Training](https://www.gdandtbasics.com/bridging-the-skills-gap/) - Address the skills gap in manufacturing with training programs that build GD&T knowledge, improve drawing interpretation, and support effective inspection.
- [What Not to Do: Avoiding Common Errors in GD&T Drawings](https://www.gdandtbasics.com/avoiding-common-errors-in-gdt-drawings/) - This series explores common errors in implementing GD&T on engineering drawings and provides practical solutions to avoiding them.
- [Measuring Runout and Circularity with V-Blocks](https://www.gdandtbasics.com/measuring-with-v-blocks/) - Jason walks through the potential issues associated with using V-Blocks and how they can affect measurements of circularity and runout.
- [GD&T Position for Bidirectional Control](https://www.gdandtbasics.com/gdt-position-for-bidirectional-control/) - In this video, Jason explains how to use a Multiple Single Segment feature control frame to achieve bidirectional position control.
- [What is Geometric Dimensioning and Tolerancing (GD&T)?](https://www.gdandtbasics.com/what-is-gdt/) - GD&T (Geometric Dimensioning and Tolerancing) uses symbols on engineering drawings to communicate design intent clearly. Here's what you need to know.
- [Why Use GD&T?](https://www.gdandtbasics.com/why-use-gdt/) - Less scrap, less rework, and drawings your suppliers actually understand. Here's the real case for ditching coordinate tolerancing and switching to GD&T.
- [How to Inspect True Position at an Angle](https://www.gdandtbasics.com/how-to-inspect-true-position-at-an-angle/) - Jason walks through an example showing how to inspect a hole with position at an angle, rather than parallel or perpendicular, to the primary datum.
- [Checking Circularity with Digital Equipment](https://www.gdandtbasics.com/checking-circularity-with-digital-equipment/) - In this Question Line Video, Jason gives a high-level overview of how polar probes and TIR checkers are used to inspect circularity or cylindricity.
- [Cylindricity Measurements](https://www.gdandtbasics.com/cylindricity-measurements/) - In this Question Line video, Jason reviews cylindricity and discusses how it is measured.
- [True Position on Bolt Circle Diameters](https://www.gdandtbasics.com/true-position-on-bolt-circle-diameters/) - Jason walks through a drawing that includes a position control on a bolt circle, explaining what the feature control frame is and is not controlling.
- [When to Use DMP Flatness](https://www.gdandtbasics.com/when-to-use-dmp-flatness/) - Brandon explains DMP flatness, its potential issues when used on stacking parts, and an alternative method for controlling flatness on these parts.
- [When to use DML Straightness](https://www.gdandtbasics.com/when-to-use-dml-straightness/) - Brandon walks through examples of surface straightness and derived median line straightness, explaining correct application and inspection considerations.
- [Symmetric Parts and GD&T](https://www.gdandtbasics.com/symmetric-parts-and-gdt/) - In this Question Line video, Jason reviews a user-submitted symmetric part drawing, explains what is incorrect, and shows how to fix it under ASME Y14.5.
- [Ring Gages to Check Size Dimensions](https://www.gdandtbasics.com/ring-gages-to-check-size-dimensions/) - In this Question Line video, Jason reviews how Rule #1 controls the size and form of a feature of size, and what this means for ring gage design and inspection reporting.
- [Size Dimensions to Avoid](https://www.gdandtbasics.com/size-dimensions-to-avoid/) - In this Question Line video, Jason discusses size dimensions to avoid with stepped surfaces and how datums and profile eliminate ambiguous dimensioning.
- [Coaxiality vs. Concentricity vs. Position](https://www.gdandtbasics.com/coaxiality-vs-concentricity-vs-position/) - In this Question Line video, Jason compares coaxiality and concentricity, as well as position, as defined by the ISO 1101 standard.
- [When to Use GD&T](https://www.gdandtbasics.com/when-to-use-gdt/) - Jason explains when to use GD&T versus traditional coordinate dimensions and compares both methods using example drawings.
- [How to Find Zero](https://www.gdandtbasics.com/how-to-find-zero/) - In this Question Line video, Jason shows how to fine the zero, or origin, for a given feature control frame.
- [The Importance of Qualifying Datums](https://www.gdandtbasics.com/importance-of-qualifying-datums/) - Jason explains how datums are qualified and the difference in how CMMs and physical datum simulators set up the datum reference frame.
- [Effects of Larger Tolerance Values](https://www.gdandtbasics.com/effects-of-larger-tolerance-values/) - Jason reviews the effects of tight position controls on features that relate to datum features with much larger form tolerances.
- [Feature of Size Flatness](https://www.gdandtbasics.com/feature-of-size-flatness/) - In this Question Line video, Jason compares flatness applied to a feature of size with flatness applied to a surface.
- [Significant Figures and Their Effects on Inspection](https://www.gdandtbasics.com/significant-figures-and-their-effects-on-inspection/) - Learn how significant figures define unspecified tolerances and how ASME Y14.43 helps determine the required accuracy of measurement equipment.
- [GD&T Tolerance Analysis – Profile](https://www.gdandtbasics.com/gdt-tolerance-analysis-profile/) - Jason walks through tolerance analysis for a profile control and shows how the feature control frame defines the location and orientation of the tolerance zone.
- [Repetitive Pattern of Features and Datums](https://www.gdandtbasics.com/repetitive-pattern-of-features-and-datums/) - Jason discusses how to control a repetitive pattern of features to a central datum using a “#X INDIVIDUALLY” note with a datum feature.
- [Comparing Profile Tolerancing Methods](https://www.gdandtbasics.com/comparing-profile-tolerancing-methods/) - Jason compares three profile tolerancing methods and explains which option he would recommend.
- [How to Use Multiple Features for a Datum](https://www.gdandtbasics.com/how-to-use-multiple-features-for-a-datum/) - Jason explains how multiple features can be used to create a single datum on a part and why it’s done.
- [How to Control True Position of an Interrupted Hole](https://www.gdandtbasics.com/true-position-of-interrupted-hole/) - Learn how to control position of an interrupted hole by treating it as a single feature or as separate features with simultaneous requirements.
- [What Tolerances Apply to Chamfers and Edge Breaks?](https://www.gdandtbasics.com/tolerances-of-chamfers-and-edge-breaks/) - Jason explains how chamfers and edge breaks are dimensioned and what tolerances apply under ASME standards when none are specified in the field of view.
- [Why You Shouldn’t Apply Bonus Tolerance Modifier to Threaded Holes](https://www.gdandtbasics.com/no-bonus-tolerance-modifier-on-threaded-holes/) - Learn why Bonus Tolerance at MMC offers little benefit on threaded holes as Jason explains how MMC works and how bonus tolerance is applied.
- [What’s the Deal with Surface vs Axis Interpretations?](https://www.gdandtbasics.com/surface-vs-axis-interpretations/) - Jason explains surface vs axis interpretations in positional tolerance at MMC, showing how ASME Y14.5 handles extreme form error and inspection decisions.
- [Meet the GD&T Basics Team: Jake DeVore, GD&T Instructor](https://www.gdandtbasics.com/meet-jake-devore/) - GD&T instructor Jake DeVore brings real-world manufacturing and inspection experience—and a passion for teaching—to every class.
- [Circularity vs Runout](https://www.gdandtbasics.com/circularity-vs-runout/) - Circularity vs runout: Learn the key differences, how each tolerance is evaluated, and what each one controls.
- [Position vs Runout](https://www.gdandtbasics.com/position-vs-runout/) - Position vs runout explained: Learn how each tolerance controls coaxial features, how they’re measured, and what they actually limit.
- [Advantages of GD&T vs. Coordinate Tolerancing](https://www.gdandtbasics.com/gdt-vs-coordinate-tolerancing/) - Everyone understands the simple plus or minus tolerances of coordinate dimensioning. So why use GD&T instead? Here are four reasons that GD&T has an advantage over coordinate tolerancing… What are the advantages of GD&T vs. Coordinate Tolerancing? Coordinate dimensioning is easy to read and understand. It’s the way most of us have learned to
- [What is a Profilometer?](https://www.gdandtbasics.com/what-is-a-profilometer/) - Ever wonder how surface finish is measured? For inspection, we use a device called a Profilometer. In this article, we will show you how profilometers work and highlight their advantages and limitations. What is a Profilometer & Why is it Used? A profilometer is an instrument used to measure the profile and surface finish of
- [3 Things Manufacturing and Quality Departments Wish You Knew About Your Drawings](https://www.gdandtbasics.com/what-mfging-and-quality-wish-you-knew/) - In this 3-Part Series, we'll review the top 3 things that manufacturing and quality departments wish you knew about your drawings.
- [Part Setup and Datum Qualification Using a CMM](https://www.gdandtbasics.com/part-setup-and-datum-qualification-using-a-cmm/) - GD&T Basics has partnered with Mitutoyo to demonstrate how to set up and inspect a part using a CMM. In this video, we examine a part designed as a training aid by Mitutoyo, inspecting it using the Mitutoyo CRYSTA-APEX S SERIES programmable CMM. Brandon John, the Engineering Training Manager for GD&T Basics, discusses the part
- [Reliable Datum Features](https://www.gdandtbasics.com/reliable-datum-features/) - In this Question Line video, Jason discusses reliable datum features. He explains that unreliable datum features can be avoided by following the functional intent of the part and walks through two drawing examples to explain the thought process behind selecting datum features.
- [CAD vs CMM Basic Dimensions](https://www.gdandtbasics.com/cad-vs-cmm-basic-dimensions/) - In this Question Line video, Jake discusses common causes of conflicting basic dimensions between a 3D model and 2D drawing and how to to investigate the source of the mismatch.
- [First Angle vs Third Angle](https://www.gdandtbasics.com/first-angle-vs-third-angle/) - In this video, Steve identifies first angle and third angle projection symbols and demonstrates how each projection method translates the 3D model into its corresponding 2D views.
- [Composite Profile with Unequally Disposed Tolerance](https://www.gdandtbasics.com/composite-profile-with-unequally-disposed-tolerance/) - In this Question Line video, Jason walks through two examples of composite profile with unequally disposed tolerance zones, discussing why and when they should be used and explaining how the zones interact to control location, orientation, and form.
- [Meet the GD&T Basics Team: Jason Richter, Technical Director](https://www.gdandtbasics.com/meet-jason-richter/) - As our Training Design Engineer at GD&T Basics, Jason Richter is responsible for creating and maintaining lessons and visual content for our courses and YouTube page, as well as hosting our GD&T Public Training Seminars.
- [Meet the GD&T Basics Team: Brandon John, Lead Trainer](https://www.gdandtbasics.com/meet-the-gdt-basics-team-brandon-john-lead-trainer/) - Making the decision to invest in GD&T training isn’t always easy. And even once you’ve made that call, you still need to pick a program that’ll teach your team what they need to know. While the concepts of GD&T are the same no matter who’s teaching, not all training programs are equal. Our instructional approach — to focus on
- [Meet the GD&T Basics Team: Steve Bobek, GD&T Instructor](https://www.gdandtbasics.com/meet-steve-bobek/) - Meet Steve Bobek, a GD&T instructor at GD&T Basics whose diverse industry background and hands-on engineering experience help students connect GD&T decisions to real manufacturing outcomes.
- [Meet the GD&T Basics Team: Molly Olson, GD&T Instructor](https://www.gdandtbasics.com/meet-molly-olson-gdt-instructor/) - Molly Olson is one of our expert GD&T Instructors, with a wealth of valuable real-world experience in quality control and inspection. She has spent nearly 20 years as a Quality Inspector and CMM Programmer and Operator across several different industries, including aerospace, firearms, robotics, and prosthetics.
- [How to Report Composite Position](https://www.gdandtbasics.com/how-to-report-composite-position/) - In this Question Line video, Jason explains how to report composite position for a pattern of holes, focusing on the challenges and methods of reporting results for the lower framework (FRTZF).
- [ASME Y14.5 2009 vs. 2018: What Are the Major Changes in the Most Recent Standard?](https://www.gdandtbasics.com/asme-2009-vs-2018/) - ASME recently released the much-awaited Y14.5 2018 GD&T Standard! Find out what has changed from the 2009 edition and what's you need to know... The rise of Geometric Dimensioning & Tolerancing has been incredibly phenomenal. A primitive concept in the 1940s, GD&T is now an internationally acclaimed system that has become the industry standard
- [The LMC Modifier](https://www.gdandtbasics.com/lmc-modifier/) - In this Question Line video, Jason explains how the LMC modifier impacts position tolerance, minimum wall thickness, and assembly clearance.
- [Design Review: The Turbo Encabulator’s Ambifacient Lunar Waneshaft](https://www.gdandtbasics.com/design-review-turboencabulator/) - In this design review, Jason examines the application of GD&T and tolerancing strategy for the Ambifacient Lunar Waneshaft used in the Turboencabulator, focusing on functional intent, manufacturability, and inspection considerations.
- [When Should I Use Basic Dimensions?](https://www.gdandtbasics.com/when-should-i-use-basic-dimensions/) - In this Question Line video, Jason demonstrates how basic dimensions paired with profile of a surface create clearer, more functional surface control.
- [Does the CAD Model or Drawing Information Take Precedence?](https://www.gdandtbasics.com/cad-model-or-drawing-take-precedence/) - In this Question Line video, Jason discusses how to approach situations where the CAD model and drawing information do not match, and how to determine which takes precedence.
- [How to Measure a Threaded Hole](https://www.gdandtbasics.com/how-to-measure-a-threaded-hole/) - In this Question Line video, learn how threaded hole location gauges are used to inspect the pitch cylinder axis and why the projected tolerance zone modifier is often the most functional spec on an internal threaded feature.
- [How to Dimension the Depth of Threads](https://www.gdandtbasics.com/how-to-dimension-the-depth-of-threads/) - In this Question Line video, Jason explains how to properly dimension the usable depth of an internal thread and reviews methods for checking it on a part.
- [Tapered Surfaces and the From-To Modifier](https://www.gdandtbasics.com/tapered-surfaces-and-the-from-to-modifier/) - In this Question Line video, Jason demonstrates how the from-to modifier can be applied to create a wedge-shaped tolerance zone for tapered surfaces.
- [Considering Form in Tolerance Stack-Up](https://www.gdandtbasics.com/considering-form-in-tolerance-stack-up/) - In this Question Line video, Jason reviews a simple part assembly to show how geometry and form factor into the tolerance stack-up analysis.
- [Flatness or Parallelism](https://www.gdandtbasics.com/flatness-or-parallelism/) - In this Question Line video, Jason reviews a submitted drawing, explaining the difference between flatness and parallelism, and gives options on how to tolerance the drawing based on what is critical to the design.
- [Checking Runout between Centers](https://www.gdandtbasics.com/checking-runout-between-centers/) - In this Question Line video, Jason walks through how to use different tools and setups to inspect the runout between centers for a submitted part drawing.
- [Rounding Basic Dimensions](https://www.gdandtbasics.com/rounding-basic-dimensions/) - In this Question Line video, Jason reviews a drawing of a clevis bracket to show the potential effects of rounding basic dimensions.
- [Designing for Coaxial Holes](https://www.gdandtbasics.com/designing-for-coaxial-holes/) - In this Question Line video, Jason reviews a submitted weldment drawing and demonstrates how to calculate the position tolerance needed for a zero-clearance fit in the worst-case assembly scenario, ensuring that the shaft can pass through two coaxial holes.
- [Quick Sanity Checks on Extrusions](https://www.gdandtbasics.com/quick-sanity-checks-on-extrusions/) - In this Question Line video, Jason shares some quick sanity checks that can help identify manufacturing issues for an extruded part being controlled by profile of a line tolerances.
- [Profile on Sheet Metal](https://www.gdandtbasics.com/profile-on-sheet-metal/) - In this Question Line video, Jason answers a question regarding how to report form variation on a part made from sheet metal.
- [Irregular Features as Datum Features](https://www.gdandtbasics.com/irregular-features-as-datum-features/) - In this Question Line video, Jason explains how an irregular feature like a hexagon can serve as a primary datum feature and discusses how this part could be inspected – touching on gage design for manual inspection and point cloud analysis using a CMM.
- [Dimensions Identified for Inspection](https://www.gdandtbasics.com/dimensions-identified-for-inspection/) - What does it mean when a dimension is circled on a drawing—and how does it impact manufacturing? In this video, Jason explains the informal use of ovals as quality control symbols and what it means for how parts are made and inspected.
- [Choosing the Right GD&T Tolerances](https://www.gdandtbasics.com/choosing-the-right-gdt-tolerances/) - In this Question Line video, Jason reviews a submitted drawing that attempts to locate two parts relative to each other and explains how to choose the correct GD&T tolerances to support the intended function.
- [Separate Requirements at MMB](https://www.gdandtbasics.com/separate-requirements-at-mmb/) - In this video, Jason explains when simultaneous requirements apply and how the “separate requirements” note affects inspection, sharing examples that illustrate reasons for using each approach.
- [Unless Otherwise Specified](https://www.gdandtbasics.com/unless-otherwise-specified/) - In this Question Line video, Jason answers the questions regarding the use of the Unless Otherwise Specified (UOS) statement on a drawing.
- [The Datum Reference Frame](https://www.gdandtbasics.com/datum-reference-frame/) - Datums are used in GD&T drawings to create a reference system for inspecting a manufactured part. This reference system is called a Datum Reference Frame (DRF).
- [Avoiding Tolerance Stacks with GD&T  ](https://www.gdandtbasics.com/avoiding-tolerance-stacks-with-gdt/) - Tolerance stacks can be a nightmare. However, when using GD&T rather than coordinate dimensioning, tolerance stack-ups within a part can be avoided.
- [Rule #1 and Title Block Tolerances](https://www.gdandtbasics.com/rule-1-and-title-block-tolerances/) - In this Question Line video, Jason answers a student's question regarding whether a default angular tolerance (found in the Title Block) must be taken into account in addition to the part meeting Rule #1 for it to pass inspection.
- [Continuous Features vs Pattern Features](https://www.gdandtbasics.com/continuous-features-vs-pattern-features/) - In this Question Line video, Jason compares two similar part drawings - one containing the Continuous Feature symbol and the other having a simultaneous requirement for a pattern of features - and discusses how the inspected values would be reported.
- [Tolerances with Draft](https://www.gdandtbasics.com/tolerances-with-draft/) - In this Question Line video, Jason introduces ASME Y14.8 and explains how to apply + or - DRAFT to size dimensions, using examples to show how to find and handle tolerances for draft features.
- [Flatness and Rule #1](https://www.gdandtbasics.com/flatness-and-rule-1/) - In this Question Line video, Jason explains how to calculate the flatness tolerance of a surface for a given example based on the size tolerances and Rule #1.
- [GD&T Interview Questions: What to Expect?](https://www.gdandtbasics.com/gdt-interview-questions/) - What should you expect during an interview for a position that requires skills in the discipline of GD&T? Whether you're interviewing for a position in engineering, manufacturing or Inspection, we will show you how to prepare a strategy and "nail" all of the questions!
- [True Position for Multiple Features](https://www.gdandtbasics.com/true-position-for-multiple-features/) - In this Question Line video, Jason walks through an example where one feature control frame is controlling position for multiple features and identifies where this practice is outlined in the ASME Y14.5 spec.
- [Tolerances for Fillets and Rounds](https://www.gdandtbasics.com/tolerances-for-fillets-and-rounds/) - In this Question Line video, Jason discusses applying tolerances to fillets and rounds, explaining why applying profile of a surface allows more direct control of the size and form than using +/- tolerances.
- [Measure and Report Unequally Disposed Profile](https://www.gdandtbasics.com/measure-and-report-unequally-disposed-profile/) - In this Question Line video, Jason explains how to measure and report the total profile deviation for an unequally disposed profile control.
- [Related vs Unrelated Envelopes](https://www.gdandtbasics.com/related-vs-unrelated-envelopes/) - In this Question Line video, Jason explains the difference between the related and unrelated actual mating envelope and walks through an example drawing to explain when and how they are used to inspect a feature.
- [Profile of a Surface with No Datums](https://www.gdandtbasics.com/profile-of-a-surface-with-no-datums/) - In this Question Line video, Jason walks through a few examples to show us the difference between profile of a surface with and without datums referenced in the feature control frame and how that affects the reported deviation.
- [Controlling a Pattern of Surfaces](https://www.gdandtbasics.com/controlling-a-pattern-of-surfaces/) - In this Question Line video, Jason discusses a user submitted drawing, explaining options for controlling profile of a pattern of surfaces.
- [Profile Unequal Zone](https://www.gdandtbasics.com/profile-unequal-zone/) - In this Question Line video, Jason discusses the ISO Unequal Zone (UZ) modifier, which is similar to the Unequally Disposed modifier of the ASME standard. He walks through an example where the UZ modifier is included in a feature control frame controlling profile of a surface and discusses how this impacts the tolerance zone.
- [Positional Control of X, Y, and Z](https://www.gdandtbasics.com/positional-control-of-xyz/) - In this Question Line video, Jason discusses the positional control of the X, Y, and Z translations for a cylindrical post on the submitted drawing. He defines the datum reference frame and zero point of the part and explains why the feature control frame in question is essential to constraining where the cylinder exists vertically.
- [Profile of a Surface vs Profile of a Line](https://www.gdandtbasics.com/profile-of-a-surface-vs-profile-of-a-line/) - In the Question Line video, Jason walks through two examples to show the design difference between Profile of a Line and Profile of a Surface.
- [Flatness - Surface vs. Feature of Size](https://www.gdandtbasics.com/flatness-surface-vs-feature-of-size/) - In this video, Brandon discusses the difference between measuring Flatness of a Surface and Flatness of a Feature of Size (FOS). Flatness of a Surface Surface flatness is the type of flatness that most people are familiar with. On a drawing, the flatness callout can point straight to the surface with a leader arrow or
- [True Position and Diametric Deviations](https://www.gdandtbasics.com/true-position-and-diametric-deviations/) - In this Question Line video, Jason answers questions regarding True Position and how to calculate diametric deviations. He discusses the difference between "True Position" and "Position" and walks through the process of determining whether the part passes inspection.
- [Datums for Castings](https://www.gdandtbasics.com/datums-for-castings/) - In this Question Line video, Jason discusses how datum targets, datum reference frames, and multiple datum structures can be of assistance in casting drawings.
- [Reverse Inspections of Orientation](https://www.gdandtbasics.com/reverse-inspections-of-orientation/) - In this Question Line video, Jason answers a question about reverse inspection of orientation and walks through an example to explain why you should not deviate from the inspection criteria given in the feature control frame.
- [Reporting Size Dimensions with a CMM](https://www.gdandtbasics.com/reporting-size-dimensions-with-a-cmm/) - In this Question Line video, Jason discusses manual vs CMM inspection and the reporting requirements of the ASME Y14.45 standard (Measurement Data Reporting standard).
- [Flatness with Datum Targets](https://www.gdandtbasics.com/flatness-with-datum-targets/) - In this Question Line video, Jason answers questions regarding datum targets and applying flatness and profile of a surface.
- [Unilateral Tolerance and Bilateral Tolerance](https://www.gdandtbasics.com/unilateral-bilateral-tolerance/) - In this article, we explain the differences between bilateral, unilateral, and unequally disposed tolerances. What is a Tolerance? Tolerances on technical drawings communicate the amount of variation permitted from a target dimension. The allowable variation can be visualized as a zone surrounding the ideal surface of the part - what is called “true profile.” For
- [When to Use MMC and MMB](https://www.gdandtbasics.com/when-to-use-mmc-and-mmb/) - In this Question Line video, Jason reviews a drawing example to explain when Maximum Material Condition and Maximum Material Boundary modifiers may be applied.
- [The Basics of Surface Finish](https://www.gdandtbasics.com/basics-of-surface-finish/) - Surface finish can be a confusing subject, especially when it comes to units or the difference between Ra and Rz. In this article, we will provide a broad overview and answer some of the most commonly asked questions... What is Surface Finish? Surface finish is the term used to describe the texture of a surface,
- [Reference Dimensions on True Position](https://www.gdandtbasics.com/reference-dimensions-on-true-position/) - In this Question Line video, Jason walks through an assembly drawing to explain the scenario where a feature being controlled by position must have a reference size dimension rather than a tolerance on the size of the feature.
- [Composite Profile Control](https://www.gdandtbasics.com/composite-profile-control/) - In this Question Line video, Jason discusses a composite feature control frame controlling profile tolerance. He walks through through the user submitted examples to explain the controls of each frame.
- [The Problem with Reporting Basic Dimensions](https://www.gdandtbasics.com/problem-with-reporting-basic-dimensions/) - In Geometric Dimensioning and Tolerancing, Basic Dimensions are theoretically exact dimensions that define the ideal exact location and orientation of surfaces and features of size. A basic dimension is shown on a drawing as a dimension inside of a box, and it will have no tolerance following it. As it is impossible to hit an
- [Why use Profile over Coordinate Dimensioning](https://www.gdandtbasics.com/why-use-profile-over-coordinate-dimensioning/) - Using the Profile of a Surface GD&T constraint instead of coordinate dimensions with plus/minus tolerances can simplify inspection procedures.
- [5 Reasons You Shouldn’t Worry About Updating to the ASME Y14.5 2018 GD&T Standard Quite Yet](https://www.gdandtbasics.com/updating-to-asme-y145-2018-standard/) - Updating to a new ASME Y14.5 standard is no easy task. It takes time and money! In this article, we discuss five of the reasons why you should consider taking your time in doing so.
- [Position Tolerance and Basic Dimensions](https://www.gdandtbasics.com/position-tolerance-and-basic-dimensions/) - The video below is in response to a question that we received on our question line from Ash. The question is as follows: "I regularly see drawings where spacing between a pair of holes is critical, but not so much the position of the pair as a whole. Often the dimension to the first hole
- [My Personal Experience with Engineering Drawing Basics](https://www.gdandtbasics.com/my-experience-with-engineering-drawing-basics/) - **As of April 1, 2022 – Engineering Drawing Basics has been renamed to Print Reading and Tolerances. The course content did not change, we simply updated the name to better reflect the product.** Engineer Essentials, owner of GD&T Basics, launched the Engineering Drawing Basics course in 2019. This course, now known as Print Reading and
- [Circular Runout VS. Total Runout](https://www.gdandtbasics.com/circular-runout-vs-total-runout/) - In this question line video, Brandon reviews the differences between the GD&T callouts for circularity, circular runout, and total runout. To examine the differences in these concepts it is helpful to first review the Geometric Dimensioning and Tolerancing hierarchy of SLOF - Size, Location, Orientation, and Form. When defining a feature, begin by specifying the
- [Runout vs Size Controlling Circularity Example](https://www.gdandtbasics.com/runout-or-size-controlling-circularity/) - Does Runout or Size control circularity when both are placed on a diameter? Watch the video to learn how this works for different scenarios.
- [Correctly Using Centerlines on Engineering Drawings](https://www.gdandtbasics.com/using-centerlines-correctly/) - Centerlines - everyone thinks they understand centerlines on Engineering Drawings, but you'd be surprised the level of confusion around this concept. In this video question response, our lead instructor goes over the real purpose for centerlines and how they are used.
- [Using a Complicated or Curved Surface as a Datum](https://www.gdandtbasics.com/curved-surface-as-datum/) - Using a Complicated or Round Surface as a Datum – 4 Holes Normal to a Curved Surface
- [How GD&T Datums Control Degrees of Freedom](https://www.gdandtbasics.com/datums-control-degrees-of-freedom/) - Video about GD&T Datums – How do they work and how do they control Degrees of Freedom (DOF)
- [ASME GD&T Exam Certification](https://www.gdandtbasics.com/asme-gdt-exam-certification/) - Some of the most common questions that we receive at GD&T Basics is regarding the ASME GDTP Certification Exams. (Yes, you can become a certified GD&T expert!) Read on to learn more about the different exams and how to become certified in Geometric Dimensioning and Tolerancing. You probably know what GD&T is and that it
- [Composite Position vs Multiple Single Segment Tolerances](https://www.gdandtbasics.com/composite-position-vs-multiple-single-segment-tolerances/) - In this video, Brandon compares a Composite Feature Control Frame and a Multiple Single Segment Feature Control Frame to show the effect of each on Position tolerance. What is a Composite Feature Control Frame? A Composite Feature Control Frame (FCF) contains two tolerance zone frameworks. It is shown to be a composite tolerance because there
- [CMM Inspection Basics](https://www.gdandtbasics.com/cmm-inspection-basics/) - Do you know how dimensions and tolerances for complex parts are measured? Often, a coordinate measurement machine or CMM is used. In this article, we will look at different types of CMM’s and discuss how they work and when they are used. What is a Coordinate Measuring Machine? A coordinate measuring machine is an instrument that is used to collect measurements of three-dimensional objects. A CMM consists of a structure that moves in three
- [How Does 1st Angle Projection Work?](https://www.gdandtbasics.com/how-does-1st-angle-projection-work/) - This post is in response to a question that we received on our question line from Gilroy. Gilroy asked us about the drawing projection method in an example problem that was a part of our Print Reading and Tolerances course, formerly known as Engineering Drawing Basics. The drawing, questions, and solution to this example are
- [Basic Dimensions and How to Report](https://www.gdandtbasics.com/reporting-basic-dimensions/) - In this video, Brandon discusses basic dimensions and why they should not be recorded on an inspection report. What Are Basic Dimensions? Basic dimensions are used in Geometric Dimensioning and Tolerancing to describe the theoretically exact location, orientation, size, or profile of a feature or datum target. Because basic dimensions are theoretically perfect dimensions, there are no tolerances
- [What Are Basic Dimensions and How Do They Work in GD&T?](https://www.gdandtbasics.com/what-are-basic-dimensions-and-how-do-they-work-in-gdt/) - A question we are often asked here at GD&T Basics is, “what is a basic dimension?” – These dimensions are often fairly confusing as they look very similar to other dimensions you may be familiar with. There are three different types of dimensions on prints: Reference Dimensions, Tolerance Dimensions, and Basic Dimensions. We’ll review brief
- [Circularity, Rule #1, and How to Report](https://www.gdandtbasics.com/circularity-rule-1-and-how-to-report/) - This video is in response to a question that we received on our question line from Amber. Amber asked us if the tolerance value for circularity can be obtained by subtracting the upper limit of diameter from the lower limit of diameter and dividing it in half. The short answer is no; that method does not
- [Cylindricity – Can you use Material Modifiers?](https://www.gdandtbasics.com/cylindricity-can-you-use-material-modifiers/) - This video is in response to a question that we received on our question line from Lokesh. Lokesh asked us if a material modifier can be used with cylindricity. Geometric Dimensioning and Tolerancing modifiers are maximum material condition, or MMC, and least material condition, or LMC. The MMC and LMC modifiers cannot be used with
- [Parallelism Feature of Size – Rules for DRF](https://www.gdandtbasics.com/parallelism-feature-of-size/) - This video is in response to a question that we received on our question line from Jamee. Jamee’s question is as follows: “For parallelism of a circular feature of size (axis) can you use two surfaces perpendicular to each other (that are both parallel to the feature axis) as datum references within the FCF to
- [Position – Controlling Threads on Features](https://www.gdandtbasics.com/position-controlling-threads-on-features/) - This video is in response to a question that we received on our question line from Tim. Tim's question is as follows: "We tend to use true position on threaded holes. Is this valid? If so, what is the proper way to measure it, and what is it "actually" measuring? Is it the true position
- [How GD&T Should Influence Your Manufacturing and Inspection Process](https://www.gdandtbasics.com/how-gdt-should-influence-your-manufacturing-and-inspection-process/) - In this video, we respond to a question asking how using Geometric Dimensioning and Tolerancing can affect internal or vendor-provided manufacturing and inspection processes. It is important to remember that the goal of GD&T is to better communicate the functional requirements of the part. Functional requirements are often related to how a part is assembled
- [Virtual Condition - Does it apply at RFS?](https://www.gdandtbasics.com/virtual-condition-mmc-or-rfs/) - In this question line video, Brandon discusses Virtual Condition and whether it can apply at Regardless of Feature Size (RFS). What is Virtual Condition (VC)? When a feature is controlled with the Maximum Material Condition (MMC) modifier or Least Material Condition Modifier (LMC), a size boundary is created based on the collection of geometric and
- [Position Tolerance vs "True Position"](https://www.gdandtbasics.com/position-vs-true-position/) - Though many people refer to the GD&T Position symbol as "True Position," they are not the same thing. Read on to learn the difference between Position and True Position and how they work together to define the position of a feature.
- [Applying GD&T to a Drawing Using Solidworks](https://www.gdandtbasics.com/applying-gdandt-solidworks-drawing/) - In this article, we outline the basic process for adding GD&T to your drawing using SolidWorks. The accompanying video goes into full detail, walking through the entire process for an example drawing.
- [Break Edges Note](https://www.gdandtbasics.com/break-edges-note/) - “Break all sharp edges and remove all burrs,” is a common drawing note used to notify the manufacturer that the sharp edges and burrs produced by the manufacturing process must be removed from the part.
- [Fillets & Rounds](https://www.gdandtbasics.com/fillets-rounds/) - Fillets and rounds are both radial edge features, with fillets applied to internal edges and rounds applied to external edges.
- [Chamfer Dimensioning](https://www.gdandtbasics.com/chamfer-dimensioning/) - A chamfer is an edge feature commonly seen on part drawings, and consists of an angled cut on an internal or external edge of a part.
- [Applying Position Tolerances to Countersunk Fixed Fastener Assembly Conditions](https://www.gdandtbasics.com/position-tolerances-to-countersunk-fixed-fastener/) - When applying position tolerances to countersunk fixed fastener assembly conditions, our design must not only ensure assembly, but also that the fastener head sits flush or below the surface of the part. We are able to determine the values required to achieve this by using the fixed fastener equation.
- [Common GD&T Student Questions: A Pattern of Holes as a Datum Feature](https://www.gdandtbasics.com/pattern-of-holes-as-secondary-datum/) - We often see a pattern of holes indicated as a datum feature in a GD&T drawing. How do we simulate this to create our datum reference frame?
- [Surface Finish and Flatness](https://www.gdandtbasics.com/surface-finish-and-flatness/) - Surface finish and flatness both limit the amount of variation in a surface – one at the micro level and one at the macro level. Is it permissible to call out both on the same surface?
- [Sheet Metal Holes as Datum Features](https://www.gdandtbasics.com/sheet-metal-holes-as-datum-features/) - If I specify a hole in a practically thin feature, such as a piece of sheet metal, is this still considered a cylindrical datum? Is this a poor choice of datum? In this article, we look at an example to help us answer these questions.
- [Rule #1 and Derived Median Line Straightness](https://www.gdandtbasics.com/rule-1-and-derived-median-line-straightness/) - "Why doesn’t Rule #1 apply to the straightness of a Derived Median Line?" In this article, we look at both surface straightness and straightness of a feature of size to understand why Derived Median Line Straightness overrules Rule #1 of GD&T.
- [Locating Datum Features](https://www.gdandtbasics.com/locating-datum-features/) - Why doesn't a feature of size that is indicated as a datum feature need to be located? In this article and corresponding question line video, we look at two drawing examples to illustrate why datum features are not located.
- [Can Minimum Wall Thickness be Ensured When Using the MMC Modifier?](https://www.gdandtbasics.com/mmc-modifier-and-wall-thickness/) - Can you use the MMC modifier and still ensure a minimum wall thickness? To answer this question, we are going to look at a drawing of a flywheel and compare how using the MMC modifier or the LMC modifier affects the minimum wall thickness.
- [Diametric Tolerance Zones](https://www.gdandtbasics.com/diametric-tolerance-zones/) - In this question line video, we explain when to use the diameter symbol in a feature control frame. The examples below illustrate the unique tolerance zones shapes and sizes for position, perpendicularity, straightness, runout, and cylindricity controls.
- [Datums, Datum Features, and Datum Simulators](https://www.gdandtbasics.com/datums-features-and-simulators/) - In this Question Line Video, Jason uses the example of a cylindrical datum feature to show how non-planar datums can be simulated and how they are able to constrain degrees of freedom.
- [Radial Hole Pattern as a Datum Feature](https://www.gdandtbasics.com/radial-hole-pattern-as-a-datum-feature/) - In this Question Line video, Jason responds to a question regarding radial hole patterns as datum features. He discusses how to set up the datum reference frame, how the datum reference frame controls degrees of freedom, and how to apply the Maximum Material Boundary.
- [Radial True Position with Composite Tolerance](https://www.gdandtbasics.com/radial-true-position-with-composite-tolerance/) - In this question line video, Jason explains how to control radial position with a composite tolerance by walking through an example of a pattern of holes on a cylinder.
- [Profile Inspection: Vectors in CMM Measurement](https://www.gdandtbasics.com/profile-inspection-vectors-in-cmm-measurement/) - Coordinate Measuring Machines (CMMs) are essential tools for obtaining precise measurements. However, to ensure accurate measurements, it is crucial to understand how to use them correctly. In this video, Jason explains the importance of recognizing and utilizing appropriate vectors when inspecting a profile or irregular surface with a CMM probe.
- [Position vs Coordinate Dimensions](https://www.gdandtbasics.com/position-vs-coordinate-dimensions/) - Geometric Dimensioning and Tolerancing, and the concept of “True Position,” originated due to a rejection of functional parts as a result of coordinate dimensioning. Let’s look at a simple assembly to illustrate why this is true, and how GD&T Position takes care of this problem.
- [Functional Gaging and CMMs](https://www.gdandtbasics.com/functional-gaging-and-cmms/) - In this Question Line video, Jason compares the use of functional gages and CMMs for inspection and discusses benefits and drawbacks of each.
- [Understanding Maximum Material Condition](https://www.gdandtbasics.com/understanding-mmc/) - "Why isn’t Maximum Material Condition always just the largest size the feature can be?” Jason answers our student's question and gives us a delicious way to remember the MMC state in this Question Line Video.
- [Virtual Condition vs Tolerance Zone](https://www.gdandtbasics.com/virtual-condition-vs-tolerance-zone/) - In our video question line, our GD&T instructors answer questions submitted by our students. In this video, we answer the question, “Is the Virtual Condition the same as the Tolerance Zone?”
- [Relating the Secondary Datum Feature to Primary Datums](https://www.gdandtbasics.com/relating-secondary-datum-feature-to-primary-datums/) - Qualification of your datum features is important to ensure that parts are inspected properly. Check out our latest article, an example of how to properly select, identify, and qualify datums!
- [Circularity - The Tolerance Zone](https://www.gdandtbasics.com/circularity-tolerance-zone/) - There can be a lot of confusion when dealing with circularity – especially when identifying the tolerance zone compared to how Rule #1 controls it. In this video, we provide a visual example to review how rule #1 controls circularity within the area between two concentric circles.
- [Position vs. Symmetry – Relative to a Datum Axis](https://www.gdandtbasics.com/position-vs-symmetry/) - What GD&T callout should you use for a flat on an otherwise cylindrical shaft? Check out this article to find the answer and more!
- [Knurling](https://www.gdandtbasics.com/knurling/) - Knurling is a process used to create a pattern on the surface of a material by displacing or deforming the surface.
- [GD&T Fundamentals Course Syllabus](https://www.gdandtbasics.com/gdt-course-syllabus/) - Take a look below for a complete list of what we cover in our GD&T Fundamentals Course. We are confident this will be the best GD&T course you will find anywhere!
- [How Tolerances Impact Machinists?](https://www.gdandtbasics.com/how-tolerances-impact-machinists/) - Precision tops the list of priorities in CNC machining since being off by a few thousandths is enough to cause serious errors. While no machine yields a 100% accuracy rate, specific approaches have been undertaken to manufacture components efficiently and economically.
- [Ask a GD&T Expert - Demos at IMTS 2022](https://www.gdandtbasics.com/ask-a-gdt-expert-imts-2022/) - We at GD&T Basics are excited to be participating in this year’s 2022 International Manufacturing Technology Show (IMTS) held in Chicago, Illinois, September 12-17, 2022.
- [Keyseats and Keyways](https://www.gdandtbasics.com/keyseats-and-keyways/) - A keyed joint is used to ensure orientation or restrict rotational movement between parts, as in the case of joining a shaft with a coupling. We discuss how a keyed joint is made and inspected in this article.
- [Introduction to Tolerances - Part II: Why Use Tolerances?](https://www.gdandtbasics.com/why-use-tolerances/) - In our last article, we introduced the concept of manufacturing tolerances & why they are necessary. In this article, we focus on the benefits of using tolerances in our part drawings.
- [Introduction to Tolerances - Part III: How are Tolerance Limits Defined?](https://www.gdandtbasics.com/how-are-tolerance-limits-defined/) - This third and final article in our Intro to Tolerances series explores how tolerance limits are determined and what types of tolerances exist.
- [Introduction to Tolerances - Part I: What is a Tolerance?](https://www.gdandtbasics.com/what-is-a-tolerance/) - In this 3-part series, we introduce one of the most important parts of an engineering drawing - Tolerances. Part I - What is a tolerance? Part II - Why use tolerances? Part III - Defining Tolerance Limits.
- [Design for Manufacturability](https://www.gdandtbasics.com/design-for-manufacturability/) - How do you create a quality design, but at the same time, keep cost and ease of production in mind? In this article we will examine three key areas in designing for manufacturability and give you several tips to get started.
- [A Comparison of GD&T Standards: ISO GPS vs. ASME Y14.5](https://www.gdandtbasics.com/iso-vs-asme-standards/) - What is the difference between the ISO and ASME GD&T standards? Read on to find the answers to these questions and more - and see our GD&T Standards Comparison Chart available to download for free below. There are many standards that define requirements for GD&T. The two most popular are published by ASME (American Society
- [Take our GD&T Skills Assessment Quiz!](https://www.gdandtbasics.com/gdt-skills-quiz/) - Having a good understanding of Geometric Dimensioning and Tolerancing is very important for anyone working in a mechanical field. GD&T is the language used in design, manufacturing, and quality inspection to communicate on engineering prints. It combines a set of symbols, rules and principles to ensure that everyone is on the same page regarding how
- [The ASME Y14.5 GD&T Standard](https://www.gdandtbasics.com/asme-y14-5-gdt-standard/) - ASME Y14.5 is an established, widely used GD&T standard containing all the necessary information for a comprehensive GD&T system. This article provides an in-depth look at of the contents, history, and purpose of the standard.
- [Concentricity - Elimination from ASME Y14.5 2018 Standard](https://www.gdandtbasics.com/concentricity-and-asme2018/) - The ASME 2018 Y14.5 GD&T Standard contains a few significant changes, including the elimination of the concentricity constraint. Check out this video article for more on this change!
- [First vs Third Angle - Orthographic Views](https://www.gdandtbasics.com/first-vs-third-angle-orthographic-views/) - Orthographic views allow us to represent a 3D object in 2D on a drawing. Orthographic views can show us an object viewed from each direction. How the views are laid out on a drawing depends on whether 3rd angle or 1st angle projection is being used. You can tell which angle projection is used by the symbol
- [Understanding the Skills Needed for Engineering Work](https://www.gdandtbasics.com/skills-needed-for-engineering/) - With just a few points of instruction in GD&T and related concepts, engineering programs could dramatically increase the confidence and ability of newly minted engineers. Here’s what every engineer ought to know before they graduate:
- [How to Use the Drill Tap Wall Chart](https://www.gdandtbasics.com/how-to-use-the-drill-tap-wall-chart/) - The most common way to produce an internal thread is to drill a hole and then use a tap to produce the thread. This is usually referred to as a tapping drill for the size of the thread that needs to be produced. There are rules of thumb that you can use to calculate the
- [How GD&T Makes Fictiv a Better Company—and How It Allows You to Create High-Quality Results](https://www.gdandtbasics.com/how-gdt-makes-fictiv-a-better-company/) - Geometric dimensioning and tolerancing (GD&T) is a system in manufacturing that can be traced back to the 1940s. It was developed by Stanley Parker while he worked at Royal Torpedo Factory in Alexandria, West Dunbartonshire, Scotland. In short, GD&T allows the drafter to accurately dimension a part and make sure it fits into its intended
- [Can GD&T Flatness be used on a Datum?](https://www.gdandtbasics.com/gdt-flatness-on-a-datum/) - A recent question we received was "Can Flatness be applied on a datum surface?" Check out the video explanation to find out how this can work.
- [Tolerance Stack Up - Chain vs Baseline Dimensioning](https://www.gdandtbasics.com/tolerance-stackup-chain-vs-baseline/) - In this video, Brandon outlines the pitfalls of Chain Dimensioning and explains how Baseline Dimensioning or GD&T can eliminate potentially unwanted tolerance stack.
- [Why Understanding GD&T Helps To Create Better Parts](https://www.gdandtbasics.com/how-gdt-helps-improve-designs/) - There are many great reasons why engineers & designers benefit from knowledge of Geometric Dimensioning & Tolerancing (GD&T). But today, we want to share with you just one reason that is particularly interesting. Even though GD&T is simply a method of communicating inspection criteria & dimensional specifications on 2D drawings, learning to use it can
- [Using Runout to Measure Concentricity](https://www.gdandtbasics.com/concentricity-vs-runout/) - The video below is in response to a question that we received on our question line from Jeff. Jeff asked us if concentricity is always equal to half of the runout value. ASME Y14.5 defines concentricity as the requirement where the derived median points of all diametrically opposed elements must align with the axis of
- [Profile Deviation Reporting](https://www.gdandtbasics.com/profile-deviation-reporting/) - This video is in response to a question that we received on our question line from Brandon. The question is as follows: "I have profile tolerance on a flat surface of 0.2 mm with respect to 3 datums. Now measuring with a CMM, I get deviations to the negative and positive side of nominal. For
- [Parallelism – Can you Reference 3 Datums?](https://www.gdandtbasics.com/parallelism-can-you-reference-3-datums/) - This video is in response to a question that we received on our question line from Ignacio. Ignacio asked us if it is a bad practice to reference three datums in a single drawing callout for the parallelism symbol. The short answer is yes, that is a bad practice. To explore this in more detail,
- [Profile of a Line Tolerance Zone](https://www.gdandtbasics.com/profile-of-a-line-tolerance-zone/) - This video is in response to a question that we received on our question line from Amar. Amar's question is as follows: "If we are given a BASIC radius of 10mm, and on the radius, we are applying a Profile of a Line Tolerance of 0.6mm, what will be the max & min size of
- [Profile of a Surface – Unilateral vs. Bilateral](https://www.gdandtbasics.com/profile-of-a-surface-unilateral-vs-bilateral/) - What is the difference between unilateral and bilateral tolerance in a profile of a surface callout? In this post, Brandon explains the difference and gives examples of how they are used. Profile of a Surface When applying a 3-Dimensional tolerance zone around a surface, usually a curved shape but could be any, the

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## Symbols

- [Profile of a Surface](https://www.gdandtbasics.com/profile-of-a-surface) - Profile of a surface describes a 3-Dimensional tolerance zone around a surface, usually which is an advanced curve or shape...
- [Multiple Identical Features](https://www.gdandtbasics.com/multiple-identical-features) - Indicates a tolerance or dimension applies to multiple identical features. Simplifies drawings by replacing repetitive callouts with a single note.
- [Slope](https://www.gdandtbasics.com/slope-modifying-symbol) - Defines the rate of change of a flat tapered surface. Used on flat features the same way conical taper is used on round ones.
- [Conical Taper](https://www.gdandtbasics.com/conical-taper) - A conical taper symbol with a dimension indicates the value is controlled as a standard taper. The value is the ratio of the diameter change to length change.
- [Arc Length](https://www.gdandtbasics.com/arc-length) - The Arc Length symbol, or the Arc Modifying symbol, is placed above a value to indicate that the arc’s length is being dimensioned on a curved outline.
- [Parting Line](https://www.gdandtbasics.com/parting-line) - Identifies the dividing line on a part where mold halves or die sections meet. More of a manufacturing note than a geometric control.
- [Dimension Origin](https://www.gdandtbasics.com/dimension-origin) - Shows that a dimension originates from a specific surface, not from the opposite end. Controls interpretation of tolerance stack in one direction.
- [Depth Symbol](https://www.gdandtbasics.com/depth) - Indicates the depth of a feature like a hole, slot, or counterbore. Replaces the word 'deep' on drawings — clean, compact, unambiguous.
- [Spherical Diameter](https://www.gdandtbasics.com/spherical-diameter) - Controls the diameter of a full spherical feature. The prefix S∅ distinguishes it from a standard diameter callout on a cylinder.
- [Diameter](https://www.gdandtbasics.com/diameter) - Indicates the dimension is a diameter, not a radius. One of the most common symbols on any drawing with cylindrical features.
- [Controlled Radius](https://www.gdandtbasics.com/controlled-radius) - A radius with a smooth, fair curve — no flats or reversals allowed within the tolerance zone. Tighter than a standard radius callout.
- [Spherical Radius](https://www.gdandtbasics.com/spherical-radius) - Applied to a spherical surface to control its radius. Works like a standard radius callout, but in all directions around the sphere.
- [Square](https://www.gdandtbasics.com/square) - Indicates a square cross-section with a single dimension. Saves space on drawings when both sides are equal — one callout covers both.
- [Radius](https://www.gdandtbasics.com/radius) - Defines a radius tolerance zone where the curve must fall between two arc boundaries. Allows slight waviness — use controlled radius when that matters.
- [Countersink](https://www.gdandtbasics.com/countersink) - Specifies the angle and diameter of a countersunk hole. Commonly paired with a depth or diameter dimension for fastener seating.
- [Spotface](https://www.gdandtbasics.com/spotface) - A very shallow counterbore used to create a clean, flat bearing surface. Common on cast or rough parts where a fastener needs a flat seat.
- [Counterbore](https://www.gdandtbasics.com/counterbore) - Specifies a flat-bottomed enlarged hole above a through hole. Controls the diameter and depth needed to seat a bolt head or fastener flush.
- [Tangent Plane](https://www.gdandtbasics.com/tangent-plane) - Applies a tolerance to the tangent plane of a surface rather than the full surface. Useful when mating contact matters more than overall surface form.
- [Restrained Condition Note](https://www.gdandtbasics.com/restrained-condition) - Specifies that the part must be measured while held in a defined restrained state. Used when in-service loads affect the measured geometry.
- [Free State Symbol](https://www.gdandtbasics.com/free-state-symbol) - Indicates a measurement taken without restraining the part. Critical for flexible or non-rigid parts that deflect under normal clamping.
- [Projected Tolerance Zone](https://www.gdandtbasics.com/projected-tolerance-zone) - Extends the tolerance zone beyond the feature itself — typically above a threaded hole. Controls where a fastener will sit in the mating part, not just the hole.
- [Continuous Feature](https://www.gdandtbasics.com/continuous-feature) - Treats interrupted surfaces as a single continuous feature under one tolerance. Eliminates the need for separate callouts on each segment.
- [Datum Target](https://www.gdandtbasics.com/datum-target) - Defines specific points, lines, or areas that establish a datum — instead of the entire surface. Used when surfaces are too rough or irregular to reference fully.
- [Envelope Requirement (E Symbol) - ISO Only](https://www.gdandtbasics.com/envelope_requirement) - An ISO-only symbol that requires the actual surface to fit within a perfect form envelope at MMC. Similar in concept to ASME Rule #1, but explicitly called out.
- [Independency](https://www.gdandtbasics.com/independency) - An ISO-only symbol that explicitly removes the envelope requirement from a feature. Allows form to vary independent of size — the opposite of Rule #1.
- [GD&T Rule #1: Envelope Principle](https://www.gdandtbasics.com/gdt-rule-1) - Requires that a feature of size have perfect form at MMC. It's a default rule in ASME Y14.5 — one every engineer should understand before drawing a size dimension.
- [Unequally Disposed Profile](https://www.gdandtbasics.com/unequally-disposed-profile) - Offsets the profile tolerance zone more to one side than the other. Useful when stock removal or coating thickness shifts the functional surface.
- [Datum Feature](https://www.gdandtbasics.com/datum) - A datum is theoretical exact plane, axis or point location that GD&T or dimensional tolerances are referenced to....
- [True Position - Position Tolerance](https://www.gdandtbasics.com/true-position) - The Position tolerance is the GD&T symbol and tolerance of location. The True Position is the exact coordinate, or location defined by basic dimensions or other means that represents the nominal value. In other words, the GD&T "Position" Tolerance is how far your feature's location can vary from its "True Position".
- [Circularity](https://www.gdandtbasics.com/circularity) - The circularity symbol is used to describe how close an object should be to a true circle...
- [Parallelism](https://www.gdandtbasics.com/parallelism) - Parallelism is a fairly common symbol that describes a parallel orientation of one referenced feature to a datum surface or line...
- [Cylindricity](https://www.gdandtbasics.com/cylindricity) - The Cylindricity symbol is used to describe how close an object conforms to a true cylinder...
- [Runout](https://www.gdandtbasics.com/runout) - Runout is how much one given reference feature or features vary with respect to another datum when the part is rotated 360° around the datum axis.
- [Concentricity](https://www.gdandtbasics.com/concentricity) - Concentricity, is a tolerance that controls the central derived median points of the referenced feature, to a datum axis. Concentricity is a very complex feature because it relies on measurements from derived median points as opposed to a surface or feature’s axis.
- [Perpendicularity](https://www.gdandtbasics.com/perpendicularity) - Perpendicularity is a fairly common symbol that requires the referenced surface or line to be perpendicular or 90° from a datum surface or line...
- [Total Runout](https://www.gdandtbasics.com/total-runout) - Total Runout is how much one entire feature or surface varies with respect to a datum when the part is rotated 360° around the datum axis...
- [Maximum Material Condition (MMC)](https://www.gdandtbasics.com/maximum-material-condition) - Maximum Material Condition (MMC), is a feature of size symbol that describes the condition of a feature or part where the maximum amount of material (volume/size) exists within its dimensional tolerance.
- [Least Material Condition (LMC)](https://www.gdandtbasics.com/least-material-condition) - Least material condition is a feature of size symbol that describes a dimensional or size condition where the least amount of material (volume/size) exists within its dimensional tolerance...
- [Regardless of Feature Size](https://www.gdandtbasics.com/regardless-of-feature-size) - Regardless of feature size simply means that whatever GD&T callout you make, is controlled independently of the size dimension of the part. RFS is the default condition of all geometric tolerances by rule #2 of GD&T and requires no callout.
- [Feature Control Frame](https://www.gdandtbasics.com/feature-control-frame) - In GD&T, a feature control frame is required to describe the conditions and tolerances of a geometric control on a part's feature...
- [Profile of a Line](https://www.gdandtbasics.com/profile-of-a-line) - Profile of a line describes a tolerance zone around any line in any feature, usually of a curved shape...
- [Angularity](https://www.gdandtbasics.com/angularity) - Angularity is the symbol that describes the specific orientation of one feature to another at a referenced angle...
- [Straightness](https://www.gdandtbasics.com/straightness) - The standard form of straightness is a 2-Dimensional tolerance that is used to ensure that a part is uniform across a surface or feature. Straightness can apply to either a flat feature such as the surface of a block, or it can apply to the surface of a cylinder along the axial direction. It is defined as the variance of the surface within a specified line on that surface.
- [Symmetry](https://www.gdandtbasics.com/symmetry) - GD&T Symmetry is a 3-Dimensional tolerance that is used to ensure that two features on a part are uniform across a datum plane...
- [Flatness](https://www.gdandtbasics.com/flatness) - GD&T Flatness is very straightforward. It is a common symbol that references how flat a surface is regardless of any other datums or features...

## Categories

- [Uncategorized](https://www.gdandtbasics.com/category/uncategorized/)
- [Form](https://www.gdandtbasics.com/category/form/)
- [Profile](https://www.gdandtbasics.com/category/profile/)
- [Orientation](https://www.gdandtbasics.com/category/orientation/)
- [Location](https://www.gdandtbasics.com/category/location/)
- [Runout](https://www.gdandtbasics.com/category/runout/)
- [GD&T Symbol Rules and Examples](https://www.gdandtbasics.com/category/gdt-symbols/) - Articles related to GD&T symbol rules and walk-through examples of GD&T Symbols and their uses
- [GD&T Design and Application](https://www.gdandtbasics.com/category/design-application/) - Articles related to design concepts or application of GD&T to engineering prints
- [Inspection of GD&T](https://www.gdandtbasics.com/category/inspection/) - Articles related to inspection of engineering prints and interpretation of GD&T for inspection purposes
- [GD&T & Print Reading Basics](https://www.gdandtbasics.com/category/print-reading/) - Articles related to reading engineering drawings and interpreting GD&T on the prints
- [ASME and ISO Standards](https://www.gdandtbasics.com/category/gdt-standards/) - Articles related to the two main GD&T Standards, ASME and ISO
- [Career Advice](https://www.gdandtbasics.com/category/career-advice/) - Articles related to Mechanical Engineering Career Advice – from our team at GD&T Basics

## Tags

- [GDandT Symbol True Position](https://www.gdandtbasics.com/tag/gdandt-symbol-true-position/)
- [GDandT Symbol](https://www.gdandtbasics.com/tag/gdandt-symbol/)
- [True Position](https://www.gdandtbasics.com/tag/true-position/)
- [form](https://www.gdandtbasics.com/tag/form/)
- [circularity](https://www.gdandtbasics.com/tag/circularity/)
- [orientation](https://www.gdandtbasics.com/tag/orientation/)
- [parallelism](https://www.gdandtbasics.com/tag/parallelism/)
- [cylindricity](https://www.gdandtbasics.com/tag/cylindricity/)
- [runout](https://www.gdandtbasics.com/tag/runout/)
- [location](https://www.gdandtbasics.com/tag/location/)
- [concentricity](https://www.gdandtbasics.com/tag/concentricity/)
- [perpendicularity](https://www.gdandtbasics.com/tag/perpendicularity/)
- [total runout](https://www.gdandtbasics.com/tag/total-runout/)
- [Profile](https://www.gdandtbasics.com/tag/profile/)
- [profile of a line](https://www.gdandtbasics.com/tag/profile-of-a-line/)
- [angularity](https://www.gdandtbasics.com/tag/angularity/)
- [straightness](https://www.gdandtbasics.com/tag/straightness/)
- [symmetry](https://www.gdandtbasics.com/tag/symmetry/)
- [flatness](https://www.gdandtbasics.com/tag/flatness/)
- [Profile of a Surface](https://www.gdandtbasics.com/tag/profile-of-a-surface/)
- [MMC GDandT symbols](https://www.gdandtbasics.com/tag/mmc-gdandt-symbols/)
- [LMC GD&T Symbol](https://www.gdandtbasics.com/tag/lmc-gdt-symbol/)
- [Least Material Condition](https://www.gdandtbasics.com/tag/least-material-condition/)
- [GD&T Symbol Regardless of Size](https://www.gdandtbasics.com/tag/gdt-symbol-regardless-of-size/)
- [GD&T Symbol Featured Control Frame](https://www.gdandtbasics.com/tag/gdt-symbol-featured-control-frame/)
- [Datums in GD&T](https://www.gdandtbasics.com/tag/datums-in-gdt/)
- [Datum symbol](https://www.gdandtbasics.com/tag/datum-symbol/)
- [engineering drawings](https://www.gdandtbasics.com/tag/engineering-drawings/)
- [dimensions and tolerances](https://www.gdandtbasics.com/tag/dimensions-and-tolerances/)
- [asme y14.5](https://www.gdandtbasics.com/tag/asme-y14-5/)
- [GD&T](https://www.gdandtbasics.com/tag/gdt/)
- [GD&T Training](https://www.gdandtbasics.com/tag/gdt-training/)
- [common datum GD&T](https://www.gdandtbasics.com/tag/common-datum-gdt/)
- [how to choose datums GD&T](https://www.gdandtbasics.com/tag/how-to-choose-datums-gdt/)
- [datum reference frame definition](https://www.gdandtbasics.com/tag/datum-reference-frame-definition/)
- [First Angle Projection](https://www.gdandtbasics.com/tag/first-angle-projection/)
- [GD&T Profile](https://www.gdandtbasics.com/tag/gdt-profile/)
- [GD&T Position](https://www.gdandtbasics.com/tag/gdt-position/)
- [Hole Pattern](https://www.gdandtbasics.com/tag/hole-pattern/)
- [Datum Reference Frame](https://www.gdandtbasics.com/tag/datum-reference-frame/)
- [GD&T Runout](https://www.gdandtbasics.com/tag/gdt-runout/)
- [Size Tolerance](https://www.gdandtbasics.com/tag/size-tolerance/)
- [GD&T Runout Tolerance](https://www.gdandtbasics.com/tag/gdt-runout-tolerance/)
- [Tolerance Stacks](https://www.gdandtbasics.com/tag/tolerance-stacks/)
- [Chain Dimensioning](https://www.gdandtbasics.com/tag/chain-dimensioning/)
- [Baseline Dimensioning](https://www.gdandtbasics.com/tag/baseline-dimensioning/)
- [Tolerance Stack up](https://www.gdandtbasics.com/tag/tolerance-stack-up/)
- [Centerlines](https://www.gdandtbasics.com/tag/centerlines/)
- [ASME Standard](https://www.gdandtbasics.com/tag/asme-standard/)
- [Design for Manufacturability](https://www.gdandtbasics.com/tag/design-for-manufacturability/)
- [DFM](https://www.gdandtbasics.com/tag/dfm/)
- [Circular Runout](https://www.gdandtbasics.com/tag/circular-runout/)
- [Print Reading](https://www.gdandtbasics.com/tag/print-reading/)
- [GD&T Interview Questions](https://www.gdandtbasics.com/tag/gdt-interview-questions/)
- [ISO Standard](https://www.gdandtbasics.com/tag/iso-standard/)
- [ASME GD&T Standard](https://www.gdandtbasics.com/tag/asme-gdt-standard/)
- [Bilateral Tolerance](https://www.gdandtbasics.com/tag/bilateral-tolerance/)
- [Unilateral Tolerance](https://www.gdandtbasics.com/tag/unilateral-tolerance/)
- [Unequally Disposed Tolerance](https://www.gdandtbasics.com/tag/unequally-disposed-tolerance/)
- [ASME GDTP Exam](https://www.gdandtbasics.com/tag/asme-gdtp-exam/)
- [GD&T Professional Certification](https://www.gdandtbasics.com/tag/gdt-professional-certification/)
- [CMM Inspection](https://www.gdandtbasics.com/tag/cmm-inspection/)
- [Basic Dimensions](https://www.gdandtbasics.com/tag/basic-dimensions/)
- [Position](https://www.gdandtbasics.com/tag/position/)
- [Coordinate Tolerancing](https://www.gdandtbasics.com/tag/coordinate-tolerancing/)
- [Position Tolerances](https://www.gdandtbasics.com/tag/position-tolerances/)
- [Surface Finish](https://www.gdandtbasics.com/tag/surface-finish/)
- [Lay](https://www.gdandtbasics.com/tag/lay/)
- [Waviness](https://www.gdandtbasics.com/tag/waviness/)
- [Surface Roughness](https://www.gdandtbasics.com/tag/surface-roughness/)
- [Concentricity. Symmetry](https://www.gdandtbasics.com/tag/concentricity-symmetry/)
- [Continuous Feature](https://www.gdandtbasics.com/tag/continuous-feature/)
- [Size Tolerances](https://www.gdandtbasics.com/tag/size-tolerances/)
- [Coordinate Dimensioning](https://www.gdandtbasics.com/tag/coordinate-dimensioning/)
- [CMM](https://www.gdandtbasics.com/tag/cmm/)
- [Profile Tolerances](https://www.gdandtbasics.com/tag/profile-tolerances/)
- [ASME Y14.5 2009 Standard](https://www.gdandtbasics.com/tag/asme-y14-5-2009-standard/)
- [ASME Y14.5 2018 Standard](https://www.gdandtbasics.com/tag/asme-y14-5-2018-standard/)
- [ASME Standard Changes](https://www.gdandtbasics.com/tag/asme-standard-changes/)
- [Expert Advice](https://www.gdandtbasics.com/tag/expert-advice/)
- [Coordinate Dimensions](https://www.gdandtbasics.com/tag/coordinate-dimensions/)
- [Composite Position](https://www.gdandtbasics.com/tag/composite-position/)
- [Multiple Single Segment](https://www.gdandtbasics.com/tag/multiple-single-segment/)
- [Third Angle Projection](https://www.gdandtbasics.com/tag/third-angle-projection/)
- [Line Profile](https://www.gdandtbasics.com/tag/line-profile/)
- [2-D Tolerance](https://www.gdandtbasics.com/tag/2-d-tolerance/)
- [Feature of Size](https://www.gdandtbasics.com/tag/feature-of-size/)
- [GD&T Symbols Details Surface Flatness](https://www.gdandtbasics.com/tag/gdt-symbols-details-surface-flatness/)
- [Flatness Measurement](https://www.gdandtbasics.com/tag/flatness-measurement/)
- [Flatness Tolerance Zone](https://www.gdandtbasics.com/tag/flatness-tolerance-zone/)
- [Datum](https://www.gdandtbasics.com/tag/datum/)
- [Rule #1](https://www.gdandtbasics.com/tag/rule-1/)
- [maximum material condition](https://www.gdandtbasics.com/tag/maximum-material-condition/)
- [Pitch Cylinder Diameter](https://www.gdandtbasics.com/tag/pitch-cylinder-diameter/)
- [Threaded Features](https://www.gdandtbasics.com/tag/threaded-features/)
- [Position vs. Symmetry](https://www.gdandtbasics.com/tag/position-vs-symmetry/)
- [What is a Tolerance](https://www.gdandtbasics.com/tag/what-is-a-tolerance/)
- [How are Tolerance Limits Defined?](https://www.gdandtbasics.com/tag/how-are-tolerance-limits-defined/)
- [Why Use Tolerances?](https://www.gdandtbasics.com/tag/why-use-tolerances/)
- [restricted state](https://www.gdandtbasics.com/tag/restricted-state/)
- [solidworks](https://www.gdandtbasics.com/tag/solidworks/)
- [tangent plane](https://www.gdandtbasics.com/tag/tangent-plane/)
- [keyed joints](https://www.gdandtbasics.com/tag/keyed-joints/)
- [keyway](https://www.gdandtbasics.com/tag/keyway/)
- [keyseat](https://www.gdandtbasics.com/tag/keyseat/)
- [counterbore](https://www.gdandtbasics.com/tag/counterbore/)
- [threads](https://www.gdandtbasics.com/tag/threads/)
- [spotface](https://www.gdandtbasics.com/tag/spotface/)
- [countersink](https://www.gdandtbasics.com/tag/countersink/)
- [knurling](https://www.gdandtbasics.com/tag/knurling/)
- [radius](https://www.gdandtbasics.com/tag/radius/)
- [controlled radius](https://www.gdandtbasics.com/tag/controlled-radius/)
- [diameter](https://www.gdandtbasics.com/tag/diameter/)
- [square](https://www.gdandtbasics.com/tag/square/)
- [spherical radius](https://www.gdandtbasics.com/tag/spherical-radius/)
- [spherical diameter](https://www.gdandtbasics.com/tag/spherical-diameter/)
- [chamfer dimensioning](https://www.gdandtbasics.com/tag/chamfer-dimensioning/)
- [edge features](https://www.gdandtbasics.com/tag/edge-features/)
- [fillets](https://www.gdandtbasics.com/tag/fillets/)
- [rounds](https://www.gdandtbasics.com/tag/rounds/)
- [chamfer](https://www.gdandtbasics.com/tag/chamfer/)
- [break edges](https://www.gdandtbasics.com/tag/break-edges/)
- [remove burrs](https://www.gdandtbasics.com/tag/remove-burrs/)
- [depth](https://www.gdandtbasics.com/tag/depth/)
- [dimension origin](https://www.gdandtbasics.com/tag/dimension-origin/)
- [parting line](https://www.gdandtbasics.com/tag/parting-line/)
- [arc length](https://www.gdandtbasics.com/tag/arc-length/)
- [conical taper](https://www.gdandtbasics.com/tag/conical-taper/)
- [slope](https://www.gdandtbasics.com/tag/slope/)
- [datum features](https://www.gdandtbasics.com/tag/datum-features/)
- [bolt circle](https://www.gdandtbasics.com/tag/bolt-circle/)
- [virtual condition](https://www.gdandtbasics.com/tag/virtual-condition/)
- [MMC](https://www.gdandtbasics.com/tag/mmc/)
- [unrelated actual mating envelope](https://www.gdandtbasics.com/tag/unrelated-actual-mating-envelope/)
- [related actual mating envelope](https://www.gdandtbasics.com/tag/related-actual-mating-envelope/)
- [Senior GDTP Exam](https://www.gdandtbasics.com/tag/senior-gdtp-exam/)
- [Technologist GDTP Exam](https://www.gdandtbasics.com/tag/technologist-gdtp-exam/)
- [GDTP Exam tips](https://www.gdandtbasics.com/tag/gdtp-exam-tips/)
- [tolerance zone](https://www.gdandtbasics.com/tag/tolerance-zone/)
- [derived median line straightness](https://www.gdandtbasics.com/tag/derived-median-line-straightness/)
- [LMC](https://www.gdandtbasics.com/tag/lmc/)
- [diametric tolerance zone](https://www.gdandtbasics.com/tag/diametric-tolerance-zone/)
- [multiple identical profiles](https://www.gdandtbasics.com/tag/multiple-identical-profiles/)
- [extracted integral feature](https://www.gdandtbasics.com/tag/extracted-integral-feature/)
- [extracted derived feature](https://www.gdandtbasics.com/tag/extracted-derived-feature/)
- [datum simulator](https://www.gdandtbasics.com/tag/datum-simulator/)
- [functional gage](https://www.gdandtbasics.com/tag/functional-gage/)
- [per unit basis](https://www.gdandtbasics.com/tag/per-unit-basis/)
- [Go/No-Go Gages](https://www.gdandtbasics.com/tag/go-no-go-gages/)
- [multiple identical features](https://www.gdandtbasics.com/tag/multiple-identical-features/)
- [inspection](https://www.gdandtbasics.com/tag/inspection/)
- [v-blocks](https://www.gdandtbasics.com/tag/v-blocks/)
- [composite feature control frame](https://www.gdandtbasics.com/tag/composite-feature-control-frame/)
- [reference dimension](https://www.gdandtbasics.com/tag/reference-dimension/)
- [maximum material boundary](https://www.gdandtbasics.com/tag/maximum-material-boundary/)
- [datum target](https://www.gdandtbasics.com/tag/datum-target/)
- [derived median plane](https://www.gdandtbasics.com/tag/derived-median-plane/)
- [asme y14.45](https://www.gdandtbasics.com/tag/asme-y14-45/)
- [castings](https://www.gdandtbasics.com/tag/castings/)
- [ring gage](https://www.gdandtbasics.com/tag/ring-gage/)
- [MMB](https://www.gdandtbasics.com/tag/mmb/)
- [coaxiality](https://www.gdandtbasics.com/tag/coaxiality/)
- [feature control frame](https://www.gdandtbasics.com/tag/feature-control-frame/)
- [unequal zone](https://www.gdandtbasics.com/tag/unequal-zone/)
- [ASME Y14.8](https://www.gdandtbasics.com/tag/asme-y14-8/)
- [pattern of features](https://www.gdandtbasics.com/tag/pattern-of-features/)
- [asme y14.43](https://www.gdandtbasics.com/tag/asme-y14-43/)
- [measurement accuracy](https://www.gdandtbasics.com/tag/measurement-accuracy/)
- [unspecified tolerances](https://www.gdandtbasics.com/tag/unspecified-tolerances/)
- [UOS](https://www.gdandtbasics.com/tag/uos/)
- [separate requirements](https://www.gdandtbasics.com/tag/separate-requirements/)
- [true geometric counterpart](https://www.gdandtbasics.com/tag/true-geometric-counterpart/)
- [extrusion profile](https://www.gdandtbasics.com/tag/extrusion-profile/)
- [tapered surface](https://www.gdandtbasics.com/tag/tapered-surface/)
- [from-to modifier](https://www.gdandtbasics.com/tag/from-to-modifier/)
- [projected tolerance zone](https://www.gdandtbasics.com/tag/projected-tolerance-zone/)
- [orthographic views](https://www.gdandtbasics.com/tag/orthographic-views/)