10.5 Profile Applications: Conicity, Extruded and Irregular Shapes, and Profile-Controlled Datum Features

ASME GDTP Technologist Y14.5-2009

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1 Chapter 1: Scope, Certification Logistics, Fundamental Rules & General Dimensioning

1.1 ASME GDTP Technologist Exam Scope, Prometric Logistics, & Certification Rules 1.2 Fundamental Rules of ASME Y14.5-2009 (Rules a through p) 1.3 Engineering Drawing Standards, Drawing Units, & Basic vs. Toleranced Dimensions 1.4 Dimensioning Features: Diameters, Radii, Chamfers, Countersinks, Counterbores, Spotfaces, Keyseats & Slots 1.5 Application of Dimensions & Location of Features: Lines, Leaders, Reference Dimensions, Rectangular vs. Polar Coordinates

2 Chapter 2: Features, Limits of Size, & Material Condition Principles

2.1 Features, Features of Size, & Limits of Size 2.2 Rule #1 (Taylor Principle / Envelope Rule), Its Exceptions & Overrides 2.3 Material Condition Concepts: MMC, LMC, & RFS Calculations

3 Chapter 3: General Tolerancing & Symbology

3.1 Direct Tolerancing, Limit Dimensioning, & Angular Tolerancing 3.2 The 14 Geometric Characteristic Symbols, Feature Control Frames, & Special Modifiers 3.3 Screw Threads, Gears & Splines, Angular Surfaces, Tapers & Statistical Tolerancing 3.4 Feature Control Frame Placement, Combined Frames, Tolerance Zone Definition & Tabulated Tolerances

4 Chapter 4: Datum Reference Frames & Degrees of Freedom

4.1 Theoretical Datums, Datum Feature Simulators, & Physical Datum Features 4.2 Degrees of Freedom Constraint & The 3-2-1 Datum Precedence System 4.3 Planar, Cylindrical, & Width Datum Feature Establishment

5 Chapter 5: Advanced Datum Applications: Targets, Boundary Modifiers, Customized Frames & Restrained Condition

5.1 Datum Target Points, Lines, Areas, & Movable Datum Simulators 5.2 Material Boundary Modifiers (RMB, MMB, LMB) & Datum Shift Calculations 5.3 Functional Datum Feature Selection, Multiple Datum Reference Frames & Simultaneous vs. Separate Requirements 5.4 Rotational Constraint About a Datum Axis or Point & Customized Datum Reference Frames 5.5 Irregular & Complex Datum Features, Mathematically Defined Surfaces, Restrained Condition & Datum Feature Controls

6 Chapter 6: Form Tolerances

6.1 Flatness & Straightness Controls for Surfaces & Features of Size 6.2 Circularity & Cylindricity Controls, Differences, & Inspection

7 Chapter 7: Orientation Tolerances

7.1 Parallelism Controls for Planar Surfaces & Cylindrical Features of Size 7.2 Perpendicularity & Angularity Tolerances with Basic Angles & Tangent Plane

8 Chapter 8: Location: Position Fundamentals & Calculations

8.1 Position Tolerancing Fundamentals, True Position, & Coordinate Conversions 8.2 Bonus Tolerance & Virtual Condition Calculations for Internal & External Features 8.3 Projected Tolerance Zones (Ⓟ Modifier) & Fixed vs. Floating Fastener Formulas 8.4 Zero Positional and Orientation Tolerancing at MMC and at LMC 8.5 Surface vs. Axis Interpretation of Position & the Boundary Concept for Slots, Tabs & Noncircular Features

9 Chapter 9: Location: Patterns, Composite Controls, Coaxial & Symmetrical Relationships, and Functional Gaging

9.1 Hole & Slot Patterns, Multi-Segment Frames, & Composite Position Tolerancing 9.2 Functional Gaging Principles & Inspection Verification of Position 9.3 Coaxial Holes, Counterbored Holes, Non-Parallel Axes, Spherical Features & Bidirectional Position 9.4 Concentricity & Symmetry Tolerances Under ASME Y14.5-2009 9.5 LMC Applied to Position: Wall Thickness, Breakout Protection & Boundary Calculations

10 Chapter 10: Profile Tolerances

10.1 Profile of a Line & Profile of a Surface Fundamentals & Basic Geometry 10.2 Bilateral, Unilateral, & Unequally Disposed Profile Boundaries (Ⓤ Modifier) 10.3 Composite Profile Tolerances vs. Multiple Single-Segment Profile Controls 10.4 Profile Verification, Coplanarity Controls, & Non-Rigid Parts 10.5 Profile Applications: Conicity, Extruded and Irregular Shapes, and Profile-Controlled Datum Features 10.6 Modifier Rules for Profile & Combined Controls (Profile with Position, Orientation and Runout)

11 Chapter 11: Runout Tolerances & Comparative Control Analysis

11.1 Circular Runout vs. Total Runout Interpretation & Dial Indicator Verification 11.2 Comparative Analysis: Runout vs. Form, Orientation, & Concentricity Controls

10.5 Profile Applications: Conicity, Extruded and Irregular Shapes, and Profile-Controlled Datum Features

Key Takeaways Explain This Topic AI

ASME Y14.5-2009 para. 8.4.2 states that a profile tolerance may control conicity either as an independent control of form or as a combination of size, form, orientation, and location, and that in each case the feature must be within its size limits.

Profile applied to a cone without datum references refines form only and never replaces the size dimension, so a perfectly conical feature can still be rejected for size.

The all-around symbol of para. 8.3.1.4 applies the profile tolerance around the true profile in the view where it is specified, while the all-over symbol of para. 8.3.1.6 applies it to all three-dimensional surfaces of the part.

Para. 8.4.1.1 defines coplanarity as two or more surfaces having all elements in one plane and permits profile of a surface to treat them as a single interrupted surface, a job flatness cannot do because flatness applies to only one surface.

Profile of a surface applied to a datum feature is the standard way to satisfy the para. 4.9 requirement that complex or mathematically defined datum features be controlled directly, and such a control may reference only higher-precedence datums.

Last updated: September 2026

10.5 Profile Applications: Conicity, Extruded and Irregular Shapes, and Profile-Controlled Datum Features

Quick Answer: Para. 8.4 covers what profile is actually applied to. Para. 8.4.1.1 treats coplanarity — two or more surfaces with all elements in one plane — as a single interrupted surface. Para. 8.4.2, Conicity , states that a profile tolerance may control the conicity of a surface in two ways: as an independent control of form, or as a combination of size, form, orientation, and location — and in each case the feature must still be within its size limits . Profile is also the standard means of defining an extruded (linear-swept) outline and any irregular shape that cannot be described by analytic geometry, and it is the normal way to satisfy the para. 4.9 requirement to control a complex datum feature directly .

Conicity (Para. 8.4.2)

A cone is the most instructive profile application because it exposes the full range of what profile can control.

Callout Style What Profile Controls Datum Reference Size Still Applies?

⌓ 0.2 with basic angle and basic diameter, no datums Form only — conicity is a refinement of size None Yes
⌓ 0.2 | A with basic angle and basic diameter Form and orientation to the datum axis Datum axis A Yes
⌓ 0.2 | A | B with all basic dimensions Form, orientation, and location Full frame Yes

The standard's own two illustrations map onto the first and second rows: a conical feature controlled by a profile of a surface tolerance where conicity of the surface is a refinement of size , and the same control oriented to a datum axis . The recurring sentence is the one candidates skip: in each case, the feature must be within size limits.

Why this matters. Profile applied without datums to a cone does not replace the size dimension. A cone can be perfectly conical, perfectly formed, and still be rejected because its diameter at the gage line is out of tolerance. Profile refines; the size dimension still governs.

Recall the taper specification options of para. 2.13 , which cross-reference this paragraph directly. Method (b) — a size tolerance combined with a profile of a surface tolerance applied to the taper — is method 8.4.2 seen from the General Tolerancing side, and method (d) is a composite profile tolerance .

Extruded and Irregular Outlines

Where a part cross-section is swept along a straight line — an extrusion, a machined pocket of constant section, a stamped bracket outline — the true profile is defined by basic dimensions in the section view , and a profile of a surface tolerance controls the swept surface over the stated extent. Two mechanisms from para. 8.3.1 do most of the work:

All-around (8.3.1.4) : where a profile tolerance applies all around the true profile of the designated features of the part , in the view where it is specified. The symbol is a circle at the bend of the leader. It follows the 2D outline in that view — it does not wrap onto surfaces in other views.

All-over (8.3.1.6) : a profile tolerance may be applied all over the 3-dimensional profile of a part unless otherwise specified. The symbol is two concentric circles at the leader bend.

Limited segment (8.3.1.5) : where segments of a profile have different tolerances , the extent of each may be indicated by reference letters and the between symbol — for example A ↔ B .

For genuinely irregular shapes the boundary concept applies, and para. 8.8 combines profile with position so that the profile tolerance controls the shape and size of the feature while the positional tolerance establishes a theoretical boundary shaped identically to the true profile . ALL-AROUND (8.3.1.4) ALL-OVER (8.3.1.6) BETWEEN (8.3.1.5)

○ ◎ A ↔ B
┌────────────┐ ┌────────────┐ ┌──●──────●──┐
│ │ │▓▓▓▓▓▓▓▓▓▓▓▓│ │ A B │
│ 2D outline│ │▓ every 3D ▓│ │ only this │
│ in THIS │ │▓ surface ▓│ │ segment │
│ view │ │▓▓▓▓▓▓▓▓▓▓▓▓│ │ │
└────────────┘ └────────────┘ └────────────┘
Coplanarity as a Profile Application (Para. 8.4.1.1)

Coplanarity is the condition of two or more surfaces having all elements in one plane. A profile of a surface tolerance may be used where it is desired to treat two or more surfaces as a single interrupted or noncontinuous surface . In this case, a control is provided similar to that achieved by a flatness tolerance applied to a single plane surface .

The specification pattern is a profile feature control frame with no datum reference (when the requirement is purely that the pads be co-surfaced) or with datums (when the interrupted surface must also be located), accompanied by a note such as 2 SURFACES or a 2X designation. Flatness cannot do this job — flatness applies to one surface — which is why coplanarity is a profile topic rather than a form topic.

Profile-Controlled Datum Features

Para. 4.9 requires datum features to be controlled directly by geometric tolerances or indirectly by dimensions such as size . For a complex or mathematically defined datum feature (para. 4.13), there is no size dimension to lean on and no simple form control that fits — so profile of a surface applied to the datum feature itself is the standard answer.

Two patterns recur:

Profile without datums on the datum feature : controls the datum feature's own form, so that the theoretical datum feature simulator has a well-formed surface to contact.

Profile referencing higher-precedence datums on the datum feature : controls the datum feature's form and its orientation or location relative to datums earlier in the precedence order. Datum feature B may be profiled to A; it may never be profiled to C.

Para. 8.4.1.1 supplies a third pattern that is easy to miss: interrupted coplanar surfaces may themselves serve as a datum feature , with the profile-controlled composite surface establishing a single datum plane from all of the pads together.

Datum Feature Type Direct Control of Choice Reason
Planar surface Flatness One surface, no size
Cylindrical feature of size Rule #1, or straightness/cylindricity Size dimension is available
Interrupted coplanar pads Profile of a surface Flatness cannot span multiple surfaces
Conical seat Profile (or angularity + size) Combines size, form, orientation

Complex / mathematically defined contour Profile of a surface Only control that follows an arbitrary true profile