# Fully Constrained Sketches and Clear Drawings

> Separate fully constrained CAD sketches from complete manufacturing drawings, with clear tolerances, datum references, and an RFQ checklist.

Canonical page: https://appalachiantool.com/wiki/fully-defined-drawings.html

Updated: 2026-11-06T01:55:48Z

Fully constrained describes how CAD geometry behaves. A fully defined manufacturing package describes what to make and how to decide whether it conforms. Review both before sending a part for quotation: a locked sketch does not, by itself, communicate acceptable manufacturing variation.

## What fully constrained means in a CAD sketch

Autodesk defines a fully constrained Fusion sketch as one in which all sketch geometry has its size and position completely defined through constraints and dimensions. In degrees-of-freedom terms, no unintended geometric movement remains. Dimensions establish values; geometric constraints establish relationships. A circle with a defined diameter can still move if its center position remains unconstrained. [[1]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-1)

Build constraints around design intent. A centered feature should remain centered when surrounding dimensions change; a relationship intended to stay parallel should remain parallel. Use the sketch's constraint status and controlled edits to check the intended behavior. Fully constrained geometry can still embody an incorrect design, so review the relationships as well as the status indicator.

Avoid adding redundant driving dimensions. Fusion distinguishes driving dimensions, which control geometry, from driven dimensions, which report values determined elsewhere. Autodesk documents using a driven dimension when another driving dimension would overconstrain the sketch. More dimensions are not automatically a better definition. [[2]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-2)

## A manufacturing definition has a different purpose

ASME Y14.100 addresses preparation and revision of engineering drawings and associated lists. ASME Y14.41 addresses digital product-definition data sets and digital drawings. A model-based package can carry manufacturing requirements; a bare solid containing nominal geometry should not be assumed to contain them. [[3]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-3) [[4]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-4)

Identify the released drawing and model revisions, units, governing standards and editions, and the controlling source if documents disagree. Include material specification and condition, required treatments or coatings, surface requirements, and complete thread requirements where applicable. Identify the finished state in which requirements apply.

For each manufactured feature, the package should resolve its intended size, location, orientation, and other relevant geometric requirements. Use appropriate callouts, notes, model annotations, or explicitly invoked general specifications. Do not infer acceptance from the number of decimal places displayed by a CAD measurement tool.

## Define requirements once and distinguish dimension types

State each controlling dimensional requirement once, with a clear scope. If a repeated value helps readability, identify its informational role instead of creating competing acceptance requirements. Reference dimensions provide auxiliary information and do not independently govern manufacturing or inspection; SOLIDWORKS' discussion explains this established distinction. A reference value should not receive an invented acceptance tolerance just to make every visible number look complete. [[5]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-5)

Basic dimensions in ASME practice describe theoretically exact geometry. They work with the applicable geometric control rather than carrying their own plus/minus acceptance band. KEYENCE's explanation of theoretically exact dimensions illustrates the separation between the ideal target and the tolerance stated in a feature-control frame. Interpret the actual drawing under its declared system. [[6]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-6)

ASME Y14.5 provides the rules for size and geometric controls, including form, orientation, location, and datum references. A hole's diameter and its relationship to the mating assembly are different design questions. Tightening one size tolerance does not automatically define all of those relationships. [[7]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-7)

## Follow one hypothetical bracket from sketch to inspection

Imagine a bracket with a seating face, a locating hole, and two mounting holes. This is an illustrative review exercise, not a finished design or a tolerance recommendation. In CAD, constrain the intended hole centers and diameters and establish the bracket outline. Check that a deliberate width change preserves the intended relationships.

Then review the manufacturing definition separately. Which face seats against the assembly? Which feature locates the bracket? What size variation is acceptable for the locating hole? How must the mounting-hole pattern relate to the assembly references? The design authority must select the datum scheme and controls that answer those questions.

If basic dimensions establish the nominal hole locations, find the corresponding geometric tolerance. If an overall dimension merely summarizes already controlled geometry, keep its reference role clear. Ask the inspection team how it will establish the required alignment and report the controlled characteristics. No arbitrary tolerance or machine-capability promise is needed to identify these missing decisions.

## Use ISO standards as a coordinated definition

For an ISO drawing, separate presentation from acceptance. ISO 129-1:2018 addresses how dimensions and tolerances are presented, not their application or meaning. ISO 8015:2011 supplies fundamental GPS interpretation principles and treats the drawing as the complete documentation package. Select explicit editions and applicable amendments; do not import ASME defaults into an ISO definition. [[9]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-9) [[10]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-10)

Then connect each requirement to its purpose. ISO 1101:2017 provides geometric-specification symbols and interpretation; ISO 5459:2024 addresses datums and datum systems. Use these together to explain what geometry is controlled and the references against which it is evaluated. ISO 14405-1:2025 addresses linear-size indications and size characteristics. It does not choose the characteristic appropriate to your function; engineering must make that decision. [[11]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-11) [[12]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-12) [[13]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-13)

General tolerances also need explicit invocation and applicable scope. ISO 2768-1:1989 excludes theoretically exact and auxiliary bracketed dimensions; it does not supply defaults for an unspecified drawing. Check the edition, class, feature, and size interval. [[8]](https://appalachiantool.com/wiki/fully-defined-drawings.html#source-8) See [GD&T and general tolerances](https://appalachiantool.com/wiki/gdt-tolerances.html) for more detail. When calculating missing geometry, distinguish [derived nominal values from acceptance requirements](https://appalachiantool.com/wiki/geometry-from-drawings.html).

## Check the RFQ package before release

* Confirm units, part identity, revision, and drawing/model precedence.
* Resolve missing size, location, orientation, and datum information.
* Distinguish controlling, basic, and reference dimensions.
* Confirm material condition, thread details, finish, and processing state.
* Include invoked specifications and approved clarifications.
* Agree inspection deliverables and who approves design changes.

Use [CMM inspection planning](https://appalachiantool.com/wiki/cmm-inspection.html) to connect requirements to reports and [the five-axis machining guide](https://appalachiantool.com/wiki/5-axis-machining.html) to discuss access and setups. Review [ATM's machining processes](https://appalachiantool.com/capabilities.html) and [equipment register](https://appalachiantool.com/equipment.html), then [send the released package for review](https://appalachiantool.com/contact.html). Keep unresolved design questions visible. The [Machining Knowledge hub](https://appalachiantool.com/wiki/index.html) provides related planning guidance.

## Questions before you quote

### Does a fully constrained sketch mean the drawing is complete?

No. It defines CAD geometry's behavior. The manufacturing package must also communicate tolerances, material and finish requirements, applicable standards, and acceptance conditions.

### Should every displayed dimension have its own tolerance?

No. Reference dimensions are informational, and basic dimensions work with applicable geometric controls. Define each acceptance requirement clearly without redundant or conflicting controls.

### Can the shop choose missing tolerances?

The shop can discuss manufacturing options and identify omissions. The responsible design authority should approve the functional requirements before production.

## Sources and technical basis

1. [Autodesk Fusion: fully define and constrain sketches](https://help.autodesk.com/cloudhelp/ENU/Fusion-Sketch/files/SKT-FULLY-DEFINE-CONSTRAIN-SKETCH.htm)
2. [Autodesk Fusion: driving and driven sketch dimensions](https://help.autodesk.com/cloudhelp/ENU/Fusion-Sketch/files/SKT-SKETCH-CREATE-DIMENSIONS.htm)
3. [ASME: Y14.100 engineering drawing practices overview](https://www.asme.org/wwwasmeorg/media/resourcefiles/career%20education/training/y14-100-2017-sell-sheet.pdf)
4. [ASME: Y14.41 digital product-definition data practices](https://www.asme.org/codes-standards/find-codes-standards/y14-41-digital-product-definition-data-practices/2026)
5. [SOLIDWORKS: reference dimensions and auxiliary information](https://blogs.solidworks.com/products/solidworks/discussion-about-dual-dimensions/)
6. [KEYENCE: theoretically exact dimensions and geometric controls](https://www.keyence.com/ss/products/measure-sys/gd-and-t/basic/drawing-symbol.jsp)
7. [ASME: Y14.5 dimensioning and tolerancing scope](https://www.asme.org/codes-standards/find-codes-standards/y14-5-dimensioning-tolerancing/2018/drm-enabled-pdf)
8. [ISO: ISO 2768-1:1989 scope and exclusions](https://www.iso.org/obp/ui/?_escaped_fragment_=iso%3Astd%3A7748%3Aen)
9. [ISO: ISO 129-1:2018 dimension presentation](https://www.iso.org/standard/64007.html)
10. [ISO: ISO 8015:2011 GPS fundamentals](https://www.iso.org/standard/55979.html)
11. [ISO: ISO 1101:2017 geometric specification](https://www.iso.org/standard/66777.html)
12. [ISO: ISO 5459:2024 datums and datum systems](https://www.iso.org/standard/87855.html)
13. [ISO: ISO 14405-1:2025 linear sizes](https://committee.iso.org/standard/14405-1?browse=tc)

## Related guides

* [Gdt tolerances](https://appalachiantool.com/wiki/gdt-tolerances.html)
* [Cmm inspection](https://appalachiantool.com/wiki/cmm-inspection.html)
* [5 axis machining](https://appalachiantool.com/wiki/5-axis-machining.html)

[Request a part-specific machining review](https://appalachiantool.com/contact.html?intent=wiki-fully-defined-drawings)