Mechanical CAD Software: Inventor, Fusion and File Longevity

Mechanical Desktop, Inventor and Fusion: Why More Features Do Not Fix Inefficient CAD

Engineering software should make design work faster, clearer and more dependable. Before a platform promotes advanced features, it must perform the fundamentals of mechanical design efficiently.

Every mechanical model begins with basic geometry:

• Lines

• Circles

• Arcs

• Dimensions

• Constraints

• Extrusions

• Revolutions

• Holes and patterns

If creating and modifying this geometry is unnecessarily complicated, expanding the software with more functions does not solve the problem. It simply builds additional complexity on an inefficient foundation.

For experienced designers, the true test of CAD software is not the number of features listed in its marketing material. The test is how quickly and reliably it can turn engineering intent into an accurate, editable model and a clear manufacturing drawing.

When Pencil Drawings Outlive Digital Engineering Files

Many industrial companies still possess ink and pencil drawings created 40, 50 or even 70 years ago.

Those drawings may be faded, marked up or incomplete, but they remain accessible. They do not require a software licence, subscription, cloud account, compatible operating system or specialist conversion utility.

An engineer can retrieve the drawing, scan it, measure it and use it to understand the original equipment.

The same cannot always be said for digital information created only 20 years ago.

Some companies produced large numbers of drawings and mechanical models using Autodesk Mechanical Desktop. Those files may still be stored on a server, but the software required to interpret their complete design intelligence is no longer readily available.

The DWG file may open, but that does not necessarily mean the original mechanical model has survived. Parametric features, assembly relationships, mechanical components and design intent may be difficult—or sometimes impossible—to recover completely.

This creates an uncomfortable reality: an old pencil drawing may be more useful than a supposedly intelligent digital model.

Mechanical Desktop Must Be Part of the Discussion

Mechanical Desktop is important because it demonstrates that the current debate is not simply about choosing between Inventor and Fusion.

It reveals a longer Autodesk product sequence:

AutoCAD → Mechanical Desktop → Inventor → Fusion

Mechanical Desktop was built on AutoCAD and provided mechanical parts, assemblies, solid modelling and production drawings within an environment familiar to existing AutoCAD users.

Companies invested in the product, trained employees and created substantial libraries of engineering information. Mechanical Desktop was then discontinued, and users were encouraged to move towards Inventor.

Recovering those files today is not necessarily straightforward. Autodesk’s own Mechanical Desktop conversion guidance can require Mechanical Desktop 2009 and an older compatible version of Inventor.

Autodesk documentation has also warned that unrecognised geometry or features may be skipped during conversion and that links to the original Mechanical Desktop files may not be maintained.

That is not a minor inconvenience. For an engineering company, it represents a loss of accessible design information.

Mechanical Desktop should therefore be treated as a warning about relying entirely on proprietary native file formats.

Did Inventor Successfully Replace Mechanical Desktop?

Inventor was intended to move Autodesk users into a more modern parametric and assembly-based mechanical-design environment.

Inventor remains an active product. Autodesk currently sells Inventor for mechanical design, documentation and simulation.

However, continuing to sell a product does not prove that it successfully changed the mechanical CAD market.

In our view, Inventor has had a limited impact compared with established alternatives such as:

• SolidWorks

• PTC Creo

• Siemens NX

• CATIA

• Solid Edge

• IronCAD

Pro/ENGINEER—commonly known as Pro/E—had already established history-based parametric mechanical modelling before Inventor entered the market. Pro/E subsequently became PTC Creo, and it remains an important advanced engineering platform.

SolidWorks developed a strong position in mainstream mechanical design, machinery, fabrication and product development. Solid Edge established its own combination of parametric and synchronous modelling. IronCAD continues to offer a flexible mixture of direct and parametric design.

Inventor never clearly displaced these systems.

For companies already committed to AutoCAD, Autodesk Vault and Inventor files, continuing to use Inventor may be practical. However, that does not make it the strongest choice for a business purchasing a new mechanical CAD system.

Among the established mainstream mechanical solid modellers, we consider Inventor one of the weakest investments for a new operation.

Why Would Autodesk Need Fusion?

If Inventor had provided Autodesk with a completely successful mechanical-design platform, it is reasonable to ask why the company needed to develop and promote another overlapping system.

Autodesk Fusion is newer, but newer does not automatically mean better.

The relevant question is not how many additional capabilities Fusion contains. The question is whether it makes the fundamental work of mechanical design faster and more dependable.

Can an experienced designer efficiently:

• Create lines, circles and arcs?

• Apply dimensions and constraints?

• Modify a sketch without producing unpredictable failures?

• Build and revise a solid model?

• Control relationships between components?

• Generate an accurate drawing?

• Change a dimension and have the model and drawing update correctly?

• Recover and reuse the design years later?

These are the tests that matter.

A mechanical designer should not have to fight the software to create or modify basic geometry. If an established system makes simple sketching, constraints and drawing production less efficient, adding more functions does not correct the weakness.

It expands it.

More Features Are Not the Same as Greater Productivity

Software companies frequently measure progress by adding commands, environments and services.

Engineering companies should measure progress differently:

• How long does the design take?

• How easily can it be changed?

• Can another designer understand the model?

• Does the drawing update reliably?

• Can the files be transferred to a client?

• Will the information remain accessible?

• Can the design be recovered without maintaining obsolete software?

A long feature list can make a product appear powerful while the daily design workflow remains unnecessarily complicated.

Lines and circles may sound basic, but they are the foundation of mechanical CAD. Every bracket, shaft, frame, chute, conveyor and machine assembly begins with basic geometry and design relationships.

If that foundation is inefficient, the entire system becomes inefficient.

Fusion Does Not Automatically Correct Inventor’s Weaknesses

Autodesk has not officially announced that Fusion will replace Inventor. Both products continue to be offered.

However, Autodesk’s continued investment in Fusion raises questions about Inventor’s long-term strategic position.

Fusion should not be assumed to be better simply because Autodesk has expanded it.

If its basic sketching, modelling and drawing workflows do not provide a clear improvement over Inventor—or over competing systems—then Fusion does not solve Autodesk’s mechanical CAD problem.

It creates another platform, another native data structure and another potential transition for customers to manage.

Mechanical Desktop users were directed towards Inventor. Inventor users are now being encouraged to connect with or consider Fusion. Engineering companies are entitled to ask whether this represents genuine progress or another change in product direction.

What Should a New CAD Buyer Consider?

Mechanical Desktop is discontinued and should not form the basis of a new engineering system.

Inventor may still be required where a client already maintains an established Inventor environment. However, Hamilton By Design would not recommend selecting Inventor as the first choice for a completely new mechanical-design operation without first comparing it carefully against stronger alternatives.

The principal alternatives include:

SolidWorks

SolidWorks remains a strong choice for machinery, fabrication, industrial equipment, assemblies and production drawings. It provides a widely understood parametric workflow and broad manufacturing compatibility.

Hamilton By Design uses SolidWorks 3D modelling for mechanical components, machinery, plant modifications, reverse engineering and fabrication-ready deliverables.

Solid Edge

Solid Edge combines traditional parametric modelling with synchronous technology. This can provide greater flexibility when modifying imported models or geometry without a complete feature history.

PTC Creo

Creo is the continuation of Pro/ENGINEER and remains a strong platform for advanced parametric design, product development and complex engineering applications.

IronCAD

IronCAD provides direct and parametric modelling within one environment. Its flexible design approach can suit machinery, fabrication and businesses that do not want to follow a strictly history-based workflow.

Siemens NX and CATIA

NX and CATIA remain high-end systems for complex product development, automotive, aerospace and major manufacturing environments. They may exceed the needs and budgets of smaller engineering operations, but their industry position is well established.

Protecting Engineering Information

Regardless of which CAD platform is selected, important engineering information should never be retained only in one native format.

A controlled project archive should include an appropriate combination of:

• Native CAD parts and assemblies

• Parasolid models

• STEP models

• SAT files

• DWG or DXF drawings

• Controlled PDF drawings

• Bills of materials

• Design calculations

• Revision records

• Engineering notes

Neutral formats may not preserve every modelling feature, but they provide an additional level of protection against software changes and discontinued products.

The objective is to ensure that the engineering information can outlive the computer, software version and designer who originally created it.

Final Thoughts

Mechanical Desktop demonstrated how quickly intelligent digital engineering information can become difficult to access when a software product is discontinued.

Inventor was promoted as the replacement, but it did not displace the strongest mechanical CAD platforms. Autodesk then introduced Fusion, creating another overlapping product without proving that it provides a more efficient foundation for basic mechanical design.

The central issue is not whether Fusion contains more features.

The issue is whether it allows designers to create and modify lines, circles, dimensions, constraints, models and drawings more efficiently than the tools already available.

If the core design process is inefficient, expanding the product does not make it better.

For engineering businesses purchasing software today, the safest approach is to select a proven mechanical-design platform, test it using real everyday work and maintain neutral records that protect the company’s engineering history.

Software will continue to change. Engineering information must remain usable.