SolidWorks, Fusion 360, Inventor, or AutoCAD: What Actually Ships Machines

Every engineering forum has the thread. SolidWorks or Inventor? Is Fusion 360 ready for real machine design? Is AutoCAD dead yet? The threads run hundreds of posts and settle nothing, because everyone argues from preference and nobody argues from inventory.

So we counted our inventory. Our file server holds every machine we have designed, quoted, and built across more than two decades, and file counts do not have opinions. The census: roughly 229,000 AutoCAD DWG files, about 84,000 SolidWorks files - parts, assemblies, and drawings - 2,700 STEP files, and then the rounding errors: a few hundred Inventor files, a few hundred SketchUp models, and 27 Fusion 360 files. Twenty-seven.

That is the honest answer to the CAD question, at least for a shop that builds custom automation: it is not one package, it is two, and they are not competitors. They do different jobs.

Why 2D refuses to die

The quarter-million DWGs are not legacy sediment. New ones get made every week, because a large fraction of what a machine builder draws is not a solid model problem. Electrical schematics, panel layouts, pneumatic diagrams, facility layouts, fab prints for laser-cut plate - these are fundamentally 2D documents, consumed by people who work in 2D: the panel shop, the electrician, the laser house, the customer's facilities group.

There is also the longevity argument, which nobody appreciates until year fifteen. A DWG we drew in 2003 opens today, on current software, and the machine it describes is often still running and still needs service. Parametric assemblies age worse - features break, references go stale, file formats stop round-tripping. When a customer calls about a machine older than the intern, the 2D drawing set is what answers the phone.

Why 3D earned its 84,000 files

Everything mechanical gets modeled. Not because renders impress anyone, but because a custom machine is built exactly once, and the assembly model is the only place mistakes are cheap. Interference checks, reach studies, guarding clearances, the discovery that the gearbox you picked cannot physically come out for service - all of that costs nothing in the model and costs a rebuild on the floor. The drawing package for the fab shop falls out of the model, and the model becomes the machine's memory for the retrofit that arrives five years later.

Which parametric package matters less than the forums think. Ours won two decades ago on the criteria that actually decide it: what the shop already knows, what the local job market can hire, and what your customers and vendors send you. Those three feedbacks compound - every year of files makes the incumbent harder to leave, which is exactly why the trace amounts on our server are trace amounts. The Inventor and SketchUp files are almost all imports, customer data, and experiments. The experiments never earned a second seat, not because the tools are bad, but because switching costs are real and the incumbent was not failing.

The neutral currency

The 2,700 STEP files are the quiet heroes of the census. STEP is how CAD packages talk to each other without a fight - vendor models coming in, our geometry going out to customers who run something else. If you build machines, your real CAD standard is whatever you use internally plus disciplined STEP exchange at the borders. Anyone who insists a whole supply chain standardize on one package has never been in a supply chain.

Where the answer is quietly changing

The interesting shift is not package-versus-package. It is that a CAD archive has become a dataset. We have written before about batch-harvesting part footprints from a decade of our own AutoCAD drawings - a quarter-million DWGs stop being sediment and start being a parts library the moment software can read them at scale. The next step, which we are deep into, is generation: electrical drawings produced from a parts database and a set of layout rules rather than drawn line by line. The draftsman does not disappear - the draftsman moves up a level, curating the library and the rules instead of placing every rectangle by hand.

That changes the calculus for new shops. The question is becoming less "which package do your people click fastest" and more "which formats can your tooling read, generate, and audit." File formats that are open, stable, and script-friendly age better under automation than ones that are none of those things - a sentence that explains a lot about why our oldest format is still our busiest one.

The buying advice

If you are outfitting a machine-building shop today: one parametric 3D seat per mechanical designer, chosen by local hiring pool and customer overlap rather than feature charts. Keep real 2D capability for electrical and fab work - it is not nostalgia, it is the native language of half your subcontractors. Enforce STEP at every boundary. And whatever you pick, plan for the archive you are creating, because in twenty years it will be worth more than the licenses ever cost.

The full tooling notes - what we script against DWG, how the drawing-generation pipeline is structured, and the archive-mining writeup - live in the Saber knowledge base. And if your CAD archive is a quarter-million files of untapped parts library, that is a project we are actively good at. Contact form is on the site.