"Could you send the STEP along?" It sits at the bottom of a customer's email, almost casually, as if they were asking for a read receipt. For you it is a bigger question: that single file contains geometry your department spent weeks on.
Technically, to export a STEP file from Inventor takes a moment. The real questions come before and after: what actually travels along in such a file, how much of your machine do you want to share, and what do you agree with the recipient so nothing goes wrong on the other side? That is what this article is about, practical and without legal hair-splitting. And because exporting should be routine work, we show where a toolbox like Thundercad takes that routine off your hands.
What is inside a STEP file, and what is not
STEP is the exchange format virtually every CAD system can handle; that is why it is the standard request from customers, suppliers and engineering partners. But a STEP is not a copy of your Inventor file. What the recipient gets:
- the exact 3D geometry of parts and assemblies, including the structure of the assembly tree;
- part names and, depending on your export choices, some of the properties such as material;
- colours and the position of every component relative to the rest.
What is not inside: your parametric design. Features, sketches, parameters, iLogic rules, drawings and tolerances do not travel along, and threads come across as a graphic representation at best, not as an editable definition. The recipient can measure, rebuild and edit your model as "dead" volume, but cannot see how it was designed or why.
That is the heart of sharing right there: a STEP gives away the shape, not the thinking. For a machining supplier that is exactly enough. For a competitor, incidentally, it is too; which is why you choose deliberately what you export.
Decide per recipient what they actually need
The question "can I have a STEP" says nothing about what the recipient really needs. A machining shop turning three shafts for you has enough with the bare parts. A customer fitting your machine into their line only needs the outside and the interfaces: mounting dimensions, flange positions, piping connections. Only an engineering partner who genuinely co-designs needs the complete assembly.
So turn the question around: which decision does the recipient have to make with this file? Look at it that way and you will almost always share less than was asked for, without the recipient missing anything. It saves file size too: a complete machine as STEP quickly runs into hundreds of megabytes, while an interface model fits in a few.
Two examples from practice. A sheet metal supplier building a complete frame for you gets the assembly of that frame, but without the drive unit that goes in later. And the customer who only wants to know whether their conveyor lines up gets a model in which your machine is one closed outer shell: all interface dimensions are correct, the internals remain yours.
From complete machine to interface model: choose deliberately
Between "share everything" and "share nothing" there are three sensible levels in practice:
- The complete assembly: only for parties actually working on the design with you. Even then, strip out components that do not matter, such as internals you would rather not have floating around.
- The interface model: the outside of the machine with all its mating surfaces, but without the internals. In Inventor you can build such a simplified variant with a derived model in which internal components are excluded.
- Individual manufactured parts only: for suppliers making one part or one subassembly for you, without the context of the rest.
Record per customer type which level is the default, so not every engineer has to reinvent that wheel. And remember: once a file is out the door, it stays with the recipient. Choosing deliberately up front is easier than asking for it back afterwards.
Exporting individual parts or complete sets for customers and suppliers on a regular basis? With Thundercad that becomes a matter of seconds instead of a click route per file.
Try 30 days freeMake agreements with the recipient
Most STEP misery does not start in the export but in the expectations around it. So agree a few things explicitly. Which protocol version the recipient can read, for instance: AP214 and AP242 are common, and one mismatch means a file that will not open. What the governing source is: the model or the drawing; in case of a difference nobody should have to guess. And how you deliver revisions: revision in the file name, and with every change a complete fresh delivery instead of one loose part sent after the fact.
Also agree what the file is meant for: quoting, checking the installation, or manufacturing. That is not a contract but a working agreement, and it prevents your interface model from quietly circulating as a production model. How to organise those deliveries themselves, with fixed folders and without endless mailing back and forth, is covered in delivering files to subcontractors without the email ping-pong.
Check the export before it goes out the door
A STEP that comes out fine on your machine can still surprise the recipient: a mirrored part, missing faces, an assembly that falls apart. So inspect your own export the way the recipient will receive it. Reopen the file yourself, in Inventor or in a free viewer, and compare mass and main dimensions with the original. Large deviations almost always point to units or to lost geometry.
Make the exporting itself as small as possible. With Export STEP from Thundercad you export the active model in one action, without walking the same click route through the menus every time; a relief if you do it ten times a week. If it concerns the full package for an order, PDFs and DXFs included, set it up properly right away: the complete production package: what do you deliver, and to whom? lists which format belongs to which recipient.
Frequently asked questions
Can the recipient extract my parameters or design history from a STEP?
No. A STEP contains only the resulting geometry with structure, names and colours; features, sketches, parameters and tolerances do not travel along. The recipient can measure and rebuild the shape itself though, so share deliberately: whoever has the volume has the dimensions.
Which protocol version should I pick when exporting?
Ask the recipient; it costs one line in an email. If you get no answer, AP214 is a safe choice for manufacturing parties in practice. When in doubt, send one test file first and ask for confirmation before you deliver the complete set.
How do I stop exporting from being manual work on every order?
Record your choices once: which level you share per customer type, how files are named and who checks. The clicking itself you then hand over to tools like Export STEP; try Thundercad 30 days free and measure the difference on your next delivery.