CAD Dictionary

What is an AutoCAD SAT file?

An AutoCAD SAT (ACIS Solid Model) file is a widely used 3D solid model format based on the ACIS modeling kernel. SAT files store precise boundary representation (B-Rep) geometry and are commonly used to exchange 3D solids between CAD applications. This guide explains what SAT files are, how to open/convert them, step‑by‑step workflows, common errors and fixes, alternative methods, and practical tips for reliable interoperability.

Explanations (Explications)

  • What is an SAT file?
    • An SAT file is a file format created by the ACIS geometry kernel that contains 3D solid geometry (surfaces, edges, faces) using B-Rep representation. It can be saved in ASCII or binary form.
  • Why use SAT?
    • Interoperability: SAT is supported by many CAD programs (AutoCAD, SolidWorks, Rhino, Fusion 360, FreeCAD, etc.), making it useful to share models across different systems.
    • Archiving: SAT preserves accurate solid geometry for long-term storage.
  • Limitations
    • Version/compatibility issues can occur because SAT files correspond to ACIS kernel versions.
    • Some applications prefer STEP or IGES for assemblies, parameter history, or broader industry support.
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How SAT files are used (Usage & Examples)

  • Interchange: Transfer 3D solids between AutoCAD and other CAD systems.
  • collaboration: Send models to partners who do not use the same native CAD format.
  • Archiving: Save a precise solid model without CAD history for future use.
  • Downstream workflows: Use SAT files for CAM, rendering, simulation, or conversion to meshes.

Step-by-step: Open, Import and Export SAT files

Opening or importing a SAT in AutoCAD

  1. In AutoCAD, type IMPORT (or go to Application menu > Import).
  2. Select .sat as the file type and choose the SAT file.
  3. If prompted, check units and insertion scale. Set to match the original model units to avoid scaling issues.
  4. Confirm import options. The file will be inserted as a 3D solid or a set of solids.
  5. Verify model integrity using commands like PROPERTIES and visually inspect for missing faces.

Exporting an SAT from AutoCAD

  1. Prepare the model: ensure solids are cleaned (no duplicate geometry), and apply any Boolean operations.
  2. Type SAVEAS or EXPORT.
  3. Choose *ACIS (.sat)** as the format.
  4. If available, select the ACIS/SAT version for compatibility (choose an older version if the recipient uses older software).
  5. Save and send the file; include a screenshot and unit information.

Opening SAT in other CAD programs (SolidWorks, Rhino, Fusion 360, FreeCAD)

  • SolidWorks: File > Open > choose .sat > use import options to stitch or heal geometry.
  • Rhino: File > Import > choose .sat > check scaling and units.
  • Fusion 360: Upload .sat to Data Panel and open or insert into a design.
  • FreeCAD: File > Import > choose .sat.
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Alternative methods and conversion tools

  • Use STEP (.step/.stp) when you need broader compatibility and assembly support.
  • Convert SAT to other formats using:
    • Desktop tools: Autodesk Fusion 360, SolidWorks (save as), Rhino (Export), FreeCAD.
    • Commercial translators: Datakit, Okino, TransMagic.
    • Online converters: reliable cloud services (verify privacy/security before uploading sensitive models).
  • To get a mesh (for 3D printing), convert SAT → STL with controlled tessellation/facet tolerance.

Common errors and fixes

  • Error: Unsupported or newer SAT version
    • Fix: Ask the sender to export as an older SAT version or open it in software that supports newer ACIS kernels. Use a translator tool that handles multiple ACIS versions.
  • Error: Scale/units mismatch
    • Fix: Confirm and set the correct units at import. If already imported wrong, scale the model back by the unit conversion factor (e.g., multiply by 25.4 for inch→mm).
  • Error: Missing faces, gaps, or non-manifold geometry
    • Fix: Use the CAD program’s healing or stitch tools (SolidWorks Import Diagnostics, Rhino’s Join/Match tools, FreeCAD Part Heal). Re-run Boolean operations to fuse parts.
  • Error: File won’t open / corrupted
    • Fix: Try opening in another CAD app; if the SAT is ASCII, inspect it in a text editor for obvious corruption. Request a re-export or send the file as STEP instead.
  • Error: Slow performance with complex SAT
    • Fix: Reduce model complexity, suppress unnecessary features, or export a simplified version. Use level-of-detail or export as a tessellated mesh for visualization tasks.

Practical tips for reliable SAT exchange

  • Always include units, coordinate origin, and export version information when sending a SAT file.
  • Prefer ASCII SAT for easier troubleshooting and recovery when file corruption occurs.
  • For broadest compatibility, export to STEP in addition to SAT if recipient tools accept it.
  • Provide a preview image and a short text note describing what the file contains and any critical assumptions (units, Coordinate system, intended use).
  • Keep an original native file with history and parameters in case downstream edits are required.
  • When preparing complex assemblies, export individual parts as SAT or use an assembly-aware format (STEP) to preserve structure.
  • Set appropriate tolerance/facet settings when converting to meshes (STL) to balance file size and fidelity.
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FAQ

What is the difference between SAT and STEP files?

SAT is an ACIS B-Rep format tied to the ACIS kernel and focuses on solid geometry. STEP is an ISO standard widely supported across CAD systems and often better for assemblies and long‑term interoperability.

Can I edit a SAT file directly in AutoCAD or SolidWorks?

Yes — many CAD programs import SAT as editable 3D solids, but the file does not contain feature history. You can perform solid modeling operations but won’t have native parametric features from the original authoring software.

How do I fix a SAT file that won’t open due to version incompatibility?

Request the sender to export using an older SAT (ACIS) version, or use a translator application (e.g., Fusion 360, Datakit) that supports a wide range of ACIS versions.

Is SAT suitable for 3D printing?

You can convert an SAT solid to STL for 3D printing. Ensure correct units, manifold geometry, and appropriate mesh tolerance to avoid print failures.

Can SAT contain assemblies and multiple parts?

SAT can store multiple solids but it’s not optimized for assembly metadata. For complex assemblies with structure and constraints, prefer STEP or native assembly formats.

What should I do if faces are missing after import?

Try the CAD tool’s heal/stitch functions, run Boolean unions, or re-import with different import options. If the problem persists, request a clean export or supply the model in another neutral format like STEP.

Are SAT files human-readable?

SAT files can be ASCII (human-readable) or binary. ASCII SAT files can be inspected in a text editor which can help detect corruption; binary SAT is compact and not readable.

Which software reliably supports SAT?

Common applications: AutoCAD, SolidWorks, Rhino, Autodesk Fusion 360, FreeCAD, Inventor and many professional translators (Datakit, Okino). Always verify the exact version support for ACIS/SAT compatibility.

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