Convert SAB to SAT

A receiving CAD system may accept ASCII ACIS models but reject binary .sab files, requiring an export to .sat. The conversion is also useful when a text-based ACIS file is needed for inspection or exchange, although it usually increases file size.

What the SAB format is

.sab is the binary form of the Spatial ACIS model format, used by applications built on the 3D ACIS Modeler. It can contain exact boundary-representation solids, surfaces, wire bodies, topology, attributes, and assembly-related data.

SAB is a CAD geometry format, not a polygon-mesh format. Its entities can include analytic planes, cylinders, cones, and NURBS surfaces, allowing an ACIS-compatible importer to retain precise boundary geometry instead of receiving only tessellated triangles. ACIS-based CAD applications, translators, engineering systems, and supplier-data workflows may create or consume it.

What the SAT format is

.sat is the text-based ASCII form of the ACIS model format. It exchanges precise ACIS solids and surfaces between compatible CAD applications and geometry translators.

ASCII data can be inspected with a text editor and is accepted by systems that do not support SAB, but SAT files are commonly larger than equivalent binary SAB files. Both formats depend on ACIS release compatibility. Renaming .sab to .sat changes only the filename extension and does not convert the file.

How to convert the file

With CAD Exchanger Desktop

CAD Exchanger Desktop is a suitable general-purpose option only when the installed version lists SAB as an input format and ACIS SAT as an output format; supported formats can vary by edition and release.

1. Make a backup copy of the original .sab file. Establish the source units and ACIS version from the sender or producing application because ACIS data may not provide enough unit information for an unambiguous import.
2. Open CAD Exchanger Desktop and select File → Open, then choose the SAB file.
3. Check the imported body count, assembly structure, units, and any unsupported-entity warnings.
4. Choose File → Save As or File → Export, select ACIS SAT or .sat, and choose ASCII or text output if the dialog distinguishes it from SAB.
5. Set the output units explicitly when the application provides that option. Avoid changing modeling tolerances unless the destination system requires it.
6. Open the resulting SAT in the receiving CAD application and verify dimensions, body count, holes, blends, trims, face continuity, colors, and assembly placement.

For batch work or files containing unsupported vendor-specific entities, commercial translators such as Datakit or TransMagic may be appropriate, provided their current format matrices confirm SAB import and SAT export. The Spatial ACIS SDK can perform the conversion programmatically, but it requires development work, licensing, and compatible ACIS releases.

With an ACIS-based CAD application

If an installed CAD application opens SAB, use its File → Open command, then choose File → Save As or File → Export and select ACIS SAT. Menu names differ by product. Confirm that the output is SAT rather than STEP, STL, or another exchange format.

With an online converter

CAD Exchanger Web is an option for non-confidential models if its current online format list explicitly shows SAB input and SAT output. Upload the source file, select SAT as the output, run the conversion, and download the result; verify the model in a CAD application afterward. Do not upload proprietary, regulated, unreleased, or security-sensitive geometry to an online service. Many generic file-conversion websites support neither ACIS variant, so a site must explicitly list both extensions before use.

Compatibility and quality limits

• The conversion normally preserves analytic geometry and B-rep topology because SAB and SAT are different encodings of ACIS model data; it does not inherently convert the model into a polygon mesh.
• ACIS release differences can prevent opening the result or cause unsupported entities to be omitted or altered. Check blends, trims, colors, layers, names, annotations, and assembly metadata.
• SAT generally stores final B-rep geometry, not the original parametric feature tree, sketches, constraints, or design history. A receiving application may therefore import independent bodies rather than native editable features.
• SAT can be substantially larger than SAB and exposes model data as readable text. Retain SAB when compact binary storage or reduced casual visibility is required; ASCII is not encryption.
• Units require particular attention: an apparently correct shape can have the wrong scale if the source and destination applications use different unit assumptions. Measure a known feature after import.