STEP Reviewer Support
STEP Reviewer is an Apple-native CAD review app for STEP and IGES models on Mac, iPhone, iPad, and Apple Vision. It processes models on device, preserves assembly structure and colors where available, and provides focused review, inspection, capture, and tessellated export tools.
What is STEP Reviewer?
STEP Reviewer is a viewer and inspection utility for neutral CAD exchange files. It is designed for engineers, manufacturing teams, suppliers, customers, and reviewers who need to inspect a model without a full CAD authoring system.
The app imports exact CAD data through Open CASCADE Technology (OCCT), builds an interactive tessellated representation, and exposes assembly structure, source orientation, material colors, PMI where supported, measurement, sections, capture, and mesh export. It is not a feature-based CAD editor and does not modify the source file.
Which model formats can STEP Reviewer open?
- STEP:
.stepand.stp - IGES:
.igesand.igs
Which formats can STEP Reviewer export?
STEP Reviewer can export tessellated model data as binary STL, GLB, USDA, USDC, and USDZ. These are mesh exports for viewing and exchange; they do not preserve exact B-rep geometry, editable CAD features, constraints, or imported PMI.
- STL contains triangles only and does not include colors, materials, assembly structure, units, or PMI.
- GLB and USD-family exports preserve simple material colors where available.
- Thin, open, or inconsistently oriented source surfaces can remain open in mesh output.
What review tools are available?
- Assembly structure: Browse the imported hierarchy, focus a node, and show or hide a node together with its descendants.
- Model interaction: Rotate, pan, zoom, reset, focus selected objects, and choose X-Up, Y-Up, or Z-Up source orientation.
- Rendering quality: Use Preview for responsive full-model interaction or Detail for denser tessellation.
- Appearance: Inspect imported colors and materials where the source file provides them.
- Exploded view: Separate assembly parts to inspect their spatial relationship.
- Cross section: Slice on YZ, XZ, or XY planes, reverse the retained half, fill cut faces, and auto-scan.
- Capture: Create screenshots with arrow, rectangle, and text annotations, or record model interaction with configurable duration, watermark, and optional synchronized microphone narration.
- Recent models: Reopen app-managed imported copies and filter longer recent-file lists.
How do measurement and PMI work?
On iOS and macOS, measurement tools cover point, edge, face, distance, angle, radius, and diameter workflows where the imported geometry provides a valid target. Results can be focused in the viewport and duplicate annotations near an existing result are reused instead of stacked.
Free users can keep up to two measurement results. Unlimited Measurements removes that limit. Measurement is not available in the current visionOS release.
Imported PMI and GD&T can be filtered and reviewed on iOS and macOS when the STEP file contains supported annotations. Spatial PMI is not available in the current visionOS release, and unsupported or absent source annotations cannot be reconstructed by the app.
What is different on Apple Vision?
visionOS opens the model in an immersive spatial review scene and centers it in the visible region. View-centered placement is the default. World and horizontal-plane anchors are available on supported hardware after you grant world-sensing access.
visionOS screenshot and recording actions are Model View Capture. They capture the app's model view and do not promise recording your surrounding environment. Measurement and spatial PMI are intentionally unavailable in the current visionOS version.
What are the system requirements?
A STEP or IGES file will not open
Confirm that the extension is supported and the file is a valid, complete STEP or IGES exchange file. If the file is stored in a cloud provider, wait for it to finish downloading. Try a smaller known-good model to separate file-content problems from device resource limits. When reporting a repeatable import failure, include the file format, platform, OS version, and the exact error text.
The assembly tree, colors, or PMI are incomplete
STEP Reviewer shows information present in supported source entities. Exporter settings, STEP application protocol, unsupported entities, missing references, and malformed files can reduce hierarchy, colors, names, or PMI. IGES commonly carries less product-structure metadata than STEP.
A large model imports or responds slowly
Use Preview quality for interactive review, close other memory-intensive apps, and avoid repeatedly expanding very large structure branches. Detail mode deliberately performs denser tessellation and can require substantially more time and memory.
Screenshot or recording is unavailable
Make sure the feature is unlocked and a model is loaded. Enable microphone access only if narration is needed. On macOS, full app-window recording requires Screen Recording permission; model-only capture does not promise every system-owned UI surface. On iOS and visionOS, Photos permission is needed only for Save to Photos.
A visionOS spatial anchor is unavailable
World and horizontal-plane anchors depend on compatible physical hardware, world-sensing permission, and a detectable environment. The simulator keeps those choices unavailable. Use View Centered when room anchoring is not available.
An exported mesh looks different from the CAD model
Exports contain tessellated triangles, not the exact CAD boundary representation. Increase source/detail quality before export when appropriate, and remember that STL has no standard material or assembly support. Open or inconsistently oriented source surfaces can remain open in the exported mesh.
What are STEP and IGES?
STEP is the ISO 10303 family of standards for exchanging product-model data. IGES is an earlier neutral exchange format used for curves, surfaces, and solids. The quality and completeness of either format depend on the exporting CAD system and its settings.
Can STEP Reviewer edit or repair CAD models?
No. STEP Reviewer is a review, inspection, capture, and tessellated-export app. It does not provide feature-history editing, constraint editing, geometric healing controls, or STEP export.
Does STEP Reviewer work offline?
Yes for local model import, review, capture, and export. App Store purchases, subscription status refresh, and Restore Purchases require Apple's services. A cloud file provider may also require a network connection to download a selected file.
What is Open CASCADE Technology?
Open CASCADE Technology (OCCT) is an open-source 3D modeling and CAD data-exchange library. STEP Reviewer uses OCCT on device for STEP and IGES import, geometry transfer, tessellation, assembly metadata, materials, and supported PMI extraction. License and acknowledgement details are available in About STEP Reviewer inside the app.
How do I get help?
For a bug report, include the platform, OS version, device model, file format, model size, exact error text, and reproducible steps. Do not send confidential CAD files unless you are authorized to share them.
