Importing a STEP assembly into OrcaSlicer: mesh and parts

What actually happens when OrcaSlicer opens a STEP file

The wiki says STL is OrcaSlicer’s basic slicing format and that other supported formats, including STEP, are converted to STL during import. The slicer therefore works with a mesh, not the CAD parametric feature tree. Keep the source document if you need to revise the design; the wiki does not describe preservation of its history here.

The wiki describes both deflections as mesh-quality parameters: lower linear deflection follows curvature more closely, and smaller angular deflection gives a more precise representation. It says a finer mesh increases file size and processing time. Choose based on the detail to represent and inspect the mesh; the wiki gives no universal setting.

The STL vs 3MF guide compares information associated with those formats. The OrcaSlicer wiki also distinguishes exporting a model as generic 3MF from saving a project; the final section summarizes that distinction for this software.

The import dialog and its two tessellation controls

On STEP import, OrcaSlicer’s dialog offers linear and angular deflection to control mesh quality. The wiki defines linear deflection as the maximum distance between the original surface and its polygonal approximation, and angular deflection as the maximum angle difference. Lower/smaller values give a more precise representation; inspect the result for the curves and details in your file.

The wiki describes the tradeoff between representation and resources: a finer mesh increases file size and processing time. It sets no threshold for flat faces, cylinders, or pockets. If facets remain visible or a surface detail matters for your model, compare settings and inspect the preview instead of copying a universal recommended value.

A "Don't show again" checkbox hides this dialog for future STEP files. If you checked it and want the settings back, the wiki gives the path: Preferences, then the option to show the STEP mesh parameter setting dialog. For everything else in the application, the OrcaSlicer page is the starting point.

Splitting compounds and compsolids into distinct parts

The “Split compound and compsolid into multiple objects” option makes the import separate parts of the same object, according to the wiki. It specifies that each solid and each shell outside a solid becomes a part; faces outside any shell remain grouped. This definition does not promise a one-to-one match with every named part in the CAD file.

Consider a suggested scenario: you expect an enclosure, its lid, and several inserts. Before import, prepare a list of expected elements and reference dimensions. After splitting, compare that list with displayed parts and Assembly View. Counts or names may differ: look for geometric correspondence rather than assuming one entry represents each component. No file for this scenario was imported for the article.

Without splitting, check the structure actually shown before assigning separate settings. The wiki describes the option as a way to obtain distinct parts of one object, but does not list every case of merging or lost metadata here. Behavior may depend on the STEP structure and installed version.

Finding the structure again in Assembly View and rearranging the bed

The wiki presents Assembly View as a view of the hierarchy of an imported STEP assembly. It recommends splitting compounds/compsolids on import and then using Split for easier manipulation; the page says Auto arrange can be used while keeping the structure displayed in that view. Check this with your file and version.

In your record, note the OrcaSlicer version, source file, both deflections, and whether splitting was enabled. Keep dimensions and a parts list before rearranging them. After Split and Auto arrange, compare that record with what you see on the bed and in Assembly View. This suggested check helps identify a missing or unexpected element before preparing the print.

Before arranging, inspect the object list and compare displayed dimensions with expected dimensions. A mismatch can arise at different steps; appearance alone does not prove an unexpected unit. The unitless STL guide covers STL meshes; for STEP, also check units used at CAD export and dimensions shown after import.

Repositioning parts with the point and face assembly tools

The wiki distinguishes Assemble, which creates a bed assembly from multiple imported objects, from the view and alignment tools. It recommends merging objects before Assemble so they are treated as parts that can be adjusted on the Z axis; without merging, objects remain separate and each part must have a face touching the bed. Check this condition in the software before placing a part above the bed.

Point and Point Assembly creates assembly instructions by selecting model points with Shift-click. Face and Face Assembly asks you to select two faces, then offers parallel alignment, center coincidence, or flipping object 2 based on face 2’s normal. The page describes positioning operations; inspect the result visually.

These documented tools position objects on the bed. The page does not establish a mechanical constraint or clearance validation; if parts must fit together, check the geometry in CAD and inspect the corresponding slicer preview. The FreeCAD page separately describes a design tool.

Checking the triangulation before slicing, then picking the right export

Inspect curved surfaces in the imported mesh. If visible tessellation does not suit the detail you need, reimport the STEP with lower deflections and compare; the wiki notes that this increases file size and processing time. The slicing preview can show the geometry the software prepares, but it does not replace dimensional checks or a fit test.

The wiki distinguishes three outputs: a model in generic 3MF without printer, material, or process information; a saved project with objects, settings, and configurations; and Gcode.3MF with already sliced G-code and those information fields. Choose for the stage you need to retain. Statements about information recovered during G-code import concern OrcaSlicer’s documented workflow; they do not turn a sliced file into a CAD document or guarantee printer compatibility.

If someone hands you a 3MF whose origin you do not know, the unknown 3MF projects page explains how to inspect what it contains before you open it.

Sources and limits

• OrcaSlicer — Import/export wiki, October 14, 2026
• OrcaSlicer — Assembly tools, October 5, 2026

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.