OrcaSlicer primarily relies on STL meshes for slicing, but STL files may come with several limitations.

Typically, STL files feature a low polygon count, which can adversely affect print quality.
In contrast, STEP files offer the option of importing a higher-quality mesh that more accurately represents the original design. However, be aware that both high-polygon STL and STEP files can increase slicing time.

When working with models that have a high polygon count, the Simplify Model option can significantly reduce complexity and help decrease slicing times.

This function is especially useful for improving the performance of the slicer or achieving a specific faceted look for artistic or technical reasons.

To access the Simplify Model option, right-click on the object to simplify in the "Prepare" menu.

It is recommended to enable the "Show Wireframe" option when running a simplification process to visually inspect the outcome. However, be cautious: overly aggressive simplification may lead to noticeable detail loss, increased ringing, or other printing issues.

• Detail Level: Control the level of detail in the simplified model by choosing from five preset options. This setting allows for a balance between mesh fidelity and performance.
• Decimate Ratio: Adjust the ratio between the original model's polygon count and that of the simplified model. For instance, a decimate ratio of 0.5 will yield a model with approximately half the original number of polygons.

Fix Model repairs the mesh errors that make a model slice unpredictably or break other tools such as cut, mesh boolean and painting. It works on Windows, macOS and Linux.

• Running Fix Model
• What it fixes
• Parts
• Painting

• An object or a part: right-click it in the 3D view or in the object list and choose Fix Model, or click the warning icon next to it in the object list.
• A plate: right-click a plate, in the 3D view or in the object list. Fix All repairs every object on that plate, and Fix All Plates every object of the project.
• After a cut: when a cut leaves open edges, the Cutting Tool offers to fix the result.
• From the command line: --repair repairs every loaded model before slicing.

A progress dialog follows the repair and can cancel it. A notification then lists the models that were repaired and those that could not be, and counts the ones that needed no repair. Each run is a single undo step.

• Holes and cracks are closed, including gaps between triangles that should share corners and T-junctions. A missing cap at the end of a tube is filled as a ring, so the bore stays open.
• Orientation: flipped triangles take the orientation of their neighbours, and a model turned inside out is turned outward.
• Duplicates: coincident duplicate triangles are removed, and so is the internal wall between two solids that touch face to face.
• Stray geometry: flat patches and other pieces that enclose no volume are removed.
• Self-intersections: small ones inside a part, such as slivers and folds, are removed. Larger overlaps, such as two bodies crossing each other, are left in place, because slicing merges them anyway.
• Nested shells follow the same rule as slicing: a shell inside a solid that faces inward stays a cavity, and one that faces outward, adding nothing, is removed.

A model that needs no change is left untouched. A part that cannot be turned into a solid, such as a single flat sheet, is left as it was and listed as failed.

Fix Model repairs each part in place and never splits it, so cavities stay cavities. When the repaired part holds several separate solids, Split to Parts separates them.

Painted supports, seams, colors and fuzzy skin stay on every part the repair does not change. On a part whose mesh changes, the painting is moved onto the repaired mesh when Preferences > Developer > Keep painted feature after mesh change is enabled, and removed otherwise.