ALIGNSCAN

AlignScan / Guides / Orient STL to origin

Guide

Orient an STL to the origin

An STL file has no object transform, no units and no origin marker. It is just triangles with coordinates. "Orienting an STL to the origin" therefore means changing those coordinates so the part sits where you want relative to (0, 0, 0) and faces the way you want.

Do it in this order

  1. Rotate first. Centring a tilted mesh and then rotating it moves it off the origin again. Square the mesh to the axes, then translate.
  2. Pick a centring rule.
    • Bounding-box centre to origin: predictable and symmetric; good for fixtures, boxes, brackets.
    • Surface centroid to origin: the area-weighted centre of the surface. Better for lopsided shapes, because a long spike will not drag the origin.
    • Sit on the floor: lowest point at Z = 0, handy for slicers and rendering.
  3. Choose the up axis. CAD, Blender and almost all slicers use Z-up. Many game and web viewers use Y-up. Exporting Y-up is a further rotation of 90° about X; picking the wrong one is the classic "my model is lying down" problem.
  4. Export and re-import to confirm. The bounding box should now straddle the origin as expected.

Skip the manual work: drop your scan into AlignScan. It runs in your browser and the file is never uploaded.

Open the aligner →

What stays the same

Rotation and translation are rigid, so distances, angles and volume are preserved. AlignScan does not touch triangle count, order or topology. It rewrites coordinates (and stored normals) in place, so the file is byte-for-byte the same everywhere else.

Units

STL carries no unit. Slicers assume millimetres; CAD tools ask you on import. Centring is unit-independent, but if your scan arrived in metres, scale it in your CAD or mesh tool, not by editing coordinates by hand.

Related guides