3D printing · Meshes · CAD drawings
Some software still only reads STL. 3MF stores an indexed mesh with metadata; STL wants a flat triangle soup. The geometry survives intact — the metadata does not, because STL has nowhere to put it.
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stl · 3mf · obj · ply · amf · dxf · svg · gcode
STEP export merges coplanar triangles into real planar faces, so flat surfaces come through as single selectable, dimensionable planes and CAD imports them quickly. Curved surfaces stay faceted, and there are no parametric features — a mesh has no record of them. Simplify is optional here; leave it off for the most accurate dimensions.
Working
Every triangle comes through exactly. Units, materials, colours and build-plate placement are dropped, because the STL format has no field for any of them. If the 3MF was in millimetres, treat the STL as millimetres.
Older slicers that predate 3MF, mesh repair tools, print services whose upload form only accepts STL, and a good deal of CAM software that never adopted the newer format. Some 3D print farms still specify STL in their submission guidelines regardless of what their slicer can read.
An STL writes out every triangle corner separately, so a vertex shared by six triangles is stored six times. Expect the STL to be roughly three times the size of the 3MF it came from. That is the format working as designed, not a fault in the conversion.
The STL produced here is binary. ASCII STL files are around five times larger for identical geometry and exist mainly for human readability; every slicer and mesh tool reads binary.
See all supported formats — meshes, 2D drawings and g-code, all converted in your browser.
Older slicers, mesh repair tools, some print services and a good deal of CAM software only accept STL.
The geometry is preserved exactly. Units, materials, colours and build-plate placement are dropped because STL has no field for them.
STL writes out every triangle corner separately, so a vertex shared by six triangles is stored six times. Expect roughly three times the size.
If a file will not convert, or the result looks wrong, I would rather hear about it. Include the format and roughly what you were doing — that is usually enough to reproduce it.