3MF vs OBJ: which one is the better choice

Community 3D Printing
1

3MF model has too many triangles, however when I simplify the model to slightly lower quality, the surface became very rough. Export to Obj doesn’t have this issue. My questions are:

  1. Which format is better for 3d printing: 3MF or OBJ?
  2. Is there any feature such as “voxel remesh” in Shapr3d that I can remesh before export the model?

Photos: (Top) 3MF imported to Bambu Studio, (Middle) Lower down the quality of 3MF, (Bottom) Obj imported to Bambu Studio.

Thank you!

3MF 1558074
3MF 15580741188×865 167 KB

3MF Simplified to Low Quality
3MF Simplified to Low Quality829×858 104 KB

OBJ 795104
OBJ 7951041206×903 137 KB

2

The difference between OBJ and 3mf is mostly just metadata. Both convert the CAD geometry into a polygon object, I can’t know for sure but I’d wager they actually do it with the same algorithm.

OBJs can have color information on vertices, however I never succeeded in getting that information into the slicer. I don’t know if shapr doesn’t add that info to the OBJ file in the first place or if Bambu Studio fails to read it.

When you use the direct export option to Bambu Studio, it uses a 3mf file to do so. It can retain color information on a per-object basis, not on a polygon level though.

I usually use 3mf or stl for the tranfer to the slicer, functionally I don’t think there’s a difference to OBJ though. They all basically do the same thing.

Just use the highest quality on all exports.

3

Different result with different slicers, mainly; Cura, Simplify, Prusa, Lychee.

My (mono print, FDM/SLA) preferences/experiences, with no tweaking in S3D:

STL to be on the safe side.
OBJ often gets scaled wrong but corrected with a higher quality.
3MF equals STL but off chart in universe.

4

Neither format is really the problem. 3MF and OBJ are both triangle meshes. The rough surface comes from simplifying an already-triangulated CAD export: decimation merges triangles across curved surfaces, which is the look in your middle photo.

What usually fixes it:

  1. Don’t simplify in the slicer. If the file is too heavy, lower the export resolution in Shapr3D instead. That spreads triangles evenly over the curves rather than collapsing them.
  2. Or give Bambu Studio a STEP instead of a mesh. Recent Bambu Studio versions import STEP and ask for linear and angular deflection on import, so you pick the smoothness-vs-size trade-off there. Around 0.01–0.03 mm linear and 5–10° angular is plenty for a 0.4 mm nozzle.
  3. Voxel remesh: I’d avoid it for mechanical parts. It rebuilds the surface on a grid, so sharp edges and small holes get rounded. It’s great for sculpts, not for CAD parts.

On 3MF vs OBJ for printing: 3MF. It stores units and can carry colours and plate settings. OBJ has no units, so parts can come in at the wrong scale.