Saving a file in a different format usually does not reduce the file size sufficiently. First, it is important to distinguish between mesh files and CAD files.

Mesh files

(.3ds, .stl, .obj, .wrl, .fbx, .dae, .ply, .magics, .mgx, .x3d, .x3dv, .3mf, .zpr)

For mesh-based files, reducing the file size generally means reducing the number of vertices and polygons (triangles or quads), as is typically done with STL files. This directly affects the mesh density and therefore the geometric accuracy of the model, either locally or globally. In many cases, meshes are far more detailed than required for the intended application.

When very large mesh files are uploaded, the following sanity checks should be performed:

• Was the design saved at the correct scale?
  The STL format does not contain unit information. At Materialise, 1 unit equals 1 mm.
• Was the model exported with an appropriate level of detail?
  In many 3D software packages, triangles are generated during export rather than during the design phase.

If either of these parameters is incorrect, the triangle count can increase dramatically. For example, a model intended to be saved in millimeters may be interpreted as being several meters in size while still retaining micrometer-level detail.

Saving the model in 3MF format instead of STL can already help, as 3MF includes a clear convention for units.

CAD files

(.igs, .3dm, .fbx, .prt, .zpr, .sldprt, .catpart, .stp, .step)

For CAD files, reducing file size is more challenging. These files contain exact mathematical descriptions of geometry, resulting in effectively infinite resolution. As such, mesh density cannot simply be reduced.

The only effective way to reduce CAD file complexity is to simplify the model by removing unnecessary details, such as:

• Small fillets
• Minor holes
• Fine features that are below the printing resolution

In practice, CAD files should rarely reach upload size limits. When they do, it is often because a full assembly has been uploaded (e.g. an entire car with all components instead of only a dashboard).

CAD files are generally preferred because we can convert them into meshes with the appropriate level of detail. However, one limitation is that CAD files do not guarantee a manifold (watertight) model.

Design considerations

The design itself also plays an important role in file size:

• Some designs inherently require a high level of detail (e.g. lightweight structures or textured meshes). Our Design and Engineering services can assist in these cases.
• For sculpted or organic designs, triangle reduction is often appropriate. Most sculpting software provides built-in tools for this purpose.

It is always best to set the correct level of detail during export from your design software, as this is where the most information is available.

If the file is still too large after export, you may consider performing post-export triangle reduction.
Materialise Magics is particularly well suited for this task.
Alternatively, MeshLab or Blender offer various triangle reduction tools, for which many tutorials are available online.