Round objects are no longer round after export

Pac3

Hello,

I have noticed that a round 3D object is no longer round after exporting from Onshape. When I open the exported 3MF file in the Windows 3D viewer, clear corners are visible on the cylinder.

Also in other programs in which this 3D model is loaded, the cylinder is no longer round but is composed of many straight lines.


Onshape cylinder


Cylinder in Windows 3D-viewer. Note the straight lines on the cylinder.


Here you can clearly see the individual straight lines that make up the cylinder. I use the pre defined "fine" 3MF export setting. An fine stl export has the same error.

I would like to have a round cylinder as the exported file, because I am 3D printing the object and the lines are clearly visible in this print.

This anomaly occurs in some of my projects but not in all of them.

What am I doing wrong?

Best

_anton

Could you share a link to the document? (Edit: for clarity, a mesh export like STL will never be truly round, but you should be able to get it fine enough that it doesn't matter on a 3D printer.)

rafael_telgmann

If your slicer accepts step files, select the step format. I had the same experience with cylindrical objects. Step works much better. 

Pac3

_anton said:

Could you share a link to the document? (Edit: for clarity, a mesh export like STL will never be truly round, but you should be able to get it fine enough that it doesn't matter on a 3D printer.)

Here is the document link: 

With simular projects I did not have this kind of issue.

rafael_telgmann said:

If your slicer accepts step files, select the step format. I had the same experience with cylindrical objects. Step works much better. 

Currently I use cura slicer. I will check if a steop file is possbile to slice.

_anton

See if you get the same results with a simplified cylinder like this? https://cad.onshape.com/documents/95f2b421de38f98e9030d3aa/w/31672c6e468958db3829fb6b/e/1d830590896acae5364054f9

I still see tessellation at the fine export setting, but it looks fine enough to not be visible in practice. You can fiddle with the custom tessellation setting parameters as well.

Pac3

_anton said:

See if you get the same results with a simplified cylinder like this? https://cad.onshape.com/documents/95f2b421de38f98e9030d3aa/w/31672c6e468958db3829fb6b/e/1d830590896acae5364054f9

I still see tessellation at the fine export setting, but it looks fine enough to not be visible in practice. You can fiddle with the custom tessellation setting parameters as well.

Hello again. The resolution is much better with the test cylinder you have provided. I still see tessellation, but there are significantly more lines and the cylinder looks much rounder in the overall picture.

With custom export settings I also get a much better resolution for my project. I still wonder why the "fine" setting is not sufficient here.

Anyway, thank you very much for your help.

_anton

In the interests of shedding some light on this, could you submit a support ticket? It may be an actual export bug.