"Export" as .STL works, but "Save As" gives an error?

I’ve noticed that when I try to “Save As” for a .stl, I get the warning below. However, If I use “Export Selected” as .stl, it works fine. Why?

Likely the mesh is open or has some other defects. Did you run _Check?

I did not. I get this message no matter what I create and try to save to .stl. But they all 3D print fine when exported.

I just ran “Check” and it says the object is a valid Rhino object.

So many things can go wrong…

Best thing as usual is to share a file so someone can take a look

I get this with all the parts. Here is just one.

2_Bike_Tool_Tray_Arm.3dm (809.6 KB)

Save As and Export both works here in Rhino 9 WIP. What mesh settings are you using?

I guess by settings you mean this? I just go with what comes up.

Actually, several parts are now working in both methods, but this one is giving me the error. Check says valid rhino object.

4_Stand_Collar_PARK_ANGLE.3dm (5.5 MB)

Those are blocks so the check will not work too well on them.

Explode the blocks to the underlying solids. Then run Show Edges command. There is a set of Nake edges on one side of the collar. This image shows it:

Mirroring the good side probably fixes this.

Thanks. The sides are not the same. So I’ll need to figure out how to fix that.