Misbehaving Surface

Hi guys, new to this forum.

I ran into an issue while modeling. My 3D printing program was telling me that the model I made was “inside out”. I went back and checked it with the Check command and found a single surface that was causing an issue. I got this message:

“Rhino surface object is not valid. ON_Brep.m_T[5].m_bRev3d = false, but closed curve directions are opposite.”

How do I go about fixing this issue? Any advice?


If you can post your model, it will be a lot easier for us to give useful advise. Based on the error, extracting the surface, untrim (KeepTrimObjects=Yes) and retrim might get you there.

Here is a Wiki article that might help for dealing with bad objects…
And another one for getting things solid for 3D printing in general…