Recently,i have been struggling to figure out what the problem with the coversion,from .sldprt to .stl. I need that kind of file to conduct a fluid simulation,using Flow-3D.By the way,does anybody uses Flow-3D?  The problem is that there is always  a size error,especially the structure of cylinder.I guess i should give some pictures for more detail.

Φ60x30

From the picture,you can learn that the coordinate Y and extent Y is not the perfect number.

How to deal with it ?

Thanks very much!!