Hello,
I have certain objects which are located wholly within the vacuum chamber. I wish to include them in my model as they have a significant outgassing load and they are also an obstacle for the path of the gas atoms to the pump.
My first attempt to import from the STL file resulted in these objects behaving like they had a vacuum inside them - so they were emitting gas from the inner (solid) surface rather than the outer (vacuum facing) surface.
I decided I could solve the problem by asking the CAD designer to separate these pieces out of the design. I would then import the solid pieces one by one, but swap the normals on those pieces which were previously causing the gas atoms to be emitted from the wrong surface.
Unfortunately, the imported pieces do not appear in the correct location and are offset with respect to the main vacuum chamber. The CAD designer assures me that he stored the STL files with the correct coordinates.
What is the best way to solve such a problem ? I see there is an “Align to” menu option under facet, which perhaps I could use - if I manage to find facets which can be aligned!
Thank you for your patience, your message reached me on holidays and I’m just back.
The one-off solution is to fill the volume of vacuum areas, i.e. create the inverse of the geometry as a solid. Most CAD designers have a “sculpt” or “fill volume” function for this, where the user sets up boundaries and a seed facet, and the algorithm finds the body inside. Then you open that body in Molflow and no further task is to do.
Alternatively, your approach of inserting the STL later and flipping the normal also works.
Molflow reads the coordinates as they are in the STL file, without moving them. If the scale is correct (so no problems when choosing units), then the wrong location is inherent to the STL file, not Molflow. I understand that you have to choose between the word of the designer and mine, but I’m sure Molflow doesn’t move objects on its own
The align command won’t work as it requires two identical shaped facets which can be snapped together. You don’t have such as one object is inside the other.
You should use the Facet/Move command to offset the inserted bodies, and if necessary, do 90deg rotations (Facet/Rotate) if the orientation also changed.
Sorry that I can’t be of more help, in your place I’d use a 3rd party STL viewer (Win10 has “3D builder” built in) to prove that the coordinates of the parts are not correct and ask the deisgner to correct them.
