this: normal_vector = normal_vector + face.normal will not work as expected, if you set normal_vector to reference the integer object 0, because the integer +() method will get called, and it is not likely that it would know how to handle an argument that references a Geom::Vector3d object. Smarter to create either a unit vector object to start with, or a zero length vector: normal_vector = Geom::Vector3d.new(0,0,0) THEN, when you call the +() method using: normal_vector = normal_vector + face.normal the special vector addition API method will get called. In other words your statement is evaluated as if it were written: normal_vector.=( normal_vector.+( face.normal ) ) This is one of the important things about Ruby... = and + (etc,) are not really operators, they are instance method names.

Hello, I think I found where the problem lies: After testing many variations to my formulas, without success, I had the idea of changing the internal units of the component. Being Belgian, I naturally use metric units, so my component was configured with "cm". So I converted all numeric values in inches and reconfigured the component to use same unit. Miraculously, everything works now as expected , even when using the component in a model configured in metric units. I think there's a bug in the function CURRENT("LenX/Y/Z") which should return a value expressed in inches, whatever the choice of internal units. Well, I hope my experience will serve the other! Thank you for your attention, Gerard