Time came to add the details to the class43 plain model. When trying to intersect one of the details with the lower valance, imported as stl object, the troubles came: FreeCAD doesn’t support stl proper handling and it was not really possible to do boolean operations between FreeCAD objects and and stl import. Perfectionist as I am, as well as my modelling partner is 😉 , I took the chance to re-think the cabin as a complete FreeCAD project. The basic shape is still created intersecting the extrusions of the three orthogonal profiles, this time created with Inkscape from the blueprint and imported directly into FreeCAD in svg format.
The cabin is again split into two parts: the upper part and the lower valance.
The cabin basic design, still needs to be rounded on the spiky side edge and smoothed on the top, before proceeding to the fine filing. It is easier to re-build the shape of only the upper part of the cabin inside FreeCAD: with just one simple “fillet” action on the side edge, the basic rounded shape is there.
Smoothing the ridge on the top is a little bit more tricky: applying a fillet to any short edge doesn’t work well, as the segments composing the ridge are oriented in different angles. Then the solution is to cut away the spiky part of the ridge, leaving a smoother surface instead.
I created a profile which was cutting out the ridge, but at the same time including the whole upper cabin. The solid generated revolving it around the longitudinal axis includes the cabin, cutting out just the thin part of the ridge to be removed. The boolean difference of the two shapes does the rest of the job: the result is the original cabin, with a smooth surface instead of the ridge.
This shape is now ready to have the windows cut out, before being exported in stl format to be finely adjusted inside Blender.
The lower valance Lorenzo designed with OpenSCAD shows a significant improvement compared to the original basic model I created with FreeCAD.
Nevertheless it remains too spiky and irregular in the inside profile. Here comes into play my skills as a new Blender user: I had a lot of fun learning the basics of meshes manipulation to adjust, recreate and smoothen it.
Now it’s time to adjust the other profiles to this new refined lower valance and re-create the upper part of the cabin.
Class 43 IC125: the body
Tracing the locomotive body profile with Inkscape and creating a unique path with it was fun and quite an easy job. The tricky part started when I imported the drawing inside FreeCAD: the path created inside Inkscape was not straightforward to be converted into FreeCAD objects. After some trials I found the workaround (I used my experience as software CAD engineer 😉 ): to make the created objects completely compatible with the FreeCAD version I currently use. Now the locomotive section is ready and extruded through the whole length of the body.
I’m ready for the new 3D geometry challenge: the cabin.