On Mon, Aug 29, 2016 at 6:33 AM, Christopher Sean Morrison <brl...@mac.com> wrote: > >> I am working on MEMS devices which have nanoscale through macroscale >> features... 5 microns is HUGE for some of the things I will be doing. > > What are you going to be doing with these models? That is to say, once you > have your model, are you planning on feeding it to a 3D printer, export it to > some other software, create rendered visualizations, perform some sort of > analysis?
I want to generate rasters of the model, which will be converted to either a bitmap for a nano-CNC milling machine (Focused Ion Beam), or g-code for a laser-engraver to do direct-write photolithography. I've also got lofty goals of feeding such models into physical simulators, this has been my general plan once I had a reasonable model: http://en.wikiversity.org/wiki/CAD_to_FEniCS_example http://fenicsproject.org/documentation/dolfin/1.0.1/python/demo/pde/navier-stokes/python/documentation.html >> I had been assuming that 'subatomic through galactic' statement was >> good reason to avoid commercial softwares (as well as all other >> open-source CAD tools) > > You can see an example of the larger end of the scale with the “ringworld” > demo (only available in source compilations) used for visualization. It > creates a model approx 3.06e11 meters wide. I’ve modeled atomic structures > myself before for 3D printing demos. Cool, will check it out. I've so far made a small model with some nanometer up to millimeter features and things seemed to go pretty well, even upon exporting to STL (after tweaking the output quality a bit). My issue there was actually my Python TCL generation, being two nested X,Y for-loops for creating millions of cylinders (nanopores). I scaled down my model for sake of ease and time, but I think I'll tackle that issue by making a small group of holes, then [learning how to] duplicate them, translating, grouping all new cylinders again, repeat this copy-paste operation tiling sort of operation until done. > >> Have I been duped/mislead/ignorant? Should I move on to other tools, >> or can someone explain what the user 'brlcad' was warning me of? Was >> this a false alarm, should I be worried? > > Pushing to those limits is certainly possible, sometimes will require > creative adjustments, but whether it’s adequate will greatly depend on what > you intend to do with the model once you have it. > > For what it’s worth, I don’t know of any other CAD system that lets you go > that small outside of software specialized for exactly that purpose, but > maybe something exists. Yeah this is pretty much why I've not learned any other CAD system, aside from KiCAD (specialized for electrical circuit boards). I even asked an AutoCAD developer when I met him at a local event once about this sort of dynamic range, and the tool wouldn't even accept such small numbers. I think he also gave the 'just use bigger units' workaround as an offer... but I pretty much brushed it off because I knew BRLCAD seemed to offer what I wanted. Thanks for your reply! -Nathan ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ BRL-CAD Users mailing list brlcad-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/brlcad-users
