Parasolid

You click “Fillet,” pick an edge, type a radius, and hit the green check. The edge rounds off. Done. Until it isn’t. Until you get “Fillet operation failed” on a perfectly reasonable-looking edge. Or until the same 2mm radius works on one edge but blows up on the adjacent one. Or until your model rebuilds fine in SolidWorks but the same STEP file fillets differently in Inventor. These aren’t random bugs. They’re the predictable result of three completely different geometric kernels making three completely different decisions about how to roll a ball along an edge. We decompiled the DLLs, read the exported symbols, and walked through the open-source code to see what’s actually happening. ...

Every SolidWorks user has opened a .SLDDRW file thousands of times. You place views, add dimensions, print to PDF, send it to the shop. But what’s actually inside that file? Is it vector graphics — maybe SVG behind the scenes? Is it a database of coordinates? How does a drawing “know” what the 3D model looks like from the front? We decompiled the SolidWorks interop DLLs, inspected exported symbols from native C++ libraries, and dug through the API documentation to answer these questions. Here’s what we found. ...

The Universal Language of CAD Data Exchange Picture this: an aerospace engineer in Seattle needs to share a turbine blade design with a manufacturer in Germany, or a product development team needs to collaborate across multiple CAD platforms. They all rely on one file format that every system understands—STEP. STEP files have become the backbone of modern engineering collaboration, making it possible to exchange data seamlessly between different CAD systems, manufacturers, and engineering teams worldwide. Yet many engineers use STEP files daily without really understanding how they work or how to get the most out of them. ...