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Ask HN: What are the issues with working with large CAD design files?

• sbuk 5y ago
  What kind of CAD? Architectural/Constuction? Mechanical/Electrical schematics? From an architectural viewpoint, linked files are problematic. It's rare that a model is entirely self contained. Linking (XREFs) are commonplace and loading external files can be problematic. CAD models also gather 'junk' - symbols (blocks in AutoCAD parlance), which need purging from time to time.
  • cjcassar 5y ago
    One of the issues I have come across is combining mechanical and electrical designs together. I've been told that is quite a clunky process. Is it common enough to dedicate time to solving? I'm not sure, what do you think?
    • brudgers 5y ago
      For AEC in the US, it is clunky because mechanical and electrical work is typically subcontracted to other firms. Those firms serve many other firms. Their CAD files reflect how they produce their work. The architect doesn't dictate the CAD file organization of their consultants...it's not worth paying for because it will just slow down the project. Reconciling the MEP layouts tends to be manual, but it's just part of the job. Automation may happen on large projects, but that's not most projects. Is it worth solving? No. The economics don't work out. The problem has been solvable for more than thirty years. The nature of the business relationships and the cost sensitivity of design fees and the disruption of changes to methods make it mostly a non-starter. In mathematical terms it's in NP. A job shop scheduling problem where each workstation has no slack capacity. There's no money in solving it. The limits on profits are almost entirely in the class of clients a firm has not in its work methods.
  • brudgers 5y ago
    It says a lot about architecture that XREF's are still considered a bit exotic. They were introduced with AutoCAD r11 in 1990. One of the things it says is why Autodesk went to a subscription model. Another is why Autodesk deprecated AutoLisp. These on top of how little the economics of most architectural firms benefit from new features.
    • sbuk 5y ago
      It's not AutoCAD. Revit linking is (or was when I last looked 3 years ago) an unmitigated toxic hell stew! Autodesk are an absolute blight on the architecture and engineering worlds. While there is hand wringing going on around Apple/Google being investigated for antitrust, one of the biggest offenders goes unnoticed because it is 'niche'. Architectural firms don't make much money at the best of time, these parasites suck the life out of them.
      • brudgers 5y ago
        You can always draw by hand.
        • sbuk 5y ago
          At times I came close :)
• lostdog 5y ago
  Some of the videos from the Marble Machine X project show Fusion 360 cracking under the pressure. A big problem is that you need each part at full resolution when you're editing that part, but when you look at the whole machine, you don't need to render every thread for the hundreds of custom bolts. CAD programs don't seem to have this multi-resolution understanding implemented well.