Hull wall thickness?

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  • jphatton
    Lieutenant
    • Jan 2021
    • 84

    #16
    I've been using Rhino since 2016 for CAD modelling and design. I settled on Rhino after testing some other CAD software, as it provided a good range of functionality was reasonable intuitive to learn and has with good help/tutorial support.

    My primary interest up to now with CAD modelling has been to construct digital models to document things that interest me (submarines, sounding rockets and target drones to be specific :-), based on drawings and photos ie. integrating the reference material into a 3D model which can be used to document specific configurations which can then be used to generate derived drawings, cross sections or images. This year I finally got a 3D FDM printer and have started experimenting with printing the CAD models.

    Rhino is one of the software used in naval design and building architecture, so has useful tools for modelling submarines. It uses NURBS rather than meshes to construct curves and surfaces and with experience it is possible to get smoothly lofted surfaces from construction curves (either classic lofts of cross sections, swept lofts along reference rails between sections or network surfaces built up from a series of intersecting curves). There is also a parametric modelling application called Grasshopper which is included in Rhino which can be used to generate models based on equations and varying input parameters. I made some quick models of various small axisymmetric AUV hulls using this method from Myring hull equations & NACA airfoil sections, as well as a reasonable approximation of a Thresher / Permit submarine hull using the Myring equations.

    For 3D printing the files need to be exported as mesh files which is relatively straightforward but I found the default settings too coarse for printing, so this needs some adjusting to get right. However, you can visualise the 3D print in the slicer software before printing. A fairly comprehensive tutorial can be found here;



    In addition there are a set of mesh tools for directly working with meshes or deriving things from them. Also there is good support for import and export of many other file formats.

    Ultimately, the choice of which software to use for modelling comes down to what you want to do and how much time, effort and budget you want to invest. I assume that many of the other software out there can do similar things to Rhino & there are some good examples of CAD modelling work done with other packages on this forum.

    The key thing is taking the time to learn the tools and build up the skills, as with all modelling pursuits :-)






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    • Albacore 569
      Commander
      • Sep 2020
      • 294

      #17
      Hi Bob,

      I notice in your Argonaute Hull print in PVC material with it's 3 mm plus thickness you also laminated fiberglass cloth on top inside only too. I think that is an excellent idea for an extra measure of torsional stiffness without a lot of extra material. You're the experts, but I felt maybe that is an important factor to consider in this discussion perhaps too?
      Last edited by Albacore 569; 11-03-2023, 01:17 PM.

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      • Subculture
        Admiral
        • Feb 2009
        • 2113

        #18
        Learning CAD is like learning a machine tool, you have to know what bits do what and the best techniques. I chose Fusion 360 because it seemed fairly intuitive, plus tons of tutorials online and it does most of what I would need it for.

        The parametric design can get out of hand sometimes if you make an error early on.

        Also I've yet to really get to grips with forms, and still get into a pickle with that. I mainly using it for certain parts and blend it with traditional hand-crafting to create what I'm after.

        I think the software still has ways to go before it can be considered user friendly.

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        • Thorbrandr
          Lieutenant Commander
          • Mar 2022
          • 124

          #19
          Working on this...been busy.

          Fusion360 is free for a limited functionality for a limited time. Tried it. Did not like it. Also, the AutoDesk's reputation on policies on subscriptions and updates is not good. They have been known to ditch support for older subscribers and versions. Seen that from a few angles.

          Will try to give more info on Rhino soon.

          Comment

          • Subculture
            Admiral
            • Feb 2009
            • 2113

            #20
            The limits on functionality for the free version are unlikely to bother most hobbyists in this game.

            I did have a go with Rhino some years ago, but found it difficult, so it's horses for courses.

            Comment

            • Thorbrandr
              Lieutenant Commander
              • Mar 2022
              • 124

              #21
              Originally posted by QuarterMaster

              How about some specifics regarding this decision, aside from the ME's(?) recommendation. Pro's, cons?

              Finally getting a moment to respond on this....

              First, the ability to easily do splined and blended body structures and do general design is a key feature that my ME likes. He does an incredible amount of fast concept and physical design development.

              In a professional work environment this is important: "All licenses are permanent and do not expire. Prices include support and service releases for the current version. There are no maintenance fees."

              The ME has had issues with dropped support for Autodesk SW products, including expiring licenses, forcing a complete new purchase or subscription for a running copy. He found the overall cost of ownership over time higher with Autodesk products than Rhino's model. My EX was an architectural designer...same complaints with AutoDesk. This was a major part of our adopting Rhino for our consulting work.

              The ME uses his tools for hobby work, not just work. He has tried Fusion360, including the free version. free version limits too much of the capability, and he hates the user interface. I tried the free Fusion360 as well. I could not stand the interface, and couldn't do some of the operations I needed. Rather than risk messing with AutoDesk for an expensive subscription model, I have decided to go the Rhino route.

              Still, it comes down to what you like and what you can afford.



              Comment

              • QuarterMaster
                Rear Admiral
                • Sep 2015
                • 1209

                #22
                Originally posted by Thorbrandr


                Finally getting a moment to respond on this....

                First, the ability to easily do splined and blended body structures and do general design is a key feature that my ME likes. He does an incredible amount of fast concept and physical design development.

                In a professional work environment this is important: "All licenses are permanent and do not expire. Prices include support and service releases for the current version. There are no maintenance fees."

                The ME has had issues with dropped support for Autodesk SW products, including expiring licenses, forcing a complete new purchase or subscription for a running copy. He found the overall cost of ownership over time higher with Autodesk products than Rhino's model. My EX was an architectural designer...same complaints with AutoDesk. This was a major part of our adopting Rhino for our consulting work.

                The ME uses his tools for hobby work, not just work. He has tried Fusion360, including the free version. free version limits too much of the capability, and he hates the user interface. I tried the free Fusion360 as well. I could not stand the interface, and couldn't do some of the operations I needed. Rather than risk messing with AutoDesk for an expensive subscription model, I have decided to go the Rhino route.

                Still, it comes down to what you like and what you can afford.



                Thank!

                In the long run, if the SW is worth it, I'll pay the price.

                I go by the old adage, "Feel the big pain once up front, or continue to feel multitude of pains afterward."

                I LOATHE subscription licensing, more so being forced into it to give the a continuous stream of cash to the developer for little true benefit. I dig it, needs change, thing become antiquated, life EVOLVES, but man, I'd rather buy new software every five than leasing. As I tend to use 10-20% of a programs capabilities, new bells and whiskies often don't interest me. As long as they can correct bug's with free fixes, I'm good. But I also understand some people prefer renting rather than buying and can only afford that level.

                Yeah, AUTODESK...I learned in the mid '90's at a Seminar the term, "Prisoner of Choices." as it tried to please EVERYONE. So I have my own beef.

                Thanks again, I will to look into it.
                ​​​​​​​
                v/r "Sub" Ed

                Silent Service "Cold War" Veteran (The good years!)
                NEVER underestimate the power of a Sailor who served aboard a submarine.
                USS ULYSSES S GRANT-USS SHARK-USS NAUTILUS-USS KEY WEST-USS BLUEBACK-USS PATRICK HENRY-K432-U25-SSRN SEAVIEW-PROTEUS-NAUTILUS

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