triming bulkheads, etc against hull in autocad

Discussion in 'Software' started by Grant Nelson, May 4, 2006.

  1. Grant Nelson
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    Grant Nelson Senior Member

    Hi,
    Why I can not figure this out is beyond me... I think I understand what I have learned in AutoCad, and then when I want to do something practical, it just doest not seem to be possible..

    Basically I want to take a 3d female form like half a hollowed out sphere (ah, or like a hull maybe...) and then toss an oversized 3d box right across it (like a bulkhead) and then trim away the 'bulkhead' to just the part that is inside the femail forms... hull...

    Seems to me that either trim or one of the boolean tools (subtract, etc.) will the the command I want to use, but when I have to indicate the trimiming surface, well... you guessed it, AutoCad reports that is not an allowed object for this part of the Trim function...

    The boolean functions seem to do everything but leave the bulkhead part I want..

    Now I can not believe that triming a solid to fit inside another solid is not some simple process in AutoCad... but I will be darned if I can figure it out..

    Can someone out there give me a short explaination, or point me to one...?

    Many many thanks!

    Grant
     
  2. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    First I will say that you should try Rhino :) It has all the surface modelling tools that you are missing in AutoCAD, including trim, match, merge, fillet etc.

    In AutoCAD, if you have the hull (and deck?), the skin, as a solid object, then you can make an oversized bulkhead that extends outside the skin. Then you have to make a copy of the hull (and deck) before you subtract those copies from the bulkhead. Now you can separate the outside part of the bulkhead and delete it.
     
  3. bhnautika
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    bhnautika Senior Member

    Grant Just a thought, make sure the surface/solid to be trimmed lies with in the cutting surface(s)no over flow or gaps. I don’t know about Auto Cad but some programmes treat surfaces and solids differently
     
  4. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    That's right, IN AutoCAD both the hull and the bulkhead have to be solids. Then you can subtract the hull from the bulkhead.
     
  5. Grant Nelson
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    Grant Nelson Senior Member

    Nice work around for AutoCAD - but it seems to confirm what I feared: AutoCad, even with release 2007 with a lot of PR around its 3d capabilities is not really set up to design/construct in 3d... at least not for shapes that are not straight and geometric...

    What I did find was that there are 3d surfaces, and (3d) solids... if you work with surfaces you can do more triming, extruding, lofting, etc... but if you have solids, you still have to use surfaces to trim and extent to... which is sometimes impossible because you can not create a surface that exactly matches the surface of an irregular solid... at least that is my guess.

    But I still hope that I am wrong about all this... AutoCad has a lot of great functions that would make it nice to use to design the interior, etc. of yachts..

    Anyways, thanks for your replies so far!
     
  6. SailDesign
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    SailDesign Old Phart! Stay upwind..

     
  7. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    I agree strongly with Steve!
    Design the hull in Rhino and it will be smooth (as you like it) and have the shape you want. Then you can export all sections to AutoCAD if you want.
     
  8. SailDesign
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    SailDesign Old Phart! Stay upwind..

    Raggi - you are a man of impeccable taste with a great depth of knowledge!
    I can say this because I am, as well. :)
    Steve
     
  9. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    Seems like we agree on alot :)
     
  10. Grant Nelson
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    Grant Nelson Senior Member

    you guys are real bad... maybe we need a separate forum for self appreciations... ;-)

    OK, seems senority wins... ( I could claim some, I used AutoCad for the first time in 1984 or 85 - is that possible? - or was that the Symphony PC package.. and helped market AutoYacht in 1988 or 89...)... but that was another life... Rhino for 3d and ACad for 2d...

    Can I explore the thread a bit more - hoping for more great agreement...?

    I fair my hulls in MaxSurf, then export to Rhino, where its accepted that the superstructure can be designed. But then what? Do you guys design the interiors in Rhino? It seems it would be best to do it in some kind of 3d package - given the curving 3d hull constraint - thus my original question? So are you to (already agreeing I am sure) saying Rhino is suited to 3d joiner, stringer, etc. design, enought so that you can take sections of it to make 2d ACad views for finishing off for the builders? Or is your (many many many years of) experience that you make the main hull and super structure, and then do the rest more or less the old way in 2d?

    :)

    Grant
     
  11. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    I have in recent projects made quite complete surface models in Rhino with frames, bulkheads, longitudinals as surfaces with no thickness. Then I export sections and outlines of all flat surfaces as 3D dxf or dwg. In AutoCAD I have som lisp routines that for example make one layout for each layer group. I name the layers after location, a bulkhead at X=4000 (mm) is drawn on a layer called X4000 and we have a layout with that name also. Then we have the layers like X4000_Dim, X4000_Txt, X4000_3D. When a frame or bulkhead is "cleaned up" in AutoCAD (or BricsCad!) I have a macro that runs the command bpoly (boundary) to create a region and the extrude that to the default bulkhead thickness. In that way I make 3D solids of all the internal structure. Rhino gives the area and weight estimate of the skin, while AutoCAD gives the weight of the structure. In one large project I also automated the numbering of title blocks etc, I think we had one dwg with 70 layouts :)
     
  12. SailDesign
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    SailDesign Old Phart! Stay upwind..

    All my hulls are done in AutoShip, and deck, interior, etc in Rhino. It is a full 3D program.
    Here are a couple of interiors - some from early days (simple renderer) and some from Flamingo.
    http://www.boatdesign.net/gallery/showphoto.php/photo/1145/size/big/ppuser/909
    http://www.boatdesign.net/gallery/showphoto.php/photo/1143/size/big/ppuser/909
    http://www.boatdesign.net/gallery/showphoto.php/photo/616/size/big/ppuser/909

    Steve (typing with one hand while the other patted himself on the back :))
     
  13. JPG Designs
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    JPG Designs Pieces and Parts

    Grant,

    To make a bhd solid in autocad, you would need a closed polyline and extrude it the thickness that you want.

    The get the shape of the "bhd", you can section the solids of your "hull" to the plane of the "bhd" get the edges of the "bhd". These sections will have to be exploded, line or pline segments added to close "bhd" and then joined using pedit to closed pline. Then you can extrude for thickness.

    Hope this helps.

    JPG
     

  14. Murdock
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    Murdock Junior Member

    Hi folks, may I give my 2 cents for the day,

    Once you have an extruded surface done in Autocad, (a MESH, as is called) you can convert it to solid with a tiny routine in LISP, routine called M2S (Mesh-to-Solid, dumbie yeah?), once applied, you can play with the solid transformed.
    Just download, load it in your Autocad session (command>APPLOAD), call it with (command>M2S),& experiment with it.
    Warning: It generates the solid from the figure down as on the selected plane (UCS), if you want it solidified/extruded on any other direction, change UCS.
     

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