Hulling a concave object

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Hulling a concave object

 Hi All,I've designed a wing with variable profile. I built it up out of thin slices of incrementally different wing profiles and union()'d them together. However when I slice (with slic3r) with two top layers, two bottom layers and 10% infill, I get a nearly solid print. I suspect this is because the flat faces of the wing slices are see as valid geometry and must be supported and laid down.Is there a good way of taking only the surface of a shape that is comprised of many smaller shapes? Hull() would work if there weren't concave sections of the wing. My current hack is to subtract the wing from a big cube, then subtract the resulting cube from another cube of the same size, leaving a solid wing sans slices.Anyone got a more elegant solution? _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscadhttp://openscad.org - https://flattr.com/thing/121566
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Re: Hulling a concave object

 Have a look at how 3D knots are drawn here: http://kitwallace.tumblr.com/post/74713917178/openscad-revisited. Basically it makes a list of 2D slices and creates a mesh to join them using recursive functions to make lists.On 24 September 2014 22:48, tjhowse wrote:Hi All,I've designed a wing with variable profile. I built it up out of thin slices of incrementally different wing profiles and union()'d them together. However when I slice (with slic3r) with two top layers, two bottom layers and 10% infill, I get a nearly solid print. I suspect this is because the flat faces of the wing slices are see as valid geometry and must be supported and laid down.Is there a good way of taking only the surface of a shape that is comprised of many smaller shapes? Hull() would work if there weren't concave sections of the wing. My current hack is to subtract the wing from a big cube, then subtract the resulting cube from another cube of the same size, leaving a solid wing sans slices.Anyone got a more elegant solution? _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscad http://openscad.org - https://flattr.com/thing/121566 _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscadhttp://openscad.org - https://flattr.com/thing/121566
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Re: Hulling a concave object

 Administrator In reply to this post by tjhowse On Sep 24, 2014, at 17:48 PM, tjhowse <[hidden email]> wrote: > Is there a good way of taking only the surface of a shape that is comprised of many smaller shapes? Hull() would work if there weren't concave sections of the wing. My current hack is to subtract the wing from a big cube, then subtract the resulting cube from another cube of the same size, leaving a solid wing sans slices. > > Anyone got a more elegant solution? Am I correct in my understanding that you have one solid volume which contains internal cavities, and you want to remove the internal cavities, leaving only the outer shell?  -Marius _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscadhttp://openscad.org - https://flattr.com/thing/121566
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Re: Hulling a concave object

 @nophead: I'll look into that when I get home. I might have to un-blackbox the airfoil generator I'm using: http://www.thingiverse.com/thing:14179@Marius: Not internal cavities, but internal coincident faces that shouldn't exist.On 25 September 2014 08:07, Marius Kintel wrote:On Sep 24, 2014, at 17:48 PM, tjhowse <[hidden email]> wrote: > Is there a good way of taking only the surface of a shape that is comprised of many smaller shapes? Hull() would work if there weren't concave sections of the wing. My current hack is to subtract the wing from a big cube, then subtract the resulting cube from another cube of the same size, leaving a solid wing sans slices. > > Anyone got a more elegant solution? Am I correct in my understanding that you have one solid volume which contains internal cavities, and you want to remove the internal cavities, leaving only the outer shell?  -Marius _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscad http://openscad.org - https://flattr.com/thing/121566 _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscadhttp://openscad.org - https://flattr.com/thing/121566