Simple bridge form

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Simple bridge form

ashuan
Hello,

I want to build a simple 3D form who look like a bridge.

Description :
* i have a bezier simple arc who are extrude for transform this arc to a
bridge

I want than the middle of this bridge are more narrow than begin and end.
What the prefered way for doing that ?

Thanks



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Re: Simple bridge form

ashuan
I have find this about the global 3D form :
https://www.mathcurve.com/courbes2d.gb/croixdemalte/croixdemalte.shtml

And i wan't this like a bridge.

Who could i do that ?



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Re: Simple bridge form

cbernhardt
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Re: Simple bridge form

Ronaldo
In reply to this post by ashuan
The shape of a Bezier curve follows its control point specifications. What is the header (name and arguments) of the Bezier function you are using and what are the arguments you set for the upper arc of the bridge? I could give you some suggestions based on them.


2017-11-24 12:23 GMT-02:00 ashuan <[hidden email]>:
Hello,

I want to build a simple 3D form who look like a bridge.

Description :
* i have a bezier simple arc who are extrude for transform this arc to a
bridge

I want than the middle of this bridge are more narrow than begin and end.
What the prefered way for doing that ?

Thanks



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Re: Simple bridge form

jdawgaz
I did this to show a simple bridge.

$fn = 120;

db = 200;  // diameter of bridge -- higher is flatter
dw = 35;   // width of bridge -- higher is wider   
do = 1.1;  // offset of either side in the middle

module bridge()
{
  intersection()
  {
    difference() 
    {
      rotate([0,90,0]) translate([db/2,0,0]) cylinder(d=db, h=dw, center=true);
      rotate([0,90,0]) translate([db/2*do,0,0]) cylinder(d=db, h=dw+10, center=true);
      
      translate([-db/2*do,0,0]) cylinder(d=db, h=dw, center=true);
      mirror([1,0,0]) translate([-db/2*do,0,0]) cylinder(d=db, h=dw, center=true);
    }
    cube([dw,200,10], center=true);
  }
}

difference()
{
  bridge();
  translate([0,0,-2]) scale([1.25, 1, 0.95]) bridge();
}



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On Fri, Nov 24, 2017 at 10:43 AM, Ronaldo Persiano <[hidden email]> wrote:
The shape of a Bezier curve follows its control point specifications. What is the header (name and arguments) of the Bezier function you are using and what are the arguments you set for the upper arc of the bridge? I could give you some suggestions based on them.


2017-11-24 12:23 GMT-02:00 ashuan <[hidden email]>:
Hello,

I want to build a simple 3D form who look like a bridge.

Description :
* i have a bezier simple arc who are extrude for transform this arc to a
bridge

I want than the middle of this bridge are more narrow than begin and end.
What the prefered way for doing that ?

Thanks



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Re: Simple bridge form

ashuan
In reply to this post by cbernhardt
Thanks, yes, it's seem ok.
I have just a problematic point :
* i need to have the middle of this shape more narrow than the begin and the
end.

Is it possible with your proposal ?



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Re: Simple bridge form

ashuan
In reply to this post by jdawgaz
Thanks for this code, it's exactly look like what i want.

I have look for my ideal parameters.
I have change those like that :
db = 20;   // diameter of bridge -- higher is flatter
dw = 40;   // width of bridge -- higher is wider  
do = 1.2;  // offset of either side in the middle

I have a little bug (screenshot).

I try to understand your code proposal :
<http://forum.openscad.org/file/t2049/2017-11-27_1243.png>
* i have a cube minus
* * two cylinder (left and right)
* * one cylinder (down)
* * one cylinder (top)

If my understand are exact, i have just to change the compute of left &
right cylinder.



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Re: Simple bridge form

cbernhardt
In reply to this post by ashuan
Yes, just difference two more cylinders.
<http://forum.openscad.org/file/t1309/arch2.jpg>



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Re: Simple bridge form

ashuan
Thanks a lot, it's perfect.



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Re: Simple bridge form

ashuan
I have change your code like following.
Now, i just have to destroy (if possible) the x, y, z correction
and applicate my parameter like shape_Length, shape_Width, shape_Height,
bridge_Width, bridge_Height.

Thanks again.


shapeColorTop     = "red";
shapeColorLeft    = "red";
shapeColorRight   = "red";
shapeColorDown    = "red";

shapePos_x        = 10 - 75;  // true value, correction
shapePos_y        = 10 + 45;  // true value, correction
shapePos_z        = 00 - 10;  // true value, correction

shape_Length      = 110;  // Longeur
shape_Width       = 40;   // Largeur
shape_Height      = 30;   // Hauteur
bridge_Width      = 15;   // Taille étroite du pont
bridge_Height     = 05;   // Hauteur étroite du pont

translate([shapePos_x,shapePos_y,shapePos_z]) {
difference() {
    difference() {
        choiceColor(shapeColorTop) {
        rotate([90,0,0])
        translate([0,-25,0])
        cylinder(h=50, r1=65, r2=65, center=false, $fa=2);
        }
       
        choiceColor(shapeColorDown) {
        rotate([90,0,0])
        translate([0,-11,0])
        cylinder(h=100, r1=50, r2=50, center=false, $fa=2);
        }
    }
   
    // remove the lower portion
    choiceColor(shapeColorLeft) {
    translate([-75,-75,-90])
    cube(size=[150,100,100], center=false);
    }
   
    // make arch more narrow in center
    choiceColor(shapeColorRight) {
    translate([0,80,0])
    cylinder(h=100,r1=100,r2=100,center=false,$fa=2);
    }
       
    choiceColor(shapeColorDown) {
    translate([0,-130,0])
    cylinder(h=100,r1=100,r2=100,center=false,$fa=2);
    }
}
}

// color gesture
module choiceColor(couleur)
{
    if (couleur == "default") orange() children();
    if (couleur == "green")   green() children();
    if (couleur == "blue")    blue() children();
    if (couleur == "orange")  orange() children();
    if (couleur == "violet")  violet() children();
    if (couleur == "red")     red() children();
    if (couleur == "postit")  postit() children();
    if (couleur == "marron")  marron() children();
    if (couleur == "black")   black() children();
    if (couleur == "white")   white() children();
    if (couleur == "human")   human() children();
}
module green()  color("LimeGreen", 0.5) children();
module orange() color("Gold", 1) children();
module blue()   color("SteelBlue", 0.5) children();
module violet() color("DarkOrchid", 1) children();
module red()    color("FireBrick", 0.8) children();
module postit() color("Cornsilk", 0.8) children();
module marron() color("Peru", 0.8) children();
module black()  color("Black", 0.7) children();
module white()  color("White", 1) children();
module human()  color("SteelBlue", 0.9) children();





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