Hey everybody
I am in my first week of Openscad, hope you will help me in the right
direction.

I think I may have made a mess of my project, but I hope you can see what I
did wrong.

My difference() text cutout on one arm of my project is not working properly

• its not really cutting away any material, but seems like a "shadow"
  instead on the preview...
  Does it mean that my cutout is working? I have done several other text
  cutouts without problems, maybe its because its a mirrored part?

I know most of my code should be cleaned up, but my project goes haywire
every time I change something at this point, and I really just want a rough
prototype for printing.

Best
Anders

My project (the part in bold should be my problem):

//rotering af urholder til print:
rotate([90,150,0]){
//rundt rør
rotate([0,0,60]){
difference(){
cylinder(h=45, r=26, center=true, $fn=150);
cylinder(h=41, r=23, center=true, $fn=80);
translate([22,0,0]){
rotate([0,90,0])cube([46,40,9], center=true);}}
translate([16,0,0]){
rotate([0,90,0])cube([45,38,3], center=true);}
}
//venstre fod

difference(){
translate([0,-33,30]){
rotate(a=45, v=[1,0,0]){ cube([34,3,50],center=true);
}}
//trækker indersiden af cylinder fra
cylinder(h=45, r=24, center=true, $fn=80);
//hul til snor til rorline
translate([8,-30,30]){
rotate([-45,0,0]){    cylinder(h = 10, r=2, center = true, $fn=60);}}
//trækker skrå sider på fod fra
translate([8,-52,0]){
rotate(a=-15,v=[0,0,1]){ cube([55,55,55]);
}}
mirror([1,0,0]){
translate([8,-52,0]){
rotate(a=-15,v=[0,0,1]){ cube([55,55,55]);
}}}
}
//højre fod

mirror([0,0,1]){
difference(){
translate([0,-33,30]){
rotate(a=45, v=[1,0,0]){
cube([34,3,50],center=true);
//Navn i urholder
rotate([0,-90,90]){
translate([-8,-5,-10]){
linear_extrude(height=20){
text("NBL", $fn=150);}}
}}}
///trækker indersiden af cylinder fra
cylinder(h=45, r=24, center=true, $fn=80);
///trækker skrå sider på fod fra
translate([8,-52,0]){
rotate(a=-15,v=[0,0,1]){ cube([55,55,55]);}}
mirror([1,0,0]){
translate([8,-52,0]){
rotate(a=-15,v=[0,0,1]){ cube([55,55,55]);
}}}
}}
//bagerste fod

difference(){
translate([-30,-23,0]){
rotate(a=20, v=[0,0,1]){ cube([50,3,45],center=true);
}}
//trækker hul til urrem fra
rotate([0,-90,45]){
cylinder(h=62, r1=23, r2=14, center=true, $fn=80);}
//trækker indersiden af cylinder fra
cylinder(h=46, r=23, center=true, $fn=80);
///trækker skrå sider på fod fra
translate([-47,-28,-43]){
rotate(a=-15,v=[0,-1,0]){ cube([55,55,55], center=true);}}
mirror([0,0,1]){
translate([-47,-28,-43]){
rotate(a=-15,v=[0,-1,0]){ cube([55,55,55], center=true);}}}
}
//platform til sugekop h
difference(){
translate([0,-52,54]){
rotate(a=10,v=[1,0,0]){
cube([17,3,15], center=true);}}
translate([0,0,55]){
rotate([90,0,0]){
cylinder(h=120, r=2.5, center=true, $fn=200);}}
}
//platform til sugekop v
mirror([0,0,1]){
difference(){
translate([0,-52,54]){
rotate(a=10,v=[1,0,0]){
cube([17,3,15], center=true);}}
translate([0,0,55]){
rotate([90,0,0]){
cylinder(h=120, r=2.5, center=true, $fn=200);}}
}}
//platform til sugekop bag
difference(){
translate([-60,-31.5,0]){
cube([17,3,26], center=true);}
translate([-61,0,0]){
rotate([90,0,0]){
cylinder(h=120, r=2.5, center=true, $fn=200);}}
}
}

--
Sent from: http://forum.openscad.org/

[ For anybody else:  the * in front of the mirror() invocation is the
forum software saying "bold". ]

I think you're having two problems:

• I think that one of the things you're seeing is rendering problems
  in the previewer.  Does it look different if you do F6 instead of
  F5?  Fix this by adding "convexity=10" to your linear_extrude().
• What I see is a straightforward extrusion, not a difference / cutout.

Let's apply some indentation:

mirror([0,0,1]){
   difference(){
      translate([0,-33,30]){
         rotate(a=45, v=[1,0,0]){ 
            cube([34,3,50],center=true);
            //Navn i urholder
            rotate([0,-90,90]){
               translate([-8,-5,-10]){
                  linear_extrude(height=20, convexity=10){
                     text("NBL", $fn=150);
                  }
               }
            }
         }
      }
      ///trækker indersiden af cylinder fra
      cylinder(h=45, r=24, center=true, $fn=80);
      ///trækker skrå sider på fod fra
      translate([8,-52,0]){
         rotate(a=-15,v=[0,0,1]){
            cube([55,55,55]);
         }
      }
      mirror([1,0,0]){
         translate([8,-52,0]){
            rotate(a=-15,v=[0,0,1]){
               cube([55,55,55]);
            }
         }
      }
   }
}
//bagerste fod

Now the problem becomes more apparent.  You have a cube and the text,
minus a cylinder, minus two cubes.

Option 1:  add in another difference():

mirror([0,0,1]){
    difference(){
        translate([0,-33,30]){
            rotate(a=45, v=[1,0,0]){ 
                difference() {			// NEW
                    cube([34,3,50],center=true);
                    //Navn i urholder
                    rotate([0,-90,90]){
                        translate([-8,-5,-10]){
                            linear_extrude(height=20, convexity=10){
                                text("NBL", $fn=150);
                            }
                        }
                    }
                }
            }
        }
        ///trækker indersiden af cylinder fra
        cylinder(h=45, r=24, center=true, $fn=80);
        ///trækker skrå sider på fod fra
        translate([8,-52,0]){
            rotate(a=-15,v=[0,0,1]){
                cube([55,55,55]);
            }
        }
        mirror([1,0,0]){
            translate([8,-52,0]){
                rotate(a=-15,v=[0,0,1]){
                    cube([55,55,55]);
                }
            }
        }
    }
}
//bagerste fod

Option 2:  Move the text out to be a child of the original difference()
(and duplicate the transformations):

mirror([0,0,1]){
    difference(){
        translate([0,-33,30]){
            rotate(a=45, v=[1,0,0]){ 
                cube([34,3,50],center=true);
            }
        }
        translate([0,-33,30]){		// COPIED
            rotate(a=45, v=[1,0,0]){ 
                //Navn i urholder
                rotate([0,-90,90]){	// MOVED
                    translate([-8,-5,-10]){
                        linear_extrude(height=20, convexity=10){
                            text("NBL", $fn=150);
                        }
                    }
                }
            }
        }
        ///trækker indersiden af cylinder fra
        cylinder(h=45, r=24, center=true, $fn=80);
        ///trækker skrå sider på fod fra
        translate([8,-52,0]){
            rotate(a=-15,v=[0,0,1]){
                cube([55,55,55]);
            }
        }
        mirror([1,0,0]){
            translate([8,-52,0]){
                rotate(a=-15,v=[0,0,1]){
                    cube([55,55,55]);
                }
            }
        }
    }
}
//bagerste fod

Thank you so much. (:

I ended up adding an extra difference and it looks great! Added a cube to
hold the 2 floating pieces in my B. But i don't really get how it makes a
difference, as you only moved it below my translate and rotate? Is there a
maximum of how many elements i can subtract with difference?

I guess I am just being blinded by my own hideous code. :-)

Best

--
Sent from: http://forum.openscad.org/