OpenSCAD making complex parts

I need to make a whole bunch of complex parts that involve complex curves and have been using the hull() command to make them, for an arch, for example I need to use about 50 short hull() segments, otherwise the hull() command fills in the area inside the arch. I need that area not filled in. Anyone have a good idea on doing that? Thinking maybe a module that divides the arch into 50 segments each of identical lengths, but one of you may have a smarter idea :)

Thanks in advance.

The simplest way to make an arch is to use the rotate extrude command to create a 180 degree curve and then resize it to get that upward arch.

Quote:

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resize([20,50,3])rotate_extrude(angle=180,convexity = 10) translate([20, 0, 0]) circle(d = 1);

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A simple one line Arch generator :-)

Adjust the roundness of the shape by changing '$fn='

So a simple parametric arch script looks like this:

Quote:

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// CA's simple arch generator

$fn=80; // change to adjust roundness of arch ie: numbers between 4&20 make some interesting shapes

ah=30; // arch height
aw=40; // arch width
at=3; //arch thickness
bt=5; //beam thickness
bw=50; // adjusts beam width - larger numbers make narrower beams

resize([aw,ah,at])rotate_extrude(angle=180,convexity = 10) translate([bw, 0, 0]) circle(d = bt);

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Not sure you can do it any simpler. Obviously you'd need to make a slightly smaller arch and difference it to thin the top part down.
Although you can also do that by adjusting beam thickness and arch thickness.

But basically that's a pretty versatile one line arch generator :-)

what other shapes do you need ?

Throw in an angle adjuster and you can make any curve:-)

Quote:

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// CA's simple curve and arch generator

$fn=50; // change to adjust roundness of arch NB: numbers between 4&20 make some interesting shapes

ca=90; // angle of curve - 180 makes an arch

ah=30; // arch height
aw=40; // arch width
at=3; //arch thickness
bt=5; //beam thickness
bw=50; // adjusts beam width - larger numbers make narrower beams

resize([aw,ah,at])rotate_extrude(angle=ca,convexity = 10) translate([bw, 0,0]) circle(d = bt);

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So to make a smooth arch with a pointed top you could generate a 90 degree curve then mirror it to join two together with a more pointed apex.

The applications are almost endless.
Rotate the 90 degree curves around the centre and you'd get a sort of pergola effect.
I've also rotated the whole thing to sit flat on the usual plane:

Quote:

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// CA's simple arch and curve generator

$fn=8; // change to adjust roundness of arch NB: numbers between 4&20 make some interesting shapes

ca=90; // angle of curve
ch=0; // curve height adjuster

ah=60; // arch height
aw=40; // arch width
at=3; //arch thickness
bt=5; //beam thickness
bw=50; // adjusts beam width - larger numbers make narrower beam

module curve(){
resize([aw,ah,at])rotate_extrude(angle=ca,convexity = 10) translate([bw, 0,0]) circle(d = bt);
} // end mod curve

nps=10; //number of pergola segments

module pergola(){
rotate([90,0,0])for (i = [1:nps]) rotate([0,(360/nps)*i,0]) curve();
} // end mod pergola

pergola();

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Attachment 16875

Add enough pergola sections and you can make interesting 'buildings'.

Basically it's now a fairly useful little script.
I know I'll be using it again ;-)

Oh yeah, a 2 segment pergola is an arch :-)
So no need to use the curve module.

Also using 180 curve with the pergola module makes a whole bunch of different shape arches.