OpenSCAD

⸺ by Charles Iliya Krempeaux

OpenSCAD is an (CAD) software application with its own built-in programming-language.

Unlike many other CAD software applications which use a GUI to create, edit, and manipulate objects, OpenSCAD creates, edits, and manipulates objects via a scripting programming-language. For example:

	cube([50,75,100]);

OpenSCAD scripts are usually stored in .scad files.

OpenSCAD includes many features similar to many imperative programming-languages; including:

variables,
• control structures (such as if-statements and loops),
• modules, and
• libraries.

For those already familiar with programming-languages such as C, C++, C#, D, Dart, Go, Java, JavaScript, PHP, and others — OpenSCAD uses curly-brackets. For example:

	for (a =[x1,x2,x3]){echo(a);}

OpenSCAD provides two main methods for 3D-modeling:

creating complex object from combinations of simpler shapes, and
• extruding 2D shapes (contained in .dxf or .svg files) into 3D shapes.

OpenSCAD is especially geared towards mechanical, rather than artistic, aspects of 3D computer-aided design. Thus OpenSCAD can be useful when one wants to create a model that one wants to 3D-print.

Units

All dimensions in OpenSCAD are measured in (the somewhat confusingly named) "unit".

The convention used by a lot of people doing 3D-printing is:

	1 unit = 1 millimeter

But OpenSCAD is in a sense unit-less.

And it is a good idea to explicitly size your model when preparing it for 3D-printing.

Cuboids

One basic 3D shape that OpenSCAD provides built-in support for is the cuboid.

To create a cuboid use the cube command. For example:

	cube([50,75,100]);

The parameter to the cube command specifies the width, length, and height of the cuboid. Note that the cube command will put one corner of the cuboid at the origin — [0,0,0].

Spheres

Another basic 3D shape that OpenSCAD provides built-in support for is the sphere.

To create a sphere use the sphere command. For example:

	sphere(20);

The paraemter to the sphere command specifies the radius of the sphere. Note that the sphere command will put the center of the sphere at the origin — [0,0,0].

Cylinders, Cones, and Truncated Cones

Three other basic 3D shape that OpenSCAD provides built-in support for is the cylinder, the cone, and the truncated cone.

To create a cylinder, cone, or truncated cone use the cylinder command. For example, this is a cylinder:

	cylinder(h=50, r1=20, r2=20);

Note that r1 and r2 have the same value. When r1 and r2 have the same value, you get a cylinder (rathe than a cone or a truncated cone).

And, for example, this is a cone:

	cylinder(h=50, r1=20, r2=0);

In that example, r2 is zero. But having r1 be zero (and r2 not be zero) would also produce a cone.

And, for example, this is a truncated cone:

	cylinder(h=50, r1=20, r2=5);

In that example, r2 is smaller than r1 (and neither is zero). But having r1 be smaller than r2 would also be a truncated cone.

Note that the cylinder command will put the center of one end of the bottom circle at the origin — [0,0,0].

Importing 3D Models

OpenSCAD has the ability to import shapes from other 3D applications if those shapes are stored in an .stl file.

You can import these models with the import command. For example:

	import("3dbenchy.stl")

Centering

By default, a sphere is centered at the origin — [0,0,0]. However, cuboids, cylinders, cones, and truncated cones are not, by default, cetered at the origin.

To make it so cuboids, cylinders, cones, and truncated cones are centered at the origin, use the center=true paramter. For example:

	cube([50,75,100], center=true);

And:

	cylinder(h=50, r1=20, r2=5, center=true);

Etc.