Getting started with KerfScript: your first laser cut design written as code

Open the playground. The Clock face example is already running. Under Settings, drag Size and watch two things change at once: the clock in the preview, and the number after size = in the code. The sliders and the code are the same thing.

Pick other designs under Start from: a finger-jointed box, gift tags from a list of names, a tilt maze or a slot-together sculpture. Each one is ordinary KerfScript you can read and change.

Clear the editor and type one line: rect([80, 40], r = 6);. That is a rounded rectangle, 80 by 40 mm, with 6 mm corners. Everything outside a layer is cut, so this is already a finished cut file.

Now punch a hanging hole. difference() takes the first shape and removes the ones after it: difference() { rect([80, 40], r = 6); translate([8, 20]) circle(d = 5); }. You can spread it over several lines, KerfScript does not mind.

Measurements are in millimetres, the x axis points right and the y axis points up. A rectangle starts at [0, 0], so the hole sits 8 mm from the left edge, halfway up. If you make a typo, the line turns red and the Console under the editor says what went wrong.

Add a line at the end: engrave() translate([44, 20]) text("Hello", size = 12, halign = "center", valign = "center");. The text goes on the engrave layer, so your laser fills it in instead of cutting it out.

Text uses Roboto unless you add font = "Pacifico" or the name of any other font on MyLaserTools. Letters are turned into outlines, so the file looks the same on any computer. Use score() instead of engrave() for a thin line, like a fold mark or a border.

Move the numbers into variables at the top of the code and use the variables below. A comment after a variable turns it into a control under Settings:

• width = 80; // [40:5:200] makes a slider from 40 to 200 in steps of 5.
• label = "Hello"; makes a text box.
• hole = true; makes a switch.
• shape = "round"; // [round, square] makes a list to choose from.
• A comment line just above the variable becomes its description, and /* [Size] */ starts a new group.

If you have used the OpenSCAD customizer, these are the same comments.

• Kerf. Wrap your design in material(thickness = 3, kerf = 0.15) { ... } and every cut outline moves out by half the kerf, so slots and tabs fit. Cut the Kerf and fit test example once to measure your own laser.
• Finger joints. finger_rect([100, 60], "out") draws a panel with finger joints sized from the material thickness. Join an "out" edge to an "in" edge of the same length.
• A whole box. Start with use <kerf/box> and box([120, 80, 50], lid = true); gives you six panels that fit together. The Finger-jointed box example shows it with sliders.
• Several pieces. Name each piece with part("side", qty = 2) { ... }. The playground lays them out on sheets and lists them under Parts with their sizes and cut length.

• Turn a list into a sheet: open Gift tags from a list, type your names separated by commas and cut a whole set at once.
• Measure your laser with the Kerf and fit test, then put that kerf into every design you write.
• Read the KerfScript language reference for every shape, transform and function.