Documentation
Designing for laser cutters and CNC routers
Draw flat parts as constrained sketches with the material thickness as a parameter, or start from the box and living hinge generators; all the laser tools are under Laser ▾ in the toolbar. When you export, enter the kerf: outlines move out and holes move in by half of it, and the SVG or DXF is written in colour layers that LightBurn and xTool read as separate operations.
How do I make the material thickness a parameter?
Open Parameters and add a user parameter named thickness with the thickness of your sheet, say 3 mm. Use the name wherever the thickness matters: slot widths, tab lengths, the depth of finger joints, the offset between parts that slot together. Change the parameter when you switch material, and everything that uses it follows. See Parameters for writing expressions such as thickness + 0.1.
The laser tools make thickness, finger (the finger width they aim for) and kerf for you the first time they need them. Once a design has them, the left panel’s Laser · sheet section shows them, to change in place.
How do finger joints work?
Choose Laser ▾ › Finger joint… with a straight line of a sketch selected, and the line becomes fingers and slots. Select two lines of the same length instead, the edges of two parts that meet, and the first gets tabs at its ends and the second slots, so they interlock. The slots are as deep as the material is thick, so when thickness changes, the joint changes with it, and the number of fingers follows finger. Because the joint is part of the sketch, the rest of the outline stays constrained around it.
How do I make a box?
Choose Laser ▾ › Laser box… and give the box’s width, depth and height, inside or outside, with or without a lid. Each panel becomes a component extruded to the thickness, so the box stands assembled in 3-D, where Interference check confirms that no two panels overlap; all the panels are also laid out flat in one sketch, ready to cut. The panels use the thickness parameter, so the classic change, 3 mm plywood to 6 mm, is one number: the joints, and the panels around them, follow.
A hole or a line you draw in a panel’s own sketch goes into the 3-D part and the flat layout, and stays through a rebuild. Constraints you add to the generated outline are dropped when the number of fingers changes. Boxes are rectangular for now, without dividers or sliding lids.
How do I make a living hinge?
A living hinge is a pattern of short cuts that lets a stiff sheet bend. Select a rectangle in a sketch and choose Laser ▾ › Living hinge…, then set the cut length, the bridge left between cuts, the row spacing and whether the cuts run along the long or the short side. The hinge is rows of straight, staggered cuts that fill the rectangle and are drawn again when you resize or move it. How far a hinge bends before it breaks depends on the material, so cut a test piece of your sheet first.
What is kerf, and how is it compensated?
The beam or bit removes a strip of material along every cut, typically a fraction of a millimetre wide on a laser. Cut exactly on the drawn line and every part comes out smaller by half that width on each side, and press fits turn loose. Enter your machine’s kerf when you export: outer outlines move out and holes move in by half the kerf, so parts come out the size you drew. Engraving and scoring lines are not moved, nor are open cut lines such as hinge slits. Measure your kerf by cutting a square of known size and measuring what you get.
How are colours and layers used?
Select sketch lines and choose Set to cut, Set to engrave or Set to score; text engraves and everything else cuts until you say otherwise. The SVG or DXF uses one colour per operation: cut red #FF0000, engrave blue #0000FF, score black #000000, and the DXF also puts them on CUT, ENGRAVE and SCORE layers. LightBurn and xTool Creative Space both read colours as layers, so you assign power and speed to each colour once and reuse those settings for the next file.
Can I get the flat parts out of a 3-D model?
Yes. Select a flat face or a plate body and choose Export for laser to get its outline and holes. Export all plates takes every plate in the design, meaning a body of one thickness all over such as an extruded sketch, and lists the bodies it leaves out. The plates are grouped by thickness and nested by their bounding rectangles, turned 0° or 90°, onto sheets of the size you set, one file per sheet; more than two files come as a zip. A box, a shelf or an enclosure designed as a 3-D assembly of plates comes out ready to cut.
SVG or DXF?
Use SVG unless your software or your cutting service asks for DXF. Both carry the colour layers and exact sizes. A DXF of a single sketch is also available from the sketch’s Save As DXF, without kerf and without the cut, engrave and score layers (see Export).
Does this work for CNC routers?
The design side does: the same constrained outlines, the thickness parameter and the joints, exported as DXF or SVG for your CAM program. For a router, set the kerf to the cutter’s diameter only if your CAM program does not offset the tool itself.