Laser engraving a map
A line-drawn map is almost the perfect file for a laser engraver: it is all strokes, with no photos or gradients. This guide explains how to prepare it so it comes out clean on wood, leather or acrylic.
Why a line map suits a laser
Laser engravers work in two ways. In line mode (what many programs call “line”, “score” or “vector”) the head follows each stroke, like a pen. In fill mode (“fill”, “engrave” or “raster”) it sweeps the piece from side to side, row by row, burning the dark areas of an image.
An ordinary map, made of patches of colour, forces you to use fill: slow, and with edges that depend on resolution. A PlotMyMap map is already made of lines, including the hatching of buildings and parks and the lettering, which is single-stroke. You can engrave the whole thing in line mode, which is faster, sharper and uses less material.
There is another advantage: the same file serves for engraving and cutting. The edge of the map is just another line, so you can engrave the drawing and cut out the piece in its own shape in the same job.
Which file to use
Use the SVG. It is vector, like the laser's line mode, and every common program opens it: LightBurn, xTool Creative Space, Glowforge's app, LaserGRBL through its importer, or Inkscape if you want to touch it up first.
The PlotMyMap SVG comes with one layer per colour: streets on one, buildings on another, water on another, the frame and the lettering on their own. Most laser programs group lines by colour, so each element of the map arrives as a layer you can switch on, switch off or engrave at its own power.
The PNG can also be engraved in fill mode, but you lose all of the above: the laser has to sweep the whole piece and fine lines depend on the image resolution. Keep it for when your machine's software does not accept vectors.
Set the size before drawing
As on paper, size rules. Choose the real size of the piece as your paper: a 10 cm coaster, a 20 × 30 board or whatever you are going to engrave. If it is not a standard size, the “Custom” paper takes millimetres.
Set the margin to zero if you will cut the piece along the edge of the map, or to a few millimetres if the piece is already cut and you want a clean border around the engraving.
For a coaster or a round ornament, choose the circle shape: the frame comes out as a perfect circle the laser can cut. A 10 cm square at 1:8,000 shows about 800 metres of ground, a whole neighbourhood or a village centre.
Density: how much detail each material takes
The laser spot is not infinitely thin. On a diode machine it is roughly one or two tenths of a millimetre, and on wood the burn spreads a bit more. Two lines less than half a millimetre apart merge into a smudge.
So it pays to think of the map at the size of the piece. A coaster with a whole city at 1:25,000 comes out as a blur; the same coaster with an old town at 1:6,000 reads perfectly. If in doubt, bring the scale closer.
PlotMyMap already helps: with “Adapt to scale” on, it merges or drops whatever would be smaller than useful detail on paper. If some areas still look crowded, in the map elements you can open up the hatching of buildings or parks (more millimetres between lines) or remove minor streets and paths.
Each material takes a different level of detail. Birch plywood and MDF take a lot of detail and give an even toasted tone. Woods with a strong grain, like pine, burn unevenly. Leather likes lines a little further apart. Cast acrylic engraves a frosted white and looks great lit from the edge.
Engrave, score and cut: the order
In the laser program, give each layer its job. The usual setup: the map drawing (streets, buildings, water, contours) in line mode at low power, so it marks without going through; the title on the same layer or a little stronger; and the frame in cut mode, at whatever power your material needs to go through.
Always cut last. If you cut first, the piece can shift or drop slightly and the engraving will come out offset. Most programs run layers in number order: leave the cut layer at the end.
If you do not want some element, switch its layer off in the laser program instead of deleting it from the file: you can try combinations without downloading the map again. Contour lines, for instance, look lovely on wood, but on a small piece they can be too much.
Test before the good piece
Power and speed depend on each machine and each material, so there are no numbers that work for everyone. Engrave one corner of the map on an offcut of the same material first, with two or three settings, and keep the one that gives the thinnest line without breaking through.
Watch the hatching above all: it is the first thing to clog. If its lines merge, lower the power, raise the speed, or go back to PlotMyMap and space them further apart.
On wood, a layer of masking tape before engraving prevents smoke stains around the lines. Peel it off afterwards and the wood tone stays clean.
Safety and ideas
Never engrave PVC or vinyl: when burned they release chlorine, which is toxic and corrodes the machine. Work with ventilation or fume extraction and never leave the laser unattended while it runs.
Some ideas that work very well: a set of coasters with a city's neighbourhoods, a chopping board with the family village, a wooden box with the wedding map on the lid, an acrylic lamp with the city engraved, or a leather tag with a mountain route.
For a present, mark the spot that matters with PlotMyMap's pin or heart and put the coordinates in the subtitle: on wood, that detail is the first thing people look at.
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