Laser-engraving the covers

I have access to a laser cutter, so my plan was to use coloured paper for the covers and engrave a typographic design. Coloured paper generally lightens when engraved with a laser, giving an effect that is difficult to achieve by any other means. 

However, getting a good result requires some experimentation, and all lasers and papers behave differently. I found (using a Trotec Speedy 300 laser) that these settings worked well:

  • Speed: 30%
  • Power 90%
  • DPI: 500
  • Options: ‘High quality’ setting, which means “Uniform laser engraving by consistently traversing the entire job width at the same speed so that acceleration and speed remain constant across the entire graphic.”

The laser moves very fast from left to right and back again while it’s engraving. Without this high quality setting it slows down as it gets to the end of each pass, which makes the left and right edges of the engraved area more heavily marked. 

I found that mid-toned papers worked best. In this image, on the left is one of my first tests with some no-brand black cartridge paper. The engraved areas have a green tint and are uneven and grainy. On the right is some Colourplan ‘Nubuck Brown’ which gave a much cleaner finish.

Laser placement jig

When the laser is running, fans suck air out of the chamber to exhaust smoke. This tends to lift the paper off the bed. The conventional solution is to tape it down with masking tape, but I wanted a solution that would not risk damage to the paper, and would also make it easy to accurately position material repeatedly. 

So I designed a little jig in Illustrator and laser-cut it out of 3 mm MDF:

It has a few key features: 

  • It’s sized a little over A4 (350 x 250 mm).
  •  Inside is a cutout a little under A4: 5 mm undersized all round (ie. 287 x 200 mm).
  • Marked with a very light cut on the frame is a rectangle marking a size larger than A4 that I can make all my artwork at. It doesn’t really matter what this size is, as long as you can use the same size for the artwork. I made it 10 mm oversized all round (ie. 317 x 230 mm). I produce all my artwork at this size – including bleeds, so I can precisely align my origins for the artwork and the laser in the same place. In the second image, you can see the laser at its starting point in the top left corner of that marked rectangle.
  • There are 4 crosshairs with small circular holes placed at the corners of an A4-sized rectangle. The holes allow you to look through the frame and check that the paper is placed in exactly the right spot.

In combination, these features allow me to:

  • Hold down the paper in a fixed repeatable spot on the laser bed each time
  • Align the laser at a fixed repeatable origin point each time
  • Snap align my artwork file to the laser origin in the laser control software

In case it’s useful, you can download a copy of this frame artwork in PDF format here.

One thing to note – my artwork has a safe area around the edge where I can safely mask off the paper with the jig. In fact there is a small region on the left and right sides where I need to trim back the frame to allow one element to be engraved right up to the edge and onto the bleed region. This type of hold-down frame won’t work if the artwork to be engraved is largely full-bleed.

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