HOW TO: Manually Align Laser Cutting to Printed Material

By Michael Reilly
The goal is to load a printed piece of paper in the laser and cut a specific area. Sounds simple enough, but it’s not. The margins we set in our document are rarely the same as what prints, and while printing presses align each sheet on two edges prior to entering the press, our laser/inkjet printers and copiers just pull a sheet off the stack and feed it through, so each sheet may travel through the printer slightly differently.
Screen Shot 2013-10-24 at 9.56.02 PM
Screen Shot 2013-10-24 at 9.40.24 PM The first step is to add marks to the print job that we can use for reference. Here I drew a + mark with a fine line weight. I also drew in the cut lines (shown in red.) We need the cut lines, the reference marks and the artwork all aligned. When you print, you want to print only the reference marks and art.
Next, get a piece of 1/16″ clear acrylic or similar rigid, clear material. Cut a piece long enough to cover both marks at the top of the page and secure it to your top ruler. Make sure it’s wide enough to cover the marks if you put the sheet under it. Screen Shot 2013-10-24 at 9.43.09 PM
Screen Shot 2013-10-24 at 9.43.22 PM Use the laser pointer to find a position on the art board that puts the marks over the clear acrylic. Use a low power to scribe those marks onto the acrylic. If the material overlaps with the area to be cut out, use the laser to trim the material back, but not so much that it allows the material to deform.
Stand so you can look straight down on the marks while inserting a print under the acrylic, visually aligning the printed marks to the scribed marks. Typically, the scribed lines will hide the black lines from view. Screen Shot 2013-10-24 at 9.43.31 PM
Screen Shot 2013-10-24 at 9.39.48 PM Cut the job and it should align perfectly. If you align one end and find that the marks don’t line up on the other, then when you try cutting it will start out lined up on one end and gradually become more and more misaligned.
That is caused by a variety of factors. If you’re printing with inkjet, heavy ink coverage soaking into the paper can cause the paper to expand in size. If you’re printing with laser or copier, the fuser will drive moisture out of the sheet causing it to shrink slightly. Changes in humidity between the place it was printed and the place you laser cut it can cause sheets to change size. In fact, if you move a stack of paper from one environment to another, the edges of the stack will gain/lose moisture faster than the middle. This is the reason i-Cut is worth the money if you do this often. i-Cut uses a camera to read special marks on the sheet, allowing it to stretch/skew the cut lines so they line up with the printed artwork no matter what.
Doing this without i-Cut is possible, but is challenging, but not impossible. Find some tracing paper or parchment paper. Put it in the laser and cut all 4 marks in it. Use a marker to note how the sheet was placed in the laser. Lay the sheet over one of your prints. Align the top-left mark, then try to align the top-right mark. Chances are, you can align it vertically, but the mark will be off by some amount left-to-right. Get it as close as possible and tape the sheet to the print temporarily. Using calipers, measure the distance the mark is off. Go into your graphics program, select all the elements and change the width by the amount measured. Mark the cuts on the parchment so you know they are old, then repeat in a different spot of the sheet. You may need to go through several rounds of this, tweaking the width, height, possibly even shew or shear to get it in alignment.
Once you get it in alignment, mark the previous etched lines on the acrylic, shift the image over a bit and make new marks. Now it should be in alignment. With any luck, it will stay in alignment throughout the run. But it’s always possible that something in the printer changed, or one stack was more exposed to the environmental changes than another, and you will have to tweak again. With experience, you can guess at tweaks within a run as it’s usually a line’s width here or there.

Photos of this process

In alignment
Out of alignment