Laser Cutting a Jigsaw Puzzle

by MACE

My 2.5 year old grand-niece loves jigsaw puzzles. I thought it would be a nice to make a custom puzzle for her using a photograph of people she knows.

Here’s how I did it.

My approach was to take a photograph, glue it to a substrate and laser cut it into interlocking puzzle pieces. I’ve seen my niece assemble 25-piece puzzles, so I wanted to keep the total number of pieces to about that number. The pieces need to be an appropriate size to fit her little fingers. Combining this with the 25+/- constraint, I decided to order an 8×10 print and to cut it into a 5×4 matrix. Twenty pieces is a little light on piece count but it matches the aspect ratio of the photo.

Puzzle pieces need to be sturdy. Simply cutting the photo into pieces wasn’t satisfactory. The pieces need a stiff backing. I considered three materials — 1/16″ basswood sheet, acrylic, and heavy card stock. I ran test cuts on all three materials. I printed three 5×6 test photos and used Locktite 300 spray adhesive to glue the photos to each of the above materials and let them cure overnight. Then I covered the photos with blue painters tape to prevent charing of the photo. It’s best if the width of the tape is LESS THAN the size of a puzzle piece. The 300 adhesive helps ensure that the photo does not separate from the substrate either during the cutting process or when removing the blue tape.

The first material I tested was the card stock. I’d picked up some mat board typically used for picture framing. I cut a series of 1″x1″ squares through the tape, photo and substrate with various laser settings. The best setting seemed to be 10% speed, 100% VC, 100% power and 2 passes. The pieces cut very cleanly. The edges of the square were darkened, but the backside only had a little bit of soot and the blue tape completely protected the photo. The next test cut was a single, 2″x2″ jigsaw-puzzle-shaped piece. I found and downloaded a vector image of a single puzzle piece. It printed beautifully. The stiffness was perfect — just like a commercial puzzle — and fit well when dropped back into the hole left in the test material. I didn’t bother test cutting the other materials.

Finding a 5×4 vector jigsaw puzzle template for the production run was more difficult. I found plenty of .jpg images, but converting them to vectors for cutting exceeded my Inkscape skills. I ended up buying a collection of 13 templates in .svg format on ETSY for $2.50.

For the production run, I printed an 8×10 image and glued it to the mat board. In Inkscape, I opened the 5×4 puzzle template and sized it to 7.5″x9.5″ — slightly smaller than the image. I colored the interior lines blue and the outline red. The plan was to cut the blue first and the red last. This way, the pieces would stay together until the outer perimeter cut through. I added a second layer to the bottom of the layer stack, imported the original .jpg that I had printed and resized it to 8×10. With the two layers superimposed, I made whatever subtle changes were necessary to ensure the best placement of pieces within the boundaries of the photo. Once satisfied, I turned the background/photo layer off and sent it to the laser.

Surprisingly, the settings from the test cuts failed on the production run and I ended up using speed 30% and 3 passes. Once cut, I took each piece out of the laser one at a time, stripped the blue tape and reassembled the puzzle to ensure all pieces fit nicely.

When stripping the tape, there’s always the risk of pulling up the photo as you scrape along the edge of the piece trying to get a foothold to pull. By keeping the width of the tape small, you can ensure that the center of the piece with have two strips of tape overlapping each other.

It’s far easier to scrape at that seam to get started. Once the first one strip of tape is removed, it’s easy to start the second by scraping across the flat, center surface of the puzzle piece instead of along the edge of the piece.

Here is the final result.

I did eventually test cut the other materials. The 1/16″ basswood was sturdy, but a little thin. The acrylic was beefy thick, but light and strong.

Here are the details of the mat board purchased from Michael’s:

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