T1W5: Laser Cutting Nightlights

Now Meeting in the Innovation Studio - Primary School Building Room 120!

Last week we introduced the laser cutter and worked on designs for an anodized aluminum nameplate. This week I hope everyone will finish engraving their nameplates and start on the design of their acrylic night lights.

Engraving and Cutting an Acrylic Nightlight

Although we could only engrave the surface of the aluminum, with acrylic (AKA Plexiglas) sheets we can cut all the way through the material along lines drawn in our vector graphics editor. We can also engrave images like we did with the aluminum name plates. To do both on the same object requires some additional steps because of the way the laser cutter software works.

Open this file with the outline of the blank acrylic in Google Drawings and make a copy that you can edit.

You can add text, graphics, and images inside the circular region as you did with the nameplate. Keep in mind that the lasered output will be gray scale only, so you can select the image and select Format->Format Options->Recolor->Grayscale to visualize this. Under Adjustments, you can set the Brightness and Contrast to maximize visibility of your image.

You can leave the outline of the acrylic blank round, or cut it into any shape you would like - you can follow the outline of the image inside. Use the Polyline or Curve tool and start the line outside the circle, then go all the way around your design and exit again on the other side of the base. You should leave the rectangular tab at the bottom intact so it can plug into the illuminated base.

Here is my version of a Furby nightlight design. The red line is the outline of the cut that will change the shape of the acrylic piece.

Preparing Files For The Laser

The laser cutter software has some issues with files from Google Drawings so we have to follow a process for exporting the artwork.

When the vector artwork is exported, the laser software will generate a rectangular box the size of the work area that we want to ignore. To do this, the vector lines we want to use should be in a different color like red or blue. If you have both cutting and scoring lines they should be in different colors so you can assign them different power levels in the software.

The software needs two separate PDF files, one with the images and fonts to engrave, and the other with the vector lines to cut and score. There is no easy way to do this in Google Drawings so you have to temporarily delete the other kind of objects, export the file as a .PDF, and then undo the deletion to get your original design back.

You should create two .PDF files - one called [ProjectName]_vector.pdf with the vector objects only, and another called [ProjectName]_image.pdf with the image and font data to engrave. You can save a third file that's just [ProjectName].pdf with your whole design for reference.

Setting up the Cut

Connect to the laser cutter webpage and clear the captured work area image if needed (IMPORT->CLEAR CAPTURE). Then run IMPORT->FILE and select the [ProjectName]_image.pdf file you created. Import it as ENGRAVING data. Without changing anything about the imported design, run IMPORT->FILE again and select [ProjectName]_vector.pdf. Import this file as a CUT file. Both files should be imported in the same place (the upper left) on the work area, with the same alignment as your original design.

Remove the plastic films from your acrylic blank and position it in the laser cutter bed. Use painter's tape to tape the bottom edge of the acrylic to the metal ruler to keep it from moving during the cut.

Run IMPORT->CAPTURE to get a scan of the work area. Now press CTRL-A to select both files and move them on top of the image of the acrylic blank, zooming in if necessary.

Setting Cut Type and Power Levels

First select the material by choosing MATERIAL->ACRYLIC with a thickness of 1/4" (ours is a little thinner).

Then click on the image and font object that we want to engrave. Choose the halftoned GRAYSCALE mode and change the DEPTH to 40 (click on the gear to see the numeric values).

Now select the vector object, which will include the rectangular bounding box and the acrylic outline. You should see circles with multiple colors at the top of the Print Settings box. We don't want to do any cutting on the bounding box and acrylic outline, so click on the black circle (color #222222) and set HEAT and DEPTH to zero for those lines.

Click on the color tab of the other lines you do want to use and set CUT or SCORE depending on what you want for that line. For CUT lines, set the power levels to 100 20 100 and 1 PASS. For SCORE lines, use 35 100 50 and 1 PASS.

When everything looks good, let me double check the settings and then click START to send the design to the laser. You will get a window that lists the two files you imported. Make sure the [ProjectName]_vector.pdf file is listed second so the cuts will be done after the engraving. If not, drag and drop the file names to reorder them.