Laser Cutting at CABE

In this operation, the laser beam travels over the entire area of your shape. Raster engraving is a marking operation used for decoration or information. The laser will quickly vaporize a thin debossing into the top surface of the material. The depth of this debossing can be adjusted roughly with different speeds. This operation requires the area to be filled with pure black color. If your design has fuzzy edges, or gray areas, those will be interpreted as a halftone in the laser software. This way it is possible to engrave grayscale images. Raster engraving is useful for marking text onto a design. It can also expose a different color in some specially designed layered materials. The time required for raster engraving is dependent on the overall area the laser must travel to reach your black-filled designs.

Raster engraving is the only operation that can be used with bitmap images such as jpegs, pngs, gifs, or bmps. All color will be reduced to a black and white halftone in the software, so make your own grayscale first.

Vector cutting is an operation that can cut your material all the way through. This operation is used for making specific shapes and cutting material to size. Here the laser slowly travels along a thin line in your design while vaporizing all the material along its path. This operation requires more than an image. We need to program the laser with vector lines. If you use CAD or Illustrator you are familiar with vectors. Instead of pixels describing an image, vectors are mathematical formulas that describe the shape of a line. This makes them perfectly scalable and allows us to program a robot to carefully follow such lines. For vector cutting your lines need to be very distinct from any raster engraving art. Vector cutting lines must be pure red in color and include a stroke that is as thin as possible; 0.1 pt will work in most cases. The laser software is programmed to recognize these lines and the laser will follow them exactly. Vector cutting is like cutting with a saw in that some material will be removed during the process. This is called the kerf and for lasers generally measures .005” but will vary based on your material thickness. If you need exact cuts that account for kerf, try a test cut with your material first and measure your results. In the sample above there are horizontal pylons connecting the counters in the middle of some letters. Keep in mind that vector cutting can completely separate your material into pieces, and some of those pieces (like the counter inside an "O") you may want to retain. This operation adds time to your job based on the length of all your cut paths.

This operation is halfway between raster engraving and vector scoring. Like raster engraving, it is used to mark your material, but it is programmed like vector scoring. In this operation, the laser travels along the vector line you designed, but does so quickly just removing a small amount of material from the surface. To design for this operation, use a thin line of 0.1 pt or less but with a pure blue stroke color. This color will differentiate your vector scoring designs in the laser software. Vector scoring is a faster way to make marks on your material that are less dense than raster engraving. A good example could be a grid of thin boxes denoting windows on a facade or building footprints. Like vector cutting, this operation adds time to your job based on the length of all your vector scoring paths.

We prefer to accept PDFs for laser cutting. PDFs can carry accurate vectors and bitmaps and maintain scale well. They are also smaller files which puts less pressure on our laser computers. If your PDF is drawn poorly, the laser operators will allow you to modify your design and return with a decent PDF. Your page size should match your material size, also being no larger than 18" x 32".

AutoCAD is the first CAD program most PhilaU CABE students are taught. You can use the following AutoCAD DWG template to lay out your design for cutting. Please copy your design geometry into this document for laser preparation.

This file has three layers that correspond to the three laser operations. You can use these layers to color your designs, or style them in a different fashion, as long as it matches the requirements described above 100%. There is no negotiating with the laser software. If your line is too thick, it will not cut.

While you may bring your DWG or DXF files to the laser lab to cut, we insist you try to export a PDF first for the overall efficiency of the laser cutting process.

It is easy to generate laser files in Adobe Illustrator and graphic designers may feel more comfortable generating complex designs in this vector software. Illustrator also handles text far better than any CAD program. The same color and line rules apply. You should set your artboard size to match your material size. Please “outline” your text to avoid font problems. Laser operators will not bother with installing fonts. You must also work in the RGB colorspace. You can change this in the file menu. Do this first before drawing or adding anything to your document. You may need to switch the color palette to show RGB values. For reference the black is 0 red, 0 blue, and 0 green. For red and blue, those color sliders must be set to the max of 255. You can easily save PDFs from Illustrator. Checking “Preserve Illustrator Editing Capabilities” during saving will not affect the PDF output, but will help your revisions.

Any CAD program can save DXFs and you can export these as PDFs from AutoCAD. Any other vector program, such as free Inkscape, can print PDFs though the OS. These files will retain all the correct color and line weights that you chose during your setup.