Laser

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You must be properly trained and membership-level qualified to use the laser!

About

Our members pitched in and bought a laser for the space! It's a 45W Full Spectrum H-Series 20x12Desktop CO2 Laser, and can do raster engraving and vector cutting. It has a honeycomb cutting table surface, exhaust vent, and a removable bottom for cutting larger things. The laser tube is water cooled from the blue bucket under the table. With the printer driver, anything that can be printed can be laser'd, but it a bit easier to laser things in PDF or dxf format

Lasering area: 20” x 12”

Design Software

The computer next to the laser cutter is configured for member use and lasering. Here's a list of the installed design software:

  • Inkscape
  • Draftsight
  • FSL RetinaEngrave 3D drivers

Basics of laser cutting

The laser cutter at Hive76 is a sophisticated CNC machine that use focused infrared lasers to vaporize materials based on your instructions. There are three operations that this vaporization can be described as: raster engraving, vector cutting, and third that has aspects those combined called vector scoring.

Raster engraving

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

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.

Vector scoring

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.

Preparing your file

Any CAD or vector drawing program can generate laser cutting files. Keep in mind the 3 types of operations discussed above and use them to design your file:

  • Raster engraving
Black filled objects
Vector or bitmap
  • Vector Scoring
Blue 0.1pt stroke paths
Vector only
  • Vector cutting
Red 0.1pt stroke paths
Vector only

You must not include any other lines in your file that are not described above. Lines of any greater thickness or other color will be interpreted as shapes for raster engraving. For example, a simple 1pt green box around your design will increase your laser time by over an hour as the laser travels over the entire area of the box to engrave the green box as a light raster engrave.

Size and scale

You must work in full 1:1 scale for your design. Your dimensions in your design file must represent real dimension of your laser cut objects. The laser has a max sheet size of 12” x 20”. Your material can be no larger than this. If it is even an eighth of an inch over, it will not sit flat on the cutting bed and the laser beam will not be in focus. You can cut any sheet material to size with a hand saw. The max thickness of your material is constrained by the power of the laser. We can cut up to 1/4” material in most cases. For thicker materials, you should plan a test cut first. Always test a laser cut with a circle, as they are harder for the machine to cut than straight lines.

Materials

The majority of laser cutting is done with three materials: Approved Materials

  • Wood, plywood
  • Paper, cardboard, chipboard
  • Acrylic (aka PMMA, Plexiglas)

The list of materials we can’t cut is much longer: Prohibited Materials

  • Anything containing chlorine
  • Polycarbonate (aka Lexan)
  • PVC (aka vinyl)
  • Styrene, polystyrene
  • Foam Core (the core is polystyrene)
  • Metals

There are many other materials that may be cut including most “natural” materials, but these should be approved by Chris Thompson or the Quartermaster before laser cutting.

File types

PDF

PDFs work best for laser cutting. PDFs can carry accurate vectors and bitmaps and maintain scale well. They are also smaller files which puts less pressure on the laser computer. Your page size should match your material size, also being no larger than 12” x 20”.

Illustrator

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. The laser computer may not have your font installed. 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.

Others

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.

Questions

If you have questions about use of the laser cutter, please ask in the #general channel in Slack.