KSA Fab Lab

KSA FAB LAB > Laser Cutters

Overview

The Fab Lab currently has two different laser cutters available for student use. While made by different companies, they share a number of similarities. Each laser cutter is the technological equivalent to a pen plotter - only instead of moving an inked tip around the plot area, it moves a laser.

Laser Cutter comparison chart

	ULS	Epilog	Significance
Work Area	12" x 24"	24" x 36"	This is the maximum area which can be engraved or cut by the laser cutter. Actual material size may be a bit larger, but the laser can only travel this far. Additionally, your data should not actually extend all the way to the borders of your material (or beyond) or else problems may occur.
Laser Power	30 watts	60 watts	Laser power affects the thickness of material you can cut through, the types of material that can be used, and how quickly the machine will produce your work.
Focal Length	2"	4"	Focal length determines the point at which the laser beam reaches its full intensity. Longer focal lengths allow you to cut through thicker material while maintaining good cut quality.

Engraving vs. Cutting

The laser cutters can perform two basic operations: engraving and cutting. Engraving is similar to drawing; it involves marking the surface of a material. Engraving can be done from either raster or vector data. Cutting involves cutting completely through a piece of material. While this is possible to do based on raster data, that would be a stupendous waste of time - so cutting operations are always performed based on vector data.

Vector vs. Raster

The difference between vector and raster data depends largely on the software you use, and the manner in which you use it. In practice, the laser cutters often end up processing raster data by default - vector operations are achievable only when the following conditions are met:

The program you are using must support vector data. Essentially, this means you should use AutoCAD, FreeHand, or Illustrator. While it is possible to generate vector data using Photoshop or other programs, doing so is often more trouble than it's worth.
Your linework must be set to 0 thickness. This is critical - any number other than zero will result in your lines having a thickness, which will cause them to be processed as raster data. This is even true with "hairline" widths in FreeHand, and lines in AutoCAD that assign thicknesses "ByLayer".
Your linework must be explicitly assigned a color. This happens most frequently in AutoCAD, as students depend on the "ByLayer" setting to assign colors. In practice, the laser cutters have proved unable to read layer properties reliably, and so process lines with this setting as raster data, if they processes them at all.
Your linework must match the color the laser cutter expects. Simply put, your line should be one of the simple colors in AutoCAD:

Black, Red, Green, Yellow, Blue, Magenta, or Cyan.

Other colors, including orange can prove problematic and are best avoided. At best, such colors are interpreted as a percentage of one of the above colors, and are cut inaccurately. At worst, they are ignored completely.
The laser cutter must expect data in the correct format. For the ULS laser cutter, this means you must set the colors you are using to either "Vector" or "Raster/Vector" in the ULS driver. For the Epilog, this means that you must send AutoCAD files to the "Legend Win32 Vector Only" driver, rather than the "Epilog Engraver Win32" driver. Please note that, although the Epilog Engraver driver claims to be able to support vector data, it does not do so consistently.

Questions?

If you have any questions about anything contained in these documents, please contact Matt Bernhardt at bernhardt.7@osu.edu, or 614.292.7595.