This project was done on Epilog Helix 45W CO2 laser. The laser is capable of cutting and engraving designs up to 24"x18". Since this was my first experience with this laser, I started with a small project. I took a set of cork coasters (you can find them online or at a local store) and engraved pictures on them. You can also buy a roll of uncut cork from a hobby store and cut circles out using the laser.
Step 1: Prepare the File.
You may also want to adjust your image. I usually convert the image to greyscale (Bitmaps->Mode->Greyscale 8bits). This gives you a better idea of what the final product will look like. Ideally your image should have high contrast and a wide range of shades. The cork is not a great photographic medium. When you engrave the details will be lost and the image will be blurry. To compensate for this, use Brightness/Contrast/Intensity adjustment (Ctrl+B). Boost the contrast and correct Intensity so you have a good outline of major features. Don't worry if your whites are a little blown out. The goal is different from a regular photo enhancement.
Once you have finished with the image, add a circle around it and change the line width to hairline. This will be used later as a vector cutline either for cutting out coasters from a roll and/or for checking outline in a dry run
If you want to engrave several coasters, you can put multiple images on the same page, but I would suggest doing them one by one. If you miscalculate power settings, you can burn all your coasters.
Step 2: Adjust Laser Settings.
Note that these settings are not set in stone. They depend on many factors, including the material and the image.
Change Job Type to Vector in printer settings dialog for the next step.
Place your material in the upper left corner of the platform and focus the laser using the magnetic tool.
Step 3: Dry Run
Open the laser printer cover.
Send your document to the printer and press Go button on the printer (cover must be open!). This will cause the laser to trace you design without actually burning it.
Adjust your design (or the material) so the laser does not move out of the coaster!!!
If you are using pre-made coasters and are not cutting the cork, remove the circle added in Step 1.
Open print dialog and click on Preferences. Change Job Type to Combined.
Step 4: Print
Hopefully you'll get a good picture on the first run. If not, adjust the power and try again. Try not to overdo the power. It's better to have a slightly underexposed picture since burned cork has a pretty strong smell.
You can wash out some of the burnt material with soapy water and paper towel. If your soap has a strong smell, it will also help to suppress the odor. Be gentle, though, as cork can crumble easily.
If you still can't salvage your piece, try with lower power settings. I've burnt two coasters because I started from recommended settings from wood. Cork turned out much more gentle.