Hello, I'm Geordie and I currently work at ADX Portland running the Laser Cutter and Engraver. My job is to take in customer's projects, set them up and run them on the laser. As a result, I've learned a few tricks for how to set up jobs to get the best results, and in this Instructable I'm going to pass them on to you.
The laser I work with is an Epilog Helix and the program we use to run it is Corel Draw. I'm going to try to write in general terms so you can use what ever laser and program you want to.
Note: For several of these tips it is important to understand the difference between Vector files and Bitmap files. Vector files are mathematical formulas defining lines, circles etc. These are created by programs like Adobe Illustrator, Inkscape, AutoCAD and Corel. Bitmap files are collections of individual pixels. This included digital photos, Adobe Photoshop files, JPGs etc. With the Epilog laser (and I'm assuming other ones) you can only cut with a vector file. You can engrave with either vector or bitmap files. For several of my tricks you need your file to be a vector file for the trick to work.
Before we get to tips for cutting and engraving, lets start with some good ideas for preparing to cut or engrave.
Masking: If your going to engrave on something be aware that the smoke for the the engraving can stain the edges of the engraved surface. If you don't want that cover the surface with masking tape to protect it. The masking tape won't decrease the power of the laser much (bump up the power a bit if you feel it needs it) and the masking tape will protect the material around the engraving from the smoke. After running the engraving just peal the masking tape off. I use this a lot if I'm engraving on leather.
Presets: Your laser should have some suggested settings for cutting or engraving different materials and different thicknesses. You should also be able to load these settings into your computer or laser and save them as presets. Be sure to name them something that makes sense so you can easily find them That way the next time you need to engrave on leather or cut 1/8" thick acrylic, you can just find the preset for that material.
Test cuts: Even when I have a preset for cutting a material I usually try to run a test cut in it before I run the full job. Nothing is worse than taking the material out of the laser and finding that it didn't cut all the way through. I create a small circle or square (about 1/4" or 1/2" wide) and cut out in corner or on some scrap material. Then I can see if I need to increase or decrease the power before I run the final cut.