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5 Common Mistakes in Laser Engraving and How to Avoid Them

04 October 2017

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Whether you are an experienced engineer or a novice maker, learning the proper uses of design equipment to avoid pitfalls and mistakes takes time and experience.

From time to time, issues come up that leave designers wondering what they did wrong or how they could do something better. This is true in any field and laser engraving is no different.

Knowing how to avoid these mistakes so they don’t come up again is half the battle. With that in mind, Epilog Laser offers five of the most common mistakes when it comes to laser engraving and suggestions for how to avoid them in future projects.

Figure 1: Hearty fabrics can withstand high power but lighter fabrics may work better with a lower power engraving. (Source: Epilog Laser)Figure 1: Hearty fabrics can withstand high power but lighter fabrics may work better with a lower power engraving. (Source: Epilog Laser)Mistake 1: Engraving Fabric but the Laser Burns through the Material

The first step in avoiding burning fabric with a laser engraving/cutting machine is to understand what fabric can withstand the process and at what temperatures. Heartier fabrics such as denim, canvas and leather can withstand higher power settings during engraving. But when it comes to delicate fabrics, it is important to start on a high speed setting and a low power setting—maybe 5 percent to 10 percent. Then if the fabric can withstand it, increase the power from there until you get the results you are looking for.

When it comes to direct-to-garment engraving, it is helpful to lower the dots per inch (DPI) at which you engrave. The higher the DPI, the more material will be removed. Engraving at a lower DPI helps ensure the laser just slightly vaporizes the top layer and doesn’t burn entirely through the fabric. Most fabric engravings do fine at 150 to 300 DPI.

Mistake 2: Acrylic Doesn’t Produce a Frosty White Engraving

Figure 2: To get a frosty white finish, use cast acrylic materials. (Source: Epilog Laser)Figure 2: To get a frosty white finish, use cast acrylic materials. (Source: Epilog Laser)More than likely, this is caused by using the wrong acrylic in the application. Two types of acrylics are typically used in laser engraving and both are suitable for different applications.

Cast acrylic sheets and objects are made from a liquid acrylic that is poured into molds that then can be set into various shapes and sizes. This type of acrylic is ideal for engraving because it turns a frosty white color when engraved, making it suitable for awards and plaques. It can be cut with a laser, but it won’t give projects flame-polished edges.

The other type used in laser engraving is called extruded acrylic, which is formed into sheets by a machine. Extruded acrylic is generally less expensive than cast acrylic because it is formed through a higher-volume manufacturing technique. However, it does react very differently with the laser-engraving machine. This type of acrylic cuts cleanly and smoothly and produces a flame-polished edge; however, when engraved, it doesn’t produce that frosted look, but rather a clear engraving. So make sure you are using cast acrylic if you want a frosted white finish.

Mistake 3: Inconsistent Glass Engraving Figure 3: Using a lower DPI or 80 percent black may help glass engraving avoid cracking or a rough finish. (Source: Epilog LaserFigure 3: Using a lower DPI or 80 percent black may help glass engraving avoid cracking or a rough finish. (Source: Epilog Laser

Oftentimes, when a laser strikes glass it will fracture the surface but not engrave deeply or remove the material needed to engrave fully. The fractured glass surface will produce a frosted appearance, but can be rough and chipped depending on the type of glass that is being engraved. While the frosted look is desired, no one wants a rough surface or chipping.

In order to produce a smooth frosted finish, try incorporating one or several of the tips below:

  • Use a lower resolution, about 300 DPI, which will produce a better result on glass as you separate the dots you are engraving.
  • Change the black in your graphic to 80 percent black to improve the engraving quality.
  • Run your laser engraver with Jarvis Dithering in the driver (this dithering pattern can be found in Epilog’s print driver), which will help to provide a smooth finish.
  • Sometimes, applying a thin, wet sheet of newspaper or a paper towel to the engraving area will help with heat dissipation and improve the engraving process. Just make sure there are no wrinkles in the paper after it is applied.
  • Another way to dissipate heat is to apply a thin coat of liquid dish soap – either with your finger or a paper towel to the area you’re engraving.
  • Finally, if there are shards of glass after engraving, polish the area with a non-scratch scour pad.

Mistake 4: Wood Engraving Produces Different Results on the Same Setting

Wood is one of the most laser-friendly materials available not only because it can be cut very easily, but also because it engraves very well.

However, different woods have different reactions when they are laser-engraved and produce different characteristics. Lighter woods, like cherry or maple, produce a nice contrast where the laser burns away the wood, while denser woods require more laser power to cut or engrave.

When laser engraving wood, grain density can change dramatically depending on the type. Cherry, alder, walnut and maple have fairly little veins of grain in them, while oak has medium to large veins. For example, if a large box was engraved into a piece of cherry and a piece of oak, the box engraved into the cherry would have a very uniform appearance, the area engraved or the background would be smooth with little variation in height. The oak on the other hand would vary greatly in height and have a very non-uniformed appearance.

Here are some tips when engraving with wood:

  • Maple and alder are some of the the most popular woods for engraving, providing a rich contrast.
  • Bare wood engraving produces smoke and debris during the process and can become embedded into the grain of the wood. To reduce this effect, always engrave from the bottom up – this helps draw any smoke away from the engraving.
  • When engraving stained wood, excess smoke and debris can be wiped off the surface of the wood after engraving with a damp cloth.

Mistake 5: Laser Engraver Doesn’t Perform as Fast Anymore

Figure 4: Different wood types produce different types of finishes and characteristics; knowing how they act may impact a laser engraving project. (Source: Epilog Laser)Figure 4: Different wood types produce different types of finishes and characteristics; knowing how they act may impact a laser engraving project. (Source: Epilog Laser)Clean your machine! Much like other types of design equipment, a clean machine produces better results than one that is not properly maintained. Epilog includes the typical types of maintenance requirements in its user manual. But if a drop in performance happens quickly, checking and cleaning the optics may be the first step in correcting the problem.

Epilog recommends inspecting the optics in the laser—the lenses and mirrors—weekly and cleaning as needed. If you’re cutting materials that produce more residue – like wood or acrylic – you may find your optics need to be cleaned more frequently. Typically, optics are clear gold in color and are bright and shiny. If they are cloudy or have smudges or debris, it’s time to clean them.

Conclusion

The mistakes listed above are common among makers and designers that use laser engraving machines, especially those just beginning to use the equipment. But as you can see they are easily avoidable if you have the knowledge to correct the mistake.

Epilog Laser helps designers and makers through every step in the process of purchasing the right laser engraver, selecting the right materials to use, and understanding how to combat common mistakes including a library of knowledge base articles and helpful support for those experiencing challenges.



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