Common Mistakes in Laser Engraving and How to Avoid Them

Whether you are an accomplished engineer or a novice maker just starting out, learning the proper use of your design equipment can save you time and energy by avoiding potential problems and mistakes. From time to time, problems arise that leave designers wondering what they did wrong or how they could have done it better. This is true in any field, and laser engraving is no exception. Knowing how to avoid these mistakes and not repeating them is half the battle. With that in mind, let's explore the five most common mistakes in laser engraving and how you can avoid them on future projects.

Mistake #1: The Laser Burns Through the Material When Engraving Fabric

The first step to avoiding burning through fabric when using a laser engraving/cutting machine is to understand which fabrics can withstand the process and the temperatures the fabric can withstand. Sturdier fabrics, such as denim, canvas, and leather, can withstand higher temperatures when engraved. But for softer fabrics, it is most important to start with a fast speed (close to or equal to 100%) and a low power (about 5% to 10%). Test these initial settings on some spare material to see if the fabric can withstand engraving at these settings, and gradually increase the power until you get the results you want.

When engraving directly onto garments, it may be helpful to lower the dots per inch (DPI) of the engraving area. The higher the DPI, the more material will be removed. Engraving at a lower DPI ensures that the laser only slightly vaporizes the surface material and does not burn completely through the fabric. A DPI between 150 and 300 will work well for most fabrics.

Error 2: Acrylic material cannot be engraved with a matte white effect

This is most likely due to using the wrong acrylic for the engraving application. There are two common types of acrylic used for laser engraving, and both are suitable for different purposes.

Cast acrylic sheets and objects are made by pouring liquid acrylic into molds of various shapes and sizes. This type of acrylic is ideal for engraving because it turns a matte white when engraved, making it suitable for medals. You can also cut this material with a laser, but you will not be able to achieve a flame-polished edge.

Another type of acrylic used for laser engraving is extruded acrylic, which is a sheet that is made by a machine. Extruded acrylic is generally less expensive than cast acrylic because it is made through a high-volume production process. However, when engraved with a laser engraving machine, this material produces a very different result. This type of acrylic cuts very cleanly and smoothly, and produces a flame-polished edge. However, it does not produce a matte white finish, but rather a fairly sharp engraving. So, if you want a matte white finish, make sure you use cast acrylic.

Error 3: Contradictory Glass Engraving

Typically, when the laser hits glass, it will break the surface of the glass without engraving deeply or removing material needed to fully engrave. The broken glass surface will have a frosted appearance, but may be rough and chipped depending on the type of glass being engraved. While a frosted appearance is desirable, no one wants a rough or chipped engraved surface.

To produce a smooth frosted finish, try combining one or more of the following tips:

Using a lower resolution, around 300 DPI will produce better results on the glass as you move the engraving position.

Change the black in the graphic to 80% black.

Sometimes, placing a thin layer of damp newspaper or paper towel over the engraving area can help dissipate heat and improve the quality of the engraving. But make sure the paper is wrinkle-free after it is placed.

Another way to dissipate heat is to use your fingers or a paper towel to apply a thin layer of dish soap to the engraving area.

Finally, if there are glass fragments after engraving, clean the engraving area with a scratch-free scouring pad.

Error 4: Wood Engraving Gives Different Results with the Same Settings

Wood is one of the most suitable materials for laser engraving because it is easy to cut and engraves very well.

However, different woods react differently to laser engraving and will give different results. Lighter woods, such as cherry or maple, will produce very rich contrast as the laser ablates away the wood, while stronger woods will require higher laser power to cut or engrave.

Depending on the type of wood you are working with, the grain density will vary greatly. Cherry, alder, walnut, and maple have very tight grains, while oak has a medium to coarse grain. For example, if you engrave a large square in cherry, the resulting appearance will be very uniform, with a smooth engraved area and less height variation. However, if the same large square is carved in oak, the height will vary greatly and the appearance will be very non-uniform.

Here are some tips for carving wood:

Maple and alder are some of the most popular woods for carving and provide a rich contrast.

The process of carving bare wood will produce smoke and debris that can become embedded in the grain of the wood. To reduce this effect, always carve from the bottom up, which will help to draw away any smoke as you carve.

When carving stained wood, use a damp rag to wipe excess smoke and debris off the surface of the wood after carving.

Error #5: The Laser Engraver Doesn't Run As Fast As It Used To

Clean your machine! Just like any other type of design equipment, a clean machine will produce better results than one that is not properly maintained. Your laser machine's user manual contains maintenance requirements. If performance is degrading quickly, the first step to fixing the problem may be to check and clean the optics.

We recommend checking the optics (lenses and mirrors) in your laser machine weekly and cleaning them as needed. If the material you are cutting produces more debris, you may need to clean the optics more often. Typically, optics should be a clear golden color that is bright and shiny. If they look blurry, or have smudges or debris on them, it's time to clean them.

Conclusion

The mistakes listed above are very common among makers and designers using laser engravers, especially those who are just starting to use these devices. But as you can see, these problems are easily avoided if you have the awareness to correct them.