Updated: Nov 9
When it comes to laser cutting, there are quite a few things to consider before you start a project. From how your design looks to which settings work best with each material, laser cutting is much more than putting an item in your machine and pressing "go." One critical element that often gets overlooked is "kerf." Kerf, in the context of laser engraving, plays a pivotal role in achieving precision and accuracy.
What Is Kerf?
Kerf exists in many different manufacturing and woodworking fields. Kerf refers to the width of the material that is burned away when cutting through it. Think of it as the groove or channel left behind when you slice through a material with a laser cutter. Laser cutting is one of the most difficult fields to adjust for kerf in. In CNC machines, kerf is simply the size of the bit you are using. Laser cutters, however, have many more influencing factors than just a bit size when determining kerf which makes it much more difficult. Kerf can be influenced by the power of the laser, the speed at which it moves, the focal length, compressed air pressure, and the characteristics of the material being engraved.
Kerf is important to understand as it can impact your ability to make very precise cuts. For example, if you are cutting pieces that will be fit together (such as puzzle pieces), kerf can cause your pieces to not properly fit together even though your digital model or drawing seemed accurate.
Adjusting For Kerf
The biggest question when it comes to kerf is how do you account for it? Unfortunately, there isn't a simple answer to that. As much as we would love to be able to provide you with the exact amount you need to offset your project to adjust for the kerf value, it isn't just a single number. As we stated before, kerf is influenced by a variety of factors. What works to account for kerf on one material may not work on another. The only way to truly account for kerf is by running some cuts on your machine and using a precise measuring tool, such as a caliper, to determine how much material is "missing" after the cut. This number would be your kerf value.
Once you determine what the kerf is in a certain set of parameters, you would then offset the cut paths by the amount of the determined kerf value. If you are using a software such as LightBurn, you can actually set your design to adjust for kerf itself and all you have to do is provide the offset value. Not all software has this function, however, so you made need to adjust your files manually in whatever software you use to create them prior to importing the file into your machine.
Adjusting for kerf is a difficult and complex skill to master. Even once you figure out how to do it, there are so many materials and scenarios where your kerf value will be different that is seems rather daunting. Keep in mind that it isn’t always necessary to offset cut paths to account for the kerf. Not all projects need to precisely fit together or be an exact size, and the kerf would generally not be noticeable if something doesn’t need to be an exact fit. If you find yourself completing a project that needs to adjust for kerf, perseverance will be essential. As with many skills in the laser engraving field, trial and error is ultimately the best way to figure it out.