Wood is one of the cheapest natural materials available for cutting or engraving. One popular laser working application is tailored cabinetry. The tool has the ability to create breathtaking inlays that personalize your projects and really ignite the imagination. Before getting started with your upcoming wood engraving project, choose your grain carefully.
Two Key Factors to Consider
When it comes to working with a material like real wood, its natural inconsistencies can render unpredictable results. The best way to work with such a versatile material using a laser engraver is to find the most uniform types of wood with the right resin content and less streaking.
What Is Streaking?
A mineral streak is an area on the wood that looks like a dark stain smudging the lighter wood. Some carpenters avoid this by cutting around the streaks or bleaching them out because they take away from the design. Others feel it gives the wood more character and incorporate it into their design. When working with lasers, opting for minimal streaking ensures better detailing.
Wood resin or sap levels make a significant difference in the burn type. Woods with high resin content burn darker because the laser beam burns the sap. With lower resin woods, there’s less burning, resulting in a lighter cut. An interesting thing to note is that the season in which the tree was cut and where it was cut affect the resin levels.
Sap transports nutrients and water throughout the plant. During the colder months, it will drop down in the trunk to prepare for winter and then redistribute in the spring. If the wood you’re using was cut down in the fall, depending on where it was cut, it could burn darker during one session and lighter during another. The upper portion of a tree that was cut down in the fall has a lower resin content and will burn lighter, while the lower cuts burn darker. It’s a good idea to test the wood first so you can see what you’re working with.
Difference Between Hardwood and Softwood
Short of doing a molecular analysis of the tree’s structure, the best way to figure out the difference between a hardwood and a softwood is to remember that hardwoods have broad leaves and are flowering plants, like oak and maple. These are deciduous trees. Softwood trees, on the other hand, are evergreens, like pine and spruce.
Hardwood is darker and heavier and can last for decades because it’s naturally weather-resistant. It’s used for high-end furniture. By contrast, softwoods are lighter and less expensive and need to be treated for weather resistance, which help them to last for a decade or so. Softwoods have less impact on the environment when cut and are used for construction materials.
As with anything, there are exceptions. Some softwoods are harder to work with than many hardwoods and vice versa. When it comes to choosing the best wood for laser cutting and engraving, three species are easier to work with and can produce great results.
Best Wood for Laser Engraving and Cutting
Cherry (Prunus serotina) is one of the most popular wood species for cabinets and furniture. While it’s pink when first cut, over time it darkens into the rich reddish-brown many recognize. Cherry wood is easy to work with and to cut.
Alder (Alnus rubra) looks similar to cherry wood in that it darkens over time. It’s a softwood and considered one of the best woods for laser engraving, producing a dark burn.
Hard maple (Acer saccharum) is an off-white, tan or yellowish wood. While it’s harder to work with than cherry wood because of its density, it’s great for laser engraving and finishes beautifully.
Other Woods to Consider
Basswood (Tilia americana) is a soft and workable wood that’s lightweight, making it good for easy and quick engraving.
Balsa (Ochroma pyramidale) is a much softer wood that’s good for engraving with a laser machine but has a coarse texture. The heartwood is reddish-brown, while the sapwood is off-white or tan. It’s not very lustrous but can stain and finish well. One problem with balsa is that it’s susceptible to nicks and dents.
Can You Use a Laser on Plywood?
Plywood consists of thin layers of wood veneer that have been glued and pressed. Because the engineering process uses the cross-graining technique, it reduces expansion and splitting, making it a relatively stable wood product. When lasering plywood, results depend on the quality. High-quality plywood has the wood grain rotated every 45 degrees, increasing axial strength, while thinner, lower-quality plywood is only arranged at right angles.
Two types of plywood that are good for laser cutting are birch and bamboo laser plywood. Like maple and cherry, birch is a dense but easy-to-use hardwood that’s readily available. It’s great for beginners looking to get into laser cutting because it cuts smoothly and reliably. If you’re feeling more adventurous, bamboo ply board may be an option. It’s a dense wood grain that has a fine, delicate look when engraved, making it a great candidate to work with.
Why You Should Avoid Laser Cutting Fiberboard
Fiberboard is made of wood fibers that are output from pulp mills. It’s encased in a wood veneer that’s glued together and comes in low-, medium- and high-density. High-density fiberboard (HDF) or hardboard is made from highly compressed fibers with an average density range of 40 pounds to more than 60 pounds per cubic foot, sometimes higher. Medium-density fiberboard (MDF) has a slightly lower density range, 31 to 62 pounds per cubic foot. Both are strong enough to be used for construction and furniture, but that doesn’t necessarily make them good wood for laser engraving and cutting.
When it comes to laser cutting, MDF is the more common material. The problem with MDF is that it’s too dense to get a good result. When the laser hits it, it tends to char and produce a darker burn that looks more like an overdone design than a clean cut. Additionally, the glue that the MDF uses doesn’t work well with the laser. Some sources claim that as long as it’s no thicker than 1/4” it will work well, but that doesn’t make up for the drawbacks and won’t guarantee a problem-free process.
Laser Parameters You Need to Tweak
CO2 lasers are great for working on wood because you can vary the power settings, and they have quite a few capabilities that can make cutting wood pleasant and easy. It’s important to note that you’ll get an edge burn when you put a laser to wood. The extreme heat vaporizes the material, and that’s why having a wood with lower resin levels reduces the burn effect. To make the most of the experience, here are a few other factors to consider.
Engraving and Cutting Parameters
In general, you want wood that’s no more than 1/2” thick. A 1/4” piece would be ideal. For the 1/2” piece, you’ll need a 90-watt CO2 laser, and for 1/4” you’ll need half the power. When engraving, you’ll need to increase the spot size for a darker engraving result. This will increase the burn, resulting in weaker detailing.
With a laser cutter, start at a cutting speed of about 5%, for example, and gradually adjust until you get the quality outcome you want. If you start with a piece of wood that’s about 3 millimeters thick, which is about 1/10” thickness, you’ll be able to gauge what you’ll need to do to achieve good results for a 1/4” piece, which is about 6 millimeters.
Getting the Right Optics
For better detailing, you’ll need a shorter focal length coupled with the right parameters. This is where it can get tricky. While a shorter focal length leads to refinement, wood thickness requires a longer focal length for optimal results. For wood, try a 1.5-inch or 2-inch lens. Along with getting the cutting and engraving parameters right for the type of wood you choose, you’ll need to make a note of the right optics.
Preparing Your Material
Before doing your first run, prepare yourself and your material. That means ensuring you have on your personal protective equipment, such as goggles and a mask. With any substance, you’ll have dust and particles floating up. This is particularly true with wood, and this kind of debris can get into your machine, causing malfunctions. One way to counteract this is to glue application tape — the kind of tape used for vinyl graphics — on your wood. This is safe to use and will not only minimize dust but may also reduce material burn. When done, remove the tape to see how it came out. Test this out on a separate piece before doing your first official run so you can ensure all your parameters are right.
You may do everything possible to reduce dust, but you’ll never be able to eliminate it. If you leave wood dust in your machine, it will clog up your hardware and damage your optics. Remember, wood dust contains resin and oil, which will stick to your equipment. Clean your laser regularly to keep it in great shape for your engraving and cutting projects
Wood is a great material for engraving keepsakes and gifts. It has a personal feel that makes it even more special. Whether you’re planning to engrave or laser cut, Thunder Laser USA stands ready to help you find the system that works for you. Call us at 903-522-4070 to speak to one of our professionals, or email us at [email protected].