So… What is a Laser Cutter?
A Laser Cutter is a machine in the class of precise, computer-controlled equipment. The tool head is a laser focusing device which holds a mirror and a lens. By transmitting a high power emitted laser through the focusing lens, and controlling the path of the tool head, you can cut or engrave thin woods, certain plastics and foams, and even metals. The Laser cutter, also called a laser engraver, has precise control over the X and Y position of the head and the power of the laser emitted.
What are the parts of a Laser Cutter?
Very simplistically, the parts of a Laser cutter are the gantry, which has motors and a timing belt setup to control the X and Y position of the tool head.
The tool head which has mirrors and a focusing lens to direct the thin cutting laser down towards the work piece.
of course the laser, which is emitted from a high voltage CO2 laser generating tube embedded in the machine.
And Mirrors that work to redirect this laser toward the part you want to cut.
The gantry is usually on top of a fixed plate or frame where you put your material. This fixed plate usually has holes in it, otherwise it could reflect the laser’s light dangerously, and it would have to be frequently replaced.
To clean the dust and fumes generated from cutting, there is usually a network of vacuums to suck it up. Because safety is important we would also add this in a critical part of a laser cutter
What are the types of Laser Cutters?
The main variation in laser cutters is the type of emissive laser and the focal length of the lens. CO2 lasers are the most common, but also have the most restrictions. All of the lasers we work on here are CO2 lasers. They can cut woods, some plastics like acrylic, and they can engrave on metal with the help of a special marking substance. These lasers can get their lenses damaged by reflections off the work material, so you cannot cut through reflective metals. You can also cut woods maximally half an inch thick.
There are crystal lasers that generate their laser beam from crystal excitation. These tend to be more powerful and cut thicker and stronger materials than a CO2 laser. They are still susceptible to back reflections from the workpiece. Because they are higher power, their parts tend to wear out a bit quicker.
The last type is a fiber laser, which uses fiberglass to amplify the strength of a laser through the device. These lasers tend to be very efficient and very powerful. They are not susceptible to back reflections, so they can cut through metal much easier than other lasers.
The other distinction between lasers is the focal length of the lens. The shorter focal lengths allow for less variation when you align the lens to the workpiece, as compared to longer focal lengths, which are more forgiving with that tolerance. However, if you align a shorter focal length laser properly with a flat workpiece, it will generate very clean engraves, miniscule kerf widths and minimal charring and taper on efficient cuts. Longer focal lengths tend to have slightly larger kerfs, but still provide very clean and finished parts.
What are Laser Cutters good for?
The biggest advantage to laser cutters is that they are FAST. They work much faster than CNC routers and 3D printers. Additionally If you need parts like box joints that slot together, the laser cutter has very small kerf, so you can control the tolerance of that fit very well. One unique feature of laser cutters is that they can engrave. While CNC routers and 3D printers can create embossed and debossed surfaces, the laser cutter can do that and also modulate the power of the laser to make a flat engraving on your part by selectively charring the material to give it a blackened color. This can be extended to creating full grayscale images with a laser cutter. Cutting flat pieces in complex shapes or simply assembled 3D geometries are perfect for the laser. Laser cutters can also be easier to design for because they can take large variety of 2D file types: images, vectors, pdfs, etc.
What are Laser Cutters bad for?
Like anything else laser cutters have some drawbacks as well to consider. They do not have a third axis of control like CNC: you cannot control the depth of a laser cut with precision. You can control the power of the laser, and the focal height, which somewhat determines that third axis… but again, not with any level of precision that could be relied on. As a result you can only cut flat parts out on a laser, so designing for 3D laser cutting can be tricky, but there is software that can help. Lasers also have some material restrictions as cutting certain plastics like polycarbonate releases toxic fumes. You also cannot cut metals with the common CO2 lasers due to the reflectivity of the metal.
Laser cutting also leaves a charred blackened edge. This can look nice, however it is distinct and sometimes also smudges and excess char needs to be wiped off. In particular when cutting thicker pieces of wood on a laser the charring can be fairly substantial.
How do I design for a Laser Cutters?
Because laser cutters follow simple 2D paths, you can generate these files in a lot of ways. One of the most common workflows for this process is using a vector editor like inkscape or adobe illustrator to make shapes with lines and fill colors: the lines are cut lines and the fill color signifies an engraving. If you only wanted to engrave, you could generate a file using jpegs, pngs, or even pdfs that have a discrete colors.
You can also generate another 2D cut file type called a DXF using Computer Aided Design (CAD) software. You can make DXFs from sketches in your CAD models.
There are tons of apps out there as well that produce files as well, and are really user friendly. We love finding different apps, and are constantly discovering new fantastic tools.
Safety involved with a Laser Cutters?
Safety is important. As mentioned, you want to make sure you have proper ventilation and you are only cutting save materials on the laser. If there is a persistent fire in the laser cutter, hit the emergency stop immediately. You may want to consider wearing laser-safe glasses as you make the cut just in case there is a reflection outside the laser. Make sure you have a safety hood over the laser when cutting which protects yourself from the raw laser beam. If you see dangerous fumes generated, make sure you evacuate the space. If you see a large fire that doesn’t extinguish easily, use a fire blanket or extinguisher approved for putting out CO2 laser fires.
Our rule of thumb is that we never leave a laser cutter unattended. If it is running and actively burning material there always must be someone in its vicinity to keep an eye on it and step in if needed.
So there you have it, laser cutters. They are probably our most used digital tool in our Makerspace, and because of their speed a really convenient asset to have in the shop.
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