How to use LightBurn laser cutter software, and use a laser cutter to create a simple Tangram project.
This month, we will be working with popular laser cutter software LightBurn; creating a simple Tangram project; learning about some of the Functions available in LightBurn; and starting to set up our project ready for actual cutting on the Laser.
IMAGE TYPES
Probably the first thing that we would need to know is the two different ways images are put together and what that means for laser cutters. There are two popular ways of creating an image file on a computer; one is the very common Raster method, also known as a bitmap; the other is a Vector file. So, what is the difference and why does it matter?
A great explanation of the difference between Vector and Raster images can be seen on the Adobe website (See our Reading & Resources section at the end for the web link).
What is a raster file?
Raster files are images built from pixels — tiny colour squares that, in great quantity, can form highly detailed images such as photographs. The more pixels an image has, the higher quality it will be, and vice versa. The file size an image also depends on the file type and compression used (for example, JPEG, GIF, or PNG).
What is a vector file?
Vector files use mathematical equations, lines and curves with fixed points on a grid to produce an image. There are no pixels in a vector file. A vector file’s mathematical formulas capture shape, border, and fill colour to build an image. Because the mathematical formula recalibrates to any size, you can scale a vector image up or down without affecting its quality.
A bit technical, right? So, let’s look at that in a bit more detail and with an example or two.
Raster images use bit maps to store information. This means a large file needs a large bitmap. The larger the image, the more disk space the image file will take up. As an example, a 640 x 480 image requires information to be stored for 307,200 pixels, while a 3072 x 2048 image (from a 6.3 Megapixel digital camera) needs to store information for a whopping 6,291,456 pixels. We use algorithms that compress images to help reduce these file sizes. Image formats like jpeg and gif are common compressed image formats. Scaling down these images is easy but enlarging a bitmap makes it pixelated or simply blurred. Hence for images that need to be scaled to different sizes, we use vector graphics.
Making use of sequential commands or mathematical statements or programs which place lines or shapes in a 2-D or 3-D environment is referred to as Vector graphics. Vector graphics are best for printing since it is composed of a series of mathematical curves. As a result, vector graphics print crisply even when they are enlarged.
In physics: A vector is something that has a magnitude and direction. In vector graphics, the file is created and saved as a sequence of vector statements. Rather than having a bit in the file for each bit of line drawing, we use commands which describe a series of points to be connected. As a result, a much smaller file is obtained.
Still clear as mud? Ok then, think of a raster image like a fax machine where the print head tracks backwards and forwards over the paper and prints a dot or “pixel” or leaves it blank. As the paper advances and more lines of dots are printed, an image appears.
A vector image is more like a plotter used for blueprints. The pen goes down and the paper moves under the pen and the pen tracks backwards and forwards to trace out some mathematical line or curve, and then the pen goes up. ››
›› Why does this even matter at all? Well, think of a laser cutter as more like a plotter; instead of a pen that draws there is a laser that cuts. Laser cutters are very accurate, and being able to plot a curve mathematically means they can very accurately cut shapes. If a laser cutter worked like a normal bitmap printer, like a photo printer, then it could still cut but the cuts would be accurately placed but not particularly clean.
Laser printers can and actually do print Raster Images, but instead of cutting through the material, they etch the surface of the material by adjusting the power of the laser as the laser passes over the material. The images tend to be monotone like a black and white photo but they still look cool. There are advanced methods of laser cutting in colour too by adding certain dyes to the material before or after cutting. There are also tricks to adding colour to a laser cut in other ways, but we get ahead of ourselves.
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Raster Graphics |
Vector Graphics |
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Composed of Pixels |
Composed of Paths |
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Refresh process is independent |
Flicker when the number of primitives in the image are too large |
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Graphic primitives are specified in terms of end points and must be scan converted into corresponding pixels |
Scan conversion isn't required |
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Mathematical curves, polygons and |
Drawn continuous and smooth lines |
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Image file size depends on |
More efficient smaller file size |
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File extensions include |
File extensions include |
Knowing about the two different image types, we can move on to the software. Hello LightBurn.
LightBurn Software
LightBurn is a very popular software package for laser cutters. It is fully customisable for just about any printer, mainly because most laser cutters are based on the same underlying technology as 3D printers and plotters. Because all of these devices only use a handful of controllers from a few manufacturers, standardisation has come about by default.
There are many free and paid software packages out there. LightBurn is popular, powerful and relatively cheap to subscribe to at about $40 per year. Fortunately, there is a free 30-day trial which is fully functional. Download from:
https://darklylabs.com/help-centre/manuals/support-lightburn/
The LightBurn program will ask for a laser cutter to install. In our case, we will be using the Emblaser II, which is the laser cutter used at our local library. The Emblaser II also comes with pre-prepared libraries of material settings.
When the software asks for the laser cutter, select the ‘Emblaser 2 / Core’ option and just follow the prompts, setting it up as a Serial laser and Origin at the front left.
Note: If you have another printer, then install that instead.
Looking at the user interface, the grid in the middle is obviously the model space.
The tools indicated by green on the left are the drawing tools. Pressing the Esc button on the keyboard a couple of times will always default to the top tool, the pointer, which is used to select objects.
The tools surrounded in yellow are the working tools to save, copy or manipulate the selected objects in some way.
The tools surrounded by the blue are the laser, console, camera, libraries, etc.
There are a few other things in the interface, but these are the main ones to know about. The only other important thing is you will notice at the very bottom of the Interface there is a big line of coloured boxes. These are the cut select boxes. These are extremely useful when cutting because certain cuts should be done before or after other cuts. Lasers are very accurate so you may wish to engrave your detail into the material before moving it by cutting the piece out of a larger sheet of material. This is where these cut select or layer boxes come in handy. You may also have different power settings or image/cut types you need to separate, so we use these.
Tangram
The author’s wife (often referred to as “Trouble”) is a High School teacher in a regional school. She is a trained Biological Researcher and a Science and Mathematics Specialist. She even does maths problems in her spare time for fun? She recently asked for some laser-cut Tangrams so she could introduce them to her students for learning purposes. She needs about fifteen sets, so this is our project for today (Happy Wife – Happy Life. Right?).
The tangram is a dissection puzzle consisting of seven flat polygons, called tans, which are put together to form shapes. The objective is to replicate a pattern (given only an outline) generally found in a puzzle book using all seven pieces without overlap. Alternatively, the tans can be used to create original minimalist designs that are either appreciated for their inherent aesthetic merits or as the basis for challenging others to replicate its outline. It is reputed to have been invented in China sometime around the late 18th century and then carried over to America and Europe by trading ships shortly after. It became very popular in Europe for a time, and then again during World War I. It is one of the most widely recognised dissection puzzles in the world and has been used for various purposes including amusement, art, and education. (Source: Wikipedia)
We start by selecting the Box Drawing Tool from the left menu and draw a big box in the middle of the canvas. We don’t really care how big it is right now because we are going to adjust the size anyway.
To adjust the size, first click on the width box (highlighted in yellow) and change the value to 200mm. Because the aspect is locked by the lock icon, the height may not be the same. If this is the case, click the lock, enter 200mm into the height box, and then click the lock again. The drawn box should now be 200mm x 200mm.
In engineering CAD drawing, we always try to simplify what we do by adding elements to make what we are doing easier, then deleting those elements afterwards. This helps us get what we want, where we want it, with great precision. Almost everything we do is with basic shapes that we then modify into complex shapes.
The first thing we want to do to make the job easier is to move the 200mm x 200mm box so that it centres on the origin. To do this, simply change the XPos and YPos fields to 0mm.
This box will be the outline of the Tangram, and because we want it to be the last cut of the project, we want to separate it from the rest of the cuts to maintain their precision. So before we go on, we will click on the pointer tool, and hit Escape a few times so that nothing is selected. You will notice on the bottom row of coloured squares that the first black square is highlighted. We are going to change that to the blue square next to it by simply clicking on it to highlight it. Now that we have the box situated on the origin, it is easy to draw lines inside it. Select the pencil tool (below the pointer). Looking at the x: and y: positions below the layer icons should make it easy to position the pencil over one corner until the pencil tool changes to a small cross Icon - this means the cursor is at the intersection of two lines. Left click and as you move the mouse towards the opposite corner a line appears. When the cursor changes to the small cross again, left click again and it will snap to the correct position. You will notice that the line joins the two points but still wants to draw. We don’t want this, so just press Escape ONCE and it will stop. If you make a mistake, look for the little back arrow icon on the working tools (highlighted in yellow in the earlier image).
We now have a diagonal blue line going from opposite corners. Now repeat the process and draw a line from one of the other corners to the origin, which just happens to also be the middle of the first line you drew. If all goes well, it should look a bit like this.
Notice in the laser control box, there are now two layers. For now, that is all we need to know.
Continuing on, we need to draw the triangle in the opposite corner to the bigger triangle we just created. Because we centred our box on the origin, we already know that one corner of this triangle will be at the intersection of the x-axis and the side of our box – but where is the other corner? This is where we start using some engineering tricks. Let us introduce you to construction lines. We don’t want to keep any construction lines but they may be useful multiple times. The ability to hide them is useful, so we will set another Layer. With the new layer highlighted, select the circle drawing tool and draw a circle with its centre on the opposite corner to the triangle we have just drawn. The circle tool works a little different to what you may expect, left click and hold when the small cross icon appears and hold the left mouse button (LMB) until the small cross appears again at the opposite corner of our box. This will put a large circle inside our box with its centre at the origin. Manually change the x-pos and y-pos coordinates to (100, -100). This will centre the circle on the corner of our box where we want it; the top of the circle will touch the x-axis exactly where the vertical side of our box crosses the same axis, and the circle will cut the horizontal side of our box at the same distance from the circles centre. These are the two points we need to make the smaller triangle. Change the layer back to blue; fire up the pencil and draw a new line connecting these two points. It should look like this image.
Now that we have another couple of points to work with, we can draw a few more lines to finish it off.
A few years ago, when we learnt AutoCAD, we would have drawn this object differently from the way we will show you here. This is because when we learned CAD initially, we didn’t know about the power of constraints. LightBurn is NOT a CAD program but it does have some CAD-like features. Part of the reason for this is that LightBurn can actually import some CAD Drawings and convert them directly to vector images for laser cutters. Many CAD files are really vector images in disguise with some other embedded information.
Since we now need to draw a square, for completeness we will draw some construction lines first. Fire up the pencil and on the construction layer, draw a line from the origin to the bottom right corner of the big box. Draw another line from the intersection of the circle and the bottom line, holding the shift key will make it track horizontally, vertically or at 45°. We want to draw a 45° line from this point to somewhere outside the left side of the big box. Switch to the blue layer and draw the lines we want to complete the square, using the intersection of our construction lines as a guide. It should now resemble this.
Now, we are almost home with our Tangram. Switch to the construction layer, holding the shift key, and draw a pencil line vertically from the intersection of the small triangle in the bottom right to past the top of the big square. Flip back to the line layer and using the construction lines, draw in the vertical blue line to complete the final smallest triangle we need. It will look a bit like this.
This is a bit hard to see with all of our construction lines so we will turn them off. We could delete them as we do not really need them anymore. In engineering, some designs are very fluid. They can be modified and tweaked a great deal. It is easier to set up one or more sets of construction lines that can be used multiple times and hidden when not needed. To hide our lines, go to the Cuts/Layers box and click the two switches that say Output and Show. They are BOTH important because if you only turn off Show, the laser will still cut those lines.
Now that we have created our Tangram, we are almost ready to laser cut it. We can also do a few things to show some simple functions of LightBurn first. We are first going to move the Tangram into the centre of the canvas by changing the x-pos and y-pos. This is just to let us use the grid on the canvas to help orient things. Then we are going to create some text using the text tool. We want to create a number of sets of this Tangram. There is a way that serial numbers can be set up in the laser tools section of the LightBurn software. We did try to nut it out for this project but ran out of time to work out how to do it, so we will do it manually this time. Using the text tool, cut & paste and the rotate function along the top tool section.
Our Tangram is essentially finished. For any further changes, it makes sense to tell the software to group the cuts together so that we don’t leave anything behind if we move
it or such. To do this, simply left click and drag the entire shape and contents, and either hit the group button on the side or go to the arrange tool on the top menu and select group from the drop-down menu.
The next thing we want to do is re-size the Tangram and move it closer to the origin. The current size of 200mm x 200mm is great for a one-off, but is too big and wasteful of material unless we are cutting other things on the same piece of material and we make it fit. Simply select the Tangram and change the width, height or size. In our case, we are making ours 140mm x 140mm because the material we have is 300mm x 500mm. Since we need multiple sets, we can easily get six sets to a sheet. We will then position the Tangram by dragging it into place manually.
If you wanted to, you could just cut out the Tangram as it is but we need lots of them. We are going to position the shape, and then use the copy and paste commands to make several copies. Since we need at least 15, we will set it up to cut six on a sheet of our selected material. There is a method of “Mass Producing” copied shapes in the variable text section of the laser window. We have not yet worked out how that works, so for now we will just renumber to sets of Tangrams by hand. If all goes well, and you also want to make multiple copies, your screen should now look something like this.
Next month, we will look at setting up the cuts; different materials from the library; how certain cuts could or should be made under certain circumstances; other places on the Internet to get free laser cut models; and a few really cool ways you can use your laser cutter and be productive.
NEXT MONTH: Laser Cutting Continued