Coordinates and Job Origin
This next section covers a fundamental concept in the world of lasering: your laser has a work area — the bounds within which it can cut or engrave graphics — how do you tell it exactly where to do that for any given project?
The answer depends on your type of laser, personal preferences, and needs. We'll run through your choices, and explain how they work, below.
Selecting a Start From Mode¶
There are three options for determining where graphics will output in your laser's work area.
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Absolute Coordinates tells Lightburn to output graphics in your laser's work area at a location that matches their position in your Workspace.
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Current Position tells LightBurn to output graphics relative to the position of the laser head at the moment you start a job.
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User Origin tells LightBurn to output graphics relative to a custom-defined origin that you set before starting a job.
All three are available in the Start From dropdown menu in the Laser Window.
The 9-dot Job Origin selector beneath the dropdown menu determines the orientation of output relative to the Current Position or User Origin. It will be grayed out if you have Absolute Coords selected (Absolute Coords always uses the same pre-determined Job Origin), but clickable if you choose Current Position or User Origin.
Note for Galvo Users
If you have a Galvo laser, you won't see the Start From mode dropdown menu or 9-dot Job Origin selector in the Laser Window — that's because Galvo lasers always use Absolute Coordinates positioning.
Absolute Coordinates¶
Absolute Coordinates is often the the most inuitive option. The grid in your LightBurn Workspace has a coordinate system that matches the physical work area of your laser. The 0,0 position in your Workspace's coordinate system is the same as the location of your laser's Machine Origin.
With Absolute Coords selected as your Start From mode, anything you place in the LightBurn grid will be output in the corresponding location in your machine's work area, relative to that shared 0,0 point.
Not sure where your Machine Origin is? Click here
The Machine Origin is the same origin LightBurn identified (or you selected) when you first set up your laser. If LightBurn identified it for you, you most likely won't ever need to change it again.
Almost all GCode-based diode lasers use the lower left corner as their origin, and, for DSP lasers, the origin is the same as the location the laser homes to when you first turn it on (usually the back right corner).
If output to your laser is mirrored or backwards, you may need to change the Origin setting in the Device Settings window.
Note
Using absolute positioning requires a laser with a a fixed origin. If you have a small diode laser that does not have homing switches, you will need to manually home the machine. See: Machines without homing sensors / limit switches.
In the image below, the four hexagons placed in the middle of the LightBurn grid will be cut in the middle of the machine work area. The green square in the lower left of the image represents the Job Origin, and the red square in the same place shows the Machine Origin. When using Absolute Coords, these are always in identical locations.
Using a Camera With Absolute Coordinates Positioning
If your laser came with a camera, or you install one yourself, you'll be able to take a picture and produce an Overlay of your laser's work area in your LightBurn Workspace.
This allows you to position graphics directly over material you've placed in your laser, and use Absolute Coordinates positioning to cut or engrave them in the correct location. Be sure not to select a different Start From mode when you're working with a camera, or things won't line up properly!
See Camera Control Window for more information on using a camera.
Current Position¶
With Current Position selected, your job outputs relative to wherever the laser head is located when you press the Start button. The Job Origin control in the Laser Window tells LightBurn how to orient output relative to the laser head.
In this image, we're starting from the Current Position, with the Job Origin set to the lower left:
Notice that the green Job Origin indicator has moved. This represents the position of the laser when you start the job, so the laser is going to move slightly up and to the right from wherever it is, cut the four hexagons, and go back to where it started.
Now imagine that you want to etch this four hexagon pattern onto a coaster or a phone case. Lining it up from the lower left is not easy. If you change the Job Origin setting to center, you get this instead:
The job will be centered around the current position of the laser head. If you position the laser head directly over the center of the item you want to etch, the output will be centered on the item.
Jogging Your Laser
Both Current Position and User Origin require you to jog your laser into a desired position to define a custom origin. LightBurn has a few tools for adjusting the location of your laser's head within its work area — the most straightfoward option for beginners is to use the arrow keys in the Move Window. By default, the Move Window is hidden behind the Cuts / Layers Window — click the Move tab to expose it.
The arrow keys move your laser up, down, right, or left. You can set the amount the laser travels with each click in the Distance field, and the rate at which it travels in the Speed field.
User Origin¶
User Origin works almost exactly the same as Current Position, except that the starting location is programmable. To set a User Origin, you must first jog your laser to the location you want your job to start from, then set the origin.
Some lasers with digital displays, such as those with Ruida controllers, have an Origin button which you press to set the origin. GCode-based systems use the Set Origin button in the Move Window in LightBurn to do the same thing.
For supported systems, use Clear Origin to remove and reset a custom-set origin.
After setting the origin, you are free to jog your laser around its work area. With User Origin selected as the Start From mode, the laser will always move back to that programmed location and start the project from there.
You can also use the Go to Origin button in the Laser Window to command your laser to travel back to the origin you've set.
As with Current Position, the Job Origin setting determines how output will be oriented relative to the user-defined origin.
The best way to get familiar with the way the different Start From modes is to test them out — next we'll explain how to do that using LightBurn's Framing features.
For more help using LightBurn, please visit our forum to talk with LightBurn staff and users, or email support.