How do I calibrate my thermal printer?
Each push of the printer's button should eject exactly ONE label.
On most thermal printers you hold down the button for a certain amount of time and then let go.
Is your printer printing extra labels? Is your text mis-aligned? Your printer may need to be calibrated.
Why do we need to calibrate a printer?
It might seem obvious to us humans, but label printers are simple robots. We can easily see where a label starts and stops... but a printer needs a few helpful hints.
When a printer "knows" the length of the label we can say that the printer is "calibrated." You can easily test this with most printers by pressing the button on the top of the printer.
Does the printer eject exactly one label when you press the button? If not, you need to calibrate.
How does calibration work?
Most label printers print from a roll and since labels come in different shapes and sizes, the printer needs a way to reliably detect how long each label should be. Inside the printer are sensors. Thermal label printers have at least one kind of label sensor.
The two most common sensors are:
Gap Sensor: Detects the gap between two labels by sensing the different transparency of label backing vs. the label material. This works for standard die-cut labels.
Black-line Sensor: Detects a color change on the back of a tag. This works for tags where there isn't a material change between two perforated tags.
The black-line sensor also works to detect holes in the label where the backing "changes color" based on the absence of the material (hole). We assume the inside of your printer is dark...
Running a Calibration from Label LIVE
If you are using a thermal label printer supported by Label LIVE then you can often run a calibration from the Print tab. Make sure the "USB Thermal Printer" version of your printer is selected, and then scroll to the bottom. Click Commands and click Calibrate. You may choose between available sensor options or "Automatic."
Automatic label sensing works "most of the time." Shaped labels like barbells (above) can confuse calibration because you could technically use "gap" sensing if you moved the gap sensor to the edge of the label – where the barbell is the thickest. Not all label printers have movable sensors - so you're best to experiment. You can almost always rewind labels that failed to calibrate.
Most printers allow you to trigger a calibration from a combination of button presses on the printer.
Hold down the top button until you hear a beep, then let go.
ZEBRA printers can be calibrated by holding down the top button until the light flashes once, then twice, then let go.
Other models such as TSC, GoDEX, SATO, etc. may require you to power-off and hold the button during power-on for a certain period of time, or until a light changes color... Some printer models have dedicated calibration buttons.
It is always best to search the Internet for your exact model's instruction manual. You will find a lot of different functions using these otherwise hidden techniques.