Glossary · Function

3D printing

Auto bed levelling

The printer measures for itself whether the print plate is higher or lower anywhere and compensates for this automatically while printing.

Explained in more detail

A sensor (inductive, mechanical probe, load cell or eddy current sensor) scans the bed in a grid, often at 25 to over 100 points. This produces a height profile (mesh), which the firmware uses to adjust the Z axis during the first layers. It compensates for unevenness of a few tenths of a millimetre, but does not replace a badly skewed mechanism.

Where does the term come from?

From English: to level means "to make horizontal", and the function is often abbreviated as ABL. Strictly speaking, the bed is not levelled but measured, and the firmware compensates for the deviations.

In practice

• Have it measured again if you have changed the print plate or transported the printer. Many printers measure before every print anyway.
• Measure at the bed's print temperature, because a warm plate expands and deforms slightly differently from a cold one.
• If the printer measures with the nozzle itself, for example via a load cell, the nozzle tip must be free of filament residue.
• If the mesh shows large differences in height, check the screws and mechanics instead of just measuring again and again.

Not to be confused

Auto bed levelling does not replace the Z offset. The mesh describes unevenness across the surface, while the Z offset determines how high the nozzle starts above the bed overall.

Frequently asked questions

Do I need auto bed levelling?

Not necessarily, it also works with carefully levelled corners. ABL saves time and makes the first layer more reliable, which is why almost all new printers have it.

How often should the bed be measured?

Many current printers measure automatically before every print. Otherwise it is enough to measure again after changing the plate, after transport, or in places where adhesion problems occur.