# How bed leveling is achieved without table screws?

I have seen printers with table screws and bed leveling sensor and printers that have only bed leveling sensor (such as Prusa).

So my question is how does the bed levelling work when there is only a sensor, and no adjustment screws? What will happen if I totally remove the table from the printer and then re-assemble it? Will the print fail or what?

• Are you asking 'will the calibration persist through dissassembly/reassembly' or something else? Your question is a bit confusing, – Sean Houlihane Jul 11 '18 at 10:30
• RealMen(TM) always level manually like the universe intended. (Shamelessly stolen from some stick-shift enthusiast) – Carl Witthoft Jul 11 '18 at 12:29
• @SeanHoulihane Yes, exactly that. – OrElse Jul 11 '18 at 19:17

Note that Marlin Firmware (which is basically what drives the Prusa printers) has skewness compensation implemented. This is implemented in the configuration file, and found under header Bed Skew Compensation. You basically print a square and measure the diagonals and insert these measurements into the configuration file. Prusa printers do this automatically by using the measurements of the marker points.
• @Horitsu The bed level is usually fading out over a predefined distance, in e.g. Marlin #define ENABLE_LEVELING_FADE_HEIGHT determines that, and the height can be set with M420 Z<height>. Yes, a cube will not be perfectly cubic, that is why even with auto bed leveling you need to provide a bed as level as possible, it only should correct for very small deviations. – 0scar Jul 11 '18 at 6:18