How to Fix a Nozzle That Is Too Close to the Bed (Z Offset)

A nozzle that is too close to the bed squashes the first layer flat, leaves ridges between lines and can scrape the build plate. The fix is to raise the nozzle slightly, which usually means changing your Z offset a small step at a time and re-checking a one-layer test. Prusa’s help pages and the Klipper documentation describe the same approach, and the details differ only by firmware.

How to tell the nozzle is too close

Prusa’s first-layer calibration guide says that with the nozzle set too low “you will see the line squished completely flat,” with ridges between the lines in the test square. On textured sheets it adds that filament can curl up at the edges. Prusa also notes that in extreme cases it can clog the hotend.

Prusa describes a good result as even lines with no gaps and no ridges. It also says the exact Z value varies per machine, so judge by what the print looks like and not by a number from someone else’s printer.

Why it matters

Prusa’s i3 guide warns that “having the nozzle too low can cause the nozzle to damage your steel sheet,” and that such damage is not covered by warranty. A very close nozzle can also leave the plastic nowhere to go, so extrusion struggles. Stop a print that sounds like scraping instead of letting it finish.

Step 1: Clean the plate and the nozzle

Make sure the print surface is clean before you adjust anything, as Prusa’s guide says, and remove any plastic stuck to the nozzle tip. Leftover plastic changes the true nozzle height and makes every reading unreliable. If the plastic keeps catching, see how to fix a clogged nozzle.

Step 2: Raise the nozzle in small steps

On Prusa printers the adjustment is Live Adjust Z, reached from the LCD menu under Control on the Mini. Turning the knob counter-clockwise moves the nozzle closer, so you turn it the other way, toward zero, to move the nozzle up. Prusa gives a common range of -0.400 to -1.900 on the Mini, but stresses that it varies.

On other printers, the same setting appears as Z offset, probe offset or live Z adjust. Change it by a very small amount, such as 0.02 mm, and test again. Large jumps overshoot and leave you with gaps instead.

Step 3: Recheck with a paper test (Klipper and similar)

Klipper’s bed level documentation describes the paper test: slide ordinary paper, about 100 microns thick, between the nozzle and the bed and lower the nozzle until you feel a small amount of friction. If you feel too much friction, the nozzle is too close and you raise it with a positive Z move. Klipper recommends doing this at room temperature, because heat expands parts and molten plastic sticks to the paper and changes the feel. Do not push down on the bed while sliding the paper.

Once the position feels right, Klipper’s probe calibration page says to run ACCEPT and then SAVE_CONFIG so the probe offset is stored in the config file.

Step 4: Make the fix stick

If the fix disappears on the next print, the value was only a temporary adjustment. Save it using your firmware’s method. Klipper’s documentation says the probe calibration results become invalid after changes to the motion system, hotend position, probe location or bed tilt, so rerun the calibration after any of those, and then redo your bed mesh with BED_MESH_CALIBRATE. Prusa likewise says to recalibrate after a nozzle change, axis work or moving the printer, and to keep a separate Live Z value for each steel sheet because sheets differ in thickness.

Step 5: When the offset will not go far enough

Prusa’s guide says that if the value runs out of range and the nozzle still is not at the right height, the fix is mechanical: it describes moving the probe in its holder by 0.5 to 1 mm and restarting calibration from zero. If your printer reaches its offset limit, check the probe mounting, the hotend and the bed rather than forcing the number. For related causes of a poor start to a print, see fix a bad first layer and how to level a 3D printer bed.

Check the maker’s guidance

Menus, commands and limits differ by printer. Follow your manufacturer’s instructions for your model, and take extra care around hot parts.