Z offset and first layer

The first layer makes or breaks a print. On the G1, the most common first-layer problem is a wrong Z offset — the distance between the nozzle tip and the bed at the start of printing. This is also the #2 most-reported issue across customer cases.

Symptoms

• First layer is too squashed — very wide, glassy, hard to remove from the bed
• First layer is too high — round, “rope-like” lines that don’t stick, the print warps or detaches
• The nozzle drags or scratches the bed at the start of printing
• After a nozzle change, the first layer suddenly looks completely wrong
• After moving the machine or changing cables, the bed mesh “doesn’t load” correctly
• Customer reports: “It was fine yesterday, today the first layer is a mess”

Possible causes

1. Wrong live Z offset — most common; just needs adjustment
2. Nozzle changed but Z offset not updated — different nozzle = different protrusion → different Z
3. Bed mesh leveling not saved correctly — saved from display but G-code expects the slicer’s mesh
4. Probe Z offset drifted — the bed-leveling probe and the nozzle have different Z offsets, which can drift after cable / endstop changes
5. Bed not flat / not clean — debris, residue, scratches under the nozzle

Quick fix — live Z offset during the first layer

The fastest path. Use this whenever the first layer doesn’t look right.

1. Start the print
2. Watch the first lines (skirt or first wall)
3. While printing, on the printer display open the Tune / Z offset menu
4. Adjust in small steps (0.05 mm)

What you see	Action
Lines too squashed, very wide, shiny	Raise Z offset (positive direction, +0.05 mm)
Lines round, rope-like, lifting	Lower Z offset (negative direction, −0.05 mm)
Nozzle scratching the bed	Stop the print immediately, raise Z offset by +0.1 mm before restarting

Typical adjustments are within ±0.7 mm of the saved baseline. Once you find the right value, save it from the display so it persists.

After a nozzle change

Different nozzles have different lengths. The Z offset is invalidated every time you swap nozzles.

1. Re-run bed leveling with the new nozzle installed
2. Re-tune the live Z offset on the first print
3. Save the new Z offset

If bed leveling doesn’t seem to load correctly

This pattern: bed mesh runs visibly during homing, the screen shows a valid mesh map, but at print start the nozzle is way too high or way too low.

Common cause: the leveling was triggered from the display but the G-code expects the slicer-side mesh, or vice versa. The two paths don’t always share state.

Fix

1. Power off the printer cleanly
2. Power back on and run bed leveling from the macro menu on the display (not the slicer)
3. Save the mesh from the display
4. Restart and reprint
5. If still wrong → save the mesh from Mainsail / Fluidd (computer-side) and try again

Note

Klipper save bug workaround: if the Z offset is set correctly but resets to a different value after a save, try this sequence: set the offset to −0.1 mm, click Save Config, then set the correct value again and Save Config a second time. This forces Klipper to write a clean config entry and resolves the ghost-offset issue confirmed across multiple machines.

A walkthrough video is available on the Ginger Additive YouTube channel.

If the probe and nozzle have different Z offsets

After replacing endstops, cables, or moving the machine, the probe Z offset can drift relative to the nozzle. Symptom: bed mesh looks right but the nozzle hits the bed (or stays way too high) at print start.

1. From the printer display, find the Z offset tuning menu
2. Run a print and adjust live Z offset to the correct value
3. Save the new probe-vs-nozzle Z offset

Diagnostic flow

First layer wrong
        │
        ├── Wrong everywhere uniformly?
        │       └── Live Z offset adjustment
        │
        ├── Wrong only after nozzle change?
        │       └── Re-level, re-tune Z offset, save
        │
        ├── Mesh ran but Z is way off?
        │       └── Re-run leveling from the right source
        │           (display vs computer)
        │
        └── Wrong only in some regions?
                └── Bed not flat / debris / surface damaged
                    Clean the bed, re-level

How to prevent

• Always re-level after a nozzle change before printing
• After moving the machine, run a fresh bed leveling
• Keep the bed surface clean — wipe with isopropyl alcohol between materials
• Don’t change endstops or homing-related cables without re-running calibration
• Save your final Z offset to firmware via the display

Notes

• Pattern observed across 31+ customer cases
• The single most common first-print problem after the assembly is finished
• Live Z offset tuning is fast and the customer can do it alone — explain it once, they do it forever
• Saving from the display vs. saving from the computer: small but real source of confusion

Related notes

• Bed leveling system
• Rotation Volume calibration
• Nozzle set
• Bed adhesion sprays
• Initial calibration