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Calibration Guide
All calibrations are in Tune → Calibration, numbered in the order a new printer needs them: do 1, 2, 3, ... from the top. For background, every other calibration and troubleshooting, see the full calibration walkthrough.
The Calibration menu, numbered in the order a new printer needs.
Status lines: what ran, when, and what it measured.
| # | Menu row | You need | Time |
|---|---|---|---|
| 1 | Bed Tramming | an empty bed (and maybe a printed shim) | 5-15 min |
| 2 | Heaters (PID) | an empty, cool printer | hotend a few minutes, bed longer |
| 3 | Axis Twist | a sheet of paper | about 5 min |
| 4 | Auto Calibration | an empty bed - no tools | about 7 min |
| 5 | Input Shaper | the accelerometer | about 5 min |
| 6 | E-Steps | a ruler or caliper, a marker | about 5 min |
| 7 | Skew Correction | a printed test part, a caliper | about 30 min |
| - | then the first print: Tune → Z Offset or Fine Tune | a test print | while printing |
Below them, OTHER: Load Cell Calibration (automatic re-check or manual with a bottle), TMC Autotune (optional, quieter motors) and Bed Mesh (view or measure).
Each row says where you stand:
- Done 24 Oct - Z offset 1.752 mm, mesh range 0.16 mm (green): when it last ran and its result.
- a one-line description and the time it takes (grey): not done yet.
- Redo: Axis Twist changed (orange, with a bar on the left): something changed since, run it again. Examples: saving Axis Twist marks Auto Calibration Redo: Axis Twist changed; a shim at the front-left corner (Bed Tramming) marks Load Cell Calibration and Auto Calibration Redo: a shim was added at front left. Running the calibration clears it.
On a printer whose NebulaOS does not keep a calibration history yet, the rows show the descriptions only.
The printer probes the four corners and shows each one compared with a reference corner, with a sign: minus is lower, plus is higher. Example (rigid spacers, compared with the highest corner):
Rear: left -0.05 OK right 0.00 highest
Front: left -0.23 ADJUST right -0.12 later
and below it what to do, one corner at a time:
Front left: -0.23 mm. Add a 0.20 mm shim to raise it. Turn the printer off first, lift the bed plate at that corner and put the shim on the spacer.
With rubber or spring mounts the screen tells you which screw to turn and how far instead. Correct the corner, tap Done - measure again, repeat until every corner says OK. Details: Bed tramming.
Teaches the bed and the hotend heaters to hold their temperature steadily. Two buttons: Bed 65 C and Hotend 230 C - start with the bed. Each heats and cools a few times (the temperature going up and down is normal), then saves with one Klipper restart. The screen shows the progress: "Heating up", then "Measuring: cycle n of 6, about m min left". The hotend takes a few minutes; the bed much longer, because each of its swings takes about 3 minutes. The Calibration menu remembers both heaters. Redo it after changing a heater, a thermistor or the hotend.
It comes before Auto Calibration on purpose: the hotend oozes during the long hot phase, and Auto Calibration's nozzle clean removes that before the Z offset is measured.
A 5-point paper test across X that corrects a slightly twisted gantry for every probe. Its Save also removes the saved bed mesh (it was measured without the correction) and marks Auto Calibration Redo: Axis Twist changed - run step 4 next.
One button does everything (it used to be called Z-Offset & Bed Mesh): load cell check (cold and hot, no bottle, when the load cell is in Automatic mode), nozzle clean, Z offset, bed mesh, all saved with one Klipper restart. Remove everything from the bed and tap Start.
While it runs the page shows every step with check marks, the current one in large type with its live detail, for example:
Step 7 of 10 ✓ Load cell check
Measuring the Z offset ✓ Homing
touch 2 of 3 ...
> Measuring the Z offset
Bed mesh
Saving (Klipper restarts)
Verifying
Heating shows the temperatures (bed 61/65 C, nozzle 148/150 C), the mesh the probe point (point 41 of 81). During Saving the page says that Klipper restarts and the screen reconnects by itself - do not switch the printer off. At the end:
- Done 24 Oct with the new values, for example Z offset 1.669 mm (was 1.795), Bed mesh 9x9, range 0.16 mm and Your Z adjustment was reset to 0. - the adjustment from the first-print step was made for the old Z offset.
- or Failed: with Why, What to do and Nothing was saved.
Input Shaper and E-Steps show the same step list.
Guided pages, every step's button on the page (no popups); see the full calibration walkthrough. Input Shaper shows what it is doing (shaking, calculating, drawing) and a graph of each axis next to its result (switch Show graphs). Skew Correction is last because it needs a printed test part from a calibrated printer.
The load cell under the front-left bed screw is the sensor that feels the nozzle touch the bed. The page has two choices at the top:
- Automatic (the default). The printer checks the sensor by itself on an empty bed: no bottle, nothing moves or heats. Tap Run. After a passed check the page says Ready - Automatic needs no weight calibration; Auto Calibration uses it. You do not have to run it by hand: Auto Calibration runs the same check first. If the check fails, the page says why and offers Run again or Use Manual.
- Manual. The calibration with a 1.5 L bottle of water and a kitchen scale (about 2 minutes, nothing moves or heats): Load cell calibration (water bottle). The value you measure is used until you choose Automatic again.
The choice is saved at once and survives restarts.
Shows the active mesh. Klipper does not load a saved mesh by itself after a restart, so after Auto Calibration the page shows the saved one instead, with Saved mesh 'default' - each print measures its own mesh at the start - nothing is loaded. Only when no mesh was ever saved it says No bed mesh yet - run Calibration > Auto Calibration.
Print something with a large first layer and watch it. On the screen, Tune → Z Offset (or the Z buttons in Fine Tune, or tap the Z value on the print screen):
- Raise (farther from the bed) when the line is rough or scraped, Lower (closer) when it is round and does not stick. Steps of 0.01 mm are usually right; 0.005 / 0.001 for the last bit.
- Every tap is saved immediately. The page says Z offset adjustment: -0.040 mm, saved. The value comes back after a Klipper restart, a pause/resume and a power cut.
- Reset sets the adjustment back to 0.
- If the line ever says NOT saved (orange), the adjustment works for this print but is lost at the next restart.
Mainsail: its own Z offset arrows change the offset for the running print only (not saved by
NebulaOS). Its Save button folds the current offset into the probe z_offset in
printer.cfg and sets the NebulaOS adjustment to 0, so nothing is counted twice.
The menu's Redo lines cover the common cases; in general:
| What changed | Redo |
|---|---|
| New nozzle, new build plate | 4 Auto Calibration (then fine-tune on the next print) |
| New heater, thermistor or hotend | 2 Heaters (PID), then 4 |
| Shim at the front-left corner, or bed hardware (spacers, springs, the bed itself) | Load Cell Calibration (Automatic: just Run) and 4 |
| Corners uneven (first layer thick on one side) | 1, then 4 |
| Axis Twist saved | 4 (its saved mesh was removed) |
The front-left corner is special: the load cell sits under it, so changing that corner changes how the load cell is mounted.
Some actions are refused while the printer is busy - for example Restart Klipper or an update while a heater is on. The screen then shows a Not now popup with the reason and nothing happens:
| Reason | Popup text |
|---|---|
| a print is running | Not possible while a print is running. |
| a print is paused | Not possible while a print is paused. |
| heating or moving (a heater target above 0 counts) | Not while the printer is heating or moving. |
| a calibration is running | Not possible while a calibration is running. |
| an update or MCU flash is running | Another update is running. |
| low memory | Not possible right now: the printer is low on memory. |
| state unknown | Printer state unknown - not possible right now. |
Wait until the print or the calibration ends, or set the heaters to 0, then tap again. Calibration pages do the same on their own: while a print runs, their Run/Start buttons are not offered.