Adaptive Print Setup

Adaptive meshing and purge line

NebulaOS prepares the bed for each print in its START_PRINT macro:

• Adaptive bed mesh — probes only the area the print covers instead of the whole bed, using Klipper's own BED_MESH_CALIBRATE ADAPTIVE=1.
• Smart park — parks the nozzle next to the print while it heats.
• Line purge — draws a purge line just in front of the print area.

All three use the print's object outlines (Klipper [exclude_object]), so the slicer must write object labels. These macros are part of the NebulaOS image (/etc/nebulaos/klipper/print.cfg), not of NebulaScreen; this page describes how to use them.

Do Axis Twist Compensation first if the first layer is uneven left to right. A denser mesh does not help when the probe readings are off.

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Step 1 — Turn on object labels in the slicer

In OrcaSlicer: print settings → Others → tick Label Objects. Other slicers have a similar option. NebulaOS's moonraker.conf has enable_object_processing: True (keep it): Moonraker reads the object outlines from every uploaded file and passes them to Klipper, and it adds the labels itself when a slicer marks its objects only in comments. The NebulaOS build checks that the shipped moonraker.conf keeps this setting on.

The same setting enables Exclude Object on the print status screen: if one part fails, you can drop it and let the rest keep printing.

Step 2 — Call START_PRINT from the start G-code

In OrcaSlicer: printer profile → Machine G-code → Machine start G-code:

START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single]

To soak the bed only for filaments that warp (ABS, ASA), let the slicer add BED_SOAK=1:

START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single] {if filament_type[0]=="ABS" or filament_type[0]=="ASA"}BED_SOAK=1{endif}

START_PRINT then does, in order:

1. Checks the filament sensor; with no filament it stops with a message.
2. Starts heating the nozzle to 150 °C (below oozing) and the bed to BED_TEMP.
3. Homes if needed, moves to Z 50 while the bed heats, and waits for the bed.
4. Bed warp stabilisation, only with BED_SOAK=1 (off by default): an extra wait of 8 s per °C the bed had to heat (about 11 minutes from room temperature to 85 °C), so the bed has settled before it is measured. Without it the console says "Skipping bed warp stabilisation".
5. Clears the old mesh and probes a new one — adaptive, unless the print covers more than 75 % of the bed, in which case it probes the full bed.
6. Parks next to the print, waits for the nozzle to reach EXTRUDER_TEMP, and purges a line in front of the print (or along its left side when there is no room in front).

While it runs, speed and acceleration are capped for probing and restored afterwards.

If the parameters are left out, BED_TEMP defaults to 65 and EXTRUDER_TEMP to 230 — always pass both from the slicer.

Options

Parameter	Effect
BED_MESH_ADAPTIVE=0	Probe the full bed instead of the print area
BED_MESH_PROFILE=<name>	Load a saved mesh instead of probing
BED_SOAK=1	Bed warp stabilisation (soak) before the mesh; BED_SOAK=0 never soaks

Remove any BED_MESH_PROFILE LOAD=... line from older start G-code: loaded after START_PRINT, it would replace the fresh mesh.

Without object labels there is no print area to adapt to: expect a full-bed mesh, and park and purge near the bed's front-left corner. Turn labels on.

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Settings

The purge and park values are variables of the macro _KAMP_Settings (for example variable_purge_amount, variable_purge_margin, variable_flow_rate, variable_smart_park_height), and the start/end behaviour is in _START_END_PARAMS (for example variable_full_bed_mesh_above_percentage_full, variable_start_preheat_nozzle_temp). Both are in /etc/nebulaos/klipper/print.cfg. Without BED_SOAK, bed warp stabilisation follows the switch Bed_Warp_Stabilisation (an output_pin, which Mainsail shows with the other outputs). It is off after every Klipper start; BED_SOAK from the slicer always wins.

At the end of a print (END_PRINT), after a cancel (CANCEL_PRINT) and at the end of the cooldown, the nozzle parks at the rear left (X2 Y218) with the bed forward, so the print is presented to you. A pause or filament change parks as before.

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Credits

The purge and park macros derive from pellcorp/creality ("SimpleAF") and, through it, from KAMP (GPL-3.0). The adaptive mesh itself is Klipper's native ADAPTIVE=1.