Slicer Setup

Setting up your slicer

What this guide will help you do

Tell your slicer how to start and end a print on NebulaOS. You do this once, before your first print. Without it, the printer may skip its own preparation - the bed mesh, the purge line, timelapse - or heat up twice.

What you need

• A slicer. The examples use OrcaSlicer, which most KE owners use. Its Creality Ender-3 V3 KE printer profile is a good starting point.
• A calibrated printer - Calibration guide.

The two lines

NebulaOS has one macro that prepares a print and one that ends it:

Slicer field	Put exactly this in it
Start G-code	START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single]
End G-code	END_PRINT

The words in square brackets are OrcaSlicer's own placeholders. When it slices, it replaces them with the nozzle and bed temperatures of your filament's first layer.

The names matter. The macros are called START_PRINT and END_PRINT. NebulaOS has no PRINT_START or PRINT_END, so a profile written for another Klipper printer that uses those names will not run NebulaOS's preparation.

Step-by-step in OrcaSlicer

1. Open the printer settings (the edit icon next to the printer name), tab Machine G-code.

2. Replace everything in Machine start G-code with:

   START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single]

3. Replace everything in Machine end G-code with:

   END_PRINT

4. In the print settings, tab Others, tick Label objects. NebulaOS uses the object outlines to probe only the area the print covers, to purge next to it, and to let you cancel one object during a print.

5. Save the printer profile.

Leave out the heating, homing, mesh and purge lines a stock Creality profile may have had: START_PRINT does all of that itself, in the right order.

What START_PRINT does for you

In order: checks that filament is loaded, starts heating, homes, waits for the bed, probes a fresh bed mesh of the print area, parks next to the print, waits for the nozzle and draws a purge line. It also starts the timelapse watcher, if timelapse is on. The details, and what each step costs in time, are in Adaptive meshing and purge.

END_PRINT turns the heaters off, retracts, and parks the nozzle at the back with the bed forward, so the print is presented to you.

Optional extras

You can add these to the START_PRINT line:

Add	What it does
BED_SOAK=1	Waits for the bed to settle before measuring it. Useful for ABS and ASA. BED_SOAK=0 never waits.
BED_MESH_ADAPTIVE=0	Probes the whole bed instead of just the print area
BED_MESH_PROFILE=<name>	Loads a saved mesh instead of probing a new one

To soak the bed only for ABS and ASA, let OrcaSlicer decide:

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}

If you leave the temperatures out, START_PRINT uses 65 °C for the bed and 230 °C for the nozzle. Always pass both from the slicer.

Expected result

When you start a print, the screen shows the start steps - preparing, heating the bed, the mesh, heating the nozzle, the purge - and then the first layer begins.

Troubleshooting

What happens	What to do
The print starts without a mesh or a purge line	The start G-code does not call START_PRINT. Check the spelling and that nothing replaces it.
A full-bed mesh every time, and the purge line at the front-left corner	Label objects is off. Turn it on and slice again.
The fresh mesh is replaced by an old one	Remove any BED_MESH_PROFILE LOAD=... line after START_PRINT.
No timelapse video, and timelapse is on	The print has to start with START_PRINT. See Timelapse.

From START_PRINT, _START_PRINT_BED_MESH and END_PRINT in etc/nebulaos/klipper/print.cfg, firmware e523e8c. The OrcaSlicer field names and placeholders are OrcaSlicer's, not NebulaOS's.

Next step

Filament - load it, then Printing - start your first print and watch it.