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Printing
Start a print, watch it, adjust it while it runs, and stop it safely.
- A calibrated printer - First-time setup.
- Filament loaded - Filament.
- A sliced
.gcodefile.
Learn the difference between Cancel and Stop before you need it. They sit next to each other and they are not alternatives:
| Button | What it does | When to use it |
|---|---|---|
| Pause | Parks the toolhead and holds temperatures. Resume carries on. | A filament change, or a look at something |
| Cancel | Ends the print tidily. Asks you to confirm. | You have changed your mind |
| Stop | Emergency stop. Cuts all movement and all heaters instantly. | Something is going physically wrong |
Stop needs a power-cycle or a firmware restart afterwards before the printer will do anything again. Its label is only "Stop", not "Emergency Stop", so it is easy to press expecting a gentler Cancel. Use Cancel unless something is actually wrong.
Three ways, all equivalent:
- Mainsail - drag the file into the file list in your browser. Easiest from a computer.
- USB stick - plug it in; the printer's file browser reads it directly.
- Your slicer - if it can upload to Moonraker, point it at the printer's address.
- On the screen, open the Files tab (or Home → Files).
- Find your file. Files on a USB stick appear alongside the ones stored on the printer.
- Tap it, then confirm.
The printer heats up, may run a bed soak and a purge line, and begins.
Depending on your configuration, NebulaOS may probe only the area the print actually covers rather than the whole bed, and may purge next to the print instead of on it. Both are normal and both save time.
The print status screen appears by itself the moment a print starts, whatever you were looking at.
On the left: the thumbnail, the file name and a progress bar. On the right, ten readouts:
Extruder temperature, current or current / target
|
Bed temperature, same format |
| Chamber temperature - always shown here | Speed in mm/s |
| Z-offset - tap it to adjust live | Flow in mm³/s |
Layers, as current / total
|
Elapsed time |
| Fan speed | Time left, an estimate |
If you navigate back to the Home tab mid-print, a compact progress widget replaces the usual buttons there - tap it to return to the full screen. That shortcut is only on the Home tab.
This is the single most useful thing on this screen, and it is meant to be used.
Tap the Z-offset readout to get step buttons: ±0.001, ±0.005, ±0.01, ±0.025 and ±0.05 mm. Watch the first layer and nudge:
| What you see | What to do |
|---|---|
| Lines not fusing, gaps between them | Nozzle too high - press − |
| Lines translucent or completely flat | Nozzle too low - press + |
| Lines squished together and fused, no gaps | Correct - leave it |
Move in small steps and give the printer a few seconds to show the result.
Tune → Fine Tune, or the Fine Tune button on the print status screen.
Speed and flow here are percentages of what the file asked for. The flow figure on the print status screen is a different thing - a volumetric rate in mm³/s.
Pressure advance can also be adjusted live from Fine Tune. It is not shown on the print status screen.
From the Home tab:
-
Tap any temperature to set a target. A numpad opens - type the exact value. The reading
shows
current / target, so45 / 210means 45 °C now, heating toward 210. - Tap the target to clear it and cool down.
- There are no material presets - no PLA or PETG buttons. Type the number.
- Chamber and MCU readings are display-only.
- Fans opens the fan controls. Fans the printer manages itself are shown read-only.
If your file was sliced with object labels, the Objects button on the print status screen lets you cancel a single object while the rest carries on - useful when one part of a plate has failed.
Cancelling the last remaining object asks whether you meant to cancel the whole print.
The printer stops heating and the status screen shows the print as complete. Let the bed cool before removing the part - parts release far more easily cool, and a warm bed with a stuck part invites force you will regret.
If you were recording a timelapse, the video is rendered now and appears in Mainsail.
The job is added to the printer's record. Settings → Printer → Statistics shows the last four prints with their result and print time, along with the totals for the printer's whole life - see Statistics. The full list, with filament use and thumbnails, is Mainsail's History page (Opening Mainsail).
| What happens | What to do |
|---|---|
| The print will not start | Check the printer is not already busy, and that the file sliced correctly. |
| First layer is poor | Adjust Z offset live, as above. If one side is consistently worse, you need Axis Twist. |
| The print stops partway | Check for filament runout. After a power cut, see Power-loss recovery. |
| You pressed Stop | Power-cycle the printer, or run FIRMWARE_RESTART from the console. |
| Time remaining looks wrong | It is an estimate, and it improves as the print proceeds. |
| The part will not come off | Let the bed cool completely first. |
- Pause is fully reversible with Resume.
- Cancel ends the print; the file stays, so you can start again.
-
Stop requires a power-cycle or
FIRMWARE_RESTART. - A power cut may be recoverable - Power-loss recovery.