What controls purge temperature?

Flagship K Series Creality Flagship K2 Plus & CFS
1

I have a K2 Plus combo. I have been printing with Creality Hyper PLA. The system sets the purge temperature to 240° when a print job starts which is going to use an extruder temperature at 220°. That works fine and print jobs look great.

Now, I am trying to run print job with Nylon X. I set up the job with Orca Slicer. I specified the extruder temperature at 265°for all layers. However when I start a new print jobs, the system attempts to do a purge at 240° then as the print job goes to work the temperature rises from 240° to 265°as the actual job is underway. Fortunately, I use a skirt with about 5 loops, so that the extruder is up to temp before the actual objects start to print.

My question, what controls the purge temperature? I am using the latest version of Orca Slicer, but I can’t find anything in the slicer that seems to effect the purge temperature.

Thanks

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2

That’s a great question. I’m not sure anyone at Creality is willing or able to give a straight answer, and both Bambu Lab (which OrcaSlicer is based on) and Creality tend to keep this information vague or buried. If someone has an official link or resource, please share it.

Based on my own testing, here’s what I’ve found. Happy to hear from others as well:

The purge temperature appears to be hard-coded in the firmware and acts as a neutral value for purging, determined by the filament set as “in use” at the printer LCD Control Panel at the moment of purge. Here’s how you can see this yourself:

  1. On the touch panel, set the spool to the filament you want to test (works for both external and CMS spools).
  2. Use the extrude function on the touch panel and note the purge temperature—this is independent of the slicer.
  3. Send a simple 10x10x2mm cube model to the printer with that filament selected, and observe the purge temp.

For example, I tested with PC filament. The printer extruded from the control panel at 260°C even though the slicer profile was set to print at 300°C. For PLA, the purge temp was also lower than the print temp. I haven’t found any setting in either the filament or printer profiles that controls this behavior.

Having said that, for important overnight prints that cannot fail, when purging between different filaments (e.g., PLA vs PETG, PLA vs PC-CF), I manually purge the filament, shining a flashlight on the nozzle to verify it runs clear. It’s a manual step and a pain, but I’ve found it worthwhile insurance before starting long prints, lest I wake up to spaghetti or a glob of doom on the nozzle.

3

The response from my go-to AI agent Grok:

The Creality K2 Plus Combo (with the Creality Filament System/CFS for multi-color printing) runs on a Klipper-based firmware, unlike the Marlin-based Ender series. This means the “purge temperature” (the nozzle temp used during initial filament loading/priming, purging at the poop chute, or during multi-filament changes) is not purely controlled by slicer start G-code like on Ender printers. Instead, it’s largely handled by printer-side macros (e.g., LOAD_MATERIAL or filament load/purge routines in gcode_macro.cfg or printer_params.cfg), which often override or ignore slicer-set temps for safety or consistency during CFS operations. This leads to common complaints where the purge defaults to a fixed value (e.g., 220°C, 250°C, 260°C) regardless of your filament profile, causing jams with higher-temp filaments like PETG, ABS, or Nylon if the purge is too low. Common Default Purge Temps Reported by Users

  • Often 220°C (especially in early firmware or certain macros).

  • Sometimes 250–260°C (e.g., during CFS loading or specific slots).

  • It can stick to the previous filament’s temp or drop to a hardcoded value.

This isn’t a simple “default purge temp” setting in the UI—Creality hasn’t provided an easy toggle in the touchscreen or Creality Print/OrcaSlicer for it yet (as of recent 2025–2026 discussions).Ways to Change or Work Around It

  1. Edit the Firmware Configuration Files (Most Direct Fix – Advanced):

    • Access the printer via Fluidd (web interface, usually at the printer’s IP address).

    • Look in /usr/share/klipper/config/ or similar paths for files like:

      • printer_params.cfg — Contains sections like [custom_macro] with lines such as:

        default_extruder_temp: 220

        Change this to your desired purge temp (e.g., 250 for PETG).

      • gcode_macro.cfg — Search for macros like LOAD_MATERIAL, FILAMENT_RACK_SET_TEMP, or similar. They often have hardcoded M104/M109 commands (e.g., M109 S{printer.custom_macro.default_extruder_temp} or fixed M104 S220).

        • Replace hardcoded values with variables or higher temps.

        • Some users add conditional logic (Jinja2 if/endif) to use slicer temps.

    • Save, restart Klipper (via Fluidd), or reboot the printer.

    • Warning: This requires SSH/root access or careful editing via Fluidd. Back up files first. Wrong edits can brick macros. Community-extracted firmwares (e.g., on GitHub repos like Guilouz/Creality-K2Plus-Extracted-Firmwares) show examples of these files and fixes.

  2. Workaround in Slicer (Creality Print or OrcaSlicer – Easier, No Firmware Edit):

    • In filament profiles, set your nozzle temp higher (e.g., match or exceed what the purge forces).

    • Add custom G-code overrides:

      • In OrcaSlicer (recommended by many K2 users for better control): Go to Printer Settings → Machine G-code or Filament → Custom G-code sections (e.g., filament start/end G-code).

        • Add lines like M109 S[nozzle_temperature] or M109 S[nozzle_temperature_initial_layer] right after tool change commands (T0/T1/etc.) to force-wait for your desired temp post-purge.

      • In Creality Print: Edit filament settings (top-left logo → Tool → Manage Filaments → Edit print temperature). Some users report it syncs better on newer firmware, but purge may still override.

    • Re-slice and test. This forces the printer back to your temp after the macro’s purge.

    • For multi-color: Ensure all filaments in a print have similar temp ranges (users strongly advise against mixing vastly different temps like PLA + ABS due to purge issues).

  3. Other Tips:

    • Update to the latest firmware (check Creality’s site or Cloud app for K2 Plus Combo versions like V1.1.x). Some releases fix temp waiting, purge lengths, or macro bugs.

    • If using OrcaSlicer, follow Creality Wiki profiles — but add the M109 waits as noted in community tips.

    • Manual override: During print/start, use the touchscreen → Tune → Nozzle temp to adjust mid-process (temporary fix).

    • Report bugs via Creality forums or feedback form — many users have, and fixes appear in updates.

This behavior is a known pain point on the K2 Plus Combo (especially with CFS), often called a “firmware bug” in Reddit (r/Creality, r/Creality_k2) and Creality forums. If your forum member shares their exact slicer (Creality Print vs. Orca), firmware version, observed purge temp (e.g., always 220? 250?), and filament type, that would help narrow the best fix! In the meantime, editing default_extruder_temp in printer_params.cfg or adding M109 overrides is the most reliable community workaround.

4

You can set the purge temp to whatever your set print temp is by setting a variable in the start_print, making it global and calling it in the cfg it is needed. That way it always purges at the correct temp.

5

Can you demonstrate how this is done for the benefit of the community?

6

For example in printer.cfg you would add

[gcode_macro _GLOBAL_VARS]
variable_extruder_target: 0.0
gcode:

and in start_print you would add this under the set extruder_temp somewhere.

SET_GCODE_VARIABLE MACRO=_GLOBAL_VARS VARIABLE=extruder_target VALUE={params.EXTRUDER_TEMP}

Then in your cfg for the purge you would add this

{% set target_temp = printer[“gcode_macro _GLOBAL_VARS”].extruder_target %}

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7

??? :face_with_peeking_eye:

Among other considerations, the lower the appropriate purge temperature is employed, the less time is taken for filament swaps.