issues after filament change

[kcoughenour]

Hi,
I have a Creality Ender-3 Pro and am using a PLA+ filament. I edited my firmware to enable print pausing via the M600 command inserted into my gcode so that I can change filament colors at certain levels. Everything works fine with it, except when I resume printing, the filament doesnt stick to the existing part that was already there. Im fairly new to 3D printing, but my thoughts are that maybe its because the bed has cooled down? Or maybe when the print head returns to the part, the z axis may be too high? All guesses of course! If anyone has any thoughts on this, please help me out. Thanks!

[Roberts_Clif]

I have done many filament changes during a print. I use the advanced pause function with Park on pause
I am there before the print pauses as to chance the filament as quickly as possible.
Using pause at height on above Space X model,

Code: Select all

/**
 * Advanced Pause for Filament Change
 *  - Adds the G-code M600 Filament Change to initiate a filament change.
 *  - This feature is required for the default FILAMENT_RUNOUT_SCRIPT.
 *
 * Requirements:
 *  - For Filament Change parking enable and configure NOZZLE_PARK_FEATURE.
 *  - For user interaction enable an LCD display, HOST_PROMPT_SUPPORT, or EMERGENCY_PARSER.
 *
 * Enable PARK_HEAD_ON_PAUSE to add the G-code M125 Pause and Park.
 */
#define ADVANCED_PAUSE_FEATURE
#if ENABLED(ADVANCED_PAUSE_FEATURE)
  #define PAUSE_PARK_RETRACT_FEEDRATE         60  // (mm/s) Initial retract feedrate.
  #define PAUSE_PARK_RETRACT_LENGTH            2  // (mm) Initial retract.
                                                  // This short retract is done immediately, before parking the nozzle.
  #define FILAMENT_CHANGE_UNLOAD_FEEDRATE     10  // (mm/s) Unload filament feedrate. This can be pretty fast.
  #define FILAMENT_CHANGE_UNLOAD_ACCEL        25  // (mm/s^2) Lower acceleration may allow a faster feedrate.
  #define FILAMENT_CHANGE_UNLOAD_LENGTH      100  // (mm) The length of filament for a complete unload.
                                                  //   For Bowden, the full length of the tube and nozzle.
                                                  //   For direct drive, the full length of the nozzle.
                                                  //   Set to 0 for manual unloading.
  #define FILAMENT_CHANGE_SLOW_LOAD_FEEDRATE   6  // (mm/s) Slow move when starting load.
  #define FILAMENT_CHANGE_SLOW_LOAD_LENGTH     0  // (mm) Slow length, to allow time to insert material.
                                                  // 0 to disable start loading and skip to fast load only
  #define FILAMENT_CHANGE_FAST_LOAD_FEEDRATE   6  // (mm/s) Load filament feedrate. This can be pretty fast.
  #define FILAMENT_CHANGE_FAST_LOAD_ACCEL     25  // (mm/s^2) Lower acceleration may allow a faster feedrate.
  #define FILAMENT_CHANGE_FAST_LOAD_LENGTH     0  // (mm) Load length of filament, from extruder gear to nozzle.
                                                  //   For Bowden, the full length of the tube and nozzle.
                                                  //   For direct drive, the full length of the nozzle.
  //#define ADVANCED_PAUSE_CONTINUOUS_PURGE       // Purge continuously up to the purge length until interrupted.
  #define ADVANCED_PAUSE_PURGE_FEEDRATE        3  // (mm/s) Extrude feedrate (after loading). Should be slower than load feedrate.
  #define ADVANCED_PAUSE_PURGE_LENGTH         50  // (mm) Length to extrude after loading.
                                                  //   Set to 0 for manual extrusion.
                                                  //   Filament can be extruded repeatedly from the Filament Change menu
                                                  //   until extrusion is consistent, and to purge old filament.
  #define ADVANCED_PAUSE_RESUME_PRIME          0  // (mm) Extra distance to prime nozzle after returning from park.
  //#define ADVANCED_PAUSE_FANS_PAUSE             // Turn off print-cooling fans while the machine is paused.

                                                  // Filament Unload does a Retract, Delay, and Purge first:
  #define FILAMENT_UNLOAD_PURGE_RETRACT       13  // (mm) Unload initial retract length.
  #define FILAMENT_UNLOAD_PURGE_DELAY       5000  // (ms) Delay for the filament to cool after retract.
  #define FILAMENT_UNLOAD_PURGE_LENGTH         8  // (mm) An unretract is done, then this length is purged.
  #define FILAMENT_UNLOAD_PURGE_FEEDRATE      25  // (mm/s) feedrate to purge before unload

  #define PAUSE_PARK_NOZZLE_TIMEOUT           45  // (seconds) Time limit before the nozzle is turned off for safety.
  #define FILAMENT_CHANGE_ALERT_BEEPS         10  // Number of alert beeps to play when a response is needed.
  #define PAUSE_PARK_NO_STEPPER_TIMEOUT           // Enable for XYZ steppers to stay powered on during filament change.
  //#define FILAMENT_CHANGE_RESUME_ON_INSERT      // Automatically continue / load filament when runout sensor is triggered again.
  //#define PAUSE_REHEAT_FAST_RESUME              // Reduce number of waits by not prompting again post-timeout before continuing.

  #define PARK_HEAD_ON_PAUSE                    // Park the nozzle during pause and filament change.
  //#define HOME_BEFORE_FILAMENT_CHANGE           // If needed, home before parking for filament change

  //#define FILAMENT_LOAD_UNLOAD_GCODES           // Add M701/M702 Load/Unload G-codes, plus Load/Unload in the LCD Prepare menu.
  //#define FILAMENT_UNLOAD_ALL_EXTRUDERS         // Allow M702 to unload all extruders above a minimum target temp (as set by M302)
#endif

Though have never had any adhesion problem myself.

Example of what I would do to help with adhesion.
Similar to first layer adhesion I would print this 1st layer after filament change at a slower speed to help increase layer adhesion.

[Roberts_Clif]

Currently learning to operate my newest Anycubic Kobra 3 combo printers an the Anycubic slicer Next.
I and finding that the print tower is quicker than using the waste bucket, if there is room on build plate.

I am still getting used to them a few minutes ago 3D Printed the model link, using different colors and PLA.

The layer adhesion between the lower black layer and first color change adhesion was not sufficient, I noted nozzle temp dropped 10C.
Though this contributed to layer adhesion problem I also noted that the other layers adhesion was better.

This tells me that small changes in filament temperature can cause significant layer adhesion problems.
The print speed can also cause layer adhesion problems with more detailed models print speed should be reduced.
Looking inside to the second layer you can see the adhesion did not hold very well to the first layer

Want to note this because the Anycubic Kobra 3 print is faster than any 3D Printer I have used,
I have to remember print slower on detailed models too make sure of 2nd layer adhesion.

[Ken37]

Thanks for your sharing,this topic discussion is so meaningful,which help me a lot.