Pressure advance retraction / calibration - out of ideas?



  • Hi, so I have concluded that I need some help with tuning my retraction.

    I dont have an issue with "stringing" but more with my Z-seam.

    The seam is rather large, and it comes because of the blob of the end of an extrusion.

    I have created a small file where the printer will extrude a single extrusion and retact at then end.

    Im running a Dbot with an E3D chimera+ (water cooled) and running following settings:
    Retraction 4.0mm @ 50mm/s, -0,2mm on reatraction lenght (might need to decrease that a bit)
    z-lift 0.5mm.

    I have tried the following:
    Playing with: Retraction length(0.5mm to 6mm), Retraction speed(30mm/s to 120), Z lift (on/off), negativ retraction length. Temperature(PLA, 170 to 230 deg), movement speed (currently 120mm/s) and at last pressure advance.

    I have attatched an picture where I try to increase pressure advance from 0.05 up to 1.0 and still not seeing "under extrusion" on the reatraction "dot".
    0_1541949913792_IMG_1005.JPG

    (I know that it looks somewhat OK around 7mm up, but thats only from the side, the blob is still there and round)

    Here is how it looks without pressure advance: 0_1541949972557_IMG_1011.JPG

    This picture shows how it looks without pressure advance.

    I have a cooler on, and running a long bowden tube.

    Does anyone have any other idea what to do to get rid of the Z-seam blob?



  • I had the same issues with the corners. Tried everything the same as you did. This is how I resolved it noting that I was using Simplify 3d slicer to as my slicer. I was about to give up however I went to the Kissslicer and download Kisslicer and set it up almost to the default except for the printer hardware. Low and behold the corner blobs went away.. ok so what is the difference. I compared the settings of both slicers and discovered that Kisslicer printed perimeters Outside in . I had simplify 3d set to inside out as recommended almost everywhere. Once I changed to outside in the issues went away. Change all the pressure advance, retract, additional advance to 0 and the slowly recalibrate those settings. Just do one at a time in very small increments. I now have almost perfect parts.



  • Can you post your config.g?

    What are your Z axis speed settings?

    What are your extruder speed settings?

    Are you getting a pause at the end of the layer before the Z move to the next layer?



  • @phaedrux said in Pressure advance retraction / calibration - out of ideas?:

    Can you post your config.g?

    What are your Z axis speed settings?

    What are your extruder speed settings?

    Are you getting a pause at the end of the layer before the Z move to the next layer?

    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Tue Jul 31 2018 15:05:50 GMT+0200 (Centraleurop├Žisk sommertid)
    
    ; General preferences
    G90                                                                    ; Send absolute coordinates...
    M83                                                                    ; ...but relative extruder moves
    M555 P1                                                                ; Set firmware compatibility to look like RepRapFirmare
    
    M667 S1 X-1.0                                                               ; Select CoreXY mode
    
    ; Network
    M550 PD-bot EVO                                                         ; Set machine name
    M551 Psmorum2765                                                       ; Set password
    M552 S1                                                                ; Enable network
    M587 S"Egsdal" P"smorum2765" I192.168.1.31 J192.168.0.1 K255.255.255.0 ; Configure access point and IP addresses. You can delete this line once connected
    M586 P0 S1                                                             ; Enable HTTP
    M586 P1 S0                                                             ; Disable FTP
    M586 P2 S0                                                             ; Disable Telnet
    
    ; Drives
    M569 P0 S1                                                             ; Drive 0 goes forwards
    M569 P1 S0                                                             ; Drive 1 goes backwards
    M569 P2 S1                                                             ; Drive 2 goes forwards
    M569 P3 S1                                                             ; Drive 3 goes forwards
    M569 P4 S1 C65972                                                           ; Drive 4 goes forwards
    M569 P5 S0                                                             ; Drive 5 goes forwards
    M569 P6 S1                                                             ; Drive 6 goes forwards
    M569 P7 S1                                                             ; Drive 7 goes forwards
    M569 P8 S1                                                             ; Drive 8 goes forwards
    M569 P9 S1 C65972
                                                                ; Drive 9 goes forwards
    
    M584 X4 Y9 Z2:1:0 E6:5                                                     ; Apply custom drive mapping
    M350 X16 Y16 Z16 E16:16 I1 S2                                            ; Configure microstepping with interpolation
    M92 X200 Y200 Z800 E415:415                                           ; Set steps per mm
    M566 X1500 Y1500 Z18 E800:800                                          ; Set maximum instantaneous speed changes (mm/min)
    M203 X8400 Y8400 Z800 E2400:2400                                       ; Set maximum speeds (mm/min)
    M201 X500 Y300 Z250 E500:500                                           ; Set accelerations (mm/s^2)
    M906 X1200 Y1200 Z1000 E1500:1500 I40                                  ; Set motor currents (mA) and motor idle factor in per cent
    M84 S10                                                               ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                                                       ; Set axis minima
    M208 X320 Y290 Z500 S0                                                 ; Set axis maxima
    
    
    
    
    ; Define the X and Y coordinates of the leadscrews.
    ; Must come after M584 (Set drive mapping), M667 (Select CoreXY Mode) and M669 (Choosing Kinematics type)
    ; Motor order: Front right (1), front left (2), rear center (3).
    ; Snn Maximum correction in mm to apply to each leadscrew (optional, default 1.0)
    M671 X-50:385.0:385.0 Y170:35:310 S20 P2
    
    ; Endstops
    M574 X1 Y1 S3                                                          ; Set endstops controlled by motor load detection
    
    ; Z-Probe
    M574 Z1 S2                                                             ; Set endstops controlled by probe
    M558 P1 H5 F620 T6000                                                  ; Set Z probe type to modulated and the dive height + speeds
    G31 P500 X0 Y47 Z1.500                                                     ; Set Z probe trigger value, offset and trigger height
    M557 X20:320 Y50:280 S20                                               ; Define mesh grid
    
    ; Heaters
    M305 P0  T100000 B4725 C7.06e-8 R4700 H0                                 ; Set thermistor + ADC parameters for heater 0
    M307 H0 B1 A397.7 C1129.5 D15.1	V24.3						; set bed to bit bang 
    M143 H0 S80                                                            ; Set temperature limit for heater 0 to 80C
    M305 P4  T100000 B4725 C7.060000e-8 R4700 X5                               ; Set thermistor + ADC parameters for heater 1
    M143 H4 S360                                                           ; Set temperature limit for heater 1 to 360C
    M305 P7  T100000 B4725 C7.06e-8 R4700  X3                              ; Set thermistor + ADC parameters for heater 2
    M143 H7 S360                                                           ; Set temperature limit for heater 2 to 360C
    
    ; Fans
    M106 P5 S0 B0.0 H4:H7 T50 L255 C"Water-pump"
    M106 P6 S0 B0.0 L255 H4:H7 T50 C"Radiator fan"
    M106 P4 S0 B0.0 C"Part fan";
    
    ;LEDS
    M106 P7 S0 F100 B0.0 C"LED light"
    
    
    ; Tools
    M563 P0 D1 H4 F4                                                          ; Define tool 0
    G10 P0 X-10 Y0 Z0                                                        ; Set tool 0 axis offsets
    G10 P0 R0 S0   
                                                            ; Set initial tool 0 active and standby temperatures to 0C
    M563 P1 D0 H7 F4                                                          ; Define tool 1
    G10 P1 X10 Y0 Z0                                                       ; Set tool 1 axis offsets
    G10 P1 R0 S0                                                           ; Set initial tool 1 active and standby temperatures to 0C
    
    
    
    
    ; Automatic saving after power loss is not enabled
    
    ; Custom settings are not configured
    
    ; Miscellaneous
    M501                                                                   ; Load saved parameters from non-volatile memory
    

    1_1541964261669_Unavngivet.png 0_1541964261669_2.png



  • Your Z axis and extruder speeds look fine.

    Your external perimeter speed is maybe a little slow at 30% of 50mm/s for 15mm/s. Does it looks like the print head is pausing at the end of the layer?

    You may want to try disabling the Z hop on retraction. I've found it can really add to stringing and blobbing because the nozzle doesn't get wiped on the travel move. I only enable Z hop when I absolutely have to, like when there are many small islands that might get knocked over by the travel moves.

    And finally, you may need to use more pressure advance retraction for a long bowden tube. How long is it exactly? I think I recall seeing David mention that you may need to use around 0.8% of the length of the tube. So for you that would be retraction of around 6mm?

    Ah yes, here it is: https://forum.duet3d.com/search?term=pressure advance 8&in=titlesposts&matchWords=all&timeRange=7776000&timeFilter=newer&sortBy=relevance&sortDirection=&showAs=posts



  • @phaedrux said in Pressure advance retraction / calibration - out of ideas?:

    Your Z axis and extruder speeds look fine.

    Your external perimeter speed is maybe a little slow at 30% of 50mm/s for 15mm/s. Does it looks like the print head is pausing at the end of the layer?

    You may want to try disabling the Z hop on retraction. I've found it can really add to stringing and blobbing because the nozzle doesn't get wiped on the travel move. I only enable Z hop when I absolutely have to, like when there are many small islands that might get knocked over by the travel moves.

    And finally, you may need to use more pressure advance than 1.0 for a long bowden tube. How long is it exactly? I think I recall seeing David mention that you may need to use around 0.8% of the length of the tube.

    Ah yes, here it is: https://forum.duet3d.com/search?term=pressure advance 8&in=titlesposts&matchWords=all&timeRange=7776000&timeFilter=newer&sortBy=relevance&sortDirection=&showAs=posts

    It pauses shortly, so Can try to bump up the speed - the tube is 700mm. Can try disabling z hop, but have experiensed the plastic getting smudget without



  • So I tried the suggestions: first an Inside-out with increased speed:
    2_1542123045862_IMG_1012.JPG
    then one with outside in with increased speed
    1_1542123045862_IMG_1014.JPG
    at last, outside in with Z-hop off
    0_1542123045861_IMG_1015.JPG

    Looks the same to me.


 

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