Simulation time way off



  • It's a CR-10 v2 no extra tool (cartesian).

    Could it be related to the fact that I am using Pressure Advance or that the speed value requested are mostly never reached due to the size of the model and the acceleration.

    I don't know if that could help but you can find my current configuration below.

    ; Configuration file for Duet WiFi (firmware version 3)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v3.1.4 on Sat Jul 25 2020 09:49:56 GMT-0400 (Eastern Daylight Time)
    
    ; General preferences
    G90                                            ; send absolute coordinates...
    M83                                            ; ...but relative extruder moves
    M550 P"My Printer"                             ; set printer name
    
    ; Network
    M552 S1                                        ; enable network
    M586 P0 S1                                     ; enable HTTP
    M586 P1 S0                                     ; disable FTP
    M586 P2 S0                                     ; disable Telnet
    
    ; Drives
    M569 P0 S0                                     ; physical drive 0 goes backwards
    M569 P1 S0                                     ; physical drive 1 goes backwards
    M569 P2 S0                                     ; physical drive 2 goes backwards
    M569 P3 S0                                     ; physical drive 3 goes backwards
    M584 X0 Y1 Z2 E3                               ; set drive mapping
    M350 X16 Y16 Z16 E16 I1                        ; configure microstepping with interpolation
    M92 X80.00 Y80.00 Z400.00 E98.00               ; set steps per mm
    M566 X900.00 Y900.00 Z12.00 E120.00            ; set maximum instantaneous speed changes (mm/min)
    M203 X9000.00 Y9000.00 Z360.00 E3600.00        ; set maximum speeds (mm/min)
    M201 X700.00 Y700.00 Z50.00 E10000.00          ; set accelerations (mm/s^2)
    M906 X900 Y900 Z600 E900 I1                    ; set motor currents (mA) and motor idle factor in per cent
    M84 S1                                         ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                               ; set axis minima
    M208 X300 Y300 Z400 S0                         ; set axis maxima
    
    ; Endstops
    M574 X1 S1 P"^xstop"                           ; configure active-high endstop for low end on X via pin ^xstop
    M574 Y1 S1 P"^ystop"                           ; configure active-high endstop for low end on Y via pin ^ystop
    M574 Z1 S2                                     ; configure Z-probe endstop for low end on Z
    
    ; Z-Probe
    M950 S0 C"exp.heater3"                         ; create servo pin 0 for BLTouch
    M558 P9 C"^zprobe.in" H3 F120 T9000            ; set Z probe type to bltouch and the dive height + speeds
    G31 P500 X47 Y0 Z1.22                          ; set Z probe trigger value, offset and trigger height
    M557 X50:300 Y15:300 S50                       ; define mesh grid
    
    ; Heaters
    M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
    M950 H0 C"bedheat" T0                          ; create bed heater output on bedheat and map it to sensor 0
    M307 H0 B1 S1.00                               ; enable bang-bang mode for the bed heater and set PWM limit
    M140 H0                                        ; map heated bed to heater 0
    M143 H0 S280                                   ; set temperature limit for heater 0 to 280C
    M308 S1 P"e0temp" Y"thermistor" T100000 B4138  ; configure sensor 1 as thermistor on pin e0temp
    M950 H1 C"e0heat" T1                           ; create nozzle heater output on e0heat and map it to sensor 1
    M307 H1 B0 S1.00                               ; disable bang-bang mode for heater  and set PWM limit
    
    ; Fans
    M950 F0 C"fan0" Q500                           ; create fan 0 on pin fan0 and set its frequency
    M106 P0 S0 H1 T45                              ; set fan 0 value. Thermostatic control is turned on
    M950 F1 C"fan1" Q500                           ; create fan 1 on pin fan1 and set its frequency
    M106 P1 S0 H-1                                 ; set fan 1 value. Thermostatic control is turned off
    
    ; Tools
    M563 P1 S"Hotend" D0 H1 F0:1                   ; define tool 1
    G10 P1 X0 Y0 Z0                                ; set tool 1 axis offsets
    G10 P1 R0 S0                                   ; set initial tool 1 active and standby temperatures to 0C
    
    ; Custom settings are not defined
    
    ; Miscellaneous
    M501                                           ; load saved parameters from non-volatile memory
    T1                                             ; select first tool
    
    
    

  • Moderator

    I seem to recall @bot posting some similar observations with PA and simulation.

    Here it is: https://forum.duet3d.com/topic/15516/simulated-print-time-longer-with-pa-disabled/2?_=1596047378473

    I notice you are also using a very low E jerk value.



  • Yeah. In my case, it was just that the estimated print time was counter-intuitively lower when pressure advance was enabled, up until a certain point where the estimated time became much higher, as expected.

    I now have to rely on other methods to get accurate print estimates. I find this website: G-Code Analyser provides very accurate estimates as well as some other helpful information and visualization. (But now I remember that website doesn't support Pressure Advance, so if your extruder limits the speed due to PA, the estimates will not be accurate.)



  • @Phaedrux
    I had the feeling that those jerk values were pretty standard. What would you suggest ?
    Also, I think it should the board that should give accurate estimation instead of me trying to match its predictions.



  • @bot
    Interresting, I will give it a try.


  • Moderator

    @HDavid said in Simulation time way off:

    I had the feeling that those jerk values were pretty standard. What would you suggest ?

    120mm/min is only 2mm/s. The extruder, being a purely rotational axis doesn't have a lot of mass to move, so higher jerk and acceleration values are generally possible.

    Having a low jerk value isn't a problem per se, but it does have the consequence that in a coordinated move, the lowest jerk value will be honored. So when pressure advance is trying to rapidly pull the filament back prior to a retraction in coordination with XY movement, the low jerk value on E means that XY and movement will have to honor the lower limit imposed by the E movement. And hence, slower than requested print speed.

    Setting a higher E jerk and acceleration allows the XY movement to be unaffected by the Extruder movement during pressure advance. This can also generally improve print quality due to less dwelling at transition points like layer changes or travel moves.

    You'll have to experiment with higher values to see what works well for you, but I think in general using 3000 for jerk, accel, and retraction speed is a good starting point.



  • It did not occur to me the jerk value of E could affect XY. That is good to know. I will try that and see where it leads me.
    Thank for the tip.


  • Moderator

    @HDavid Normally (without PA) it doesn't, because the extruder is slowly and steadily extruding during the XY move and then it all stops, extruder retracts, and then XY travels to the next point to resume. Pressure advance complicates that because it's now altering the extruder speed and even stopping and reversing during the XY movement. And because it's a coordinated move, the slowest axis dictates.


  • administrators

    • Are you running the simulation under exactly the same conditions as the actual print? In particular, same height map loaded (if you are using one), and same pressure advance? Note, if the print file includes a G28 command, simulation doesn't run that; therefore if you load a height map file in one of your homing files, or set PA or max acceleration or speed, it won't be loaded when you simulate.
    • When you do the print, does M122 report a lot of hiccups if you run it during or after the print?


  • @dc42 said in Simulation time way off:

    Are you running the simulation under exactly the same conditions as the actual print?

    My workflow is: upload g-code -> run simulation -> do the real run.

    I run the G28 before every print so I guess the loaded height map during simulation is the one from the previous print.
    My pressure advance setting is set at the beginning of the g-code file, unless I miss something, I would says it is the same between print and simulation.

    I did not know of M122 before you mentioned it. I read the documentation but I am not sure when to use it and what should I look for in the results.

    Below the start of a g-code a file that takes double the time:
    It contains G28, G29 then M572 (PA)

    ;FLAVOR:RepRap
    ;TIME:7563
    ;Filament used: 25.5252m
    ;Layer height: 0.28
    ;MINX:117.65
    ;MINY:67.226
    ;MINZ:0.2
    ;MAXX:181.778
    ;MAXY:232.778
    ;MAXZ:60
    ;Generated with Cura_SteamEngine 4.6.1
    T0
    M190 S60
    M104 S200
    M109 S200
    M82 ;absolute extrusion mode
    G90 ; use absolute coordinates
    M83 ; extruder relative mode
    G28 ; home all axes
    ;M104 S120 ; set extruder temp
    M140 S60 ; set bed temp
    M190 S60 ; wait for bed temp
    G29; Auto bed leveling
    M572 D0 S0.8 ; set pressure advance value
    G1 Z5 F5000 ; lift nozzle
    G1 X2 Y10 F3000
    M109 S200 ; wait for extruder temp
    G1 Z0.3 F240
    G92 E0.0
    G1 Y190 E15.0 F1500.0 ; intro line
    G1 X2.3 F5000
    G1 Y10 E30 F1200.0 ; intro line
    G92 E0.0
    M83 ;relative extrusion mode
    G1 F3600 E-9
    ;LAYER_COUNT:211
    ;LAYER:0
    M107 P1
    G1 F1800 Z1.2
    G0 X130.784 Y67.25 Z1.2
    ;TYPE:SKIRT
    G1 F1800 Z0.2
    G1 F3600 E9
    

  • Moderator

    @HDavid said in Simulation time way off:

    I did not know of M122 before you mentioned it. I read the documentation but I am not sure when to use it and what should I look for in the results.

    Look for the word hiccups.

    Can you try simulating that file again, but this time load the heightmap and set the pressure advance before simulating it.



  • @Phaedrux
    Should I run it at a specific time, like just after a print or it does not matter ?


  • Moderator

    @HDavid said in Simulation time way off:

    @Phaedrux
    Should I run it at a specific time, like just after a print or it does not matter ?

    After a print is probably best. When you run it it displays all the counters and things and then resets them. So if you run it after a print it will show you everything that happened during that print.


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