Z and E Calibration Conundrum



  • I recently set up an old Dremel 3D20 printer (similar to FlashForge Dreamer, Wanhao Duplicator 4S) with Duet 2 Wifi. So far everything appears to be functioning normally and I'm melting plastic.

    Printer info:
    nozzle: 0.4mm
    filament: 1.75
    Cartesian printer
    Slicer: Prusa Edition Slic3r
    Layer resolution for testing: 0.3mm

    Before calibrating the extruder, I made sure the bed was levelled and I had calibrated my x,y,z steps using a calipers and measuring from known points on the printer to the print head. This seemed to have gone well... according to my calipers the requested movements vs the actual movements look fantastic.

    I'm at the stage where I am tuning the extruder and have run into some issues and I'm a little at odds at what to do. First, I used the basic "extrude 100mm" and measure method to adjust the E steps. Adjusted them in the config file and went to print a 20x20x20 xyz calibration cube with very basic slicer settings, no pressure advance or any trickery.

    Within a few layers I could tell it was over extruding. The nozzle was beginning to bury itself in plastic so I stopped the print and went back to adjust the E steps. Not sure why I did this instead of using the extrusion multiplier but regardless, I dialed it back and printed a few more cubes until I found a value that appeared to produce reasonable results (visually) as a starting point. The walls appear to be fairly consistent - no gaps, and the corners only bulge slightly. Top and bottom layers are filled in, no gaps between inner layers and perimeters.

    When measuring my cubes, both x,y read about 20.7 x 20.7 and my z consistently reads 21mm.

    So my question becomes, where do I go from here?

    Ignoring the XY for a moment, if mechanically my printer (according to my calipers) moves accurately, where does the extra 1mm height come from on my cube? Why such a disconnect between my E steps and how much filament is being pulled through the extruder? If I change my Z steps to try and reduce the height but leave my E steps then I would imagine it will results in even more "squished" layers and I will have to dial back my E steps again to compensate - further increasing the error between the measured amount of filament into the extruder vs. the expected output.

    Alternatively, if the extra Z height is coming from more over extrusion and I dial back my E steps, then it may have a negative impact on other part features and the perimeters showing gaps?

    Are there some other parameters should I be looking at ?

    Also, I'm in the process of printing a "Benchy" and as it is getting towards the upper layers of the print, I can see the nozzle slightly burying itself again and pushing down on the model / print bed due to the interference... if I reduce the E - steps or decrease extrusion multiplier, how much is "normal" and at what percentage is there something else potentially going on?

    Thanks!



  • @doublec4 said in Z and E Calibration Conundrum:

    calibrated my x,y,z steps using a calipers

    normally you do not do that.
    since the components are known they are calculated. because backlash comes into play here they readings from calipers can be inaccurate.

    can you post your config



  • Config below. The problem I have with my components is that I can't seem to find reliable info on them. The Dremel 3D20 (although it appears to be based off of flash forge / wanhao etc) might have some different parts? It had its own firmware and slicer and everything was on lock down out of the box. I guess I could count pulley teeth etc if that is what needs to be done.

    ; Configuration file for Duet WiFi (firmware version 2.03)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v3.1.4 on Sat Oct 17 2020 22:58:03 GMT-0400 (Eastern Daylight Time)
    
    ; General preferences
    G90                                      ; send absolute coordinates...
    M83                                      ; ...but relative extruder moves
    M550 P"Dremel"                       ; set printer name
    
    ; Network
    M551 P""                         ; set password
    M552 S1                                  ; enable network
    M586 P0 S1                               ; enable HTTP
    M586 P1 S0                               ; disable FTP
    M586 P2 S0                               ; disable Telnet
    
    ; Drives
    M569 P0 S1                               ; physical drive 0 goes forwards
    M569 P1 S1                               ; physical drive 1 goes forwards
    M569 P2 S1                               ; physical drive 2 goes forwards
    M569 P3 S1                               ; physical drive 3 goes forwards
    M584 X0 Y1 Z2 E3                         ; set drive mapping
    M350 X16 Y16 Z16 E16 I1                  ; configure microstepping with interpolation
    M92 X89 Y89 Z400 E150.00	    	 ; set steps per mm
    M566 X900.00 Y900.00 Z12.00 E120.00      ; set maximum instantaneous speed changes (mm/min)
    M203 X6000.00 Y6000.00 Z180.00 E1200.00  ; set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00 E250.00      ; set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E1000 I30             ; set motor currents (mA) and motor idle factor in per cent
    M84 S30                                  ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                         ; set axis minima
    M208 X290 Y155 Z125 S0                   ; set axis maxima
    
    ; Endstops
    M574 X2 Y2 Z1 S0                         ; set active low and disabled endstops
    
    ; Z-Probe
    M558 P0 H5 F175 T6000                    ; disable Z probe but set dive height, probe speed and travel speed
    M557 X15:215 Y15:175 S20                 ; define mesh grid
    
    ; Heaters
    M140 H-1                                 ; disable heated bed
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1
    M143 H1 S280                             ; set temperature limit for heater 1 to 280C
    
    ; Fans
    M106 P0 S0 I0 F500 H-1                   ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45                ; set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1 F0                         ; define tool 0
    G10 P0 X0 Y0 Z0                          ; set tool 0 axis offsets
    G10 P0 R0 S0                             ; set initial tool 0 active and standby temperatures to 0C
    
    ; Custom settings are not defined
    
    ; Miscellaneous
    M575 P1 S1 B57600                        ; enable support for PanelDue
    
    M501
    
    
    


  • @doublec4 said in Z and E Calibration Conundrum:

    M92 X89 Y89

    those are rather unusual values.

    lets calculate the values. measure the belt pitch with a ruler(spacing between the tooth)
    take the length of lets say 10 tooth and divide the length by 10 (most belts used have a pitch of 2mm)

    then count the tooth on the pulley on the motor.

    assuming a 2mm pitch belt, that would indicate a 18 tooth pulley.



  • belt pitch is 2mm and number of teeth on pulleys appears to be 18. It's a little tough to count them as they are partially obstructed and the enclosure isn't all that large, but I am pretty confident that is the correct count.



  • 18 tooth pulley is unusual.

    anyway put in the numbers
    https://blog.prusaprinters.org/calculator_3416/
    and you get
    88.89 steps/mm

    are you sure that the thermistors is a semitec one?



  • Changed to the following values based on 18T pulley and then calculated steps based on dimensions I've been getting from the calibration cube (0.7mm oversized in XY). See below config.

    I also adjusted my Z steps and I noticed slight over extrusion/blobbing in the first several layers. I toyed with the extrusion % while the print was running in the DUET interface. Brought it down to 90% and the print was coming out pretty clean on subsequent layers. Cancelled that print, brought my E steps down to 140 as you can see below and I'm going to try another cube now...

    ; Configuration file for Duet WiFi (firmware version 2.03)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v3.1.4 on Sat Oct 17 2020 22:58:03 GMT-0400 (Eastern Daylight Time)
    
    ; General preferences
    G90                                      ; send absolute coordinates...
    M83                                      ; ...but relative extruder moves
    M550 P"Dremel"                       ; set printer name
    
    ; Network
    M551 P""                         ; set password
    M552 S1                                  ; enable network
    M586 P0 S1                               ; enable HTTP
    M586 P1 S0                               ; disable FTP
    M586 P2 S0                               ; disable Telnet
    
    ; Drives
    M569 P0 S1                               ; physical drive 0 goes forwards
    M569 P1 S1                               ; physical drive 1 goes forwards
    M569 P2 S1                               ; physical drive 2 goes forwards
    M569 P3 S1                               ; physical drive 3 goes forwards
    M584 X0 Y1 Z2 E3                         ; set drive mapping
    M350 X16 Y16 Z16 E16 I1                  ; configure microstepping with interpolation
    M92 X86 Y86 Z386.5 E140.00	    	 ; set steps per mm
    M566 X900.00 Y900.00 Z12.00 E120.00      ; set maximum instantaneous speed changes (mm/min)
    M203 X6000.00 Y6000.00 Z180.00 E1200.00  ; set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00 E250.00      ; set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E1000 I30             ; set motor currents (mA) and motor idle factor in per cent
    M84 S30                                  ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                         ; set axis minima
    M208 X290 Y155 Z125 S0                   ; set axis maxima
    
    ; Endstops
    M574 X2 Y2 Z1 S0                         ; set active low and disabled endstops
    
    ; Z-Probe
    M558 P0 H5 F175 T6000                    ; disable Z probe but set dive height, probe speed and travel speed
    M557 X15:215 Y15:175 S20                 ; define mesh grid
    
    ; Heaters
    M140 H-1                                 ; disable heated bed
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1
    M143 H1 S280                             ; set temperature limit for heater 1 to 280C
    
    ; Fans
    M106 P0 S0 I0 F500 H-1                   ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45                ; set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1 F0                         ; define tool 0
    G10 P0 X0 Y0 Z0                          ; set tool 0 axis offsets
    G10 P0 R0 S0                             ; set initial tool 0 active and standby temperatures to 0C
    
    ; Custom settings are not defined
    
    ; Miscellaneous
    M575 P1 S1 B57600                        ; enable support for PanelDue
    
    M501
    
    
    


  • @doublec4 said in Z and E Calibration Conundrum:

    I've been getting from the calibration cube (0.7mm oversized in XY)

    its more likely an issue with the extrusion rather than steps/mm.

    i would keep the x y z values at the calculated ones for no.

    the slicer will normally tell you how many grams the print is.
    then measure the weight of the printed object and compare



  • @Veti Also regarding the thermistor, it is an E3D cartridge style semitec 104GT



  • @Veti I will give the weight a try tomorrow too!



  • Cube just came off the printer and dimensionally it is great now. Within +/- 0.05mm in all dimensions.

    Layers look clean, some minor ringing/ghosting on the letters but otherwise I'm satisfied for now. The edges of the cube could be a little crisper so I will look into pressure advance

    I will print and weigh some models tomorrow. I'm happy with the result but I'm still a little baffled as to why I would have to reduce my E steps so much ... seems like a major disconnect between what the slicer thinks I need for mm vs what I actually need when printing.



  • @doublec4 said in Z and E Calibration Conundrum:

    I will print and weigh some models tomorrow. I'm happy with the result but I'm still a little baffled as to why I would have to reduce my E steps so much ... seems like a major disconnect between what the slicer thinks I need for mm vs what I actually need when printing.

    i tend to reduce my e steps by 10% ob my printers, dont know why but it does produces better prints.



  • @Veti said in Z and E Calibration Conundrum:

    @doublec4 said in Z and E Calibration Conundrum:

    I will print and weigh some models tomorrow. I'm happy with the result but I'm still a little baffled as to why I would have to reduce my E steps so much ... seems like a major disconnect between what the slicer thinks I need for mm vs what I actually need when printing.

    i tend to reduce my e steps by 10% ob my printers, dont know why but it does produces better prints.

    Similarly, I always use an extrusion multiplier of 95%. I'm not able to provide a link right now but somebody did a lot of work and came to the conclusion that printed parts can tolerate quite a high degree of under extrusion without any adverse consequences but are very intolerant of over extrusion. My own tests tend to agree (usual caveats about slicers, settings etc).


Log in to reply