Bed Mesh compensation



  • I am have problems with the bed mesh compensation. When I run M561, G28, and then G29 then it probes, once finished I am getting a negative value in the mean error;RepRapFirmware height map file v1 mean error -0.17 deviation 0.16
    xmin xmax ymin ymax radius spacing xnum ynum
    35 280 20 280 -1 20 13 14
    0.115 0.108 0.108 0.09 0.075 0.078 0.062 0.055 0.05 0.043 0.04 0.03 0.015
    0.09 0.078 0.073 0.07 0.058 0.043 0.028 0.02 0.01 0.002 0 -0.008 -0.02
    0.045 0.043 0.04 0.037 0.028 0.015 0 -0.01 -0.02 -0.025 -0.028 -0.035 -0.043
    0.002 0.005 0.002 0.005 0 -0.008 -0.02 -0.025 -0.032 -0.04 -0.045 -0.05 -0.062
    -0.028 -0.025 -0.025 -0.025 -0.028 -0.035 -0.045 -0.053 -0.065 -0.07 -0.07 -0.08 -0.093
    -0.065 -0.065 -0.065 -0.057 -0.062 -0.072 -0.078 -0.082 -0.095 -0.105 -0.108 -0.115 -0.127
    -0.125 -0.12 -0.117 -0.112 -0.108 -0.117 -0.125 -0.135 -0.13 -0.125 -0.127 -0.138 -0.147
    -0.17 -0.162 -0.16 -0.155 -0.16 -0.153 -0.153 -0.155 -0.19 -0.18 -0.175 -0.18 -0.19
    -0.208 -0.208 -0.208 -0.198 -0.192 -0.2 -0.21 -0.215 -0.21 -0.222 -0.22 -0.23 -0.255
    -0.29 -0.295 -0.293 -0.285 -0.27 -0.257 -0.265 -0.257 -0.267 -0.272 -0.278 -0.275 -0.29
    -0.332 -0.31 -0.317 -0.322 -0.312 -0.308 -0.31 -0.308 -0.312 -0.32 -0.315 -0.315 -0.312
    -0.385 -0.382 -0.377 -0.358 -0.35 -0.345 -0.338 -0.343 -0.33 -0.343 -0.343 -0.345 -0.353
    -0.42 -0.418 -0.413 -0.4 -0.39 -0.387 -0.385 -0.382 -0.38 -0.382 -0.377 -0.377 -0.387
    -0.493 -0.485 -0.48 -0.46 -0.452 -0.45 -0.447 -0.44 -0.438 -0.438 -0.43 -0.433 -0.438

    I believe this is effecting my first layer, no matter what I set. When I do my Z offset steps it comes out to be .15. One thing that I noticed on this printer build is that when the G29 is running the Z axis comes up to 5.15mm adding the Z offset. I have another 3d printer at home running the Duetwifi and when it runs the G29 it does not add the z offset? This is becoming frustrating to get the first print on this machine to print. Anyone have any Ideas?
    I do not have access to wiFi at work do to restrictions, we are trying to work around. Using PanelDue 7"

    Thanks


  • administrators

    The mean error indicates that when you home Z in your G28 command, the Z=0 point that is established is 0.17mm higher than the average level of the bed.

    If the Z probe trigger height is positive, then it is automatically added to the dive height when probing starts. This is intentional, for example if your Z probe triggers 5mm above the bed and you set the dive height to 3mm, you want to start at 8mm so as to get about 3mm travel before it triggers. Some of the 1.17 beta dev versions didn't do this. G32 probing has done it since many versions ago.



  • Hi Ronnein
    Have you done a repeatability test on your probe
    I'm just curious as I am having some of the same issues



  • In my quest to figure out why my results of G29 was a half reminiscent of a a mogul run at my local ski slopes, I visited the notion of repeatability with much frustration as a result. This is because while I've pinned down the reason for my crazy results, I have very little in the way of methods to improve the madness when it comes to fixing the problem. My repeatability, at least with mini IR (latest version), vary constantly and within a range of about 0.1mm. For instance, I can go to determine my Z-offset from probe for my G31 Z value by jogging down until nearly pinning sheet of paper and set G92Z0 followed by G1Z5 to move probe up 5mm, then finally G30S-1 to find the probe trigger height and just make myself crazy because of the fact that I simply cannot obtain a value that is (a) constant between trials nor (b) consistent throughout multiple leveling attempts. I am having trouble figuring out the cause of this phenomenon and I'd really really appreciate anyone who can assist in overcoming this problem.

    Thank you for reading this long post. I am nearly there – that is, the point where I can print reliably and well with my printer. That being the case I'm also pretty close to young insane since I cannot seem to figure out the reason for the variability in my probing trigger height measurements.

    Thanks, in advance, for any and all replies assisting in resolving this issue. Oh yeah,and while I'm asking for help, maybe someone can help me with the answer to the question about probe offsets; if my price is positive a little closer to the front of the bed (opposing the Z tower) and a bit to the right of the frame (towards the Y tower) as compared to the position of the nozzle, then what are the signs of the distances in X &Y (positive or negative)??
    Hope everyone is having a nice day and that all your printers are behaving nicely. 🙂
    Jonathan



  • Hi, my experience with the IR probe is that when the bed is "naked", i.e just glass on top a sheet of black paper, I get a lot of peaks/troughs in the heightmap. When I cover the bed with blue tape, the results are much more uniform so I conclude that the reflective qualities of the surface make a big difference with regard to obtaining repeatable results. I'm still not actually using the heightmap correction when printing as I get better results (more consistent first layer height) without it.



  • @burtoogle:

    Hi, my experience with the IR probe is that when the bed is "naked", i.e just glass on top a sheet of black paper, I get a lot of peaks/troughs in the heightmap. When I cover the bed with blue tape, the results are much more uniform so I conclude that the reflective qualities of the surface make a big difference with regard to obtaining repeatable results. I'm still not actually using the heightmap correction when printing as I get better results (more consistent first layer height) without it.

    Likewise but in my case I put it down to using 3DLac on the glass. I know the bed is flat (it's 10mm machined aluminium tool plate with float glass) and it's level within 0.1mm when I do the "thin paper under nozzle test" at any point on the surface. I once tried the mesh compensation just to see, but the height map looks like the Himalayas which must be due to the 3dLac altering the reflectivity. I did think about trying a BL Touch but then I realised that if it worked, it would only confirm what I already know (that the bed is flat). So I have a black sticker in one corner of the bed (well away from any 3DLac) for the probe to use for Z homing and that's all I do.



  • @jrlederer:

    In my quest to figure out why my results of G29 was a half reminiscent of a a mogul run at my local ski slopes, I visited the notion of repeatability with much frustration as a result. This is because while I've pinned down the reason for my crazy results, I have very little in the way of methods to improve the madness when it comes to fixing the problem. My repeatability, at least with mini IR (latest version), vary constantly and within a range of about 0.1mm. For instance, I can go to determine my Z-offset from probe for my G31 Z value by jogging down until nearly pinning sheet of paper and set G92Z0 followed by G1Z5 to move probe up 5mm, then finally G30S-1 to find the probe trigger height and just make myself crazy because of the fact that I simply cannot obtain a value that is (a) constant between trials nor (b) consistent throughout multiple leveling attempts. I am having trouble figuring out the cause of this phenomenon and I'd really really appreciate anyone who can assist in overcoming this problem.

    Thank you for reading this long post. I am nearly there – that is, the point where I can print reliably and well with my printer. That being the case I'm also pretty close to young insane since I cannot seem to figure out the reason for the variability in my probing trigger height measurements.

    Thanks, in advance, for any and all replies assisting in resolving this issue. Oh yeah,and while I'm asking for help, maybe someone can help me with the answer to the question about probe offsets; if my price is positive a little closer to the front of the bed (opposing the Z tower) and a bit to the right of the frame (towards the Y tower) as compared to the position of the nozzle, then what are the signs of the distances in X &Y (positive or negative)??
    Hope everyone is having a nice day and that all your printers are behaving nicely. 🙂
    Jonathan

    Since I have updated firmware to the latest I have been having an issue with the z offset. No mater how many times I run it I get the same offset .1 when I update offset and run the print it does not apply the offset. I have change from .1 to .2 and it is still in the same place when I print, Not sure what has happened?


  • administrators

    Are you saying that the trigger height of the sensor varies by 0.1mm when you probe repeatedly at the same point? If so, that suggests either that you have the probe configured incorrectly, or that you have a lack of reproducibility in your motion system. Things to check:

    • Do you have the probe connected correctly to the Z probe connector, and configured as type 1? (P parameter in the M558 command)
    • Does the probe read around 465 when approaching trigger height, and around 535 when it reaches trigger height?
    • Are you probing at a speed that is not too high? (F parameter in the M558 command - I use F300)
    • Is there play in the joints?
    • Is there excessive friction in the movement mechanism? You should be able to make the IR sensor switch between triggered and not triggered by moving the head in the Z direction no more than 2 microsteps (at 16x microstepping) around the trigger height.


  • @dc42:

    Are you saying that the trigger height of the sensor varies by 0.1mm when you probe repeatedly at the same point? If so, that suggests either that you have the probe configured incorrectly, or that you have a lack of reproducibility in your motion system. Things to check:

    • Do you have the probe connected correctly to the Z probe connector, and configured as type 1? (P parameter in the M558 command)
    • Does the probe read around 465 when approaching trigger height, and around 535 when it reaches trigger height?
    • Are you probing at a speed that is not too high? (F parameter in the M558 command - I use F300)
    • Is there play in the joints?
    • Is there excessive friction in the movement mechanism? You should be able to make the IR sensor switch between triggered and not triggered by moving the head in the Z direction no more than 2 microsteps (at 16x microstepping) around the trigger height.

    No it does not vary, every time I test the z offset it is .1. However when I try to run a part the extruder does not move down to get a good first layer. It is like it is ignoring the offset and just printing. This is my configuration:
    ; TT3DPRINTER Duet firmware
    M111 S0 ; Debug off
    M550 TT3D ; Machine name (can be anything you like)
    M551 ; Machine password (currently not used)
    ;*** If you have more than one Duet on your network, they must all have different MAC addresses, so change the last digits
    M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address (hexadecimal)

    ;*** Wifi Networking
    M552 S0 ; Enable WiFi

    M555 P2 ; Set output to look like Marlin
    M575 P1 B57600 S1 ; Comms parameters for PanelDue
    ; Movement Section

    M569 P0 S0 ; X axis direction
    M569 P1 S0 ; Y axis direction
    M569 P2 S0 ; Z axis direction
    M569 P3 S1 ; Extruder Drive 0
    M569 P4 S0 ; Extruder Drive 1
    M574 X1 Y1 Z0 S0 ; set endstop configuration (X and Y endstop only, at low end, active high)
    M906 X1000 Y1500 Z1000 E590 ; Set motor currents (mA)
    M201 X500 Y500 Z15 E300 ; Accelerations (mm/s^2)
    M203 X10000 Y10000 Z500 E2400 ; Maximum speeds (mm/min)
    M566 X600 Y600 Z30 E120 ; Minimum speeds mm/minute
    M208 X308 Y304 Z280 ; set axis maxima (adjust to suit your machine)
    M208 X0 Y0 Z0 S1 ; set axis minimum (adjust to make X=0 the edge of the bed)
    M92 X80.45 Y80.53 Z400 ; Set axis steps/mm
    M92 E1550 ; Set extruder steps per mm (single nozzle)
    ;M92 E420:420 ; Set extruder steps/mm (dual nozzle)
    M350 X16 Y16 Z16 E16 I1 ; Set 16x microstepping with interpolation
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates…
    M83 ; ...but relative extruder moves

    ; Probe Section

    M558 P5 ; Use a simple modulated Z probe
    G31 P1000 X-27.5 Y10 Z.1 ; Set the probe height and threshold (put your own values here)

    ; Heater and thermistor section
    ;*** If you have a Duet board with 1K thermistor series resistors, change R4700 to R1000 to the following M305 commands
    M305 P0 R4700 T100000 B3988 ; Put your own H and/or L values here to set the bed thermistor ADC correction
    M305 P1 R4700 T100000 B4036 ; Put your own H and/or L values here to set the first nozzle thermistor ADC correction
    M307 H1 A350.1 C103.5 D4.0 B0
    M143 H0 S280

    ; Tool definition section

    M563 P0 D0 H1 ; Define tool 0 to use extruder drive 0 and heater 1
    G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures
    ;*** If you have a dual-nozzle build, remove or comment out the previous line, and un-comment the following 3 lines
    ;M563 P1 D1 H2 ; Define tool 1
    ;G10 P1 S0 R0 X31.10 Y0 ; Set tool 1 operating and standby temperatures

    ; Bed probe section (not needed if you us a bed.g file

    M557 X35:280 Y20:280 S20
    ;*** if you are using axis compensation, put the figures in the following command
    M556 S78 X0 Y0 Z0 ; Axis compensation here

    T0 ; select first hot end



  • DC I should have also stated that I am working on a Cartesian style printer.



  • Still having issues with the Z offset, Need help



  • Have you tried Z0.1 instead of Z.1?



  • Did you get this sorted? I'm having a similar problem on a cartesian and I'm wondering if they are related, perhaps.

    https://www.duet3d.com/forum/thread.php?id=4026

    Richard


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