Problems with setting up



  • Firmware Name: RepRapFirmware for Duet
    Firmware Electronics: Duet 0.6
    Firmware Version: 1.23 (2018-12-24b1)
    Web Interface Version: 1.22.6

    So as an Xmas present I updated from something older on my Duet powered Prusa and found that quite a lot of the behaviour had changed:

    When trying to home X or Y (after an M84 or on start up) the system told me that not enough axes had been homed. Eventually I had to manually set Z via a G92,

    Then G30 returns to approximately 5mm after finding the bed, but since G30 is only accurate once ( the variation can be 0.3mm between probings for at least the first five probes on the same spot, it requires a manual operation to accurately set 0.

    M557 doesn't seem to work. If I send M557 X20:180 Y20:180 S20 as a Gcode, then check it from the auto bed compensation panel it remains set at x0:180 Y0:180. If I set it manually from teh auto bed compensation panel, then the cset condition persists.
    Run Mesh Grid compensation works from the panel but the results are unpredictable (especially on the black PEI bed) where it suddenly dived into the deck and broke the glass, which means a new PEI sheet, new Glue sheet and new Glass.

    I thought I had followed the advice on tuning the Mini IR probe, but there is obviously somethng missing and on a Kaptan covered bed the system has just stripped the film off for the third time as it seems to compensate for a height variation that just doesn't seem to be there.

    Does anyone have any ideas what is going wrong?

    At he same time, even with bed compensation, and after extensive manual bed levelling, the micrometer shows a 4 thou hollow in thecentre of the bed, even with a brand new bit of glass that is flat when measured on the mill, even if I then turn the glass over expecting to find a bulge. (and even if there is no bulldog clip to apply warp. Is this an indication that the X and Y travel guides are bent from too many head crashes? Or have I discovered micro-gravitic anomalies?

    Any help would be welcome, I' d like print something over 20mm successfully soon after three years of trying!

    Rs3



  • @robins3 said in Problems with setting up:

    When trying to home X or Y (after an M84 or on start up) the system told me that not enough axes had been homed. Eventually I had to manually set Z via a G92,

    From the FAQ:

    I get this error message: "Error: G0/G1: insufficient axes homed"
    Recent firmware versions do not allow axes to be moved before they have been homed. The only movements allows are homing moves (G1 moves with S1 or H1 parameter) and individual motor moves (G1 moves with S2 or H2 parameter). So any Z movements that your homing files make before Z is homed should use the S2 parameter. Alternatively, add M564 H0 to config.g to allow axis movement before homing.

    @robins3 said in Problems with setting up:

    M557 doesn't seem to work. If I send M557 X20:180 Y20:180 S20 as a Gcode, then check it from the auto bed compensation panel it remains set at x0:180 Y0:180.

    I don't think the DWC reads what's been set in config.g, so it just shows a default.

    @robins3 said in Problems with setting up:

    but since G30 is only accurate once

    I'm not sure what you mean.

    Can you post a picture of your resulting heightmap? And a picture of what your bed surface looks like? The IR probe can be a little touchy on reflective surfaces. How did you measure the trigger height of the probe?

    Can you post your config and homing files?


  • administrators

    So as an Xmas present I updated from something older on my Duet powered Prusa and found that quite a lot of the behaviour had changed

    Did you read the upgrade notes, which I advise users to do on every Releases page that I publish? You need to read the upgrade notes for the released you skipped too.

    @robins3 said in Problems with setting up:

    At he same time, even with bed compensation, and after extensive manual bed levelling, the micrometer shows a 4 thou hollow in thecentre of the bed, even with a brand new bit of glass that is flat when measured on the mill, even if I then turn the glass over expecting to find a bulge. (and even if there is no bulldog clip to apply warp. Is this an indication that the X and Y travel guides are bent from too many head crashes?

    It suggests that your X axis is sagging in the middle. This is very common, it's caused by the weight of the X carriage.



  • @phaedrux "But Since g30 is only accurate once"
    I'm not sure what you mean

    Ive just spent some time following the instructions for setting up the Z probe on a kaptan covered glass bed

    I repeated the G30 S-1 several times and got the following results
    3.309,3,392, 3.665, 3.179, 3.583.

    Yesterday when I did similar the results were scattered between 2.7 and 2.3.

    What I usually do is to repeat g30 until I get three readings inside the same tenth, eg:2,55, 2.57.2.51, but by the end of a print, a return to G30 can be significantly off, even if the print itself is only hundreths of an mm of the programmed size. So the probe will report it has returned to a similar height, but manual checking with a height gauge can show an error up to about 1 mm. the probe seems tight on its mount, otherwise I would suspect that somewhere the probe had collided with something and moved.



  • You can test if your print surface is causing the probe variability by putting a plain piece of paper over the bed and testing the trigger height again.



  • @dc42 " Did you read the upgrade notes, which I advise users to do on every Releases page that I publish? You need to read the upgrade notes for the released you skipped too."

    I try to do so, but I am not sure I interpret what you meant me to understand. I often find myself looking at results, going back to the notes and thinking, " Ah, that's what he meant" My brain doesn't seem to work as people expect!

    "It suggests that your X axis is sagging in the middle. "
    it seems to affect the Y axis much more. I know that the DTI shows every touch , and I was playing with the effect of putting an AAA battery cell on the bed. the deflection registered.



  • @phaedrux Done that. Same sort of results with plain white paper. I shall try it again later with coloured paper in case the white overloaded the sensor.


  • administrators

    @robins3 said in Problems with setting up:

    I repeated the G30 S-1 several times and got the following results
    3.309,3,392, 3.665, 3.179, 3.583.

    Are you are getting that amount of variability when you do repeated probing at the same point? If so, that's not at all right. The variability should be much lower than that, it's normally determined by the friction in your mechanics. For example, I was getting 0.01mm variability on my delta printer.

    So I suspect one of the following:

    • Wrong mode set in the M558 command (should be P1)
    • Wrong threshold set in the G31 command (should be P500)
    • Probing speed set too high in the M558 command (try F300 or lower)
    • Z acceleration set too high in the M201 command
    • Faulty IR sensor


  • @dc42
    M558 set to p1, F200
    G1 set to p500
    M201 has Z15
    IR sensor is about a year old but only 6 months in service.

    The results I posted were all repeated at the same point (and today are ranged about 2.42 rather than 3.? I got three results within the same 0.5mm, nowhere near your 0.01

    mechanics, I have an M8 rod, an old RepRapStore model Prusa) and there is a bit of Z wobble. I modified the Z axis to put the drives at the bottom, with the flexible connections (from E3D) mounted on deep groove bearings to reduce the load on the Z axis motors.


  • administrators

    Yout trigger heights look very high too. Please check that the two white IR LEDs and the black phototransistor at the bottom edge of the bard are not contaminated with filament or anything else. You can clean them using a cotton bud moistened in isopropyl alcohol.


 

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