Delta homing issues (SOLVED)



  • Good afternoon gents.

    sorry to be asking for help on my first post, but im scratching my head with this

    Hardware is as follows:

    Genuine Duet wifi

    Firmware Electronics: Duet WiFi 1.02 or later

    Firmware Version: 2.02(RTOS) (2018-12-24b1)

    WiFi Server Version: 1.23

    Web Interface Version: 1.22.6

    Kossel style Delta, vertical rail height (from the bed to the end stops) is almost 900mm

    Smart effector

    Haydn Mag ball carbon arms with a length of 490.66mm

    Bed Dia is 300mm

    Linear Rails

    0.9 degree motors

    Zesty Nimble on the smart effector.

    My issue is that i can home but once i do the web interface lists the axis's in the following manner:

    X= 0 Y= 0 Z=350.1

    And if i try to initiate a "delta calibration" move only the X & Y motors move.

    Would someone with obviously better knowledge of delta's than i be able to pass comment on what my issue might be, i will try to attach copies of my config.g, bed.g & homedelta.g files

    I know its cheesy but many thanks in advance for helping a newbie with his first delta.

    Brian


  • administrators

    @brian-everts said in Delta homing issues:

    My issue is that i can home but once i do the web interface lists the axis's in the following manner:
    X= 0 Y= 0 Z=350.1

    this is normal as this is the location of the effector in the co-ordinate space of the printer rather than being the position of the individual axis (which are no doubt all the ways up at the endstops)

    Please update your bed.g to use six factor calibration (I don't know if this is the issue causing only X and Y to move - I doubt it - but S3 is not right):
    https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer#Section_Setting_up_the_bed_g_file

    Is that the bed.g file from the RepRapFirmware configurator, unedited?



  • @t3p3tony

    thanks for the prompt reply. yes i used the config tool, i didnt change the bed.g file but i did do a comparison between it and David's kossel example file which is in the sd card you guys send out.

    i will look at the bed.g section and digest until i can get me head round it.

    thanks again.

    Brian


  • administrators

    The line to change is:

    G30 P12 X0 Y0 H0 Z-99999 S3
    
    

    Change this to

    G30 P12 X0 Y0 H0 Z-99999 S6
    


  • @t3p3tony

    Thanks for that, i changed it, that seems to have cured the issue, the calibration sequence now starts, but it has presented another issue (typical)
    in the the nozzle doesnt actually get to the bed before it reports that it was not triggered and tries to move to the next point.

    one step forward, i will try speeding up the the probing speed as it looks like it "timing out" due to my very slow probing speed.

    Regards

    Brian


  • administrators

    @brian-everts said in Delta homing issues:

    @t3p3tony

    Thanks for that, i changed it, that seems to have cured the issue, the calibration sequence now starts, but it has presented another issue (typical)
    in the the nozzle doesnt actually get to the bed before it reports that it was not triggered and tries to move to the next point.

    one step forward, i will try speeding up the the probing speed as it looks like it "timing out" due to my very slow probing speed.

    Regards

    Brian

    Temporarily increase the probing dive height, for example to 50 (it's in mm). It's the H parameter in the M558 command in config.g.



  • Hi David

    Thanks for the input on the M558 command I tried that and im afraid to say that didn’t help.

    I worked out a work around (rightly or wrongly) you can advise me on its validity.

    Once I got the machine to actually start the calibration procedure I observed that the height the Z axis would “dive” to always show zero in the web interface and that dive height in mm corresponded with the amount of mm in H switch in the M665 command, the H switch states: H = height of the nozzle above the bed when all three carriages are just high enough to trigger the end stop switches. Measure it as best you can, to within about 5mm. Calibration will adjust it.

    Now I measured that as advised after homing all three carriages, and from the bed surface to the tip of the nozzle is 355mm, and with that value in the H switch of the M665 command the nozzle would never get close to the bed when I initiated the auto calibration sequence, so I made the connection between the two and I tried increasing the H value, I reached a value of 444 mm which now allow the nozzle to reach a reasonably close distance above the bed.

    Why would the original (correct) H Value not allow the nozzle close to the bed? And why does the incorrect value allow this to happen…

    So is my workaround crazy or can I leave it for now?

    Im now working through writing a macro to help me to carry out all 12 trigger height corrections.

    Detla’s are crazy machines to get your head around but so fascinating too.

    Brian


  • administrators

    It sounds to me that you have the incorrect steps/mm value for the towers in the M92 command. For example, you may have entered 80 when the true value is 100.



  • @dc42 said in Delta homing issues:

    It sounds to me that you have the incorrect steps/mm value for the towers in the M92 command. For example, you may have entered 80 when the true value is 100.

    Hi David

    I will double check that, i followed the reprap calculator.



  • Hi All

    So i have my homing issue fixed, thanks to all who helped.

    I used the RepRap config tool and it appears to have set the Switch incorrectly in the beg.g file.

    I also checked the steps per mm as advised by David, im running 0.9 degree motors so the steps per mm was wrong, the RepRap config tool appears to assume 1.8 degree motors are being used and unless its hidden somewhere, i couldnt find where to tell the tool i was using 0.9 degree motors.

    so i will mark this as solved, thanks again to everyone who assisted.


 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.