Z stop not working during homing



  • Using a Duet Wifi, my Z stop works electrically. The light on the board comes on if you manually click the switch, and M119 reports the correct information. But then if I home the printer (a delta, so all 3 axis move at once), the X and Y endstops work, while the carriage repeatedly bangs into the Z stop until power is removed.

    This occurred after having the printer down for a while and installing 0.9 degree motors. Now when I hook it back up, I can't get past this homing issue. I can't see what this would have to do with the new motors – just mentioning it just in case.

    Anyone have suggestions?

    And side question: How does the Duet Wifi know it's connected to a delta and not a cartesian? (I was thinking that perhaps it doesn't know and this is somehow causing the problem).


  • administrators

    Double check your configuration against this page:
    https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Delta_printer

    You can also use the configurator as a start point:

    https://configurator.reprapfirmware.org/

    If the endstop is otherwise working (looks like it is by your description) then an incorrect delta configuration sounds likely.


  • administrators

    The Duet WiFi only knows it is connected to a delta when it sees the M665 command in your config.g file. A tell-tale sign is that PanelDue and DWC show 1 homing button instead of 4 when the firmware informs them that it is running on a delta. Also in DWC the bed compensation button gets renamed to "Auto delta calibration".



  • Hmmm… It already knows it is a delta then, both because of the interface difference and I see the M665 command. Below is an excerpt from config.g.

    I'm sure axis steps/mm is wrong since I did not update for the 0.9 degree motors, so I'm guessing it is moving things half as fast as it thinks, but I wouldn't think that would cause a problem.

    I'm going to change steps/mm to 160 (assuming that is the correct value for a 16 tooth pulley using GT2 belt), and reduce the currents if for no other reason that when it bangs into the end and tries to keep going, I want it to do that more gently.

    Beyond that, any troubleshooting suggestions?

    ===================
    M665 R114.0 L221.5 B75 H255 ; set delta radius, diagonal rod length, printable radius and homed height
    M666 X0 Y0 Z0 ; put your endstop adjustments here, or let auto calibration find them
    M350 X16 Y16 E16 I1 ; Set 16x microstepping with interpolation
    M92 X80 Y80 Z80 ; Set axis steps/mm
    M906 X1000 Y1000 Z1000 E800 I60 ; Set motor currents (mA) and increase idle current to 60%
    M201 X500 Y500 Z500 E1000 ; Accelerations (mm/s^2, default is 1000 for XYZE)
    M203 X10000 Y10000 Z10000 E3600 ; Maximum speeds (mm/min, default is 20000 for XYZ)
    M566 X1200 Y1200 Z1200 E1200 ; Maximum instant speed changes mm/minute


  • administrators

    For a 16 tooth GT2 pulley with 0.9deg motors and x16 microstepping, there are 200 steps/mm. 160 would be right for a 20 tooth pulley.

    Please post your homedelta.g file.



  • Fixed, one of the endstops was cross wired so that the Z endstop was on the X connector.


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