Difficulty homing the Z-Axis using a 3d-touch probe.



  • BACKGROUND:

    I'm building this printer so that I can assemble prosthetic devices for myself and a friend who is also missing appendages.

    Please note that on a scale from one to 10, my knowledge level is about a 4… OK, 3. possibly 2. Does the scale accept negative integers? Anyhooo...

    Mechanically, my printer is a core x-y that started out as a Tronxy X5S-2E. Due to the absence of a controller board, it is very recently being controlled by a duet-wifi version 1.02, with firmware 1.21 (2018-03-21). (Gearbest sent the wrong board with my kit).

    CONSIDERATIONS:

    Most recently, I have successfully figured out how to home the x and y axis, and can control movement of the hot end in that plane. I have also managed to get M401 and M402 to work in extending and retracting the probe.

    Here are my config files:
    4_1537151161381_retractprobe.g
    3_1537151161381_homez.g
    2_1537151161380_homeall.g
    1_1537151161380_deployprobe.g
    0_1537151161379_config.g

    ISSUE:

    Homing z results in the bed colliding past the extended 3d-touch probe and into the hot end before I need to quickly shut it down. I am assuming that it is not registering the probe for some reason.. but i cant figure out why.

    I would be very grateful if someone could help me understand what I am doing wrong so that I can move on to the next challenge.

    My sincere thanks for your kind consideration into this matter.

    References:
    https://betrue3d.dk/bltouch-on-duet-wifi-configuratio-and-usage/#changeconfig
    https://betrue3d.dk/bltouch-on-duet-wifi-duetreprapfirmware/
    https://duet3d.dozuki.com/Wiki/Connecting_a_Z_probe#BLTouch
    https://duet3d.dozuki.com/Wiki/Using_servos_and_controlling_unused_IO_pins



  • You've done pretty well at getting things going so far.

    Couple things:

    ; homez.g
    ; called to home the Z axis
    ;
    ; generated by RepRapFirmware Configuration Tool on Fri Sep 14 2018 16:24:32 GMT-0700 (Pacific Summer Time)
    G91                                 ; relative positioning
    G1 Z0 F6000 S2                      ; lift Z relative to current position
    G90                                 ; absolute positioning
    G1 X47.08 Y36.620000000000005 F6000 ; go to first probe point
    G30                                 ; home Z by probing the bed
    
    ; Uncomment the following lines to lift Z after probing
    G91                                ; relative positioning
    G1 S2 Z0 F100                      ; lift Z relative to current position
    G90                                ; absolute positioning
    
    ; homeall.g
    ; called to home all axes
    ;
    ; generated by RepRapFirmware Configuration Tool on Fri Sep 14 2018 16:24:32 GMT-0700 (Pacific Summer Time)
    G91                                 ; relative positioning
    G1 Z0 F6000 S2                      ; lift Z relative to current position
    M98 Pdeployprobe.g                  ; deploy mechanical Z probe
    G1 S1 X-315 Y315 F1200              ; move quickly to X or Y endstop and stop there (first pass)
    G1 S1 X-315                         ; home X axis
    G1 S1 Y315                          ; home Y axis
    G1 X5 Y-5 F6000                     ; go back a few mm
    G1 S1 X-315 F300                    ; move slowly to X axis endstop once more (second pass)
    G1 S1 Y315                          ; then move slowly to Y axis endstop
    G90                                 ; absolute positioning
    G1 X47.08 Y36.620000000000005 F6000 ; go to first bed probe point and home Z
    G30                                 ; home Z by probing the bed
    
    ; Uncomment the following lines to lift Z after probing
    ;G91                                ; relative positioning
    ;G1 S2 Z0 F100                      ; lift Z relative to current position
    ;G90                                ; absolute positioning
    
    M98 Pretractprobe.g                 ; retract mechanical Z probe
    
    • You aren't lifting the print head before or after the X and Y moves because G1 Z0 means don't move at all. Not sure if that's intentional. It's not a bad idea to lift the head 5mm to give it clearance for travel.
    • Your Y position value is ridiculously precise. Maybe knock a dozen zeroes off the end of that move. Not sure if it matters. The system is probably ignoring it, but no need to taunt fate.
    • You can remove the M98 Pretractprobe.g and M98 Pdeployprobe.g. They aren't needed. G30 will deal with deploying and retracting on it's own. This may be part of the reason for the crash.
    • In your config.g you don't have a G31 Z value set. This will need to be measured.
      https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe

    If you make those changes, and follow the directions in that link, I think you'll be on your way.

    Just be ready to kill the power in case something goes wrong.



  • Thank you very much for your help. After years of research and months of building, I can almost see my newly printed prosthetics from here!

    But, I’m not quite there it would seem, and again I need to call on the collected wisdom of the masses.

    In response to your your kind suggestions:

    1: G1 Z0
    I did set G1 Z0 intentionally… the reason was that, on occasion, only one of my 2 z axis motors would engage when the G1 command was set… but this only happened during the homing process. For now, I simply make sure that there is some head space before homing. I will return to this issue once the more “show stopping” issues can be addressed.

    2: Your Y position value
    Yes it is! I hadn’t noticed it until you pointed it out… no idea why or how it got set that way. It wasnt causing any problems, so I had no reason to look I guess. Fixed.

    3: remove the M98 Pretractprobe.g and M98 Pdeployprobe.g:
    Done. Thank you.

    4: Measure G31 Z value set:

    This seems to be where I am making my mistakes it would seem.

    Unfortunately, I am unable to get the printer to “pass” the dynamic test, making further calibration impossible as I understand it.

    1: I manually home the z axis by way of G92 Z0
    2: I centre the hot end in the x-y plane
    3: I enter G30 s-1
    4: the probe extends and the bed rises to meet the hot end.
    5: The probe quickly retracts and extends once the bed makes contact.
    6: The bed stops at height 0.000
    7: The led in the probe blinks rapidly
    8: The control board reports back the error: Z probe was not triggered during probing move.

    As for wiring, I have followed the diagram provided on the attached wiring diagrams:
    0_1537215759645_Duetwifi-wiring-bltouch02.jpg

    0_1537215719785_5vTo3.3vLogicLevelConversion_xppy7j1.jpg

    I included the required 220 ohm resistor.

    My sense is that I am not directing the control board to the correct pin for the sensor… but I could be wrong.

    Again, any kind advice is greatly appreciated.



  • Is this a BLTouch Classic or Smart? Authentic or clone? V1 or V2?

    Here's some things to check:

    • Double check your wiring and crimps.
    • Make sure you're actually connected to the pins you think you are.
    • Are you using heater pin 7 or heater pin 3?
    • If you give the probe some clearance from the bed you can do some function testing by sending M280 P7 S120 I1 to put the probe into self test mode. It should start deploying and retracting the pin. If you touch the pin it should retract and go into alarm and start flashing. Then use M280 P7 S160 I1 to release the alarm. If that works consistently we can move on to the next test.
    • Raise the print head and probe a good distance above the bed. Manually send G30 in the console. The pin should deploy and start to move towards the bed. Touch the pin with your finger to trigger it. If it stops. Good. If it doesn't, kill power. Re check wiring.
    • If that all works, you can measure the trigger height. It sounds from your description like it's deploying the pin and its hitting the bed before it even gets a chance to move. Is that right? In your description of the steps you're taking, you're missing the step to raise the nozzle a ways before sending G30 S-1.


  • • Double check your wiring and crimps:
    

    Used multi-meter to check wiring – all points are good, and showing resistance. wiring is exactly as described in the previously posted photos/diagrams...

    • Make sure you're actually connected to the pins you think you are. 
    

    Yes.

    • Are you using heater pin 7 or heater pin 3? 
    

    Heater pin 7 for the control signal for the servo. “blue wire” in my case.

    • If you give the probe some clearance from the bed you can do some function testing by sending M280 P7 S120 I1 to put the probe into self test mode. It should start deploying and retracting the pin. If you touch the pin it should retract and go into alarm and start flashing. Then use M280 P7 S160 I1 to release the alarm. If that works consistently we can move on to the next test. 
    

    Passed. No problems there.

    • Raise the print head and probe a good distance above the bed. Manually send G30 in the console. The pin should deploy and start to move towards the bed. Touch the pin with your finger to trigger it. If it stops. Good. If it doesn't, kill power. Re check wiring. 
    

    This is where it fails. And yet, the wiring is good. Honest.

    The servo controlling the probe movement is working fine. The probe ‘sensor’ that sends a signal to the board when it touches something is not working. Either I have a defective probe (signal not being sent) – or my settings are off (signal not being received).

    I'm still hoping that its my settings... returning the probe for a replacement is likely going to be challenging.

    Again, many thanks. i just hope that I /we can get it working. At the very least, it may help others in the future with similar problems.

    kind regards.



  • Well you're not the first person to have issues with the BLtouch.

    Is this a BLTouch Classic or Smart? Authentic or clone? V1 or V2?

    I ask because some of the older classic probes weren't very good. Even the early Smart version 1 had some issues. And with clones it's hard to say. Could be good, could be bad. The new Smart V2 with plastic pin has been working very well for me.

    Given the price it might be worth getting a newer version as a replacement.



  • Hi,

    Early on I tried a clone BL and due to a config error on the second time probing all the points it hit the bed pretty hard and that was the end of the probe.

    It looked fine, the pin moved in and out, but it never was sensed by the firmware again.

    Frederick



  • I think the fact the probe isn't triggering would indicate that the white wire going to the probe input could have a bad connection. Try re-crimping it.



  • The probe i purchased (for just under $19) is this one:

    https://www.amazon.ca/gp/product/B07DGZV9C8/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

    it is a 3dTouch "clone" of the BLTouch as i understand it.

    I purchased it since it was being sent domestically. and I'm sick of waiting 3 months or more for parts.

    The wires for my unit are as follows:
    3 for the servo:
    black (grd)
    red (+)
    Blue (control signal)

    2 for the "probe".. presumably
    black (grd)
    yellow (Z Min)

    I'm presuming that you are referring to the yellow wire in my case... but yes, the angry pixies (electrons) are flowing freely according to my multimeter. Is it possible that I have incorrectly identified this connection in the settings? im not sure... been staring at it for far too long... need a break. eyes going crossed.



  • @fcwilt good to know... its possible that if it is that fragile something may have happened during shipping to make it inoperable.



  • I assume you're in Canada? Spool3d.ca has genuine BlTouch Smart V2 probes. Throw on a couple spools of filament and you've got free shipping.


  • administrators

    @squamish-sean said in Difficulty homing the Z-Axis using a 3d-touch probe.:

    • Raise the print head and probe a good distance above the bed. Manually send G30 in the console. The pin should deploy and start to move towards the bed. Touch the pin with your finger to trigger it. If it stops. Good. If it doesn't, kill power. Re check wiring.

    This is where it fails. And yet, the wiring is good. Honest.

    In what manner does it fail? Is an error message written to the GCode Console?


 

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