Dual Z bed leveling using BLTouch



  • I'm in the process of building the BLV corexy printer and I'm looking to utilize the dual Z bed leveling as described in the Wiki https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_Example_for_2_motors

    I"m not very good with the gcode stuff and wanted to just verify some things and have a spot to ask questions as they arise.

    Looking at the wiki, am I correct that I won't have to un-hide the second motor that I will attach to the second extruder stepper driver? Is this handled automatically by the M671 command that gets put in the config.g file?

    What I would like to do is to set it up to do an initial home of x & y and z in the center of the bed using my BLTouch and then have it probe each side of the bed in line with the 2 leadscrews to align/sync the leadscrews.

    So in my config.g I would need something like this

    M584 X0 Y1 Z2:4 ; two Z motors connected to driver outputs Z and E1
    M671 X-40:340 Y150:150 S1.0 ; leadscrews at left (connected to Z) and right (connected to E1) of X axis
    M208 X-5:300 Y0:300 ; X carriage moves from -5 to 300, Y bed goes from 0 to 300

    What I don't understand is how to do the homing. The wiki says the calibration happens when G32 is performed but how is that called/commanded? Do I need to modify the homeall and homez files other than setting my coordinates for homing z to be in the middle of the bed?

    The wiki shows this needs to be put in bed.g (I will comment out the M401 and M402 lines since I'll be using a bltouch)

    G28 ; home
    M401 ; deploy Z probe (omit if using bltouch)
    G30 P0 X20 Y150 Z-99999 ; probe near a leadscrew, half way along Y axis
    G30 P1 X280 Y150 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors
    M402 ; retract probe (omit if using bltouch)

    I appreciate any help with this. I'm just trying to get my files all set up so once I'm finished building the printer I'll be ready to go.



  • @jamesm said in Dual Z bed leveling using BLTouch:

    I'm in the process of building the BLV corexy printer and I'm looking to utilize the dual Z bed leveling as described in the Wiki https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_Example_for_2_motors

    I"m not very good with the gcode stuff and wanted to just verify some things and have a spot to ask questions as they arise.

    Looking at the wiki, am I correct that I won't have to un-hide the second motor that I will attach to the second extruder stepper driver? Is this handled automatically by the M671 command that gets put in the config.g file?

    yes as its not an additional axis.

    What I would like to do is to set it up to do an initial home of x & y and z in the center of the bed using my BLTouch and then have it probe each side of the bed in line with the 2 leadscrews to align/sync the leadscrews.

    for this add G32 to the end of homeall.g

    So in my config.g I would need something like this

    M584 X0 Y1 Z2:4 ; two Z motors connected to driver outputs Z and E1
    M671 X-40:340 Y150:150 S1.0 ; leadscrews at left (connected to Z) and right (connected to E1) of X axis
    M208 X-5:300 Y0:300 ; X carriage moves from -5 to 300, Y bed goes from 0 to 300

    M584 needs to define all motors. you forgot the e output. also see the notes in the documentation about the order.

    What I don't understand is how to do the homing. The wiki says the calibration happens when G32 is performed but how is that called/commanded? Do I need to modify the homeall and homez files other than setting my coordinates for homing z to be in the middle of the bed?

    see above.

    The wiki shows this needs to be put in bed.g (I will comment out the M401 and M402 lines since I'll be using a bltouch)

    G28 ; home
    M401 ; deploy Z probe (omit if using bltouch)
    G30 P0 X20 Y150 Z-99999 ; probe near a leadscrew, half way along Y axis
    G30 P1 X280 Y150 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors
    M402 ; retract probe (omit if using bltouch)

    I appreciate any help with this. I'm just trying to get my files all set up so once I'm finished building the printer I'll be ready to go.



  • @veti

    Thank you very much for the input. I was just copying what was in the wiki and will put the E axis in the M584 as well.

    This build is being a real pain for me trying to get all the extrusions square and level. Realized last night when I went to mount the z-motor mounts that the extrusions on the bottom sides are not level so now I have to take a bunch back apart again. UGH!!!

    In the end I'm looking forward to having a nice corexy printer. My current printers are a fairly modified Ender 3 and a slightly modified Lulzbot Taz 6 both running Duet wifi boards.



  • if you have 2020 extrusions here is what i use.
    https://www.aliexpress.com/item/32848849259.html



  • @jamesm said in Dual Z bed leveling using BLTouch:

    the extrusions on the bottom sides are not level

    I shimmed the Z steppers mount to make sure the vertical lead screws are consistent with the travel of the bed carriage all the way up. You also want to have some free play in the lead screw mount such that you can adjust it a little before to tighten the screws.



  • @veti those won't work because there is a vertical 20-40 in line with the stepper that the linear rail fastens to. I'll just take my time to make sure everything is right. I don't want to cut any corners on this..trying my best..lol



  • Since I'm utilizing a second stepper driver for the second z leadscrew, do I need to add to my existing settings like motor currents, accelerations, instantaneous speed changes with a colon after the z-setting or since both motors are for the z-axis does the single setting stand?

    Below is what I was wondering if I had to do

    M92 X200.00 Y200.00 Z1600.00:1600.00 E846.00 ; Set steps per mm
    M566 X900.00 Y900.00 Z12.00:12.00 E1200.00 ; Set maximum instantaneous speed changes (mm/min
    M203 X10000.00 Y10000.00 Z180.00:180.00 E10000.00 ; Set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00:20.00 E1500.00 ; Set accelerations (mm/s^2)
    M906 X1600.00 Y1600.00 Z1600.00:1600.00 E960.00 I30 ; Set motor currents (mA) and motor idle factor in per cent



  • no the z settings will apply to all if your M584 is correct



  • @veti Thanks again.


 

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