Dual Z-axis endstops
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The advice remains the same for now, except the detail has changed. I now suggest the following:
1. Put this command in config.g:
M584 X0 Y1 Z2:3 U9 E4 P3
This assigns your second Z motor (connected to the E0 motor output) to the Z axis, and creates a U axis that uses driver 9 (which I am assuming is not connected to any motor). The P3 parameter limits the number of visible axes to 3 in firmware 1.19beta6 and later, so that the U axis is not visible in the user interface.
2. In your homez.g file, do this:
M584 Z2 U3
G1 S1 Zxxx Uxxx
G92 Zxxx
M584 Z2:3 U9Assuming that driver 9 is not connected, assigning the U axis to it other than during Z homing prevents inadvertent movement of the U motor if a G1 command with a U parameter is executed.
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Thanks.
I Just need to add some config to make it go back from z-max (where my bed is homing currently) to z-min and use a probe to get the right distance from nozzle to bed
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This may be a stupid question but when doing this, I assume you move the extruder to the E1 connector?
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This may be a stupid question but when doing this, I assume you move the extruder to the E1 connector?
You can either use the E0 motor output for the second Z motor and E1 for the extruder (which is what I assumed in the config examples I gave above), or vice versa. Just tell the firmware which way round you have them in the M584 command.
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Thanks
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yes there are several FT5 owners running dual home z. I am still waiting to see if going to 1 z motor and linking the 2 z axis would be a better option. I have Duet WIFI so if i don't, i will eatu p my extra extruder spot if I split Z. In series you only get half the power any way so not sure if there is an up side to 2 motors in series? I know we talked about that briefly, your thoughts are always appreciated DC42! (https://www.youtube.com/watch?v=askVj4_5f9c)
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If you connect two Z motors in series, you don't lose torque at low speeds. Each provides the same torque that a single motor would at the same current setting. However, the maximum speed you can run the motors at before the torque starts dropping is halved. This isn't normally a problem because high Z speeds are not required.
Firmware 1.19beta9 includes most of the implementation of bed leveling using multiple Z motors connected to individual drivers.
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This works great. Implemented it on my big machine and I no longer have to worry if one side sags at idle. The only oddity I've noticed is that regardless of how long the machine has been on or if the Z has already been homed, when I home the Z axis from full height, the right side is hitting the endstop before the left side by about 2 seconds. However, once I have homed it and take it back to Z0, I can do a G0 to run the machine down to 10mm above the endstop and then slowly manually move it down and the hit together. Then if I run it to Z0 and home again, same 2 second lag. Must have a digit out of place somewhere. Steps are set the same. Hmmmmm.
For reference, this machine is like an Ultimaker but about twice the size so Z0 is up.
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Got it homing evenly now. just mirrored all the settings for Z to U in the config file.
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I'm glad you sorted it!
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I think it was the steps
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Bear in mind that in firmware 1.19beta10, an alternative to using dual Z endstops now is to use auto bed levelling to adjust your 2 leadscrews independently to get the bed level after homing.
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I am considering using my 2 lead screws independently also, since I can add driver 12 to the LCD connector.
Your example shows assigning U axis to an unconnected driver, which in my case there will be none. So how would I configure dual lead screw (don't have auto bed leveling setup yet – I will add that in after I get the basics configured)This is what I have now:
M584 X0 Y1 U2 V3 W4 A5 E6:7:8:9 Z10
so if I were to add 11 it would change to
M584 X0 Y1 U2 V3 W4 A5 E6:7:8:9 Z10:11 then presumably I would define B somehow? would be also 11?I can remap other axis to -- as in U etc kinda like this:
M584 X0 Y1 V2 W3 A4 B5 E6:7:8:9 Z10:11 -- then I have U freed up as a limit switch on the primary duet as apposed to the expansion board, though I haven't notice any performance difference with 19.11 support for end stops on the expansion board.
Being that I have a large bed and there is the ability to add the 12th driver -- I can drop in another TB6600 and run my 2 lead screws independently.
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The recommended approach now is to use a Z probe and to drive the multiple Z leadscrews independently during bed levelling only. However, you could use the old approach of dual endstop switches instead if you want, but in your case use the B axis for the second Z leadscrew instead of U. Then you can use the M584 P parameter to hide the B axis.
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The recommended approach now is to use a Z probe and to drive the multiple Z leadscrews independently during bed levelling only. However, you could use the old approach of dual endstop switches instead if you want, but in your case use the B axis for the second Z leadscrew instead of U. Then you can use the M584 P parameter to hide the B axis.
I have different bed leveling options I will be trying once I have a bed
I need to prep the PEI sheet with the automotive paint before I adhere it to the boro glass, that is on my queue for next week. I ordered the second TB6600 and will be setting it up for now to use the old method with 2 limit switches as you said, so I'm assuming
The correct option for me is
M584 X0 Y1 U2 V3 W4 A5 E6:7:8:9 Z10:11 B11 P7
M574 X1 Y1 Z1 U2 V2 W1 A2 B1 S1then my homez.g would be
G91
M584 Z10 B11
G1 S1 Zxxx Bxxx
G92 Zxxx
M584 Z10:11
G90So I can't really "hide" or prevent inadvertent moves of the B axis – since at the end of the Z homing it still assigned to 11 (which I suppose isn't critical as no standard gcode contains G1 B commands)
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Question on this. Can I use my bl touch instead of endstops? I have the endstops but would rather not use if i do not have to. Can we use the Z probe for both Z and U. For example, home the bed, with bl touch this would leave space between nozzle and the bed. Then move the head to the other side of the build platform and use only the U motor to move until probe is triggered again.
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I have different bed leveling options I will be trying once I have a bed
I need to prep the PEI sheet with the automotive paint before I adhere it to the boro glass, that is on my queue for next week. I ordered the second TB6600 and will be setting it up for now to use the old method with 2 limit switches as you said, so I'm assuming
The correct option for me is
M584 X0 Y1 U2 V3 W4 A5 E6:7:8:9 Z10:11 B11 P7
M574 X1 Y1 Z1 U2 V2 W1 A2 B1 S1then my homez.g would be
G91
M584 Z10 B11
G1 S1 Zxxx Bxxx
G92 Zxxx
M584 Z10:11
G90So I can't really "hide" or prevent inadvertent moves of the B axis – since at the end of the Z homing it still assigned to 11 (which I suppose isn't critical as no standard gcode contains G1 B commands)
You can hide the B axis at the end of homing by adding P8 to the first M584 command and P7 to the second. The B axis will appear during Z homing but will be hidden afterwards.
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Question on this. Can I use my bl touch instead of endstops? I have the endstops but would rather not use if i do not have to. Can we use the Z probe for both Z and U. For example, home the bed, with bl touch this would leave space between nozzle and the bed. Then move the head to the other side of the build platform and use only the U motor to move until probe is triggered again.
Use the bltouch to home Z at bed centre as normal, then use the multiple leadscrew bed levelling facility described at https://duet3d.com/wiki/Bed_levelling_using_multiple_independent_Z_motors.
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I have have an FT-5 and want to split my Z axis when homing, my Home Z.g looks like this:
; homez.g
; called to home the Z axis
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; generated by Jens Kej on Sun Mar 11 2018 15.00G91 ; relative mode
G1 Z4 F200 ; raise head 4mm to ensure it is above the switch trigger height
G90 ; back to absolute mode
G1 X-305 Y-305 F1800 S1; move XY home
G1 X150 Y150 F2000 ; put the head to be centered when you home Z
G91 ; relative mode
M584 Z2 U3 ; split Z axis in two
G1 Z-400 U-400 S1 F100 ; home the Z- and U axis
G92 Z0.1 ; tell the software that it 0,1 mm above bed
G90 ; back to absolute mode
M584 Z2:3 ; make One Z axis againthe bed is moving fine up and down from web interface but only the Z axis is trying move when I push home Z, why?
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Please post your config.g file.
