3 Z steppers - can I move it individually?

Reefwarrior · 8 May 2021, 07:40

Hi,

Sometimes due to mechanical reasons (and the wonderful accuracy of my build) I experience that some of the 3 Z axis goes out of 'alignment' - so it inadvertently tilts the bed. Is there perhaps a G-code that I can issue to let me move one of the Z stepper motors? I will make maintenance (greasing and cleaning the lead screws) a lot easier too!

Any/all help appreciated!
Tinus

dc42 · 8 May 2021, 07:57

@reefwarrior you can do this automatically if you have a Z probe. See https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors.

fcwilt · 8 May 2021, 13:25

@reefwarrior

In addition to the Z probe if you have a Z endstop for each Z stepper you can quickly home Z and get the bed nearly level.

Then you use the Z probe with the auto leveling feature to fine tune the bed leveling.

In this video you can see a grossly out of level bed homed and leveled:

Homing and Leveling of 3 Z Stepper Printer

Reefwarrior · 10 May 2021, 13:25

@fcwilt @fcwilt Hi! Thank you - yeah that seems 'better; than only relying on one sensor - it has happened where the offset between the three Z's were too much for the sensor to reach - and the nozzle ran into the bed. Specifically what am I looking for with regards to the 3 end stops? Configuration wise?

Reefwarrior · 10 May 2021, 13:26

@dc42 Thank you!

fcwilt · 10 May 2021, 14:51

@reefwarrior said in 3 Z steppers - can I move it individually?:

@fcwilt @fcwilt Hi! Thank you - yeah that seems 'better; than only relying on one sensor - it has happened where the offset between the three Z's were too much for the sensor to reach - and the nozzle ran into the bed. Specifically what am I looking for with regards to the 3 end stops? Configuration wise?

Hi,

All you need is this command:

M574 Z1 S1 P"!duex.e2stop + !duex.e3stop + !duex.e4stop but for your actual Z endstop connections.

They also must be in the same order as this command:

M584 X0 Y1:2 Z5:6:7 E3

So in this example:

duex.e2stop is for Z5
duex.e3stop is for Z6
duex.e4stop is for Z7

Reefwarrior · 10 May 2021, 15:11

@fcwilt Hi! Thank you! Will try and implement ASAP - busy struggling with something else now again

Reefwarrior · 12 May 2021, 06:25

Will the homing script basically remain the same, or is there something specific I need to do?

fcwilt · 9 Jun 2021, 18:15

@reefwarrior said in 3 Z steppers - can I move it individually?:

Will the homing script basically remain the same, or is there something specific I need to do?

You home normally - the same as you would if you only had one Z stepper.

When you have the M574 command with multiple endstops for Z the firmware knows how to handle them.

Reefwarrior · 9 Jun 2021, 18:15

@fcwilt Hi. I have now installed optical end stops; but I'm having issues with it - it only recognises a single optical end stop - and even if I trigger it; the z motor on that rail does not stop. Also; I have a BL Touch for bed probing - how do I define that; inclusive of the other 3 independent optical end stop....

fcwilt · 9 Jun 2021, 18:31

@reefwarrior said in 3 Z steppers - can I move it individually?:

@fcwilt Hi. I have now installed optical end stops; but I'm having issues with it - it only recognises a single optical end stop - and even if I trigger it; the z motor on that rail does not stop. Also; I have a BL Touch for bed probing - how do I define that; inclusive of the other 3 independent optical end stop....

You need to have an M574 command something like this (from my printer) ...

M574 Z1 S1 P"!duex.e2stop + !duex.e3stop + !duex.e4stop"*

... where you specify each endstop in the order the matches the Z stepper assignments in the M584 command (from my printer)

M584 X0 Y1:2 Z5:6:7 E3

Reefwarrior · 9 Jun 2021, 18:48

@fcwilt Hi; I will try again - but how do I now define the BL Touch; and as what?

I have this: M584 Z7 U5 V9 P3 --- the 3 Z motors are plugged in on 2 4 and 6. And They work in the order of 4 2 6 on the duex.

If I issue a M119; it tells me that there is no end stop for U and V....

fcwilt · 9 Jun 2021, 18:54

@reefwarrior said in 3 Z steppers - can I move it individually?:

@fcwilt Hi; I will try again - but how do I now define the BL Touch; and as what?

I have this: M584 Z7 U5 V9 P3 --- the 3 Z motors are plugged in on 2 4 and 6. And They work in the order of 4 2 6 on the duex.

If I issue a M119; it tells me that there is no end stop for U and V....

I do not understand your M584.

If the Z steppers are on 2,4,6 then the M584 should have Z2:4:6.

Why are you concerned with moving each Z stepper individually?

Frederick

Reefwarrior · 9 Jun 2021, 18:57

@fcwilt Hi; ok that was for maintenance purposes (cleaning and lubrication) to have each individual axis be able to move up and down.

It is 5 7 and 9; as drivers 0-4 are on the Duet2 Wifi; and then the Duex5 is 5-9 (I have used the first stepper plug; then left one open, used the next, one open, used next on the duex5).

According to documentation on the duet wiki; I need to 'split' the 3 motors; each must run to the end stop, and then need to be 'recombined' in the homez.g

fcwilt · 6 Oct 2021, 00:25

@reefwarrior said in 3 Z steppers - can I move it individually?:

@fcwilt Hi; ok that was for maintenance purposes (cleaning and lubrication) to have each individual axis be able to move up and down.

It is 5 7 and 9; as drivers 0-4 are on the Duet2 Wifi; and then the Duex5 is 5-9 (I have used the first stepper plug; then left one open, used the next, one open, used next on the duex5).

According to documentation on the duet wiki; I need to 'split' the 3 motors; each must run to the end stop, and then need to be 'recombined' in the homez.g

If you keep the steppers combined Z5:7:9 with firmware 3.2.2 or later you can home the Z axis and each motor will run until the associated endstop is triggered.

I don't understand why you would need control each Z stepper individually for the purposes of cleaning/lubrication. I have not found the need to do that.

Phaedrux · 9 Jun 2021, 19:55

See here for some examples: https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

You can use both ways interchangeably. Combine all 3 drivers as a single Z axis and use the combined M574 endstop definition to home them at once as a group. Or if you wish you can have a separate macro that creates separate axis for each Z motor for individual control and movement.

Reefwarrior · 10 Jun 2021, 07:29

@phaedrux Thank you! Question still is how do I go about with the following:

3 independent Z motors - each homing to an end stop (to get a rough levelling) and then using the BL touch to adjust each axis as required (homing using 3 z axis). I have had a couple of times now where there was some or other issue with regards to the BL Touch and I ended up smashing the bed into the nozzle....

Reefwarrior · 10 Jun 2021, 10:59

Think I may be on the point of having this completed. The individual homing works - just now the bl touch part...

Phaedrux · 10 Jun 2021, 17:37

@reefwarrior said in 3 Z steppers - can I move it individually?:

3 independent Z motors - each homing to an end stop (to get a rough levelling)

This part is automatic if you're using RRF3 and have the 3 z motor drivers combined as a single z axis and then home using the 3 endstops combined in M574. Using a G1 H1 move to home Z will move each motor until the endstop is hit.

For doing independent leveling with the probe, you'll need to set that up in bed.g.

All this and more is described with examples here: https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

Reefwarrior · 10 Jun 2021, 18:49

@phaedrux Cool! I suspected that it may be in a different file - seems I am finally grasping how this part works