3 Motor Z axis Automatic bed levelling using G32 RRF 3.01-rc3

Danal

It does work on a CoreXY, I have one.

The reason you are not getting output, nor motor movement, is because your third G30 is missing S3

My bed.g:

G30 P0 X152.5 Y0 Z-99999       ; probe near back leadscrew

G30 P1 X290   Y230 Z-99999      ; probe near front left leadscrew

G30 P2 X20    Y280 Z-99999 S3   ; probe near front right leadscrew and calibrate 3 motors

G1     X152.5   Y152.5 F10000

Dr_Ju_Ju

Thank you Ian & Danal, it was the missing S3 in bed.g.

At least I now have a starting point to work with. I've already disabled the G29 commands in bed.g so I'll build another macro to provide the functionality.

If I manually run G28 followed by G29 I get this in the console:

26/03/2020, 15:56:58 G29
9 points probed, min error -1.491, max error 1.774, mean 0.154, deviation 0.945
Height map saved to file 0:/sys/heightmap.csv

26/03/2020, 15:55:21 G32
Leadscrew adjustments made: 0.781 0.307 -1.367, points used 3, (mean, deviation) before (-0.076, 0.764) after (-0.000, 0.000)

which appears to throw things all out...

droftarts

@Dr_Ju_Ju All that G32 does is call bed.g. When defining bed mesh or doing Z levelling/leadscrew adjustment, you need to disable any other compensation with M561 and G29 S2, which you were doing in bed.g.

You need to run the leadscrew adjustment every time you power off the stepper motors, because that's when it loses position. When the stepper motors turn back on, they'll jump to the nearest full step position. Over time the bed level will drift, until you run the leadscrew adjustment again. So it's easiest just to do it every time you turn the machine on (except if you're resuming an interrupted print job).

So after power on and G28 homing, do the leadscrew adjustment. Repeat it until you're happy with its accuracy (or use the conditional gcode macro I linked earlier). The bed level should be repeatable and accurate, so running a full bed mesh should be unnecessary. I'd usually do a central G30 (probe to set Z0) afterwards, too, but that's in my start.gcode too. If needed, then create a bed mesh for the bed at the target temperature. Save this, and load it the next time you turn on the printer after you've done the leadscrew adjustment.

Then, get printing!

Ian

Dr_Ju_Ju

I'm getting closer.... and I'm already doing lots of printing on my main machine, an old Prusa i3 MK2s, but it just works....

One problem I've got at the moment, is getting some decent PETg as everyone has shut up shop, & I won't waste money on the crap from eBay, and now also Amazon....

Danal

@Dr_Ju_Ju said in 3 Motor Z axis Automatic bed levelling using G32 RRF 3.01-rc3:

which appears to throw things all out...

If this has never worked for you before, it is possible that every time you run it, bed level will get WORSE. You can literally see this with your eyes after just one or two runs.

If this happens, your motors are plugged into the drivers in the wrong order. It can be very difficult to describe in words how to get the order correct. Basically, they must be in the same order, physically, as the drivers specified in M584. In my CoreXY:

M584 X0 Y1 U2 Z3:4:5        ; X and Y for CoreXY.  U for toolchanger lock. Z has three drivers for kinematic bed suspension. 
M584 E1.0:1.1:2.0:2.1       ; Extruders for four tools.

Three is "front left", four is "back middle" and five is "front right". For me. But "front back right left" are all relative... so just try it different ways. Until it works.

Summary: If G32 makes bed level worse instead of better, change the order of motors to plugs (power off!) until it works correctly.

Dr_Ju_Ju

Thanks, everything moves correctly & can even print ok, so I'm back to swapping motors around & re-configuring....

ROFL I may just forget it & manually set up, in the end it may well be quicker....

Another thought, instead of modifying config.g, make changes to the probing order in bed.g ?? I'll play....

Danal

@Dr_Ju_Ju said in 3 Motor Z axis Automatic bed levelling using G32 RRF 3.01-rc3:

in the end it may well be quicker....

Not when you do it a hundred times over weeks or months. And, the printer will do it to the repeatability limits of the probe.

Danal

@Dr_Ju_Ju said in 3 Motor Z axis Automatic bed levelling using G32 RRF 3.01-rc3:

modifying config.g, make changes to the probing order in bed.g

Don't change config.g, nor the bed.g. Change plugs.

Physical plug ordering matching M584 matters. Probing order in bed.g does not.

Dr_Ju_Ju

@Danal Back to it this Morning & thanks, & yes just needed to swap 2 motor connectors....

I also see what you mean, that the process needs to be run multiple times, as I'm finding that the system makes a change but doesn't quite get it right, so subsequent runs get things closer.....

Methinks the process should be more like the process used for Auto Focusing Telescopes (another hobby of mine) where the process goes back and forth through the focus point, till the optimum setting is found...

Lasko

Hello,
I have a similar problem.
I have configured a BL-Touch Z-Probe using "M574 Z1 S2"
and I am trying to to 3 Point Bed Levelling via the "G32" command.
My bed.g:

M402
G1 X20 Y60 F1400
G28 Z ; home
G30 P0 X20 Y60 Z-99999 H0		; probe at point 1
G30 P1 X40 Y100 Z-99999	H0	; probe at point 2
G30 P2 X60 Y60 Z-99999 S3 H0	; probe at point 3 and calibrate the 3 z motors

Doing this, I only get:

Warning: 3/4-point bed compensation is deprecated and will be removed in a future firmware release. Please use G29 mesh bed compensation instead.
Bed equation fits points [20.0, 60.0, -4.305] [40.0, 100.0, -6.194] [60.0, 60.0, -5.399]

My M678 looks like this:

M671 X-396:171:-54 Y--86,82:235,88:-86,82 S5	   ; Koordinaten der drei Z-Achsen

So S is set to 5mm. I want the bed to physically level itself instead of only giving me this console message.

Thank you already,
Lasko

fcwilt

Hi,

I cannot make sense out of your bed.g file and your M671 command.

What are the X and Y axis min/max values?

Do you have a diagram showing the position of your lead screws in relation to the bed?

Frederick

Lasko

@fcwilt Thank you for your response,

i just noticed that I used commata instead of decimal points at the M671 command, what could be problematic...
The x-Coordiantes of the leadscrews are +396mm, +171mm and -54 mm. The y-Coordinates of the leadscrews are -86.82mm, +235,88mm and -86.82mm. The S parameter allows height correction up to 5mm per leadscrew.

This is my config.g

; General preferences
G90                                            ; send absolute coordinates...
M83                                            ; ...but relative extruder moves
M550 P"My Printer"                             ; set printer name


; Network
M552 S1                                        ; enable network
M586 P0 S1                                     ; enable HTTP
M586 P1 S0                                     ; disable FTP
M586 P2 S0                                     ; disable Telnet

; Drives
M569 P0 S1                                     ; physical drive 0 goes forwards		(X-Motor)
M569 P1 S1                                     ; physical drive 1 goes forwards		(Y-Motor)
M569 P2 S1                                     ; physical drive 2 goes forwards		(Z-Motor front left)
M569 P3 S1                                     ; physical drive 3 goes forwards		(Z-Motor back mid)
M569 P4 S1									   ; physical drive 4 goes forwards		(Z-Motor front right)
M569 P5 S1									   ; physical drive 5 goes forwards		(Extruder1)
M584 X0 Y1 Z2:3:4 E5                           ; set drive mapping 					(0-X, 1-Y, 2,3,4-Z, 5-E)

M669 K1                                        ; select CoreXY mode		(Muss nach M584 kommen, da dort neue Achsen definiert werden)

M671 X-396:171:-54 Y--86,82:235,88:-86,82 S5  ; Coordiantes of the three Z-Leadscrews

M350 X16 Y16 Z16 E16 I1                        ; configure microstepping with interpolation
M92 X160.00 Y160.00 Z1600 E420.00              ; set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00            ; set maximum instantaneous speed changes (mm/min)
M203 X3000.00 Y3000.00 Z100.00 E1200.00        ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00            ; set accelerations (mm/s^2)
M906 X1330 Y1330 Z1330 E800 I30                ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                        ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1                               ; set axis minima
M208 X320 Y272 Z300 S0                         ; set axis maxima

; Endstops
M574 X1 S1 P"xstop"                            ; configure active-high endstop for low end on X via pin xstop
M574 Y1 S1 P"ystop"                            ; configure active-high endstop for low end on Y via pin ystop
M574 Z1 S1 P"zstop+e0stop+e1stop"              ; configure active-high endstops for low end on Z via pin zstop

; Z-Probe
M558 P9 C"^zprobe.in" H10 F150 T2000           ; BL-Touch Implementation: Set Input Pin
M950 S2 C"duex.pwm5"						   ; BL-Touch Implementation: Set PWM Pin 
G31 X0 Y-47.53 Z2.7 P25                        ; BL-Touch Implementation: Set Z probe trigger value, offset and trigger height
M557 X25:105 Y25:105 S20                         ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0                          ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00                               ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                        ; map heated bed to heater 0
M143 H0 S120                                   ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" T100000 B4138  ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                           ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00                               ; disable bang-bang mode for heater  and set PWM limit

; Fans
M950 F0 C"fan0" Q500                           ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1                                 ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"fan1" Q500                           ; create fan 1 on pin fan1 and set its frequency
M106 P1 S1 H1 T45                              ; set fan 1 value. Thermostatic control is turned on

; Tools
M563 P0 D0 H1 F0                               ; define tool 0
G10 P0 X0 Y0 Z0                                ; set tool 0 axis offsets
G10 P0 R0 S0                                   ; set initial tool 0 active and standby temperatures to 0C

Before running my bed.g file, I home every axis with the opctical endstops at every leadscrew. Because this is not that exact, I want to level the bed using the BL-Touch afterwards. To Do this, i reconfig the endstop definition like this:

M574 Z1 P"nil"              ; deactivate leadscrew endstops
M574 Z1 S2		 	; Z1: Enstop at low end, S2: Using Z-Probe

After that is done, i run my bed.g

I hope you understand better what I did there now

Greetings,
Lasko

fcwilt

Hi,

In the M671 command you have a hyphen after the X and the Y. Why is that?

I don't know if commas are allowed in place of decimal points.

And unless I am confused there is no reason to disable your Z end stops to use the Z probe for auto bed leveling.

I didn't when I experimented with auto bed leveling and it all worked fine.

Frederick

Phaedrux

@Lasko Please create a new thread for your issue rather than tacking on to the end of someone else's solved issue.

Lasko

@Phaedrux
I would do it, but my problem got solved by @frederikv

The problem was the commata and the "-" in the M671 command

I chnaged a lot of code because it didn't work as I wanted for a long time. Thank you @frederikv for the Help!

Greetings,
Lasko