G1 H3 and M500 P31 to save multiple endstop on combined Z axis

KipK

Hi there

3.1.1 firmware here
So I have a printer working well with 3 point auto bed level.
I use a BL touch for probing and 3 optical endstops on Z max.

Homing sequence go to Z max on each endstop. Then when print start It does the 3 point bed leveling, and then probe the center.

I'm very glad of this setup works really well.

However, I wonder how I can setup a resume after power failure as I do with my one z axis setup.

I've tried
G1 Z400 F300 H3
M500 P31

But it only save the Z max as a global axis not one value for each motor

Ideally it should save z max for each separated Z,
Then on resume print no need to reprobe ( what is impossible in this case ) , it should restart with the correct previous bias recorded.

Is there another way of achieve this yet?

Phaedrux

You would need to split the Z axis into separate axis and save their positions independently I think.

If you tram the bed surface using the probe first, you should be able to adjust the Z max endstop positions such that they could be used to relevel on a power loss resume.

KipK

Thanks. I was not sure if I can still split Z axis on 3.x as with firmware 2.x
That should clearly work if so.

Well, Reprap 3 made this cleaner by not splitting, perhaps someday it could be interesting to add a way to save and restore leveling.

Adding a new flag to M500 P31 for saving multiple endstop position for one axis.

Phaedrux

Yes RRF3 made it simpler to use multiple endstops on a single axis, but I don't think that extends to measuring of each endstop position. Perhaps
I'll edit your title and move this to the firmware wishlist for evaluation.

KipK

Fell free to move the thread

I wonder what other interest than failure resume there is to use multiple Z max endstops instead of direct probing zMin?

Phaedrux

Using Zmax endstops has the disadvantage that it doesn't actually measure the current position of the bed surface, so it's a less attractive option outside of power loss recovery where a print is still on the bed.

KipK

Here is the different procedure I imagine, can you confirm the logic is good ?

Configure resume level macro ( macro started manually, not done at each print )

homeZ min with probe
level Z min
probe Z min
separate Z axis
home Z max H3 per Z axis with endstops
save M500 P31

start print:

home Z min with probe
level Z min
probe z min
print start

resume print after failure:

separate Z axis
home zmax H1 per Z axis with endstops
up bed 5mm
blind level:
. calculate motor 2 and 3 bias ( 1 is reference ) and move accordingly
G1 Z2 ( mz1max - mz2max );
G1 Z3 ( mz1max - mz3max );
go to previous saved position
resume print

Phaedrux

That sounds logical.

KipK

I'm on my way to try that.
If it was considered to improve for Reprap 3, method could be contained like this:

Record zmax:
G1 H3 Z400 ; as we have 3 independant motor will get zmax of each leadscrew.
M500 P31; save those values
Resume print:
G28 Z (home using zmax )
G91; relative moves
G1 Z-15; up bed 15mm
Gxx xxx ; restore saved Z bias

KipK

So how I'm doing this correcctly using conditionnal gcode ?

G1 U(move.axes[2].max-move.axes[3].max) ; restore U bias
G1 V(move.axes[2].max - move.axes[4].max) ; restore V bias
reports me errors

edit: sorry, found the information , brace were missing.

G1 U{move.axes[2].max-move.axes[3].max}
G1 V{move.axes[2].max - move.axes[4].max}

KipK

Seems tehre's something wrong on my logic.
Here is wht I've made:

Config.g:

M584 X1 Y0 Z6:8:7 U8 V7 P3 E4; three Z motors connected to driver outputs 6, 8, 7
M350 X16 Y16 Z16 U16 V16 E16 I1                                     ; configure microstepping with interpolation
M92 X200.00 Y200.00 Z400.00 U400 V400 E402.00                         ; set steps per mm
M574 Z2 S1 P"duex.e2stop";	set endstops for Z
M574 U2 S1 P"duex.e6stop";	set endstops for U
M574 V2 S1 P"duex.e5stop";	set endstops for V
; Leadscrews
M671 X-214:214:214 Y0:-121:118 S10 						    ; leadscrews at middle left, front right, and rear right

HomeZ.g:

if (!move.axes[0].homed)
  M98 P"homex.g" ; need to home X Y first 

if sensors.endstops[2].triggered 
	G91;
	G1 Z-15 F1000 H2 ; move bed up a bit
	M400			 ; wait for move to finish

M220 S100		; set back speed to 100%
G90
G1 X0 Y0 F10000; move head to the center
G30; probe Z = 0
G32; level bed
G1 X0 Y0 F10000;
G30; probe Z again
M400			; wait for move to finish

Macro to calibrate each Zmax:

M208 S1 Z-3;	Allow z to be negative
G90; 
G1 X0 Y0  F10000; 		go to the center
G1 Z30 F1000;
G30		;		 probe bed and set z=0
G32		; 		start 3 point bed leveling
G1 X0 Y0 F10000;
G30     ;	Probe for Z=0
G91		; relative mode
G1 Z10 F800				; raise nozzle
M584 Z6 U8 V7 P5 ; split z axis
;G92 U10 V10; set U V axis to 10 as Z
 
G1 H3 Z370 U370 V370 F1000; move Z, U, V down until endstops trigger and get new z limits

M500 P31		; save new z height
M584 Z6:8:7 P3 ; unsplit z axis
G90

Z max values are correctly saved for each z axis:

M208 S0 Z341.22 U314.82 V316.30

Then after a powerfailure I have a homeZmax.g macro :


if sensors.endstops[2].triggered || sensors.endstops[3].triggered || sensors.endstops[4].triggered
	G91;
	G1 Z-20 F1000 H2 ; move bed up a bit
	M400			 ; wait for move to finish

M220 S100						; set back speed to 100%
G91
M584 Z6 U8 V7 P5 				; split z axis
G1 H1 Z370 U370 V370 F1000		; move Z, U, V down until endstops trigger
G1 Z-10 U-10 V-10 F800      		; get back 10mm
G1 H1 Z15 U15 V15 F300  			; go to zmax slowly

G1 Z-30 U-30 V-30 F1000;		 			up bed 30mm

; Blind leveling
G1 U{move.axes[2].max - move.axes[3].max} V{move.axes[2].max - move.axes[4].max}; restore U V bias
M584 Z6:8:7 P3 ;							unsplit z axis
G90

Problem here is bed is completly tiled.
I don't get now where I've failed

KipK

Found it.

Seems I have to set also U and V to 0 reference after a Z probe.

Now it works.

macro calibrate Z max for each axis:

M208 S1 Z-3;	Allow z to be negative
G90; 
G1 X0 Y0  F10000; 		go to the center
G1 Z30 F1000;
G30		;		 probe bed and set z=0
G32		; 		start 3 point bed leveling
G1 X0 Y0 F10000;
G30     ;	Probe for Z=0
G1 Z10 F800				; raise nozzle
M584 Z6 U8 V7 P5 ; split z axis
G92 U10 V10; set U V axis to 10 as Z
G91		; relative mode
 
G1 H3 Z370 U370 V370 F1000; move Z, U, V down until endstops trigger and get new z limits

M500 P31		; save new z height
M584 Z6:8:7 P3 ; unsplit z axis
G90

Have to say, object models and conditionnal gcode is a killer feature.