Y Axis homing in reverse direction if acceleration increased

tsitalon1

So I've spent a good part of my day trying different combinations with the 0.9º steppers.

Setting my homing-all file to the below was the only real way I could get it to consitently home:

M913 X25 Y25		; reduce motor current to 25% to prevent belts slipping
G91                     ; relative positioning
G1 H2 Z5 F4000          ; lift Z relative to current position
G1 H1 X-333 F5000        ; home X axis
G1 H1 Y-333 F5000          ; home Y axis
G1 X5 Y30 F4000          ; go back a few mm
;G90                     ; absolute positioning
G30                     ; home Z by probing the bed
M913 X100 Y100

As soon as I go over 25% on the Y axis, it starts moving the wrong way on the Y axis.

But here's the kicker, even though I seem to have gotten it 100% consistent during homing, all that goes compltely out the window if I actual print something..

here's how that goes:

power on printer
Home-all
Print
once print is done I click print again
this time during the homing sequence, it ignores the X movement and only initiates Y towards the front of the printer.

I don't think it matters, but here is my end code in my slicer:

M915 X Y S2 F0 R0		; Stall detection - disable reporting
M104 S0			;extruder heater off
M140 S0			;heated bed heater off (if you have it)
G91
G1 H2 Z5 F4000
G90
G0 Z5 X290 Y290 F3000
M84

Phaedrux

And what M915 do you have set in config.g? What did you calculate for the H value?

o_lampe

@tsitalon1
In your end code you disable stall detection and also use M84 to switch off the motors. So the next homing will fail without re-enabling stall detection in your homeall.g.

deckingman

In addition to what others have said, motor temperature will have an effect on stall detection. So it's highly likely that the settings which work when the motors are cool, will not work when the motors are hot (after a print for example). Sensorless homing was "invented" by Prusa with the sole purpose of negating the need to fit switches thus saving a dollar or two on cost. It will never be as accurate or reliable as a simple switch (regardless of how expensive the control board is).

engikeneer

@tsitalon1 do you also have some acceleration control in your slicer? Could changing the acceleration limits you originally put in your config when running a print.

If it helps, I have a macro that sets all my motor parameters (steps, speed, accel, jerk current etc). I call this from config.g on startup, and can also call it from any other script (e.g. homing) to make sure that I know the machine settings haven't changed. Even better, I can reduce accel & jerk during homing, then reset it back so my config level with one line, and if I want to change my machine setup, I only need to change it in one place (the macro)

dc42

@tsitalon1 said in Y Axis homing in reverse direction if acceleration increased:

Setting my homing-all file to the below was the only real way I could get it to consitently home:
M913 X25 Y25 ; reduce motor current to 25% to prevent belts slipping G91 ; relative positioning G1 H2 Z5 F4000 ; lift Z relative to current position G1 H1 X-333 F5000 ; home X axis G1 H1 Y-333 F5000 ; home Y axis G1 X5 Y30 F4000 ; go back a few mm ;G90 ; absolute positioning G30 ; home Z by probing the bed M913 X100 Y100
As soon as I go over 25% on the Y axis, it starts moving the wrong way on the Y axis.

The title of this thread is "Y Axis homing in reverse direction if acceleration increased". So have you tried reducing acceleration at the start of homeall.g, and restoring it at the end, as I suggested in my earlier response?
A common issue with stall-detect homing is the motors registering as stalled immediately, so that there is no movement. Is this one of the problems you are having? If so, the solution is to back off a little before the homing move.

My CoreXY machine uses this homex.g file:

G91 			; use relative positioning
G1 H2 X0.5 Y0.5 F10000	; energise motors to ensure they are not stalled
M400 			; make sure everything has stopped before we change the motor currents
M913 X20 Y20 		; drop motor currents to 20%
G1 H2 Z3 F5000		; lift Z 3mm
G1 H1 X-400 F3000 	; move left 400mm, stopping at the endstop
G1 H2 X2 Y2 F2000 	; move away from end
G1 H1 X-400 F3000 	; repeat the homing move because it doesn't always work first time
G1 H2 X2 Y2 F2000 	; move away from end
G1 H2 Z-3 F1200		; lower Z
G90 			; back to absolute positioning
M400 			; make sure everything has stopped before we reset the motor currents
M913 X100 Y100 		; motor currents back to 100%

The M400 commands are not needed when using recent firmware.

tsitalon1

Thank you guys for your help

So finally think I got it all straight, every time I think I had a consistent homing sequence, even without printing, later on in the day it would prove me wrong.

I finally settled on a very low current and a filtering of S3 in my M915 command in config.g

So here is my final configuration:

Config.g

; Drives
M569 P0 S1                           ; Drive 0 goes forwards
M569 P1 S1                           ; Drive 1 goes forwards
M569 P2 S1                           ; Drive 2 goes forwards
M569 P3 S1                           ; Drive 3 goes forwards

M584 Y4

M350 X16 Y16 Z16 E16 I1              ; Configure microstepping with interpolation
M92 X160 Y160 Z403 E820              ; Set steps per mm
M566 X1000 Y1000 Z200 E900           ; Set maximum instantaneous speed changes (mm/min)
M203 X18000 Y18000 Z1800 E18000      ; Set maximum speeds (mm/min)
M201 X2200 Y2200 Z200 E3500          ; Set accelerations (mm/s^2)
M906 X1300 Y1300 Z1000 E700 I25      ; Set motor currents (mA) and motor idle factor in per cent
M84 S10                              ; Set idle timeout

; Axis Limits
M208 X3 Y0 Z0 S1                                    ; Set axis minima
M208 X310 Y312 Z437 S0                              ; Set axis maxima

; Endstops
M591 D0 P2 C"e0stop" S1  			    ; filament monitor connected to E0 endstop
M574 X1 Y1 S3					    ; configure sensorless endstop for low XY
M915 X Y S3 F0 R0

HomeAll.g

M913 X20 Y20		; reduce motor current to 20% to prevent belts slipping
G91                     ; relative positioning
G1 H2 Z5 F4000          ; lift Z relative to current position
G1 H1 X-333 F4700       ; home X axis
G1 H1 Y-333 F4700       ; home Y axis
G1 X5 Y30 F4000         ; go back a few mm
G30                     ; home Z by probing the bed
M913 X100 Y100

I also removed all M915 commands from both my start and end slicer gcode config. I was playing around with stall detection and forgot I had some M915 commands in there.

So I'm still not sure why I need such low current in my homing files, but I have tested this about 100 times, after a fresh power-up, both hot and cold, and printing 25 models back to back.

I'm still mapping E1 to Y axis, but I'll probably revert that back to normal after a few more days of testing.

DC42 - yes, after a print job when it would park the nozzle in the far right corner, on the next homing sequence it would trigger X as stalled and move only the Y axis.

I'll play around with your suggestions, but at this point I am satisfied and all seems to be working well.

I still find it VERY odd that moving the homing current above 20% will not trigger a stall, but instead make the Y axis motor spin in the wrong direction, but that does not happen during normal printing.. I don't understand how/why that happens..

gloomyandy

@tsitalon1 You might want to switch back to absolute positioning after you have homed. It can get very confusing otherwise.

tsitalon1

@gloomyandy said in Y Axis homing in reverse direction if acceleration increased:

@tsitalon1 You might want to switch back to absolute positioning after you have homed. It can get very confusing otherwise.

I have it in my start gcode in my slicer, but I will make the change, thank you!

dc42

It will restore the original absolute/relative mode when the macro finishes. But good practice to restore axis motion to absolute anyway.