Stall detection fails after calibrating steps/mm

[Jaran]

Hello! I have been doing some calibrations on my CoreXY printer and I have ran into some issues with my sensorless homing setup.

I simply can't get the stall detection to work after changing the steps/mm on each motor for X and Y.

I used this before the calibration:

M92 X80.00 Y80.00 Z400.00 E2771.50

And changed it to this:

M92 X79.24 Y79.64 Z400.00 E2771.50

Stall detection settings:

M915 X Y S3 F0 H300 R0

The stall detection works perfect with 80 steps/mm but with the lower ones(79.**) does not make the stall detection trigger at all. I have tried to change up the S parameter all the way down to -50 but there are no visible changes. The motors drag the extruder to the end of its axis and the belts start slipping.

I can't find anything about this in the limitations section of stall detection. Is there anything im missing here?

Thanks!

[dc42]

What speed do you use in the homing move? How does the minimum speed for stall detection reported by M915 compare with that speed?

[Jaran]

@dc42 Im running it on 3600.

My homing file looks like this:

; homeall.g
; called to home all axes
;
 
M400                    	; make sure everything has stopped before we make changes
M913 X50 Y50	       		; reduce motor current to 50% to prevent belts slipping
G91                     	; use relative positioning
G1 S1 X-400	F3600	 		; move back 400mm, stopping at the endstop
G1 X5	           			; move away from home
G1 S1 Y-400 F3600		 	; move back 400mm, stopping at the endstop
G1 Y5	           			; move away from home
G1 S1 X-400	F3600			; move towards axis minimum
G1 S1 Y-400	F3600			; move towards axis minimum 
G1 X5 Y60	                ; move away from home
G92 X0 Y0					; set coordinates to 0,0
M400                    	; make sure everything has stopped before we reset the motor currents
M913 X100 Y100		     	; motor currents back to normal
 
;G90                     	; absolute positioning
;G1 X0 Y60 F6000          	; go to first bed probe point and home Z
;G30                     	; home Z by probing the bed
 

M915 reports:

M915
Driver 0: stall threshold 3, filter off, steps/sec 300, coolstep 0, action: none
Driver 1: stall threshold 3, filter off, steps/sec 300, coolstep 0, action: none
Driver 2: stall threshold 1, filter off, steps/sec 200, coolstep 0, action: none
Driver 3: stall threshold 1, filter off, steps/sec 200, coolstep 0, action: none
Driver 4: stall threshold 1, filter off, steps/sec 200, coolstep 0, action: none

[dc42]

You are running older firmware, so M915 is not translating the full steps/sec into mm/sec. However, we can do that by hand. Assuming you are using x16 microstepping, 300 full steps/sec is 4800 microsteps/sec, divided by 80 steps/mm is 60 mm/sec, times 60 is 3600 mm/min. So your homing speed is exactly the same as the minimum stall detection speed. When you reduce the steps/mm, the minimum stall detection speed is slightly higher than your homing speed.

So you need to reduce the M915 H parameter.

[Jaran]

@dc42 I will update the firmware right away. Been a while sinse I updated last.

Thanks alot for the explanation. You were 100% right! I was a bit too quick to overlook that

It triggered right away when I reduced the H parameter.

Thanks again