Homing Failure with Damage
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I'm confused and concerned because for the first time in years, my nozzle hit the bed, HARD and drilled a hole right through my 2mm PEI sheet, and I don't know why. I'm hoping someone can give me a clue.
I don't see why this should affect it, but a few weeks ago I reduced the probing dive depth to 2mm in config.g:
M558 P9 C"zprobe.in" H2 R1 F25:10 T5000 A5 S0.03 B0
I don't see how this could cause this but since it has to do with nozzle height and it was recent I thought I'd mention it.The sequence of events was pretty simple: I turned the machine off last night with the nozzle at 1mm from the bed after doing PID autotuning. This morning I turned it on and the BLTouch tried to do it's self-test but hit the bed. My homeall.g starts with this to reset the probe in cases like this:
M280 P0 S160
The next command in homeall.g is a relative move of +5mm, so I did a home all. The nozzle went straight down and kept pushing until I turned off the power. When I turned it back on I used G1 H2 to move up, which worked, once I had popped the PEI sheet out of the hole the nozzle had buried itself in!I totally can't even think of what made this happen, since the first move of a home all should have been to "raise the nozzle" (lower the bed) up to about 6mm.
Any suggestions how to troublshoot this so I can prevent it happening again are appreciated. Or maybe it's obvious and I'm missing it.
; homeall file for use with dc42 Duet firmware on CoreXY printers ; This file assumes the endstop switches are at the low end of each axis. ; Reverse the X and Y movement for high-end switches. ; Adjust the bed upper and lower limits in config.g (M208 commands) to get the correct homing positions M280 P0 S160 ; Reset BLTouch in case of "already triggered" error G91 ; relative mode G1 Z5 H2 F400 G1 H1 X-310 Y-310 F1200 ; course home X or Y G1 H1 X-310 ; course home X G1 H1 Y-310 ; course home Y G1 X4 Y4 F1200 ; move away from the endstops G1 H1 X-10 ; fine home X G1 H1 Y-10 ; fine home Y ; If you are using a microswitch for Z homing, insert similar code for the Z axis here, ; but use lower feed rates suitable for your Z axis. G90 ; back to absolute mode ; If you homed the Z axis using an endstop switch, you can insert a G92 command here to correct the height. ; The following code assumes you are using a Z probe to do Z homing. Remove it if you are using a microswitch. ; Adjust the XY coordinates in the following to place the Z probe over a suitable spot, ; preferably near the centre of the bed if your Z probe supports that G91 G1 Z5 F200 H2 G90 G1 X150 Y150 F6000 M558 A1 F400 G30 M558 A5 F30 G30 ; This file leaves the head at the zprobe trigger height so that you can slip a piece of paper under it and then do G0 Z0 to check the height. ; If you prefer to send the printer to X0Y0Z0, un-comment the following lines ;G1 X0 Y0 F5000 ;G1 Z0 -
@DonStauffer I'd suggest that you move the BLTouch reset to be after you have lowered the bed (that way if part of the reset involves any sort of probe deployment it should be safe). I'd also suggest that you lower the motor current when performing the probe, just in case something goes wrong with the probe.
