Nozzle crashed into bed while homing - can this be avoided?
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@pandaym said in Nozzle crashed into bed while homing - can this be avoided?:
I think it might be best to not try and fix X/Y homing before this other thing is fixed, as I will have a hard time figuring out if it works then.
I disagree. I think X and Y homing must be reliable regardless because the Z homing depends on being able to accurately place the probe where you want it.
For the probe not deploying the pin it's possible there is a wiring issue. The BLTouch has a lot of wires and the crimps are often a cause of problems, so definitely double check your wiring.
G31 P500 X1 Y24 Z0.80I also note that your trigger height is very low. Typically, when the BLtouch is mounted correctly, the base of the probe body is ~8mm above the nozzle tip, which leads to a trigger height of ~2mm. This is the sweet spot for accurate and reliable results.By the way, what version of BLTouch is it? Is it genuine or a clone?
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@Phaedrux said in Nozzle crashed into bed while homing - can this be avoided?:
@pandaym said in Nozzle crashed into bed while homing - can this be avoided?:
I think it might be best to not try and fix X/Y homing before this other thing is fixed, as I will have a hard time figuring out if it works then.
I disagree. I think X and Y homing must be reliable regardless because the Z homing depends on being able to accurately place the probe where you want it.
For the probe not deploying the pin it's possible there is a wiring issue. The BLTouch has a lot of wires and the crimps are often a cause of problems, so definitely double check your wiring.
G31 P500 X1 Y24 Z0.80I also note that your trigger height is very low. Typically, when the BLtouch is mounted correctly, the base of the probe body is ~8mm above the nozzle tip, which leads to a trigger height of ~2mm. This is the sweet spot for accurate and reliable results.By the way, what version of BLTouch is it? Is it genuine or a clone?
I understand your point about the X and Y. I just assumed that it did not really matter where on the build plate the probe were for probing Z, as I am only in this phase of the build.
There truly are a lot of wires that has to be done right on the BLTouch. I checked my wiring and crimping and it all looks good.
I reconfigured a bit like you suggested, and what I noticed was that it seemed like true bed levelling was causing the issues. I therefore went through my configs and currently have them configured like this:
homex.g:
; homex.g ; called to home the X axis ; ;Prepare for homing M400 ; Finishes all current moves and and thus clears the buffer G91 ; Set to Relative Positioning G1 Z5 F1200 H2 ; Move the bed down slightly ;Prepare for sensorless homing M913 X50 Y50 ; Set motor currents to 50% M201 X500 Y500 ; Set acceleration on X/Y to 500 to improve reliability of stall detection M915 X Y S2 R0 F0 ; Configure motor stall detection on X and Y as they work together on corexy - sensitivity 2, don’t take action, don’t filter, 400steps/sec ;Sensorless homing X G1 H1 X-300 F4000 ; Move 300 mm left, stopping at the endstop - Speed is 4000 which is about twice the Hmin due to two motors working together on Corexy G1 X30 F1200 ; Move 30 mm out from Xmin ;End of sensorless homing M913 X100 Y100 ; Set motor currents back to 100% M201 X2000 Y2000 ; Set acceleration back to 2000 ;End of homing G90 ; Set to Absolute Positioninghomey.g:
; homey.g ; called to home the Y axis ; ;Prepare for homing M400 ; Finishes all current moves and and thus clears the buffer G91 ; Set to Relative Positioning G1 Z5 F1200 H2 ; Move the bed down slightly ;Prepare for sensorless homing M913 X50 Y50 ; Set motor currents to 50% M201 X500 Y500 ; Set acceleration on X/Y to 500 to improve reliability of stall detection M915 X Y S2 R0 F0 ; Configure motor stall detection on X and Y as they work together on corexy - sensitivity 2, don’t take action, don’t filter, 400steps/sec ;Sensorless homing Y G1 H1 Y-300 F4000 ; Move 300 mm back, stopping at the endstop - Speed is 4000 which is about twice the Hmin due to two motors working together on Corexy G1 Y30 F1200 ; Move 30 mm out from Xmin ;End of sensorless homing M913 X100 Y100 ; Set motor currents back to 100% M201 X2000 Y2000 ; Set acceleration back to 2000 ;End of homing G90 ; Ensure we are in Absolute Positioninghomez.g:
; homez.g ; called to home the Z axis ; ;Prepare for homing M400 ; Finishes all current moves and and thus clears the buffer G91 ; Set to Relative Positioning G1 Z5 F1200 H2 ; Move the bed down slightly G90 ; Set to Absolute Positioning ;Probe Z G1 X150 Y117 F12000 ; Move probe to middle of bed M558 F500 ; Set the first probing speed G30 ; First Z probe M558 F50 ; Set a slower probing speed G30 ; Second Z probe ;End of homing G90 ; Set to Absolute Positioninghomeall.g:
; homeall.g ; called to home all axes ;Prepare for homing M400 ; Finishes all current moves and and thus clears the buffer G91 ; Set to Relative Positioning G1 Z5 F1200 H2 ; Move the bed down slightly ;Prepare for sensorless homing M913 X50 Y50 ; Set motor currents to 50% M201 X500 Y500 ; Set acceleration on X/Y to 500 to improve reliability of stall detection M915 X Y S2 R0 F0 ; Configure motor stall detection on X and Y as they work together on corexy - sensitivity 2, don’t take action, don’t filter, 400steps/sec ;Sensorless homing X G1 H1 X-300 F4000 ; Move 300 mm left, stopping at the endstop - Speed is 4000 which is about twice the Hmin due to two motors working together on Corexy G1 X30 F1200 ; Move 30 mm out from Xmin ;Sensorless homing Y G1 H1 Y-300 F4000 ; Move 300 mm back, stopping at the endstop - Speed is 4000 which is about twice the Hmin due to two motors working together on Corexy G1 Y30 F1200 ; Move 30 mm out from Xmin ;End of sensorless homing M913 X100 Y100 ; Set motor currents back to 100% M201 X2000 Y2000 ; Set acceleration back to 2000 G90 ; Set to Absolute Positioning ;BLTouch home Z G1 X150 Y117 F12000 ; Move probe to middle of bed M558 F500 ; Set the first probing speed G30 ; First Z probe M558 F50 ; Set a slower probing speed G30 ; Second Z probe ;End of homing G90 ; Ensure we are in Absolute Positioningbed.g:
; bed.g ; called to perform automatic bed compensation via G32 ; M561 ; Clear any bed transform M401 ; TEST!!! Deploy probe - deployprobe.g G30 P0 X35 Y173 Z-99999 ; Probe near front-left leadscrew G30 P1 X265 Y173 Z-99999 ; Probe near front-right leadscrew G30 P2 X150 Y290 Z-99999 S3 ; Probe near rear-center leadscrew and adjust bed parallel to corexy kinematics M402 ; TEST!!! Retract Probe - retractprobe.g G1 X20 Y20 F12000 ; Move close to homeFor the bed.g, I tried various things to see if the probe would deploy, and ended up finding this to work. I found this particular way of doing it in the same guide I used to set up my BLTouch. This is the guide I used.
So in response to your question about trigger height, I found the value in the same guide. It basically tells you to move the nozzle down all the way to the build plate and run:
G92 Z0 ; Tell the machine we are at Z=0 G1 Z10 ; Move Z 10 mm away from nozzle G30 S-1 ; The value you get here is the offset you put in G31.The guide also notes that as low a value as possible is best, which to me makes sense, as that will leave the most clearence under the nozzle when probing. I am not sure I understand why the trigger height in itself affects the accuracy or reliability, could you explain that?
I tried to measure the physical delta, and it is actually around 8mm. The Hemera carriage with BLtouch mount is one I downloaded off of thingiverse, so I did not design this delta myself.
Last thing, yes it is a genuine BLTouch v3.1. Only clone component on the printer are the linear rails.
So where do we go from here?
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As you recommended, I also tuned the sensorless homing.
I think the main reason was that I had no H value on the M915 commands. I am running 0.9 motors, so I set that to 400 and sensitivity to 1, and now that part at least seems to work good:
https://www.youtube.com/watch?v=tnWOXK7N014 -
So while waiting to see what you guys think is going on, I went ahead and did a test print. Seems I have more issues
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I wonder if part of the issue is binding on the axis...
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@Phaedrux said in Nozzle crashed into bed while homing - can this be avoided?:
I wonder if part of the issue is binding on the axis...
I don’t think there’s any binding going on. I completely disassembled, flushed, greased and carefully assembled all the linear rails. I spent a lot of time with squares and calipers during the build and would say that the machine is very mechanically sound. That is my strong side, so I am more concerned with electronics/firmware where I am still very challenged.
I just saw the other post with @dlc60 having 45 degree layer shifts. Mine are exactly 45 deg and exactly the same direction and distance between them. I wonder if we are seeing the same thing?
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@Phaedrux
I am trying to tune some different things right now, and it just happened again
It seems completely random! This time I know for sure that the X/Y homing when fine, but still the probe did not come out, and I just managed to stop it before crashing hard..
Console says:
19.6.2020 14.55.16 Error: Z probe was not triggered during probing move Error: Z probe was not triggered during probing move Error: Homing failed -
Alright you must check your BLTouch wiring for continuity. The crimps are notorious failure points. This is by far the most likely problem at this point.
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@Phaedrux said in Nozzle crashed into bed while homing - can this be avoided?:
Alright you must check your BLTouch wiring for continuity. The crimps are notorious failure points. This is by far the most likely problem at this point.
Alright I ran through it.
I got it wired uip to IO_7
Red wire runs to 5V_EXT - Continuity, measured ~2.2 ohm
Yellow wire runs to io7.out - Continuity, measured ~2.2 ohm
Brown and black wire run to GND - Continuity, measured ~2.2 ohm
White wire runs to io7.in - Continuity, measured ~2.2 ohmEarlier today I was doing a test print, and I noticed the red LED was flickering while it was printing. Afterwards I noticed that it was blinking after homing. So I looked it up on Google, and found something that I did not comprehend entirely, but it was someone talking about the probe thinking it is too close to the bed to be able to deploy. I rebooted the machine and noticed that BLTouch did not do it's self-test either. So I allowed movement without homing, lowered the bed a lot, rebooted, and when powering it back on, it did self-test again and constant red LED.
Don't know if the LED blinking observation has anything to do with this issue, but just wanted to mention it.
I do not know much about any of this, but I would have assumed that there were a safety measure in place that immediately stopped the Z movement for G30, in case an error is thrown that the BLTouch cannot deploy for whatever reason. Maybe I could code that into my homings to create a safety net for this issue till we hopefully solve it?
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Flashing red usually indicates error state if the self test is unable to successfully deploy and retract the probe or if the pin is blocked when trying to deploy. Could also be an intermittent wiring break depending on position.
As a precaution you can add the alarm release and pin retract command to the end of config.g and start of homeall to clear any errors just in case.
You can try and take the pin out of the probe and check it/clean it by removing the set screw on the top.
