HOMING ISSUES  

RE: HOMING ISSUES

This is the behavior for minutes before each print:

https://1drv.ms/v/c/08da0a76d6f37e2a/ESsHoBhGV5RNrpVxtYiF1XcByiozDtGxOtaGs0lfqtzWkw?e=yKlLNx

The print quality seems anyway good to me:

https://1drv.ms/i/c/08da0a76d6f37e2a/EYlUrElCU5pIsawBXN6MvzgBau5n3VszkfnB7hAvQav3ew?e=7aK0ot

RE:

Sounds like you’ve covered all of the reasonable actions.  Some people have reported that raising the bed prior to starting a print seems to reduce the amount of “corner humping”.  Have you tried that?  Hopefully Prusa will fix this with an update soon.

Best of luck.  Still waiting on my conversion kit.

RE: HOMING ISSUES

Try this custom "Start G-code", which disables the hotend heating for homing & probing:

https://forum.prusa3d.com/forum/postid/750771/

Apparently, the heater causes an EMI issue regarding the loadcell signals.
It's not perfect, since the nozzle drops from 170°C to about 120°C, depending on how many probing points are done, but for me, homing becomes fast (3x X+Y Stop hit), bed goes straight up against the nozzle, "nozzle cleaning", which is just a little rectangle probing is always successful and and each of the MBL probing points is only probed 1x, not 1-5x.

Due to the temperature drop, the MBL isn't as perfect, but I'm yet to see imperfect 1st layers, so it works for me.

Here's the Start G-code a bit better sorted, added comments and added heating back up between Nozzle Cleaning and MBL Probing. Also added heating back up between the MBL Probing and last probing near the purge area.

M17 ; enable steppers
M862.1 P[nozzle_diameter] A{(filament_abrasive[0] ? 1 : 0)} F{(nozzle_high_flow[0] ? 1 : 0)} ; nozzle check
M862.3 P "COREONE" ; printer model check
M862.5 P2 ; g-code level check
M862.6 P"Input shaper" ; FW feature check
M115 U6.3.2+10364

M555 X{(min(print_bed_max[0], first_layer_print_min[0] + 32) - 32)} Y{(max(0, first_layer_print_min[1]) - 4)} W{((min(print_bed_max[0], max(first_layer_print_min[0] + 32, first_layer_print_max[0])))) - ((min(print_bed_max[0], first_layer_print_min[0] + 32) - 32))} H{((first_layer_print_max[1])) - ((max(0, first_layer_print_min[1]) - 4))}

G90 ; use absolute coordinates
M83 ; extruder relative mode

{if chamber_minimal_temperature[initial_tool]!=0}
M140 S115 ; set bed temp for chamber heating
{else}
M140 S[first_layer_bed_temperature] ; set bed temp
{endif}

M109 R{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 25) : (filament_type[0] == "FLEX") ? 210 : 170)} ; wait for temp


M84 E ; turn off E motor

;custom G-code start
M104 S0 ; turn off temperature
;custom G-code end

G28 ; home all without mesh bed level

{if chamber_minimal_temperature[initial_tool]!=0}
; Min chamber temp section
M104 S{idle_temperature[initial_tool]} ; set idle temp
G1 Z10 F720 ; set bed position
G1 X242 Y-9 F4800 ; set print head position
M191 S{chamber_minimal_temperature[initial_tool]} ; wait for minimal chamber temp
M141 S{chamber_temperature[initial_tool]} ; set nominal chamber temp
M107 ; Fans off
M140 S[first_layer_bed_temperature] ; set bed temp
{else}
M141 S{chamber_temperature[initial_tool]} ; set nominal chamber temp
{endif}

{if first_layer_bed_temperature[initial_tool]<=60}M106 S70{endif}
G0 Z40 F10000
M104 T{initial_tool} S{if is_nil(idle_temperature[initial_tool])}100{else}{idle_temperature[initial_tool]}{endif}
M190 R[first_layer_bed_temperature] ; wait for bed temp
M107 ; Fans off

G29 G ; absorb heat

;custom G-code start
M109 R{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 25) : (filament_type[0] == "FLEX") ? 210 : 170)} ; wait for MBL temp
;custom G-code end

M302 S160 ; lower cold extrusion limit to 160C

{if filament_type[initial_tool]=="FLEX"}
G1 E-4 F2400 ; retraction
{else}
G1 E-2 F2400 ; retraction
{endif}

M84 E ; turn off E motor

;custom G-code start
M104 S0 ; turn off temperature ADDED BY ME
;custom G-code end

G29 P9 X208 Y-2.5 W32 H4 ; Nozzle Cleaning by probing a little rectangle

;custom G-code start
; Heat up again and then turn off for MBL
M109 R{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 25) : (filament_type[0] == "FLEX") ? 210 : 170)} ; wait for MBL temp
M104 S0 ; turn off temperature ADDED BY ME
;custom G-code end

;
; MBL
;
M84 E ; turn off E motor
G29 P1 ; invalidate mbl & probe print area

;custom G-code start
; Heat up again and then turn off for probing near purge place
M109 R{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 25) : (filament_type[0] == "FLEX") ? 210 : 170)} ; wait for MBL temp
M104 S0 ; turn off temperature
;custom G-code end

G29 P1 X150 Y0 W100 H20 C ; probe near purge place
G29 P3.2 ; interpolate mbl probes
G29 P3.13 ; extrapolate mbl outside probe area
G29 A ; activate mbl

; prepare for purge
M104 S{first_layer_temperature[0]}
G0 X249 Y-2.5 Z15 F4800 ; move away and ready for the purge
M109 S{first_layer_temperature[0]}

G92 E0
M569 S0 E ; set spreadcycle mode for extruder

;
; Extrude purge line
;
G92 E0 ; reset extruder position
G1 E{(filament_type[0] == "FLEX" ? 4 : 2)} F2400 ; deretraction after the initial one
G0 E5 X235 Z0.2 F500 ; purge
G0 X225 E4 F500 ; purge
G0 X215 E4 F650 ; purge
G0 X205 E4 F800 ; purge
G0 X202 Z0.05 F8000 ; wipe, move close to the bed
G0 X199 Z0.2 F8000 ; wipe, move quickly away from the bed

G92 E0
M221 S100 ; set flow to 100%

RE: HOMING ISSUES

I stupidly forgot:

Credits to everyone here: https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4596
And to @David.b36 https://forum.prusa3d.com/forum/profile/david-b36/

RE: HOMING ISSUES

Posted by: @raaz-2

Try this custom "Start G-code", which disables the hotend heating for homing & probing:

https://forum.prusa3d.com/forum/postid/750771/

Apparently, the heater causes an EMI issue regarding the loadcell signals.
It's not perfect, since the nozzle drops from 170°C to about 120°C, depending on how many probing points are done, but for me, homing becomes fast (3x X+Y Stop hit), bed goes straight up against the nozzle, "nozzle cleaning", which is just a little rectangle probing is always successful and and each of the MBL probing points is only probed 1x, not 1-5x.

I think this is the first time I read that the heater/load cell interference was also found to impact the X/Y homing behavior. Wasn't this issue (and the custom G-code workaround) always described in the context of Z homing only? It makes much more sense to me in that context, since Z homing is referenced to the Nextruder load cell, while I understand X/Y homing to use the stepper motors' StallGuard detection only.

Did you really confirm that the improved X/Y homing correlates with the heater G-code change? I'm not saying you are wrong, and it would be great if we have a fix that gives more stable X/Y homing to the affected printers. It just seems quite counter-intuitive that the heater would affect the stepper motor StallGuard too -- no share cable, ground bounce etc. there.

RE: HOMING ISSUES

Posted by: @jurgen-7

Posted by: @raaz-2

Try this custom "Start G-code", which disables the hotend heating for homing & probing:

https://forum.prusa3d.com/forum/postid/750771/

Apparently, the heater causes an EMI issue regarding the loadcell signals.
It's not perfect, since the nozzle drops from 170°C to about 120°C, depending on how many probing points are done, but for me, homing becomes fast (3x X+Y Stop hit), bed goes straight up against the nozzle, "nozzle cleaning", which is just a little rectangle probing is always successful and and each of the MBL probing points is only probed 1x, not 1-5x.

I think this is the first time I read that the heater/load cell interference was also found to impact the X/Y homing behavior. Wasn't this issue (and the custom G-code workaround) always described in the context of Z homing only? It makes much more sense to me in that context, since Z homing is referenced to the Nextruder load cell, while I understand X/Y homing to use the stepper motors' StallGuard detection only.

Did you really confirm that the improved X/Y homing correlates with the heater G-code change? I'm not saying you are wrong, and it would be great if we have a fix that gives more stable X/Y homing to the affected printers. It just seems quite counter-intuitive that the heater would affect the stepper motor StallGuard too -- no share cable, ground bounce etc. there.

I completely agree with you, but maybe Prusa also uses the loadcell to detect the end-stops, additionally to the StallGuard?
Or it only uses the StallGuard, but weird loadcell signals still cause the homing to "fail"?

I can just say, that I had longer XY-banging every now and then, but since I've put in the custom Start G-code, it didn't happen again, yet.
Might not be correlated though!

RE:

Dunno if its helps, but if you have done all the calibration distance, frequency checks and x / y tests manually and succesfully, then the last thing i can suggest is to go to that menu. The menu to go into the calibration option. There should be a "set ready " or something like that. Mine is in german. Activate that ( it goes grey ). Try again to print.

RE: HOMING ISSUES

Posted by: @raaz-2

 

Posted by: @jurgen-7

Posted by: @raaz-2

Try this custom "Start G-code", which disables the hotend heating for homing & probing:

https://forum.prusa3d.com/forum/postid/750771/

Apparently, the heater causes an EMI issue regarding the loadcell signals.
It's not perfect, since the nozzle drops from 170°C to about 120°C, depending on how many probing points are done, but for me, homing becomes fast (3x X+Y Stop hit), bed goes straight up against the nozzle, "nozzle cleaning", which is just a little rectangle probing is always successful and and each of the MBL probing points is only probed 1x, not 1-5x.

I think this is the first time I read that the heater/load cell interference was also found to impact the X/Y homing behavior. Wasn't this issue (and the custom G-code workaround) always described in the context of Z homing only? It makes much more sense to me in that context, since Z homing is referenced to the Nextruder load cell, while I understand X/Y homing to use the stepper motors' StallGuard detection only.

Did you really confirm that the improved X/Y homing correlates with the heater G-code change? I'm not saying you are wrong, and it would be great if we have a fix that gives more stable X/Y homing to the affected printers. It just seems quite counter-intuitive that the heater would affect the stepper motor StallGuard too -- no share cable, ground bounce etc. there.

I completely agree with you, but maybe Prusa also uses the loadcell to detect the end-stops, additionally to the StallGuard?
Or it only uses the StallGuard, but weird loadcell signals still cause the homing to "fail"?

I can just say, that I had longer XY-banging every now and then, but since I've put in the custom Start G-code, it didn't happen again, yet.
Might not be correlated though!

Thank you for suggestions. After repeating a couple of time the procedure to "align" XY and not trying to reach perfectly 85Hz on both side but keeping a little difference (lower Hz on the side that had less space and higher Hz on the side that had more light... just to compensate a little bit) now the homing is behaving in an acceptable way... just 6-8 hit in the corner before to probe bed. 

Anyway thank you also for the G-Code because I for sure want to optimize a little bit the commands before print...I will analize and leverage any good point there...

Ciao,

Alberto.

P.S. So... till now I would say that alignment and belt tension are the key points... but also that you need to give some time of usage to the printer... repeat the alignment and try to compensate a little bit any sort of dis-alignment with low difference of belt tension... probably I have 90Hz on left and 86Hz on the right...ans now it is working pretty fine.

RE:

I had to muck around with all that too. First just somehow pushing the head back to middle and the setting tension of belts wont always work. Still dont understand. At some point i got 85 on both sides and flush front. i tried a print, very long banging. It did print in the end but after that i checked the belt tension. It was over 90 suddenly. then i turned it down again, to ~85~86 but right side was minimaly not touching. Did give me calibration errors. 

Losened the belt a bit more on the right side, still same frequncy but calibration was done quickly , no error. So the belt will pull the edge away from the stop if its to tight. And right side matter much more than left side. I did print all day with left side . it calibrated, but always took a while.

And now it only bangs around 10 times and its ready. i think my neighbors are upset.

RE: HOMING ISSUES

My belts are 81 left, 86 right. 90/86 sounds perfectly fine too.
The G-code is nothing special. It's just the default Start G-code with "stop heating" before every step of homing or probing and "heat back up to idle temp" between each step to not lose too much temperature.
No special things in there, you can just copy-paste the full code and replace what's in the Start G-code window 🙂

RE: HOMING ISSUES

To report goods news here, with another check after the printer cooled over night. Then doing the check and re adjustment of the rail and alignment. Then doing  another belt  tensioning, running a print, re-checking and another small tension adjustment, i got the printer to not recalibrate home at print start.

What i did was to really losen the belts (as in the manual, but make sure its loosend enough to show a bend bar !!!), correcting the gap and doing a tension without being to picky at first. Green in the app is enough. It did home cali, but i printed anyway. After a cool down i did it again because it seems to drift a bit and the setup needs to settle on the tension settings. 

After it settles i keep checking how it changed and reacted accordingly.

It works now. 

RE:

This is all very specific and the behavior might only apply to my printer maybe something is broken, which i dont know.
And i like to report again. The printer worked fine. Banging was very short. But i am a bit mad so i check the thing again. Loosened the belt completely and checked squareness with a metal rectangle. It showed that both brackets were slightly bend towards the back. I think that happened by repeatedly working the sides unevenly. Printer just worked. But of course i do not liked that. Bending again. This time with more light and more patience.

Then the tensioning. Both up to ~85hz...after a while is not that hard to hear if one gets close. Its faster now. Then doing a Y axis calibration. Banging... and on the print start it did a recalibration again :/. I kind of expected that. It always messes up first tensioning after driving around a bit with the motors. I dont understand why...

Anyhow, printer off and tensioning again. +-1 from 85hz. i am not fuzzy about that anymore. Then id did Y axis test. Short as it can be. Print start, shortest banging.

So for my printer its always twice. But i am sure, the tension will change when the case will heat up and it might start misbehaving. I hope it stays perfectly stable , than meaning it bangs only around ten times.

RE: HOMING ISSUES

FYI: my Belt tension went up after printer a 2:30h print by ~4-5hz. Equally on both sides.

Posted by: @mnk

This is all very specific and the behavior might only apply to my printer maybe something is broken, which i dont know.
And i like to report again. The printer worked fine. Banging was very short. But i am a bit mad so i check the thing again. Loosened the belt completely and checked squareness with a metal rectangle. It showed that both brackets were slightly bend towards the back. I think that happened by repeatedly working the sides unevenly. Printer just worked. But of course i do not liked that. Bending again. This time with more light and more patience.

Then the tensioning. Both up to ~85hz...after a while is not that hard to hear if one gets close. Its faster now. Then doing a Y axis calibration. Banging... and on the print start it did a recalibration again :/. I kind of expected that. It always messes up first tensioning after driving around a bit with the motors. I dont understand why...

Anyhow, printer off and tensioning again. +-1 from 85hz. i am not fuzzy about that anymore. Then id did Y axis test. Short as it can be. Print start, shortest banging.

So for my printer its always twice. But i am sure, the tension will change when the case will heat up and it might start misbehaving. I hope it stays perfectly stable , than meaning it bangs only around ten times.

RE: HOMING ISSUES

This made the printer usable again... Thank you so much for this. Apparently changing the printhead harness also solves this problem (if you don't get one that has the problem). This thing is supposed to be FCC compliant, but I honestly doubt that they pass EMI certification. I'm trying to convince my bosses to let me use the hour EMI testing facility to test it.

So yeah, turning off the heater while calibrating solved everything for me. The printer was square, the belts where at the right tension. It was just a dumb interference. All that for $1200... 

RE: HOMING ISSUES

Just finished my conversion. And when trying first print, it would get stuck on homing. It would just do it over and over again. Had to reset the printer to stop it. Once cooled down I rechecked the belts. Had to adjust a little bit. Then did a home in the menu a couple of times. Worked fine, couple of bumps and homed. Started print again, same issue, never got past trying to home.
Created a new printer profile with the custom Gcode shared above, homed fine and first test print going.

What I do not get though, the hardware for the extruder (loveboard, heater, sensors etc.) is all the same as for the MK4S. It never had this issue. So why would it be an issue on the CoreOne with the same hardware.

RE: HOMING ISSUES

The custom G-Code posted above didn't work for me unfortunately - still same issue of head banging for minutes at a time. Gets very annoying. 

RE: HOMING ISSUES

I went through this issue and I have to say that at the end I solved it repeating well the config of the X Y axis and belt tension.

So disable motors, bring the extruder to the front completely and check if both left and right are exactly touching the frame. If left or right have few mm of gap try to push a little bit to align as much as possible. Then bring the extruder to the back and start increasing belt tension. Keep the belt in which you had the gap a little bit more tight (maybe 3 or 4 Hz more vs the other belt). Now my homing bumbs about 10 times and then start printing with original gcode. 

RE: HOMING ISSUES

Was able to do a couple of prints. But now the homing just fails completely. Rechecked the belts multiple times. gantry seems square as both sides hit at the same time when pulling it forward.

RE: HOMING ISSUES

Ok, noticed something interesting. When it does only x, it hits the right side, when it does only Y it hits the front. But when it is doing the diagonal part, it is either not hitting the left or not hitting the front for some reason. Think this may be why it is failing.