Help with multi color printing
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Hi all,
I'm getting into multi color printing. Right now I have is set up in prusaslicer so there is a M600 on my color change. The print head parks, I run an unload macro, then I swap the filament, run a load macro, then resume the print.
I'm having issues with what appears to be under extrusion after the filament change. There is an indentation on the color change layer. It is not a layer shift, and it happens for the whole layer, independent of model size.
This is my pause.g :
; pause.g ; called when a print from SD card is paused ; ; generated by RepRapFirmware Configuration Tool v2 on Fri Nov 16 2018 19:13:04 GMT-0500 (Eastern Standard Time) M83 ; relative extruder moves G1 E-10 F3600 ; retract 10mm of filament G91 ; relative positioning G1 Z5 F360 ; lift Z by 5mm G90 ; absolute positioning G1 X0 Y300 F6000 ; go to X=0 Y=300This is my unload macro:
T0 ;Select tool G1 E-5 F500 ;Retract 5mm filament at low speed G1 E-60 F3000 ;Retract 60mm filament at high speed M84 E0 ;turn extruder motor off to let user unload if filament locked -This is my load macro:
T0 ; Select tool G1 E55 F200 ; extrude 55mm at low speed M84 E0 ; turn extruder motor off so the user can feed by hand - change for another tooland this is my resume.g:
; resume.g ; called before a print from SD card is resumed ; ; generated by RepRapFirmware Configuration Tool v2 on Fri Nov 16 2018 19:13:04 GMT-0500 (Eastern Standard Time) M83 ; relative extruder moves G1 E10 F2000 ; extrude 10mm of filament G1 R1 X0 Y0 Z5 F6000 ; go to 5mm above position of the last print move G1 R1 X0 Y0 ; go back to the last print moveThis is the gcode from a file that has a layer change in it:
G1 X136.521 Y141.794 E43.84769 G1 X136.949 Y141.853 F12000.000 ;LAYER_CHANGE ;Z:14 ;HEIGHT:0.2 G1 Z14.000 F12000.000 ;COLOR_CHANGE,T0 M600 G1 E42.44769 F2400.000 G92 E0 G1 Z14.200 F12000.000 G1 X216.752 Y221.763 G1 Z14.000 G1 E1.40000 F2400.000 ;TYPE:Perimeter G1 F3600.000 G1 X217.521 Y221.020 E1.44871 G1 X218.325 Y220.315 E1.49745I believe that there is an issue somewhere that comes from my load or unload macro and the gcode that the slicer inserts. Can anybody point me in the right direction?
Thank you
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@surgikill said in Help with multi color printing:
There is an indentation on the color change layer. It is not a layer shift, and it happens for the whole layer, independent of model size.
Can you post a photo of what you mean?
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@phaedrux Notice the angled transition from white to red
Same one with green to white.
It should look like this where the layer is solid and you can't really see the transition.
This happened on multiple of them. I'm thinking it might be my Z axis.
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Perhaps the nozzle is not completely primed when it's going back to print. What order are your perimeters printed in? Inside out, or outside in?
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@surgikill
Your macros use M83 relative extrusion, but the main gcode file is sliced with M82 absolute extrusion. (compare line 1 and 9)
I'd change everything to M83, just to be safe... -
@o_lampe said in Help with multi color printing:
@surgikill
Your macros use M83 relative extrusion, but the main gcode file is sliced with M82 absolute extrusion. (compare line 1 and 9)
I'd change everything to M83, just to be safe...RRF saves the relative/absolute extrusion status when running a macro and restores it afterwards; so this isn't strictly necessary. However, we recommend slicing with relative extrusion anyway.
Are you sure that extruding 10mm of filament is sufficient after loading new filament? Can you see the new filament coming out of the nozzle when it is doing that?
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@phaedrux It is most definitely primed. I have 9 of these parts I print simultaneously and it happens on every single one exactly the same.
@dc42 I extrude anywhere from 55-110mm of filament before the 10mm to purge and prime the nozzle, so yes, there is a ton of filament that comes out of the nozzle.
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@surgikill
does your extruder setup require higher 'chamber pressure'? It seems logical to believe, a long purge will do. But you purge in free air and the oozing filament even pulls on the molten filament in the heater chamber.
Chamber pressure begins to build up, when the nozzle is in print position above the part. Even 'pressure advance' can't help here. -
@o_lampe It's a hemera. There should be plenty of print moves to "build up" chamber pressure before it moves onto the next layer. It would also show issues with retractions as well, which it does not, and it is even on all of the parts. I think it might be an issue with my Z axis not moving back into place correctly.
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It does sound like a z height issue then, either mechanical or maybe thermal?
But you show that it doesn't happen every time, correct? So what is different between the times it happens and doesn't happen?
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@phaedrux No idea. I think it's mechanical. I'll look into my couplers and lead screws. I have no idea what happened to the one where it worked correctly. I'll change my pause and resume g-codes so it doesn't change Z height and we'll see what happens.
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@surgikill are you physically/manually loading filament into the hemera for the filament change? Could it be that there is some flex/backlash in your carriage so that it sits a bit different after a tug to pull out the old filament (or a shove to push the new one in)?
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@engikeneer Doubtful. 16mm rods on the y axis and 12mm rods on the x axis and it's really rigid, besides the fact that I just use the load/unload macro, so I don't really push on anything. I'm running a test print right now. My z couplers are kind of fucked up, so I'm guessing that's the issue.
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@surgikill said in Help with multi color printing:
My z couplers are kind of fucked up, so I'm guessing that's the issue.
You are lifting the gantry with the Z-motors? On my first Prusa i3, i placed 4.5mm steel balls between stepper shaft and leadscrew.
That way I could eliminate compression of the couplers from the changing weight and inertia of the moving extruder. -
@o_lampe It's a corexy. There are 4 Z motors. I need to get the spider couplers instead of the spring couplers.
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Yeah, definitely my Z-axis. I ran some prints and changed my pause and resume to not lift Z and the indentation is gone. Looks like I need to get some pillow block bearings for the leadscrews and new couplers.
