Under Extrusion on First Layer After Switching to MMU
 
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mechengrkj
(@mechengrkj)
Active Member
Under Extrusion on First Layer After Switching to MMU

I recently purchased a MKS printer and assembled it myself. Ran a few prints and everything ran smoothly and with good print quality. Since everything was working correctly I decided to install the MMU that I received with the purchase. This is where I began to have issues. For some reason after the calibration and initial extrusion to clear the nozzle, the first layer of the print and skirt doesn't print completely. The material seems to start extruding partway through the layer. I've run the Live Z adjustment found here: http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/life-adjust-z-my-way-t2981.html and it extrudes uniformly and has good adhesion. I then printed the Batarang that came on the SD card with the printer and it prints well. As soon as I start printing my own models, it fails. I've gone through the Batarang GCode and tried to match my print settings to the settings in there but it still has issues on the first layer. What can I do to correct this issue?

Posted : 19/09/2017 4:10 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU

Sounds as though you are using the MK2 printer profile instead of the one for the MMU.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 19/09/2017 4:16 pm
mechengrkj
(@mechengrkj)
Active Member
Topic starter answered:
Re: Under Extrusion on First Layer After Switching to MMU

I reflashed the firmware with the MMU version from the website and I am using the MMU version of the Slic3r software. Is that what you are referring to?

Posted : 19/09/2017 4:46 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU

Slic3r Printer Profile.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 19/09/2017 4:56 pm
mechengrkj
(@mechengrkj)
Active Member
Topic starter answered:
Re: Under Extrusion on First Layer After Switching to MMU

I have tried it using the MMU single extruder profile and the Multi Material profile and both have the same outcome. I've attached two pictures of what is happening to the prints. The first is still attached to the bed and the second is the underside of the print.

Posted : 19/09/2017 5:26 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU

Sorry, I don't go to third-party sites. Not really any need when pictures can be attached to posts.

Better if you zip up your G-code file and upload it, so I can have a quick look.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 19/09/2017 6:29 pm
mechengrkj
(@mechengrkj)
Active Member
Topic starter answered:
Re: Under Extrusion on First Layer After Switching to MMU

Sorry about that. I was trying to use third party hosting but apparently it didn't work so I have updated the post. I am not able to upload any files besides pictures for some reason.

Posted : 19/09/2017 8:12 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU


I am not able to upload any files besides pictures for some reason.

Zip up the G-code file and drag/drop onto a new post.

It does look as though your live Z is too high.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 19/09/2017 8:54 pm
mechengrkj
(@mechengrkj)
Active Member
Topic starter answered:
Re: Under Extrusion on First Layer After Switching to MMU

Here is my GCode. I used Life Z Adjustment procedure (proposed by JeffJordan) from this forum and if I lower it any more than it is now (-0.250um) results in a rough surface that is no longer the correct layer height.

Posted : 19/09/2017 9:01 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU

You have 2 x 4mm retractions after the initial purge line and only one 4mm prime:

G1 X240.0 E0 F1000.0
[b]G1 E-4 F1000.0[/b] ; this line needs to be removed.
G92 E0.0
; Filament gcode
; Filament gcode
; Filament gcode
; Filament gcode
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
;BEFORE_LAYER_CHANGE
;0.2
G1 Z0.200 F7200.000
;AFTER_LAYER_CHANGE
;0.2
[b]G1 E-4.00000 F3000.00000[/b]
G1 Z0.700 F7200.000
G1 X105.742 Y96.242 F7200.000
G1 Z0.200 F7200.000
[b]G1 E4.00000 F3000.00000[/b]

Remove the first retraction (as indicated above) from the start G-code section

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 19/09/2017 9:49 pm
mechengrkj
(@mechengrkj)
Active Member
Topic starter answered:
Re: Under Extrusion on First Layer After Switching to MMU

Ok I removed that line and now the skirt is printing correctly. It makes me wonder why it was in there though because I haven't changed any of that, it was all the default values?

The first layer still has issues with under extrusion. I increased the extrusion width from 0.42 mm (default) to 1.0 mm and now it prints well. I'll try lowering it a bit and see at what point it has issues but it all seems to be working for now. Thanks for the advice, I never would have found that on my own.

Posted : 20/09/2017 12:02 am
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU


Ok I removed that line and now the skirt is printing correctly.

Great, pleased to have helped.

Under extrusion on the first layer is, as I have mentioned previously, usually due to incorrect Live Z. It could also be due the the first layer set below 0.15mm. Increasing extrusion width will not help because the lines will be further apart.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 20/09/2017 9:58 am
mechengrkj
(@mechengrkj)
Active Member
Topic starter answered:
Re: Under Extrusion on First Layer After Switching to MMU

That makes sense on the Live Z adjustment. Is there a difference in the extrusion settings if you which between MultiMaterial mode and Single Extruder mode in Slic3r? The reason I ask is because if I print using Single Extruder it turns out just fine but as soon as I switch to Multi Material mode it starts under extruding, without changing the physical setup of the machine at all.

Posted : 20/09/2017 3:34 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Under Extrusion on First Layer After Switching to MMU


Is there a difference in the extrusion settings if you which between MultiMaterial mode and Single Extruder mode in Slic3r?

No idea; I don't use Slic3r.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 20/09/2017 4:43 pm
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