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The first priming extrusion before print??  

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Rufus
(@rufus)
Trusted Member
The first priming extrusion before print??

When the printer starts the print and extrudes the first bit of PLA before starting the print it isn't even on the bed. Does anyone else have this issue and what is the fix??

I am not sure what this pre print is called but my MK3 does it across the entire bed before starting the print. This XL does a small path but it starts like inches before the kickout of the print pad and drops onto the very bottom of the printer. Any ideas??

Posted : 10/11/2023 8:56 pm
MME
 MME
(@mme)
Reputable Member
RE: The first priming extrusion before print??

The XL starts before the front left tab then moves to the right a little. That's the XL way.

Posted : 10/11/2023 9:06 pm
BaconFase
(@baconfase)
Estimable Member
RE: The first priming extrusion before print??

Working as intended and personally I like it much better than the old long flat strip.

You can even see the initial priming in the sliced preview.

 

.Printables.

MK3S MMU2S, XL-5T

Posted : 11/11/2023 9:58 pm
ssill2
(@ssill2)
Noble Member
RE: The first priming extrusion before print??

I don't mind that as much, but I hate that it leaves filament drips when it does the bed leveling!   I'm not sure why it can do this before heating the nozzle and getting the filament all gooey.   I'm doing a punch of tpu prints for my wife and I noticed that even on the MK4 printers I upgraded from MK3s this behavior is there.   it's ever so annoying to go clean the plate, put it down and the first thing it does is dob filament dots all over the plate before the print....

Posted : 13/11/2023 11:22 pm
Nikhil S. liked
Rufus
(@rufus)
Trusted Member
Topic starter answered:
RE: The first priming extrusion before print??

it leaves filament drips when it does the bed leveling!

Completely agree. I really dont have an issue with this but it does seem to me to be a little unprofessional like they missed the numbers in the gcode and I am not a fan of PLA dripping off the side of my build plate on a $3K printer. Just seems like they would have moved the extraction over a little bit and shortened it.

Posted : 14/11/2023 2:23 am
Nikhil S. liked
ssill2
(@ssill2)
Noble Member
RE: The first priming extrusion before print??

I hate this so much.  these are the dots/drips it does.  This could totally be eliminated by waiting to load the filament all the way into the extruder until after the bed leveling.

Posted : 14/11/2023 3:26 pm
ssill2
(@ssill2)
Noble Member
RE: The first priming extrusion before print??

I will say that in general the dots left all over the plate have improved with latest firmware + slicer.

Posted : 04/12/2023 10:03 pm
kenryan
(@kenryan)
Active Member
RE: The first priming extrusion before print??

Is there a way to get PrusaSlicer to quit yelling at me about the toolpath outside the print are because of these?

Posted : 07/01/2024 11:01 pm
Ira S
(@ira-s)
Trusted Member
RE: The first priming extrusion before print??

As far as the initial priming purge just before the print starts, it's even worse on a multi-head printer since each extruder does it! I'm ok with the idea - to an extent - but I don't see why it needs to purge 10 inches down before it moves and wipes it off. Is there a setting that extrudes less filament before it starts crossing the edge of the build plate? If it started to extrude just as it crossed over onto the edge of the build plate there would be much less waste and mess. 

I also get the "dots" during bed leveling. Much more with PETG than with PLA. Perhaps if the extruder was at a lower temperature there wouldn't be dots? But then maybe if the filament didn't "ooze" then the bed leveling wouldn't be accurate. And it does seem to be pretty accurate when calculating the Z height for the first layer. 

Posted : 19/01/2024 7:58 pm
ssill2
(@ssill2)
Noble Member
RE: The first priming extrusion before print??

you can change the printer start gcode, it defaults for FLEX to 210 for the temp that it does the level probes at.   This puts the dots down.

So in the Custom G-code section of the printer preset

Find this line:

M109 T{initial_tool} S{((filament_notes[initial_tool]=~/.*HT_MBL10.*/) ? (first_layer_temperature[initial_tool] - 10) : (filament_type[initial_tool] == "PC" or filament_type[initial_tool] == "PA") ? (first_layer_temperature[initial_tool] - 25) : (filament_type[initial_tool] == "FLEX") ? 210 : (filament_type[initial_tool]=~/.*PET.*/) ? 175 : 170)} ; wait for temp

 

And change it to

M109 T{initial_tool} S{((filament_notes[initial_tool]=~/.*HT_MBL10.*/) ? (first_layer_temperature[initial_tool] - 10) : (filament_type[initial_tool] == "PC" or filament_type[initial_tool] == "PA") ? (first_layer_temperature[initial_tool] - 25) : (filament_type[initial_tool] == "FLEX") ? 175 : (filament_type[initial_tool]=~/.*PET.*/) ? 175 : 170)} ; wait for temp

And the dots magically go away for tpu!   It's particularly bad on sainsmart tpu since the max temp on the spool is 210, so the filament just drips out.   175 works great for both ninjaflex and sainsmart so far.  it's just annoying I have to remember to make that change every time they update the printer preset

Posted : 19/01/2024 8:21 pm
ntdesign liked
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