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Filament swap question  

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Henryhbk
(@henryhbk)
Eminent Member
Filament swap question

I must say I love, love my mini. I also have 2xmk3s’s which are my workhorses. I frequently do multi-color prints via a filament swap. I have a question regarding the purge cycle of the swap (and this applies to any of my prusa printers)

when you insert the new color it purges for a while and then asks if the new color is showing. What I’ve seen when you press Yes the printer extrudes like 4-5 additional CM and then moves out to the print dragging a long string of filament. So I’ve learned to keep forceps around the filament being extruded to wipe the nozzle clean (and it often needs a second wipe just before it moves down to touch the print as there is still drool coming). Since all 3 of my prusa printers do it, I assume this is expected behavior, but is there a way to prevent this? 9it does in fairness result in perfectly primed printing)

Posted : 25/01/2022 1:38 pm
Bob
 Bob
(@bob-2)
Reputable Member
RE: Filament swap question

I keep a pair of tweezers next to my printers just for this very purpose.  I would think it's not only expected but desired, the printer doesn't know how much filament it's drooling while waiting for you to tell it everything is ok, that last few CM of filament is just a purge to keep the nozzle full to prevent a gap when it starts printing again.  Theoretically if you leave it alone the spool of filament on the bed will pull the strand away without your intervention.  You're going to have to remove it sooner or later, I just like to do it sooner.

Cheers

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit

Posted : 25/01/2022 2:46 pm
Henryhbk
(@henryhbk)
Eminent Member
Topic starter answered:
RE: Filament swap question

@bob,

Thanks. I do the same, but at least depending on the filament and where my print is, that pile of purge often will stretch out to the part. As for the time waiting, since this happens after I said "yes" the time is 0.

Posted : 25/01/2022 2:58 pm
Bob
 Bob
(@bob-2)
Reputable Member
RE: Filament swap question

What I mean by time waiting, is the printer sits there drooling a little bit before you hit yes and then purges some to insure the nozzle is full.  You want it to purge a little after you say yes to insure there are no gaps.  I grip the filament with my tweezers, press yes, wait for the purge,  and once the print head moves sweep away the filament and toss it in the trash.

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit

Posted : 25/01/2022 3:24 pm
fuchsr
(@fuchsr)
Noble Member
RE: Filament swap question

This behavior is by design, and I believe the only way to change it is to hack the firmware. 

Posted : 25/01/2022 10:48 pm
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