Extra extrusion after color change
Newbie here.
When switching colors in a print I see the following behavior:
- After unloading first color and inserting new color I get I little bit of extrusion to get the new color ready. This looks normal.
- Then on the question "was the correct color extruded", I reply Yes.
- Then the head moves to the workpiece and immediately starts extruding while moving
This leads to a lot of misprints. My only remedy is while the head is moving trying to get as much filament out of way as possible.
Do I use the correct procedure? Why the extra extrusion?
(Brand new Mk3S+, PrusaSlice 2.4.2)
RE: Extra extrusion after color change
Can you attach a short video and more information?
even an old man can learn new things 🙂
Standard I3 mk3s, MMU2S, Prusa Enclosure, Fusion 360, PrusaSlicer, Windows 10
PRUSA MINI+ Prusalink + Prusa Connect
RE: Extra extrusion after color change
When the printer purges the old colour, resist the urge to pull the filament off the nozzle.just hold it still, reply YES the filament is clear. And the print head will move back to the model. Pulling all of the waste off the nozzle, as it.
Good luck. Joan
goes.
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Extra extrusion after color change
It's by design. It's to repressurize the hotend in case you walked away and didn't immediately press the yes button. As Joan said, needle nosed pliers are your best friend. Just press yes and then hold on to the small piece of filament extruding.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Extra extrusion after color change
Here is a video to show the problem: color switch video
Can you attach a short video and more information?
RE: Extra extrusion after color change
It's by design. It's to repressurize the hotend in case you walked away and didn't immediately press the yes button. As Joan said, needle nosed pliers are your best friend. Just press yes and then hold on to the small piece of filament extruding.
This doesn't make sense or at least is inconsistent with the Pause/Resume behavior.
If I press "Pause" and walk away for hours, there is no automatic extrusion done to "repressurize"... and it seems to work fine.
Plus how likely is it that someone returns to the printer to change the filament, removes the old filament, inserts the new, checks to see that it has extruded and then walks away before pressing yes for enough time for the hotend to depressuriz?
Even if repressurizing were required in the relatively unlikely event that you pause too long between changing the filament and pressing "yes", why not leave it to the firmware to determine if you have waited too long (and repressurize accordingly) rather than hard coding it too over-extrude every time, thereby requiring the user to awkwardly hold onto the filament with a tweezer or whatever and hope that the filament breaks off cleanly rather than landing on the printed model.
Seems ass-backwards!
RE: Extra extrusion after color change
Exactly as said above and in the video.
It is annoying.
My suggestion is to purge (pressurize) first, wait a second (to it to be manually cleaned), then move back to printing.
If you walk away from a color change, it is your own fault.
RE: Extra extrusion after color change
Going to re-hash this again. I'm doing a production print of 50+ badges, 10 per time, with 3 colour changes.
Since we know that M600 is over written in firmware by Prusa. I have looked at the firmware code (with my amateur experience in C+).
And in the latest PS the G-code for colour change we have :
M600
G1 E0.3 F1500 ; prime after color change
Basically, the prime happens after the M600 command, by that time the head already moves back to the print.
So I can't just add a pause G-code command before priming, It will pause on top of the print and prime.
Marlin M600 command has a N (no return) variable, but seems like Prusa firmware ignores that. This could be handy if used to set a custom G-code to pause and prime and something like a G61 to return to last position.
Been doing quite a few colour changes over time, I know the tricks of catching the prime/purge. It is still iffy, you can still get a few strands being put down.
As my badges mentioned in this case is flat and only a few layers. I will add another, and then discard the one where the colour changes will happen (like a purge tower with a MMU). But not ideal.
Not going to open another Github issue, there are already quite a few issues about this.