Filament change loop - never prints  

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flounder
(@flounder)
Active Member

I removed the MMU2S from my Prusa MK3S.  I then tried to print my object.  Got an error message saying it had been sliced for a different machine.  Oops.

So I went back to the slicer, added the profile for the MK3S, and resliced.

I uploaded it to OctoPrint and said "Print"

It rezeroed, did the bed level detection, and then moved the extruder up out of the way.

"Press button to unload filament".  I press it.

The filament unloads

"Remove filament immediately"

I do, although a hair-thin extrusion remains.

"Insert filament"

I put the filament back in.  It autoloads.

"Did the filament extrude?" (or something like that)

Yes.

I remove the extruded filament from below the nozzle, and hit the button to confirm "Yes".

More filament extrudes, then it moves over to draw that first line in the front of the build platform. [Why does it create this dangling blob of filament?]

It gets there, changes its mind, and returns to the position an inch or so above the build plate

"Press button to unload filament"

[lather, rinse, repeat]

I gave up.  What's wrong?

Posted : 03/12/2020 8:27 pm
karl-herbert
(@karl-herbert)
Illustrious Member
Posted by: @flounder

I removed the MMU2S from my Prusa MK3S.  I then tried to print my object.  Got an error message saying it had been sliced for a different machine.  Oops.

So I went back to the slicer, added the profile for the MK3S, and resliced.

I uploaded it to OctoPrint and said "Print"

It rezeroed, did the bed level detection, and then moved the extruder up out of the way.

"Press button to unload filament".  I press it.

The filament unloads

"Remove filament immediately"

I do, although a hair-thin extrusion remains.

"Insert filament"

I put the filament back in.  It autoloads.

"Did the filament extrude?" (or something like that)

Yes.

I remove the extruded filament from below the nozzle, and hit the button to confirm "Yes".

More filament extrudes, then it moves over to draw that first line in the front of the build platform. [Why does it create this dangling blob of filament?]

It gets there, changes its mind, and returns to the position an inch or so above the build plate

"Press button to unload filament"

[lather, rinse, repeat]

I gave up.  What's wrong?

Let me just say spontaneously: Check the status of the filament sensor. If the filament is loaded, the LCD must show the value 1, if not loaded, 0.

If you have removed the MMU2, N/A should be displayed. Maladjusted sensors are responsible for many malfunctions also in connection with the MMU2.

This post was modified 3 months ago by karl-herbert
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/12/2020 8:34 pm
flounder
(@flounder)
Active Member

@karl-herbert

I have no idea how to get that display to come up.  I tried several promising menu items, but got nothing like it.

But, to see if the filament was loaded I had loaded the filament.  At that point, it started printing the first layer.

Wow, I thought, it's working--even if I don't know why.

It finished the first layer.  Then it moved the head up out of the way and went into the load-filament sequence again.

I would include the gcode file, but it is 47MB.  So I'm including the STL file, and 595KB

Posted : 03/12/2020 8:57 pm
karl-herbert
(@karl-herbert)
Illustrious Member

@flounder

The sensor is probably unstable at exactly one point where it switches to on/off.

LCD menu i3 (pre firmware 3.9.0): https://help.prusa3d.com/en/article/lcd-menu-i3-printers_1876

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/12/2020 10:53 pm
fuchsr
(@fuchsr)
Reputable Member

Clearly the filament sensor. Same happened to me when I moved the MMU2 to the trash pile of unfulfilled hopes and dreams. I managed to get it to work by adjusting the IR sensor but in the end I actually converted back to the Mk3S style of sensor, and life's been good again.

Posted : 03/12/2020 11:34 pm
flounder
(@flounder)
Active Member

I have no idea what to do.  "Adjusting the IR sensor" means nothing to me, nor does "converted back to the MK3S style of sensor".  I do not know how to do any of these.

I bought this in the hope that it would work.  I had been told that the Prusa printers were the best.  I've had it for 18 months and been able to print three things.  I find this immensely frustrating.  All I want is a printer that prints without crises (I don't consider Z-axis calibration a crisis, I know how to do that).  But the rest of the advice I get here requires doing things I have no idea how to do.

Posted : 11/12/2020 6:27 am
Swiss_Cheese
(@swiss_cheese)
Reputable Member

@flounder

who set up your OctoPrint?

Posted : 11/12/2020 6:50 am
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