Print keep stopping to unload and load filament  

Re: Print keep stopping to unload and load filament

You will find this is your Filament Sensor which is unable to see some colours.

I can print in all materials and in all colours apart from my eSun PETG Black. The PETG black I have is a high gloss and it causes my filament sensor to unload all the time.

I just disable the sensor when I print with that specific material to get around the problem.

Re: Print keep stopping to unload and load filament

I too started having this issue as well. So the filament sensor triggers a filament change message? My issue is that the extruder moves to the front right of the print bed then I get a prompt to unload the filament, after which I'm prompted to reload then after it pushes filament through I'm prompted to verify color is correct. Then printing resumes. On a possibly related note my purge line seems to be much longer than normal, 14cm vs 10cm. It's infrequent but generally occurs around the time I get the unload filament prompt. If I see an extra long purge line I prepare myself for trouble. I've spent the last two days trying to get help from support but was given 3 things to try... Reinstall FW followed by factory reset, done several times. After last nights chat I was asked to disable filament sensor and uninstall and reinstall Slic3r for good measure. That's where I stand now. FWIW, I've had the printer since Jan and am part way through 3rd roll of Makergeeks black PETG. This is the first time I've had this issue so if it's the filament sensor I'd have to suspect that it's faulty or the issue would have appeared earlier, no?

As for the purge line, am I the only one seeing this?

Re: Print keep stopping to unload and load filament

[...] my purge line seems to be much longer than normal, 14cm vs 10cm. It's infrequent but generally occurs around the time I get the unload filament prompt. If I see an extra long purge line I prepare myself for trouble. [...] After last nights chat I was asked to disable filament sensor and uninstall and reinstall Slic3r for good measure. That's where I stand now. The purge line is entirely defined in your startup gcode. In Slic3r, you can see it under Printer Settings->Custom G-Code->Start G-Code. Towards the bottom you'll see something like:

G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line

The reason I suspect tech support asked you to re-install Slic3r is that, for the purge line to "grow", you have to have modified the gcode in Slic3r or be using pre-generated gcode files from somewhere else. They want you to get to a known state for troubleshooting. Otherwise, it's very difficult to know where problems originate. Do you by any chance have different printer settings profiles (e.g. for different nozzles)? Each profile will have its own startup gcode. If long purge lines indicate impending problems, that's a good hint to look at your printer profiles to see if there's anything different in that profile.

That filament change sequence you describe is how it operates by design. The sensor detects the end (or misreads shiny filament) at the top, moves the head and asks you to eject the remaining stub of filament before it moves past the extruder gears. Otherwise, you wouldn't be able to easily remove it. Of course, with a false trigger, the filament is perfectly fine so it is quite annoying. For now, just disabling the filament sensor with shiny, transparent or otherwise sensitive filament is your easiest solution.

Tech support is probably trying to determine whether you've got a faulty sensor. Bear with them as they go through that process.

There are some fixes about that are supposed to reduce the tendency for false triggers, but they haven't made their way into the production releases yet. When they do, you'll most likely be able to print a replacement part.

Re: Print keep stopping to unload and load filament

The purge line is entirely defined in your startup gcode. In Slic3r, you can see it under Printer Settings->Custom G-Code->Start G-Code. Towards the bottom you'll see something like:

G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line

I get that, the issue is I can print a duplicate part using the previously generated gcode and get the longer purge line or not it's a crap shoot. I'm assuming X100.0 is 100mm which is what mine is at and yet I'll still sometimes end up with a 140mm purge line. In my mind that eliminates Slic3r as being the culprit.

edit: I should add purge line travel length as sometimes the first couple of cm of the purge doesn't produce any material.

For the other I assume the way the filament run out works is what I'm seeing now. I had one instance of actually running out of filament early on and I seem to recall getting an actual out of filament error not a change filament notification, though I could be mistaken or they changed the way the notification works.

Re: Print keep stopping to unload and load filament

[...] I get that, the issue is I can print a duplicate part using the previously generated gcode and get the longer purge line or not it's a crap shoot. I'm assuming X100.0 is 100mm which is what mine is at and yet I'll still sometimes end up with a 140mm purge line. In my mind that eliminates Slic3r as being the culprit.Hmm. The purge line is printed by gcode. The line specifies where to move (X100 for example) and how much to extrude over that distance (E12.5 for example) along with speed (F1000 for example). It would be interesting to open the gcode file in a text editor and take a look, but I am not aware of any way for a line to print without explicit instructions being given to the printer. I am not aware of any way for that to happen during a normal print -- much less replacing the purge line code -- without lines in the gcode file.

edit: I should add purge line travel length as sometimes the first couple of cm of the purge doesn't produce any material.I'm still wrestling with this myself. There are a lot of sometimes-contradictory guides out there dealing with pre- and post-print retraction to deal with oozing, wiggling errant bits of dangling filament free and the like. My preferred solution is to start the purge line with a thick line of filament to grab anything dangling and fill the hotend, then resume the normal thin and thick extrusions:

G1 X20.0 E4 F1000.0 ; 20mm intro line @ 0.20
G1 X60.0 E3.2 F1000.0 ; +40mm intro line @ 0.08
G1 X100.0 E6 F1000.0 ; +40mm intro line @ 0.15

I've experimented with longer lines, but 100mm tends to get things flowing IME, so any more is just waste, especially if doing a skirt anyhow.

Depending on how aggressively you extrude at the start, you might get extruder clicks. I've had it as high as E6. One solution I've used has been to disable Linear Advance prior to the purge line and let the filament start gcode re-enable it. I'm probably over-thinking it, as so long as it is printing a good line by the time it gets to the end of the purge line, all is well.

None of this addresses your changing purge line concerns. I'm afraid I have no ideas on that point.

For the other I assume the way the filament run out works is what I'm seeing now. I had one instance of actually running out of filament early on and I seem to recall getting an actual out of filament error not a change filament notification, though I could be mistaken or they changed the way the notification works.
I recall color change and end-of-filament detection being the exact same process, but I may be mistaken. The did change the process a bit in the latest firmware release, but I haven't updated yet. It lifts the head for ease of clearing the material extruded during the change.

Edit: Looking at your pics again, it looks like your purge line is all one width. Could you open the gcode file up in a text editor and post the purge line portion? The bog-stock Prusa lines look like:

G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0

Re: Print keep stopping to unload and load filament

Edit: Looking at your pics again, it looks like your purge line is all one width. Could you open the gcode file up in a text editor and post the purge line portion? The bog-stock Prusa lines look like:

G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0

Will do when I get home, I did run a longer purge line early on but have long since reverted to the default length. I have a rudimentary understanding of GCode as we have Waterjet, Laser, Plasma and a few CNC mills in our shop though we have a dedicated person that handles our programming, I just pass on what I want done and it's magically taken care of.

Re: Print keep stopping to unload and load filament

[...] we have a dedicated person that handles our programming, I just pass on what I want done and it's magically taken care of.
Prusa should consider adding those to the online shop!

Re: Print keep stopping to unload and load filament

Quickie follow though not quite intuitive it is definitely the filament sensor causing the issue. I ran a few prints with it disconnected without issue then reconnected it and had the filament change notification within 10% of the first print, followed by 2 out of 5 prints with notifications. I disconnected again and haven't had an issue. FWIW, the inconsistent purge line length seems to have vanished as quickly as it came. Now it's time to print the new extruder assembly and tear everything apart...

Re: Print keep stopping to unload and load filament

I encountered this problem once.
It was due to filament sensor.
After cleaning with compressed air (I used my air paint brush) as the manual suggested , problem solved.

Re: Print keep stopping to unload and load filament

Longer purge line - Yes I get them randomly from time to time.

First (randomly) on MK2, later still after upgrading to MK2S and when I got MK3 here too.
Checking the GCode it is always correct and the line should only be 100mm. Running the same GCode file multiple times will from time to time give longer a purge line.
The longer purge line is always the same length, not a random length - looks like the x coordinate is misinterpreted the same way. The amount of extruded material is the same and therefore the longer purge line is thinner.

I think this is an old firmware bug that maybe is still spooking in current firmware. I have seen this behavior from the first MK2 firmware - just upgraded to 3.3.1, but I am sure it will be there too...

Cannot confirm that this gives false filament out defections as I long ago turned this feature off - to many problems.

Re: Print keep stopping to unload and load filament

Longer purge line - Yes I get them randomly from time to time.

First (randomly) on MK2, later still after upgrading to MK2S and when I got MK3 here too.
Checking the GCode it is always correct and the line should only be 100mm. Running the same GCode file multiple times will from time to time give longer a purge line.
The longer purge line is always the same length, not a random length - looks like the x coordinate is misinterpreted the same way. The amount of extruded material is the same and therefore the longer purge line is thinner.

I think this is an old firmware bug that maybe is still spooking in current firmware. I have seen this behavior from the first MK2 firmware - just upgraded to 3.3.1, but I am sure it will be there too...

Cannot confirm that this gives false filament out defections as I long ago turned this feature off - to many problems.

Thanks, I was wondering why I got the random long purge line.

BTW, I solved the filament detection problems on skelestruder if you want to give that a try.

Re: Print keep stopping to unload and load filament

Longer purge line - Yes I get them randomly from time to time.

First (randomly) on MK2, later still after upgrading to MK2S and when I got MK3 here too.
Checking the GCode it is always correct and the line should only be 100mm. Running the same GCode file multiple times will from time to time give longer a purge line.
The longer purge line is always the same length, not a random length - looks like the x coordinate is misinterpreted the same way. The amount of extruded material is the same and therefore the longer purge line is thinner.

I think this is an old firmware bug that maybe is still spooking in current firmware. I have seen this behavior from the first MK2 firmware - just upgraded to 3.3.1, but I am sure it will be there too...

Cannot confirm that this gives false filament out defections as I long ago turned this feature off - to many problems.

Maybe it was just coincidence OTOH, I re-did the extruder with the R3 parts, what I was trying to print when both came on with a vengeance, and took the opportunity to clean the mirror on the filament sensor, very lightly touched with lens wipe after blowing with rocket blower, and the unload filament and long purge lines seems to have taken a break. At least I know I'm not alone with the long purge line as chat support acted like it wasn't possible without altering the G-Code.

Re: Print keep stopping to unload and load filament

Longer purge line - Yes I get them randomly from time to time.
...

Cannot confirm that this gives false filament out defections as I long ago turned this feature off - to many problems.

Maybe it was just coincidence OTOH, I re-did the extruder with the R3 parts, what I was trying to print when both came on with a vengeance, and took the opportunity to clean the mirror on the filament sensor, very lightly touched with lens wipe after blowing with rocket blower, and the unload filament and long purge lines seems to have taken a break. At least I know I'm not alone with the long purge line as chat support acted like it wasn't possible without altering the G-Code.

I don't think there is a connection between filament sensor and long purge lines. My MK2 has long purge lines from time to time but no filament sensor.

Re: Print keep stopping to unload and load filament

Longer purge line - Yes I get them randomly from time to time.
...

Cannot confirm that this gives false filament out defections as I long ago turned this feature off - to many problems.

Maybe it was just coincidence OTOH, I re-did the extruder with the R3 parts, what I was trying to print when both came on with a vengeance, and took the opportunity to clean the mirror on the filament sensor, very lightly touched with lens wipe after blowing with rocket blower, and the unload filament and long purge lines seems to have taken a break. At least I know I'm not alone with the long purge line as chat support acted like it wasn't possible without altering the G-Code.

I don't think there is a connection between filament sensor and long purge lines. My MK2 has long purge lines from time to time but no filament sensor.

I would tend to agree but it's kind of odd how they both started occurring, quite frequently, at approximately the same time. For now both seem to have gone away, or at least aren't occurring 20% of the time so I'm a happy camper again. I have to say I'm seriously considering unplugging the filament sensor myself as I really only use it during a filament change.

Re: Print keep stopping to unload and load filament

I would tend to agree but it's kind of odd how they both started occurring, quite frequently, at approximately the same time. For now both seem to have gone away, or at least aren't occurring 20% of the time so I'm a happy camper again. I have to say I'm seriously considering unplugging the filament sensor myself as I really only use it during a filament change.

It is an odd behavior - the filament sensor on my MK3 has been off since January (was not reliable) and it has the same problem.

Re: Print keep stopping to unload and load filament

I had this exact same issue, turned out to be an OctoPrint plug-in I had installed which was supposed to allow for cancelling one object out of a failed print. Once I disabled that particular plugin, it stopped occurring. I think it was this one:
https://plugins.octoprint.org/plugins/cancelobject/

Again, after I disabled it, the error stopped occurring without cleaning the filament sensor.