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Filament dribbles out at an alarming rate  

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Phil-ament Collins
(@phil-ament-collins)
Active Member
Filament dribbles out at an alarming rate

Okay! So all of my woes started when I accidentally upgraded my MK3 to the MK3S firmware while it was still a regular ol' MK3, and through a conga line of terrible decisions I wound up at my present problem.

When I load filament into my MK3S (I tried upgrading as a solution to my problem), it just starts extruding immediately when it gets up to temp. It all just comes pouring out like soft-serve ice cream out of a machine. But instead of dispensing joy and empty carbohydrates, all this nozzle is dispensing is failed prints and despair. Seriously. I can't even run the first-layer calibration without it spaghetti monstering on me!

The Mk3S upgrade and having it on the correct firmware didn't help, changing out to a fresh nozzle didn't help, so my final guess is that there's a bunch of filament clinging to the sides of the hotend assembly and coming loose when I heat that baby up. Especially since a little bit starts oozing out even when no filament is loaded.

So, what's the best way to purge the inside? one of those 1.75mm cleaning filaments? A metal wire? Tossing out the entire heating part of the extruder and starting over? Or is there a different issue that I'm not thinking of? I appreciate any help you can give me!

Posted : 16/09/2019 2:54 am
rmm200
(@rmm200)
Noble Member
RE: Filament dribbles out at an alarming rate

Just to be clear - do you mean the extruder servo is continuously running, feeding filament off the roll?

Ignore what is coming off the nozzle for the moment - I am only asking what the extruder motor is doing.

Posted : 16/09/2019 3:28 am
Chocki
(@chocki)
Prominent Member
RE: Filament dribbles out at an alarming rate

Flash the correct firmware then carry out a factory reset, the PRUSA is known to do strange things if this is not done.

Normally a small firmware update (Incremental for instance something like 3.8.0 to 3.8.1 should be ok, but going from say 3.7.n to 3.8.n you really should be doing a factory reset, to be honest get used to doing this for every firmware update.

https://help.prusa3d.com/article/SYvbQ66IXF-factory-reset

 

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.

Posted : 16/09/2019 5:51 am
Phil-ament Collins
(@phil-ament-collins)
Active Member
Topic starter answered:
RE: Filament dribbles out at an alarming rate

@robert-rmm200

The extruder gear isn't moving at all, but the filament just keeps on pouring out of the nozzle. A little bit even comes out if there's no filament loaded.

@chocki

As for a factory reset, the one thing that worries me about that is the loss of the print time record. The manual is telling me to perform maintenance every XYZ print hours. Should I just write down the total print hours before the reset?

Posted : 16/09/2019 4:31 pm
rmm200
(@rmm200)
Noble Member
RE: Filament dribbles out at an alarming rate

My concern would be that your nozzle temperature appears to be well above the melting point of your filament.

You never actually say what type of filament you are using, what "getting up to temp" means, and what is the nozzle temperature when it is leaking?

 

Posted : 16/09/2019 8:17 pm
Phil-ament Collins
(@phil-ament-collins)
Active Member
Topic starter answered:
RE: Filament dribbles out at an alarming rate

@robert-rmm200

Sorry, I really should have specified.

I'm printing in PLA; the same PLA spool that came with my Mk3 kit. I've also printed using a variety pack of PLA filaments in different colors. (which is part of why I suspect a filament backup to be the culprit)

As for "up to temp", I'm just using the original settings on the Mk3 firmware for PLA and going up to 215 degrees (The i3 works in Celsius, right? I was never sure). The dribbling begins right around when the i3 is reading 185 degrees.

Should I take a laser thermometer to it? Where should I point the laser if I do?

Posted : 16/09/2019 11:45 pm
rmm200
(@rmm200)
Noble Member
RE: Filament dribbles out at an alarming rate

If you have one, check the nozzle temperature.

The temperature is in Celsius. And 185C is not hot enough to cause leakage.

If your nozzle is actually much hotter than that - I will have to refer you to Support. They can step you through diagnosing.

On Eshop, click the Chat button in the lower right.

Posted : 17/09/2019 12:11 am
Phil-ament Collins
(@phil-ament-collins)
Active Member
Topic starter answered:
RE: Filament dribbles out at an alarming rate

@robert-rmm200

Alright. Figured I'd give you an update.

I pointed the laser thermometer directly at the nozzle, and somehow it was reading about a hundred degrees colder than the Prusa. At the same time, no more filament is dribbling from the nozzle. Maybe I just had to let the excess come out after all. I'll have to see what happens if I unload the filament and load it back in again.

Posted : 18/09/2019 3:50 am
bobstro
(@bobstro)
Illustrious Member
RE: Filament dribbles out at an alarming rate
Posted by: @phil-ament-collins

[...] At the same time, no more filament is dribbling from the nozzle. Maybe I just had to let the excess come out after all. I'll have to see what happens if I unload the filament and load it back in again.

If you are starting each print by bringing both the nozzle and bed up to final print temps concurrently, the nozzle will usually be at full temp well before the bed. That is the temp at which filament flows, so any small amount of nozzle pressure leads to oozing before the print starts. Many of us work around this with a 2 step nozzle warmup in which the nozzle is heated to a no-ooze temp (I use 160C) until the bed is warmed, mesh bed leveling complete and any other prep steps, and only then raise the nozzle to full print temp. I've documented my startup gcode to do this here and there are many variations. 

Based on your description, I don't think flashing the wrong firmware (done that) would cause lasting problems. At worst try a full factory reset and recalibrate everything. Keep the nozzle and hotend clean with a soft brass brush to avoid drips accumulating. 

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 18/09/2019 5:27 am
vintagepc
(@vintagepc)
Member
RE: Filament dribbles out at an alarming rate
Posted by: @phil-ament-collins

@robert-rmm200

Alright. Figured I'd give you an update.

I pointed the laser thermometer directly at the nozzle, and somehow it was reading about a hundred degrees colder than the Prusa. At the same time, no more filament is dribbling from the nozzle. Maybe I just had to let the excess come out after all. I'll have to see what happens if I unload the filament and load it back in again.

laser thermometers do not work on shiny objects (metals), they are not calibrated for the emissivity so you will get wrong readings. Usually, you get IR reflections of other nearby things, e.g. colder than expected if the item itself is supposed to be hot, and hotter than expected if cold and something else nearby emits IR.

How has your filament been stored? Filament that has absorbed water will do this significantly as the water turns to steam and pushes filament out of the nozzle without any extruder movement. If you have a new roll, try it. If you don't you'll need to look up how to dry your filament in a food dehydrator. 

 

 

 

Posted : 18/09/2019 1:14 pm
Phil-ament Collins
(@phil-ament-collins)
Active Member
Topic starter answered:
RE: Filament dribbles out at an alarming rate

First off, thank you to everyone who has offered their advice on this problem.

@bobstro

Okay, I'll have to give this two-step startup code a shot! That is, after I've solved my new problem. Now the extruder gear isn't turning and filament won't feed at all. It's still dripping out at that centimeter-per-second rate from before, but only when I give it some encouragement with the acupuncture needle. I'm not sure what's wrong anymore. All I know for sure is that something has gone very, very wonky with my extruder.

@vintagepc

The filament's been sitting on the included spool holder ever since I first assembled the printer. Can't see how any water damage would have occurred.

Posted : 20/09/2019 11:58 pm
Phil-ament Collins
(@phil-ament-collins)
Active Member
Topic starter answered:
RE: Filament dribbles out at an alarming rate

Okay, scratch the whole no-extrusion thing. The bondtech gear screw got loose and I got it back into position.

Posted : 21/09/2019 12:45 am
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