Sudden failure laying down filament  

Re: Sudden failure laying down filament

First guess is a partial clog.

Have you ever done a cold pull? It is not hard and will clear up issues with extrusion

What does the filament look like if you raise the z up high and extrude filament? (settings move/axis/extruder) does it pull to the side or drop straight down? My guess is it pulls to the side and loops back to the nozzle. Or there are buildups on the leading edge of the nozzle which get caught causing that mess.

Do a cold pull and see if it helps. Here are very good instructions from bobstros page. there are other instructions elsewhere, but these work for me.

http://projects.ttlexceeded.com/3dprinting_cold_pull.html

Re: Sudden failure laying down filament

Thanks, I tried that, and it didn't seem to help. I also cleaned the nozzle on the outside with a wire brush.

There's a couple of things that seem to happen on closer inspection.

One is that loading filament is totally fine, it comes out straight, fast, even.
However when the head is pre-heated ready to print, a thin trail comes out very slowly. As this happens, it cools, and therefore curls, sometimes back onto the nozzle, meaning it then creates a loop and will pick up filament as it prints.
If it doesn't do this, ie the thin extruding filament in preheat mode comes out straight, then when it approaches the bed, it's pushed back up at the nozzle, gunking it up. It doesn't block it, however there's a blob of filament around the nozzle which picks up what it's laying down until there's just a ball.

If one removes this before printing, then it was sort of ok, and I did the first layer calibration mode to test.

However, and this is point Two, it seemed to be not really adhering to the surface. I checked the temperature of the bed, and it's reading 51 on my infra-reader, not the 60 it thinks it is...

So, I seem to have gone from perfect printing to two problems at once. I'm gonna spend more time troubleshooting than printing at this rate 🙁

Re: Sudden failure laying down filament

Huh. That is strange...

Do you have your extruder raised well above the bed while preheating before printing or is it down close to the bed? if it is close to the bed, then i can see where the filament would bunch up around the nozzle and cause the nozzle ball... It seems after some prints the nozzle likes to stay close to the bed after a print ends and therefore upon startup of a new print I could see this happening. You can either insert info into the begin GCODE in slic3rPE or the end Gcode to raise the nozzle away from the bed which may help prevent the issue.

That also helps removing the ooze with tweezers real fast before a print starts. it is going to happen as the filament is heated to melting temp. I always have a bit of ooze, but since the nozzle is away from the bed it is straight and I can remove it.

In the picture, the filament looks kinda flat which could be the nozzle is close to the bed while heating and if that is it I could see that causing the issue.

Bed adhesion issues have two sources: incorrect first layer z and dirty bed. If you have not messed with anything that would affect the live z, I would wash the bed with dish soap and water and a clean paper towel not touching it and try again with the nozzle raised well above the bed while heating...

Re: Sudden failure laying down filament

I have the nozzle far away, I filmed it a bit - rough editing but you'll get the idea.

I've solved via gcode by heating nozzle after the bed level check, however the question remains as to why this suddenly started happening.

I've been printing completely fine for 6 months, and I have not even gone through one spool yet... (I have various spools, however not used 1kg yet)

Re: Sudden failure laying down filament

David:

First, your video was spectacular and illustrated your issue very well. I see what you are saying now and yes, that gush of filament is not right... It looks like your build is good and you have been printing so it does not seem to be mechanical.

Question: what type of filament is that and what type of conditions do you keep it in? e.g. humidity wise? Did the roll ever get very hot or damp or something? If you run your fingers along the load filament stream (at the 5 second mark of the video) once it cools down if you feel bumps on it it has absorbed moisture and that could be the problem. I am in FL at 65% humidity right now and I tell you even PLA absorbs moisture. If I dry a filament and then feel the extruded stream, it is smooth. Iif it has absorbed moisture, it is bumpy from the air bubbles from steam.... The very first part of your video the string of filament looks bumpy like you note.

I did have a filament roll (not going to name the maker but not a premium brand) that had an issue kind of like that. It was brand new and did something like that on the initial load. I actually got a small puddle on the build plate after loading and the 75/75mm test square would not complete. It looked like taffy and was very runny like yours. It was a full, brand new, just unwrapped, roll, so I dried it in a filament dryer for 8 hours and it is ok to print if I watch it. I chalked it up to humidity and or less than stellar filament manufacturing.

Do you have a new roll of good filament to test out to see if it happens with other/all filaments? It could just be a bad roll. It looked like it adhered to the build plate until the end of the pattern where it just gummed up. I would test another roll if you have one to rule out bad filament. Otherwise dry the filament out for about 8 hours and try again. i got a $30 food dehydrator to use as a Filament dryer from Amazon. one of my other posts goes more in depth about it.

I hope you get it solved!

Re: Sudden failure laying down filament

I don't see any real issues in the video, though that second curl looks like old PLA on the nozzle; you might try cleaning it well: hot nozzle + paper towel works fairly well. fyi: I can get the curl with new nozzles that have been used once.

But in all cases where my PLA stops adhering, even to the point of a fur ball on the nozzle, it's one of two things, mostly the second.

1) Oily fingerprints on the filament spool.
2) Oily fingerprints on the bed.

Wash the bed with a good dish detergent, dry with a paper towel. Hard water works best as a rinse, gets more of the detergent off. Rinse and dry twice if using soft water. Liberally wipe the bed with 90%+ alcohol on a few layers of paper towel. Then wipe once or twice with acetone on a paper towel. Acetone isn't needed often.

Then never touch the bed surface with fingers or palms. If you do, clean them off immediately with some alcohol.

It makes an amazing difference I had to experience to believe.

Re: Sudden failure laying down filament

Thanks.

Jbinfl, this was a fresh opened roll from a good manufacturer, and I printed quite a few items before the next print went like that. All my spools are in an airtight container with one of those dehumdifers that you mention, and the humidity here is currently 28%.

Tim, I think the problems in the video are many. 1st the filament is running out quite fast, when it's not printing (by which I mean that first sequence shows 10cm over about 30 seconds). Secondly you can see it not adhering to the surface all the way through the layer one print. Then you can see both ridged, and bloated feeds when doing load filament. Finally when printing the layer one test, at the end, it all gums up on the nozzle.

What I did now was this. Firstly removed the nozzle, soaked in acetone, dried, and replace. There were then quite a few puffs of gas whilst loading, which I think was the acetone remnants vapourising, however that seemed to get rid of the ridges on the flow issue. I also (given I'd replaced the nozzle), spend quite a bit of time getting the first layer height right. It was right before, however after dialing it in again, it seemed to adhere much better. I then also cleaned the bed in soapy water, although i do do an isopropyl clean after, and before every print.

This actually seemed to solve everything bar the heated but not printing flow. So I changed the gcode in slicer, to heat only to 180, then do the mesh check, then raise to 5cm and heat the hotend completely, which also allows me to remove any excess before the print starts.

I don't know why this suddenly started, however that has sorted it for now, although perhaps I need more regular nozzle maintenance.

Thanks both for your input and help,

/Dave

Re: Sudden failure laying down filament

Dave,

Not sure what happened, but when I watched the video the first time I didn't get it all.

Now, right at 1:55, I can see the filament extruding and expanding much larger than the 0.4mm nozzle; this is always moisture in or contamination on the filament. It also explains the self-extrusion being so bad.

I've had this from a variety of manufacturers fresh out of a vacuum sealed bag with desiccant. Worst case to date was a roll of Prusa Beige. I used the carnage it wrought as my avatar. It would just not stick to the bed. The beige "improved" when I had used the entire first layer of filament. I suspect a handler doing the packaging had applied a fresh coat of hand cream then proceeded to pack that spool.

Good to hear this may be behind you.

Re: Sudden failure laying down filament

So, as stated, I got the self-extrusion sorted by not heating the hot end until the last moment, after the bed level check.

However I still had (after about 5 small prints), problems with adhesion.

I washed the bed again in soapy water and it went away.

I am very rigorous about cleaning the bed with isopropanol and not touching it. Looking at the powder coated bed, I think the iso actually makes it very shiny, and it stops adhering once you've cleaned it too much!

Going to wash bed in soapy water every few prints, and see what happens.

Thanks!

Re: Sudden failure laying down filament

David:

Glad you got it fixed and are back printing!

A soapy water wash is the cure all for powder coated sheet adhesion issues. I believe IPA does not actually remove all the contaminants from the sheet, but does good enough for a while until there is too much stuff on the sheet. Dawn dish soap never fails to fix issues for me. I have never used acetone on mine.

Adjusting the live z with a 75x75mm calibration square , drying the filament with a food dehydrator, and a soapy water wash of the powder coated sheet are MK3 magic bullets for most issues...

Re: Sudden failure laying down filament

What's that about calibration square...

Re: Sudden failure laying down filament

What's that about calibration square...

https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html#p117935