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casper2341

PLA stops coming out an hour into the print.

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Hi,

Hopefully someone will be able to clue me into what the issue or cause is.

Background - Running Cura 2.1.3 and 2.1 firmware on the UM2GO

Layer height: .06

Speed: 40mm/s

Support type: touching build plate

Fill density: 20%

I did an initial slice and began printing the model, everything seemed to be progressing fine, I was monitoring and realized that I forgot to enable supports so i aborted the print.

After redoing the slice with supports enabled, I proceeded to print again. The time to completion was 5 hours. So i left it to print over night.

Woke up this morning and discovered that the print had not completed. The display showed that print was complete and everything had stopped. I proceeded removed the filament and heard some grinding trying to get the filament out. In the past the nozzle end of the filament would be melted since it backs out of a heated nozzle. But this time is came our with a clean flat cut.

So thinking that there was a clog I did an atomic pull. Manually adjusted the temp to 19OC and pushed in PLA by hand. Dialed down the temp to 90C and waited for nozzle to reach it, then I pulled. There was bit of brown residue. So i repeated the whole process two more times until i had a clean residue free pull and nice cone shape.

Thinking that things were fine I put everything back together. And started the same file again.

Things looked on track so i left it once again but it again printed to rough the similar layer and no more PLA came out. It continued to go through the motions of printing but no PLA.

I wasn't the one monitoring it at the time so can say if there was any odd sounds of grinding but rather then let it continue to print air I ask the person monitoring i to abort the print.

I have attached a pic.

Any ideas on what is the cause. Could it be something with the slice from Cura? I will try a file of another model that printed successfully tonight to see if it is unique to that file.

Any help on this will be much appreciated. Up to now I have had no major issues.

I would like to add that recently I have been hearing the occasionally clicking sound when loading in filament. Like the sound of the feeder slipping.

Thanks

IMG_9023.thumb.JPG.2c6a17cf47e6fc40051b2e69dc8c44b0.JPG

IMG_9023.thumb.JPG.2c6a17cf47e6fc40051b2e69dc8c44b0.JPG

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GUDO - Thanks for the suggestion.  I had another look at the PTFE but i think the crookedness is a result of camera distortion.

In a effort to fix this i cleaned out, i unloaded the filament and did a thorough clean and check of everything.  I did the Atomic pull was clean, ran filament through the bowden and no roughness,  I use a blower to clean out the feeder of all debris and just for good measure I loosened the filament spool.  It was only half used.  And the final thing was i resliced in Cura 15.04.

So far things seem to be working and it has printed beyond the point of last failure.

What i did notice was the the support is different from when done through Cura 2.

Will report back on how it turns out and will run the previous file once more to see if 3 times a charm.

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A few things can cause the filament to stop coming out of the nozzle and grind at the feeder. The problem is distinguishing if it happens first at the feeder or first at the nozzle.

1) Excessive extruder heat. When weather/air temperature is warmer (above 20C) the combination of air temp and heat from the extruder motor moving to the filament can heat PLA enough so it gets soft in the feeder and it gets squished flat and eventually fails. This can be obvious if you know what to look for - right after a failure there is 5cm of flattened (half round) pla in the bowden just above the feeder.

2) Filament brittle. A year ago there was a bad batch of Ultimaker PLA. Some people still have it - the symptom is if you bend the raw filament it breaks much too easily and breaks in the bowden. It gets stuck temporary at the end of the bowden and so the feeder is grinding, grinding until it's all dust at the feeder. This is easy to deal with so if this is the problem I can point you to more info.

3) too many retractions. Does your print have lots of retractions in the layer that it failed? Open the gcode file and delete everything except one layer (somewhere near the problem layer) and count the G11 codes - easiest way is to "replace all" G11 with something else like GXXX just to get the count/qty. If you are doing 10 retractions for every spot on the filament this can grind it up too much and occasionally cause problems. "grep" is also a great too to count G11 in your gcode file.

4) Printing too cold/too fast. I doubt it's this as you are only printing .06 thick layers.

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Update, it managed to print the previously failed print successfully with not much issues.  So i proceeded to try another file, one that was a much simpler print, only 1 hour or so but at ultra quality.

To my disappointment this morning and again it had failed after about 2-4mm into the print.

As a test i picked another file immediately to print to see if the filament would advance. Again the feeder was stuck.  No so much a grinding but more clicking like the it was trying to push the filament and the clutch would slip thus the filament to drop back.  Looking at the filament in the bowden tube also confirmed that the filament was trying to advance but would click back.

So i did a "material change" to get the filament out,  it too a bit of a tug to get it moving out and i had to run it a second time to get the remaining bit out also.  I didn't want to forcefully pull it out stressing the feeder motor.

Examining the filament showed that there was a bit of flattening at where the feeder knurled knob grabs the filament but nothing that I would consider extreme flattening as a result of a hot feeder.

I will take some photos and post later.

This time the grinding was less than before but that may just be cause i pull it harder and faster to get it moving.

I proceeded to reload the feeder with filament ( i removed the section that had been through the feeder)

I sliced another file of the same model with High Quality settings ( default parameters for Cura 15.01 and UM2GO) and started another print

I waited till it completed beyond the previous fail spot and left it to finish printing unattended.  I will check back on it later.

So the investigation continues.  

I am wondering if it is a filament issue? too much humidity?

thanks for all the help so far.

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Not humidity. Could be heat - what is your ambient air temp? If over 22C then that could be related.

Did you check #2 and #3 above? Is it brittle? Did you count the retractions? The gcode file is easy to read - it has comments for the start of each layer and G10 and G11 are the retraction and unretractions.

What is the exact diameter of your filament (accurate to .05mm) do you have calipers?

If it's greater than 3.000mm then that's a problem.

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Hi

GR- Ambient is around 23-5C.

As for #2 it seem to be fine, doesn't break up or crack easily. Will need to check the diameter of the filament, it is an OEM spool of Ultimaker Metallic Silver.

Will need to check about the retractions for the problem file and see. Would printing at a lower default quality setting reduce retractions? Why i ask is I printed the same model but at High vs Ultra and it print out fine. Same support type and all. But will count the retractions in both to confirm later.

Neotko - The PTFE is the original. There is at most only 400-500 hours on it, maybe less. Maybe it's because i don't work it hard enough that it acting up :) Will do another atomic pull tonight to share.

With that said, i decided to test a model that i knew printed fine before but at High Quality vs Normal. I used Cura 15.04 and just used the basic settings so i believe print speed was at 50mms. It printed out fine under pretty much the same conditions as the failed prints.

so far my bad luck seems to be when i try to mess with the print speed settings. Must be setting something wrong.

I will try to print one more test with the same model at Ultra setting which is .04mm layer height I believe. If my luck holds out, then will try to mess with the settings in advanced again to narrow down the prob.

Thanks again for all the help and feedback, much much appreciated.

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Sorry, just did a check of the stats and I was drastically overestimating the printing time.  As of now it has only printed 120 hours.  I usually leave it over night so i did a rough estimation at the time. The printer has been on around 390 hours.  Its bit craze but once left it on for a weekend in the workshop by accident since i turned the LED down i didn't notice it.

Anyways, i did another Atomic pull and attached photos.  I also attached photos the most recent print at high quality mentioned before.  it seemed to print fine until near the end which had one layer that has what looks to be some under extrusion.  

The conditions of the majority of the print took place at night.  The final part happened between 9-11am where ambient temp may have risen to above 25C

Also after the atomic pull i reloaded the printer to filament.  This time with the insert filament commanded and slowly inched the filament to the bowden tube to see if anywhere was causing the the feeder to click.

All when fine until the filament got to the nozzle and filament started coming out.  advancing the filament with the dial quickly cause the clicking of the feeder.  not constant just a click every few spins of the front dial.

As for the retractions, the failed print had 2196 retractions with some of them grouped only four lines of instructions apart.  As for the successful print there were 1771 retractions. With them spaced out far apart.

The successful print with the pic attached had 2031 retractions.

At the moment it is set at 210C, should i try to increase temp?

I'm about to give in and buy another spool of filament to see if i have better luck.

IMG_9028.thumb.JPG.979c4c0646a0c53f0629efdc8a6c956c.JPG

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IMG_9028.thumb.JPG.979c4c0646a0c53f0629efdc8a6c956c.JPG

IMG_9029.thumb.JPG.1be7f155131a0527b32bb19b24a38c4e.JPG

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IMG_9031.thumb.JPG.8b01906fa36323c7efd09e62c2a7c3c8.JPG

Edited by Guest

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I don't know for sure but after reading everything I think the "retractions" is the problem. I would change this setting in Cura:

set the minimal extrusion parameter to 0.32mm or even 0.45mm.

What this does: it's the minimum distance the extruder pushes filament through between any 2 retractions - if Cura wants to do one sooner it just doesn't. Because the retraction distance is 4.5mm if you set this to 0.45mm then it will do a maximum of 10 retractions on any given piece of filament (4.5/.45). If you set to 0.32 it will be a maximum of 4.5/.32 or 14. But that's the max - it's unlikely to go over 10.

In other words this will keep the same spot of filament from going back and forth through the feeder more than 14 times.

I found that increasing this to 0.32 was enough for a print where I had the same problem long ago. I picked this vale because I was looking at a layer that was fine and a layer that was failing and reduced the number of retractions (by changing this value a few times) until the gcode file had half as many retractions on the failing layer as before. That gave me a good margin of failure because it was only just barely failing - it was working on similar layers below.

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Ok latest update after a weekend of multiple failed prints and multiple different variation of settings.

In a effort to narrow down the issue i tried a print at HQ with No retractions to see if retractions was the issue, also with a slight higher nozzle temp 215C and also the spool on the floor to minimize tension. Everything seemed to be going fine nearing 8 hours into the print. I was actually confident that I had finally been able to narrow down the issue. Then i heard a snap. The filament had snapped off at the entrance to the feeder.

After a lot of wrestling with the filament to get it out of the printer i proceeded to examine why it snapped. It has never happened before.

on closer examinations bending the PLA at different points it turns outs that my PLA was extremely brittle in certain sections. Some areas more than other while perfectly normal in places. As i unspooled even more, the problem go progressively worse. to a point where any pressure on the PLA with snap it easily.

So i and thinking that all my previous problems are a result of this (fingers crossed). I have already ordered new OEM PLA. I may also try a local supplier.

i'll report back if this proves to really be the case.

I'm extremely appreciative of all the advice and tips that everyone one has given. On the bright side this was a great crash course on the intricate details of the printer and 3d printing. I easily have much more knowledge that i would have otherwise, had the printer printed flawlessly. I have learn a lot.

Thanks again for all the help and hopefully my next post will be with good news.

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