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U2 Extended Stops Extruding

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I've been working through trying to figure out why my printer is inconsistently extruding.

Looks like it under extrudes on the second layer and on the infill. the outer shell looks ok.  I've just aborted the ones that are disks, but the prints in the pictures below that have gotten a little ways up end up failing because it completely stopped extruding.  Using the original silver PLA spool that was provided with the Ultimaker.

- have done several atomic pulls, they all look clean.

- thought it might be clogging because the bed is too close, re leveled the bed a couple times.

- started printing at a slightly higher temp (220) and that seems to give a little better results for a little while.

- reduced the print speed to 30mm/s on the basic tab.

- I assume that the PTFE Coupler is still ok (looks ok from visual inspection without taking anything apart) because the printer is so new.

- tried setting the filament on the floor to decrease resistance.

- tightened, printed, then un-tightened the tension spring on the feeder. Both failed.

I think this started happening after I tried to print something on the default Ultra setting.  Failed on both high and normal settings after that.

I did notice that around the time this last print failed, the filament was slightly losing tension at the feeder. (the white tab is all the way at the top) It wasn't making that "tock" sound, it just sounded like it was kind of slipping I think.

The filament broke inside the bowden tube on one occasion, then looked like it broke at the knurled bolt because of grinding down another time.

What do y'all think?  Thanks for reading through my post :)

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IMG_0761.thumb.JPG.04d4acbd0d37182aae35cb2c49864862.JPG

Edited by Guest

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Check your advance tab, under speed, and see if Infill is at 85mm/s. The advance speed overrides the basic speed if you have them set to non-0. (if you're using older cura)

If your basic speed is 30, and your infill is 85, it will cause all kinds of issues since 220 is too cool for 85mm/s and too hot for 30.

Try setting everything to 40mm/s on your next go in the advance tab except for initial layer speed.

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Check your advance tab, under speed, and see if Infill is at 85mm/s. The advance speed overrides the basic speed if you have them set to non-0. (if you're using older cura)

If your basic speed is 30, and your infill is 85, it will cause all kinds of issues since 220 is too cool for 85mm/s and too hot for 30.

Try setting everything to 40mm/s on your next go in the advance tab except for initial layer speed.

 

Thanks! I'll try that next and let you know how it goes.

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Check your advance tab, under speed, and see if Infill is at 85mm/s. The advance speed overrides the basic speed if you have them set to non-0. (if you're using older cura)

If your basic speed is 30, and your infill is 85, it will cause all kinds of issues since 220 is too cool for 85mm/s and too hot for 30.

Try setting everything to 40mm/s on your next go in the advance tab except for initial layer speed.

 

Thanks! I'll try that next and let you know how it goes.

 

Failed again. It stops extruding about at the same place as it did last time, about two hours into the print. The feeder is also not able to push any more filament through, so the bolt is slipping...IMG_0763.thumb.JPG.727d9c8bb4cffc50bd8e5129eb74727a.JPG Here is what the filament looks like after heating up the head right after the print and just backing it out. It sounded like it was catching a little when I was backing it out.

IMG_0767.thumb.JPG.e7d4437042a78e0804d66a6ae10444ef.JPG also, is it ok that the hot end isolator is discolored on the underside?

IMG_0763.thumb.JPG.727d9c8bb4cffc50bd8e5129eb74727a.JPG

IMG_0767.thumb.JPG.e7d4437042a78e0804d66a6ae10444ef.JPG

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I usually call the metal part the "steel coupler" or the "steel nut". The brown stuff on the bottom edge is copper grease. It's a high temperature grease with copper in it. Unless the white part is discolored which seems very unlikely as the visible part stays quite cool - room temperature mostly.

Hey I'm going to see you in Pasadena soon - I'm leaving tomorrow/Tuesday. How about you?

Anyway I don't like the height of the white part - I'm worried about the pressure on the white part due to the spring above compressing so much. So try this:

Heat nozzle to 180C (no hotter). Then stick a tool into that hole and rotate the coupler counter clockwise. The nozzle should move downwards and the white teflon part also. Don't go very far - 1mm at the most. Try to cut that gap in half maybe. If you go too far the nozzle/block will touch the fan shroud and you will have trouble heating up.

Then try it again. Even though your printer is new I'm thinking maybe the isolator got deformed anyway. You could remove it and push filament through it to test it out.

I also recommend printing an IRobertI feeder. It helps you feel the pressure on the filament and feel the resistance in different parts of the head and lets you know if the problem is the isolator or not. I don't have the IRobertI feeder still but I'm just saying - it gives you a good feel for this stuff.

Another issue might be the curvature of the filament as you get near the end of the spool. Do you have another spool of filament? A fresh one?

Also you say the filament broke - it's probably getting more brittle which is a bad sign. It means all those pieces can occasionally catch on something in the head and cause extrusion to fail. So that's another reason to try a new spool of filament.

You could also bring stl files to Pasadena and we can print whatever you want as we will have 10 printers or so at your disposal.

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Agree with GR5 on the gap being too large, but I'm not sure that would cause the problem.

This kinda looks like the problem I had. My PTFE coupler interior diameter was larger than it should have been, so what happened was when it got to retraction areas, the filament would heat up be retracted and expand into the PTFE coupler by a few fractions of mm and then cool in it. The larger diameter prevented additional filament to be extruded since the diameter is now larger than the brass tube.

If nothing works I would take apart the head (it's not that difficult!) and check the PTFE part.

My atomic pulls were looking fine like yours as well.

Have fun at Pasadena guys! I won't be there this time :/ but my doppleganer will be :p

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@gr5

My flight leaves tomorrow night around 10:00pm.

I'll try your suggestion on the coupler when I get back from the show.

I really appreciate the detailed response!

Here is the object that I wanted to try and print on the Ultimaker so that I could bring it to the show. It printed pretty well before the extrusion problems started, but there was too much overhang under the jaw for the supports to take care of it.  I've since manually added some supports in the file to help out the auto generated ones:

20150908_105240.thumb.jpg.5fb8602850e63a09b318e69e2304f014.jpg20150908_105057.thumb.jpg.c737f4eaf7d1233751ce5d364183bb68.jpg Manually added support in modo, shown in Cura:5a3310ef95e40_pastedimage0.png.e34f018629c32d87ad80d767a19c9f63.png

It would be cool to print it larger than the one in the picture in the future.

@valcrow

Thanks for your feedback!  I'm looking forward to taking it apart :)

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Edited by Guest

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Is it possible that the temperature sensor isn't reading properly?

Print head getting too cool as it moves up the print?

 

Highly likely, mine were acting up in the same way but not quite as bad. High temp therm, paste solved that. (shh don't tell ultimaker they may void my warranty)

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I replaced the PTFE coupler. The interior of the old one did look to be a hair larger in diameter than the new one. And I shortened the gap between the PTFE coupler and the steel coupler. I don't think I went too far, cause there is a spacer between the nozzle block and the fan shroud keeping them from touching each other.

But, unfortunately the feeder is still slipping and I'm still getting under extrusion.

Is there a way to test if the temp sensor is faulty before replacing it?

Edited by Guest

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Based on the video, it seems like my print head is heating up properly.

I detached and checked the bowden tube for any obstruction. Found that the filament was broken in a couple places inside of the tube. There was quite a bit of resistance at the feeder end of the tube when manually running filament though by hand. I straightened that out some and it seemed to smooth things out. I swapped out the filament with another brand.

I increased the flow rate, decreased the print speed, increased the temp... It still slips. lol

Maybe I should get a new bowden tube and try that?

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Based on the video, it seems like my print head is heating up properly.

I detached and checked the bowden tube for any obstruction.  Found that the filament was broken in a couple places inside of the tube.  There was quite a bit of resistance at the feeder end of the tube when manually running filament though by hand.  I straightened that out some and it seemed to smooth things out. I swapped out the filament with another brand.

I increased the flow rate, decreased the print speed, increased the temp...  It still slips. lol

Maybe I should get a new bowden tube and try that?

 

If there is resistance in the tube, check for a lip or bend at the end of the tube, and check to see if there is pinching where the clip and white collet goes on the tube. There should be some scratch marks from the collet, but it shouldn't be pinched.

Also broken filament is usually bad filament.

Edited by Guest

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Once pla is breaking in the tube you need to throw the rest away. Sorry. Get a new roll. How old was this roll of filament? There have been a few reports of bad filament. Usually it takes a year or two for filament to get brittle.

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Thanks George!

I have another question.

When pulling the filament back and forth by hand from the back of the feeder, through the bowden tube (while the feeder motor is disengaged and not running), should there be any moments where there is greater resistance than at other times while pulling it back and forth? moments where it is really difficult to pull it or push it through?

I took the bowden tube off, inspected it and tried pushing some filament through to test if it had any resistance before doing what I mentioned above, and it felt and looked ok.

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Have you checked to see if the 3rd fan is working? (One at the back of print head)

On new machines it should come on above 40 degree,  old machines come on straight away.

If this isn't working it can cause similar issues.

 

Yes, the fan turns on once the print head begins warming up.

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When pulling the filament back and forth by hand from the back of the feeder, through the bowden tube (while the feeder motor is disengaged and not running), should there be any moments where there is greater resistance than at other times while pulling it back and forth? moments where it is really difficult to pull it or push it through?

 

Not really - I mean it's a stepper motor so the magnets in it alternate easy/hard/easy/hard but there are 10 steps per millimeter so when pulling at any reasonable speed it just feels like a pleasant hum or vibration. If it feels like it sticks more suddenly then that's strange. Maybe the filament was ground down and has a "bite" out of it at that point? Maybe something strange is going on - maybe your motor isn't square and the shaft is tilted a bit - this can happen on some UM2's because there is a tiny hex nut under the motor *inside* the rear panel. If that is rotated wrong it pushes on the extruder stepper and tilts it and makes the filament twist as it goes through the bowden and causes problems.

Or something else wrong with the extruder - maybe you should print the IrobertI feeder? It's a great feeder and one of it's features is you shouldn't have to buy and screws or hardware more than you already have in the feeder.

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