Height problems

[ju3dan 0]

Hi everybody, I've been reading a lot of posts in this forum and they've been of great help.

I hope you can help me again. We've acquired an UM2 in the place where I work, a design Studio. We are mainly focused on the good quality of prints instead of speed, and still looking for the right print parameters.

We recently are having some trouble when printing with supports. The thing is that at some height the printer stops extruding and the extruder keeps flying arround without printing anything else. What could be the cause. The begining of the piece is well done and no problems appear.

Here are a couple of pictures of how it looks and the original design in cura.

Some of my parameters are

layer height 0.04

Shell thickness 0.8

Print Speed 20

Temperature 210

Travel Speed 150

Retraction:

Min travel 1.5

Min extrusion before retracting 0.02

retraction length 5.5

retraction speed 25

If you need any other parameter to have a better idea don't hesitate to ask

2) I have been playing around with other parameters for retraction but to this point this seem to be the "best"

3) After it stops I usually clean it the atomic way but the nozzle seems not clogged

Thanks in advance for your help

 

[DidierKlein 729]

Hi and welcome to the forum

How long have you had and used the UM2?

Have you tried printing this in 0.1mm layers? 0.04mm seems a bit to low from my point of view...

One thing that could cause this problem i think is a deformed Teflon, this particular print has a lot of retractions due to the many support structures. It could be that the filament gets more retracted than pushed back due to too much friction in the teflon, so at a moment it doesn't extrude anymore

 

[ju3dan 0]

Thanks, we've had the UM2 for 3 or 4 months now, as we speak we are trying to print with 0.1mm layers and see if there are any changes.

About your suggestion, what do you mean by the Teflon? the filament? we're using PLA in this case, could it be that the back enginge is the problem, that it gets stuck or it doesn't work properly while retraction? Is there any suggestion as to adjust pressure on the cable?

 

[DidierKlein 729]

No the teflon is located in the head

It's the white piece underneath the spring. It can happen to be deformed, i'm not sure if you have the latest Teflon which is now glass filled and deforms slower than the older Teflon.

If it's deformed the filament has more friction and it could be causing your problem

 

[ju3dan 0]

Thanks for the explanation, I'll finish this print and if it keeps doing it I'll check the teflon to see if it's deformed.

Any other idea what could be the cause? It seems too soon to be deformed since we haven't used that much.

 

[DidierKlein 729]

It's just an assumption, it happens with hot temperature prints (over 240°c) it's common.

But maybe it's something else it's just the first idea that popped in my idea since the nozzle isn't clogged

 

[ju3dan 0]

hi, I tried printing with 0,1 layers and it worked just fine. We are still trying to achieve smaller layers. we are now doing a test and looks fine for a 0,04mm height layer but with values of retraction of 7mm and 40mm/s. Is that too much? does it have any risk or bad consequences for the machine? We had some issues with the feeder, after cleaning it and replacing the screws it seems it's working fine and accepting this retraction values.

Other parameters:

Tº 210 at the beginning and then 195º,

speed 20

std parameters of retraction on cura.

 

[ju3dan 0]

It's happened again with the values I posted previously, I attach some pictures of the fail.

The print until it fails looks pretty fine, without stringing or anything, I'm lost here since I don't really know what the problem is... Any suggestions? is it really the teflon?

Thanks

 

[DidierKlein 729]

If you want to check the Teflon here's a video showing how to take the head apart (just stop to the point where he gets the Teflon out

 

Once out take some filament and pass it through to see if you can feel any friction if yes you can drill it out or clean it (sometimes some melten plastics gets stuck on the bottom).

Something other you can check before this, is trying with a different filament, what is the brand you're using? Make sure it's 2.85mm and not 3mm or +

Some people have a hard time with white filaments for some odd reasons (might be the pigment for coloring?)

 

[yellowshark 153]

Is the print doing lots of retractions? If so pull out the filament and see if it is squashed/has lots of teeth marks. If so this will be causing it to foul in the Bowden tube and cause under/no extrusion. Typical symptom is that it prints OK at the start and then fails later during the print. Solution (in my experience) is to reduce the pressure of the drive teeth on the filament.

 

[ju3dan 0]

Didier: I checked the teflon and seemed right, I passed a filament and it could move correctly. It was slightly burnt on the lower part and I removed the burnt parts a little bit to avoid future friction. We use the ultimaker PLA filament, pearl white. I've checked the thickness of the filament and seemed correct.

Yellowshark: we've tried with different settings of retractions to discard this but it always makes the same. It is true that to avoid stringing I had to set values of 7mm and 40mm/s for retraction lenght and retraction speed in the case of the photos.

The feeder is at it's minimum pressure and it's true that the filament appears really marked but I'm not sure if it's the cause or the consequence. Is there an alternative to reduce the pressure on the filament when the minimum is reached?

Thanks