Had an issue with filament being stuck. Any hints on causes?

Vertex 3D Printer Vertex - Issues while printing
1

Hi all,

Had an issue with filament being stuck - or something like that. Solved it, by disassembling things, removing the stuck filament from the nozzle & putting it back together. But I figured to write things down here anyway, so you all might be able to enlighten me what actually happened there - as I don’t really understand it as yet…

Apologies for the long post, but it seemed a good plan, when I was writing this… :slight_smile:

========== What happened, was… =========

Started around lunch time, to do a quick print of 3 (very) small parts. After the first layers, which went ahead normally, the filament’s stepper motor on the #1 extruder started to give a clicking sound & filament was being fed only very minimal to the nozzle. Only a small particle of PLA was being dropped here & there.

Aborted the print & cleaned the plate - then tried to print again. Again, only small particles of PLA were being placed.

Tried to unload the filament, using the onboard controller’s instruction set. The head heated up to (I think) 210°C, then there’s a fair amount of noise coming from the filament’s stepper motor, that is obviously trying to retract the filament.
No success. The filament isn’t budging.

Tried to unload again - same thing. I conclude, that the filament is stuck somehow.

Tried to unload a third time, during which I decide to “help” the stepper motor to retract the filament: as a result, I break the filament off, just below the mechanism… Right… :slight_smile:

Next step is to bring out the tools and remove PTFE tube & the 2 fittings (1 in the feeder unit, 1 in the hot-end).. The string of stuck filament remains, while it sticks out of the nozzle’s entry.

I then restart the unload procedure. The head heats up & as it hits 210°C, I push the filament down into the extruder. As a result, I get a bit of smoke, something that looks like a little bit of ashes (??) & then a string of blue molten filament.

At this point, I retract the string of filament that I was pushing down, which now comes out fairly easily.

I rebuild the whole thing back together.

Reloaded the filament, using the onboard controller. Reloading procedure gave another string of molten filament - so, it appeared that the blockage was removed.

Printed another key chain logo, as a test subject. Which came out better than the original one, by the way - probably due to better tension on the belts.

========== Possibilities to prevent this? =========

Yes, 2 things I’d like to ask at this point:

    1. What actually happened here, please? :slight_smile:
    1. What could I do to prevent this?

Thanks for any insight you could provide. :slight_smile:

Best regards,

Harry D.

2

What happens is there’s filament burning in the nozzle and the charred pieces of filament are blocking the way.
Why does it happen?
First because the default temperatures are too high (190-195° is enough for PLA).
Next when unloading a filament, a bit of it stays in the hot nozzle. Next time you’ll load a new filament the head will heat and burn the filament remains. It then will block the way (at first narrow the passage and finally block everything). When the filament can’t get through the nozzle, it melts a bit above the nozzle making a small blob and the filament get stuck both ways.
When you get a clogged nozzle you have to clean it with a tool (I use a drill bit) to remove all the charred remains (be careful though not to damage the nozzle).
You can clean the point with a guitar string (there are 0.35mm ones) after heating the nozzle.

Next time lower the temperature (190°) and lower the retraction too (3mm and 100-150 mm/s).

3

Hi Raby,

Thanks for your quick response, it’s really appreciated.

I’d need to apologize for dropping these following questions on you & the community here, but - being the novice that I am - I have no clue where to find these details, at the moment.
FYI, I’ll be travelling for the remainder of this week, so I won’t be able to look into the printer’s details until I get back home. But I’ll do my utmost to get smart on these things asap.

I had a feeling that the default temperature might be on the high side, as very small sized prints (top of cones, for example) tended towards having a minor structural integrity problem. New layers are added, before the earlier ones are fully solidified: causing the structure to collapse on itself a bit.

Then, when it comes to modifying the temperature settings & retraction details, as you suggested: I’ve been looking for them a bit, but am somewhat confused as there seem to be 3 places to edit these:

== 1) Manual control settings.

  • The “manual control” tab page (=“handmatige besturing”) offers manual control of the temperature. That’s probably for single print modifications only?

== 2) Slicer settings.

  • On the “slicer” tab page, with CuraEngine slicer selected, it offers 2 seperate tab pages:
    • Tab page “Filament” shows “print temperature” (currently set at 210°C)
    • Tab page “Print” shows retraction speed (“terugtrekkingssnelheid”) as 70 mm/s
      – Tab page “Print” shows retraction distance (“terugtrek afstand”) as 9 mm

== 3) Printer settings, “Vertex 3D printer”

  • Tab page “Printer”: Basic extruding temperature = 210°C

I think, I’d need to modify the settings in the CuraEngine slicer, could you confirm? I guess, these settings are then copied into the G-code files, so this would be applied when printing from SD card?
I print from both the SD card & through the USB cable: longer duration prints go from the SD card.

The settings in the printer itself, as used by the on-board controller, are those affected by these settings? I’m asking, as unloading / loading of filament is done using the on-board controller, so that would mean the pre-configured 210°C would be applied, correct?

When I’m back, I’ll look into ordering some spare parts, just in case I damage a nozzle or related part.

On a side note:
I had also wanted to add settings for 0.05mm layering and 0.2mm layering for more fine or faster printing (respectively), but I have no details on where to store that and what the values would need to be. All part of the learning curve, I guess.
Should you or anyone here have it available, I’d appreciate a link with details on how to modify these settings - assuming it would be possible?

Thanks & cheers,

Harry D.

4

Hi,

i got the same problem with the “clicking” extruder stepper. As it begins to click the printer wont extrude any filament. Just a few “burned balls” are coming out of the nozzle. I am using the default settings, too. I’ll try to print with 190°C and smaller retraction tomorrow.

Sorry for my english.
Greetings from Germany!

Billy

5

[quote=“Harry_D”]That’s probably for single print modifications only?[/quote]Indeed.

[quote=“Harry_D”]- - Tab page “Filament” shows “print temperature” (currently set at 210°C)[/quote]That’s the one you have to modify. If you want to keep the old settings (as a reminder) you can use the “Save as” button to create a new one with a name you can provide (it works for both tabs, Print and filament).

[quote=“Harry_D”]- - Tab page “Print” shows retraction speed (“terugtrekkingssnelheid”) as 70 mm/s
– Tab page “Print” shows retraction distance (“terugtrek afstand”) as 9 mm[/quote]These are the ones you have to change to 3mm and 100-150mm/s (don’t forget to save…).

[quote=“Harry_D”]== 3) Printer settings, “Vertex 3D printer”

  • Tab page “Printer”: Basic extruding temperature = 210°C[/quote]Those values aren’t actually used by the slicer. No need to modify them.

[quote=“Harry_D”] these settings are then copied into the G-code files, so this would be applied when printing from SD card? [/quote]Exactly.

[quote=“Harry_D”]I had also wanted to add settings for 0.05mm layering and 0.2mm layering for more fine or faster printing (respectively), but I have no details on where to store that and what the values would need to be. All part of the learning curve, I guess.[/quote]To create a new layer height, click on the + button. It will create a default 0.2 mm layer height. Rename it to whatever you want. For the layer height use 0.05 (for 0.05) and 0.2025 for 0.2 and keep the first layer height the same for all your settings as it won’t change (it’s determined by the nozzle-bed distance).
The first layer extrusion width you’ll have to test to get a correct first layer (80-90% is often best).

You can also lower the extrusion width in the Filament setting to 70-75%.

[quote=“Harry_D”] I’m asking, as unloading / loading of filament is done using the on-board controller, so that would mean the pre-configured 210°C would be applied, correct?[/quote]Yes. You’ll have to modify the firmware to change this.

6

Perfect, Raby - thanks a lot. :slight_smile:

I’ll get to work on this on my return - I’ll provide feedback asap.

Best regards,
Harry D.

7

Hi all,

I was printing this afternoon with the new settings - or at least, that’s what I thought… :slight_smile:

I had updated the both configuration files for PRINT and FILAMENT settings, as outlined above & gave them different names.

Then, while printing:

  • PRINT settings was correctly set to use the new config file, with settings as discussed in the forum.
  • FILAMENT settings: I had overlooked the lower portion of the screen, where FILAMENT preference settings are seperately selected (!).

So, when I started printing, the temperature went straight up to 210°C, just like it normally did - leaving me quite surprised - I then manually lowered the temperature to 190°C.

The print was a 4 hour one, so I just let it run & didn’t abort it. But it came out quite well. :slight_smile:
For the rest, I used standard layering settings - those remained unchanged for this print. Only the temperature, retraction speed & retraction distance have been updated. Was a good result.

Once completed, I then set out to see why the temperature setting wasn’t followed - and I then found out, that I had never activated the new FILAMENT preference settings in the lower section of the CuraEngine slicer page.
I’ll get smart on that & make sure, those will be correctly set with the next print.

I’ll be a bit busy this week (if the weather holds up, I’ll need to install a new front door), but I"ll try to do some further printing with these settings ASAP. Hopefully this will then also be a benefit to the other forum members with the stuck filament issues.

Will keep you all posted.

Thanks for the help, Raby - it’s all looking quite promising at the moment. :slight_smile:

Best regards,
Harry D.

8

[quote=“Harry_D”]…

  • FILAMENT settings: I had overlooked the lower portion of the screen, where FILAMENT preference settings are seperately selected (!).

So, when I started printing, the temperature went straight up to 210°C, just like it normally did - leaving me quite surprised - I then manually lowered the temperature to 190°C.
[/quote]
Ah yes, all part of the rather weird and unique Repetier user interface design, along with several other peculiar quirks you’ll come across - wait until you want to try saving specific print speeds and cooling options for particular filaments. Sigh… :wink:

9

Alas, another case on stuck filament.

Too bad, as this is a mid-size print: so doing a quick print in the morning now suddenly became the day’s main event. Well, it’s raining anyway, so …

The other one, in the back, broke loose at about the same point: I wasn’t printing that one with a brim, as I figured the 1 flat would give sufficient grip. It didn’t. :slight_smile:

To solve the blockage, I took off the tube & nipple at the extruder, preheated for PLA & then pushed the filament through the nozzle again. Then bolted the beast back together and it’s printing again. (Doing the same, while pushing at the stepper motor, though the filament tube, doesn’t work - I think the tube is giving some resistance too).

Can I ask, how often do you guys experience these blocked nozzle’s anyway?

Thanks,

Harry D.

10

Very rarely - once every ten prints perhaps? But it’s usually down to me messing about with different filaments previously.

11

Right, guys: nozzle cleaning tips needed. :slight_smile:

I unblocked the 1st extruder’s nozzle today: it’s the blue filament again (so far, I seem to have the blocked nozzles only on the blue filament - am using blue & red colors, Velleman 1.75mm PLA filament). Then again, the #1 extruder’s been doing some fairly big pieces, these last few days.

This time, however, when “feeling” the nozzle with a sample stretch of filament, the nozzle feels clean: the filament isn’t sticking on or to anything. And when unloading & reloading the filament, it’s producing a normal strand - as it should.

But when loading the filament, the stepper motor is clicking, as if the filament would be stuck. When printing, I think, I’m getting a slightly thinner filament strand deposited on the layer, though (normal Velleman settings, but with modified temperature, retraction speed & distance as outlined above). The last print, the layers were forming, but you had a bit of fluff here & there, that I normally don’t have.

Is this the moment, where we’d need to bring out the drill bit & the guitar string? I’d need some tips there… :slight_smile:

My family has a number of guitar players, so getting a string shouldn’t be an issue. But, when the nozzle is 0.35mm - what size do we take the string?

The drill is 1.75mm, I take it? Or do we take that smaller, like 1.5 or something?

Thanks & cheers,

Harry D.

12

Sounds like you might have a bit of burnt material stuck in there that can’t melt at those temperatures - you could try doing a hotter print to see if that frees it. I’d try heating up the nozzles using the manual controls, then forcing the filament through by hand - this generally will clear most blockages. If it doesn’t then you’ll have to take it apart and try to burn it out (heating the nozzle up over a flame). Drilling is your last resort, as if you make a mistake with the drill (slight wobble) you will ruin the precision of your nozzle aperture.

13

Hi Biscuitlad,

Thanks for your response, I really appreciate the help! :slight_smile:

Yes, what you describe, this what I normally try to do & that worked well for me up until now - but this time, it doesn’t quite seem to do the trick. So, you’re probably right & there’s something burnt stuck in the nozzle opening.

To take the extruder apart - well, I have a double headed extruder build: taking it apart is a fair amount of work for a printer that’s been operational for only a “few production hours”…
I’ll try & do a print on a bit higher temperature, as you proposed & see if that would unblock it. If I have to disassemble the extruder, I might as well buy a replacement nozzle first & install that. If there is no “safe” procedure to clean the nozzle, I’m probably not going to bother with it & just toss it. (Don’t know what a nozzle costs, though. Doesn’t seem to be much work on a CNC lathe - so, the part couldn’t be expensive…).

To be very honest, with all the posts in the forum on blocked nozzles, I’m rather disappointed with the fact that Velleman isn’t making any support responses in those posts themselves? (If I missed those, please correct me). Surely, seeing the frequency of the issue, this is a topic where Product Support would need to have a “formal advise” on? An instruction of sorts?

I’m suprised that we’re all just doing our best to find our way, without any guidance from the development team. For a kit-printer, I would consider the K8400 to be among the higher value products in the market: hence, I’d say that a bit of formal support & guidance would be appreciated. :slight_smile:

I’ll have me a go at the higher temperature & see what that gives.

Thanks & cheers,

Harry D.

Addition #1: At this URL http://www.k8xxx-3dprinters.crimed.be/w/index.php?title=Hotend, I found the reference back to the guitar string. I’ll also get me one of 0.35mm & see if that will help to get the nozzle opening cleaned at the normal PLA temperature (some 210°C, when using the manual control). Hopefully this will suffice.

Addition #2: Could compressed air be of any help? I’ve got a compressor…

14

UPDATE: Blockage solved - thanks, Biscuitlad! :slight_smile:

The suggestion to print at a higher temperature worked out. Probably in a different manner as you originally intended, but still - it solved the problem.

Previously, the nozzle was partially blocked. What happened is, while printing at the higher temperature, the nozzle now totally blocked. And, as we had noted previously, that is a scenario in which pushing the filament manually through a heated nozzle works quite well.

Problem solved. :slight_smile:

Think I’ll still get me that guitarstring, though - but it’s not urgent anymore.

Thanks for the help - much appreciated. Printer’s doing a little test print right now & it’s printing like there’s no tomorrow. :slight_smile:

Cheers,

Harry D.