eric.e7
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Sep 08, 2018 10:11 pm

Ok i understand.
Well i have good news. Spitfire printed with out issue, then the spool holder printed with out issues. 2 wing sections printed with out issue. All 5+ hour prints. At this point my confidence is much higher and can wait to print more PET. Maybe with it loose the gears were grinding down the filament during sections with a lot of retracts? I have no idea and have no other conclusions or data points to present except to tighten the extruder gear.
I don't think its the filament or the printer just the moron who put it together.

"Place both screws into the Extruder body and tighten them. The screw's head should be almost aligned with the printed surface."

The picture looks like the screw heads are slightly above the printed surface. Perhaps i didn't perform this step correctly or my parts are a little smaller. I don't know.

lena.b
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Sep 09, 2018 9:09 am

Phew. I'm back again. Apparently it's still happening. Just later. And, I started to compare my older MK2S prints with the newer MK2.5 ones, and it seems that they are way worse quality-wise. I thought it might be the filament (wet or something), but using a new spool has the same issues.

I'll try having a look at the PTFE tube thing, I am unsure what I did there, too long ago. So, again, taking the extruder apart. Currently, I wish I did not change the printer in the first place. It seriously enerves me and takes a serious amount of time, which I do not really have currently :-/.

@cristoph.h5: as pekka.p mentioned, you can use command M907 E750 to get it to 750mA. I used the octoprint "gcode scripts" in the settings to inject it.

vladimir.r4
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Sep 29, 2018 6:42 am

I have same problem. I thing this is problem with printer fan cover. Air flows direct to nozzle and fillament inside nozzle is chilled. Thermal senzor is in heat-block so printer dont recorded problem. I try edit original fan cover, air flow is now directed just below nozzle, and this worked for me. Yes now is overgans a bit worse but printer is now reliable. I dont heard any special sounds from extruder motor (skips) and I did not notice any pause in printing (befor many).
You can try this: https://drive.google.com/file/d/1UvCM_Y ... sp=sharing
Maybe help you :) and sorry for my english :D

edit: I use Cura and Overhangs is bad, but when i use Slic3r that printed part is almost identical with this from original fan cover :) (in Slic3r is temperature higher by 5°C)

pekka.p
Posts: 13
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Oct 11, 2018 9:30 am

Been having problems with jamming still, my print success rate is currently ~70% due to jamming on some more demanding models.
So far, best success is with these steps:
- increase stepper power to 950mA. 750mA is ok for most prints, but some require bit extra
- open room window. Chills the room temp a bit -> cooler hotend top section, less jamming
- added a silicone sock the hotend. Didn't do much regards the jamming, but temperatures are bit more stable so no harm done. Also keeps the heater block and nozzle cleaner.
- slice without z-hop. Bit faster prints and faster overall throughput of the filament -> less time for the filament to heat in the heatbreak and jam
- curse MK2.5 to hell. Doesn't help with jaming even a bit, but helps with nerves
- lastly, one thing that I've noticed that helps with multiple printers: do a cold pull before starting a print. All my printers currently have all-metal hotends and they all have jamming problems with some PLA filaments. Prusa MK2 was the most perfect of the 4 printers I have, since it's the only non-bowden setup. I've tested the difference of doing multiple prints with and without cold pull in between the prints on 2 printers now, MK2.5 and other printer that has a Prometheus v2 hot-end. With both, the cold pull between prints helps; on MK2.5 it means that challenging prints most likely won't fail with the extruder clicking and on the other printer it means that the print quality stays good when filament flow isn't hindered by partial jams and bowden's spring effect.
At first I thought it was a fluke, but after multiple tries I saw that the cold pull effect is really repeatable. Not sure why, maybe there's dirt or some filament crap that sticks to the heatbreak during prints and starts to hinder the filament flow. And cold pull removes that crap.

Edit: one more trick, but this needs to have someone babysitting the printer while it's printing. I've managed to salvage few prints when the extruder clicking starts by pausing the print, retracting 10mm, refeeding 10mm and resuming the print. This seems to allow the printer to continue at least some time before next click session. I use Octoprint and this probably cannot be done without it.

filip.k6
Posts: 4
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Oct 14, 2018 12:02 pm

Hi guys,

Does anybody resolve this issue?
I have this problem with MK3. At first, the printer worked flawlessly. But right now, I have a filament jam in 90-95% of prints.
I also switched to R3 extruder ( one of the successful prints).
I know, that the issue is not in the gcodes as I have tried several slicers or the original Prusa gcodes on the card for MK3.
No success. New PTFE tubes installed (as suggested on the support) but nothing is helping.
I did not have any issues like that with my MK2S with over 250days of pure printing time. And that was my start of 3D printing. Every issue I have had at that point was my own error, but I do not think, that this is the issue now.

Thanks guys.
Filip

manu
Posts: 68
Joined: Dec 17, 2016 8:31 pm
Location: Germany
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Oct 30, 2018 1:12 pm

Hi guys,

I'm as well at the point where printing with PLA is nearly impossible since upgrading to 2.5.
Here are the thing I already tried without success:
  • Several cold pulls
  • adjusting the idler screws to barely grab the filament
  • switched to another role of filament
  • replaced the noctua fan with the sunon 40x40mm fan which has way more static pressure
  • Played around with the temperature (from 205 to 230°C)
  • Reduced Retraction to 0.2mm
  • Increased extruder motor current to 750mA
My last resort is now disassembling the hotend and give it a through cleaning as much as I can. If this fails as well I'm lost.

I appreciate any further ideas which may help us to get this solved.

Regards

Manu
Design, Print, Repeat

manu
Posts: 68
Joined: Dec 17, 2016 8:31 pm
Location: Germany
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Nov 01, 2018 8:26 pm

manu wrote:
Oct 30, 2018 1:12 pm
Hi guys,

I'm as well at the point where printing with PLA is nearly impossible since upgrading to 2.5.
Here are the thing I already tried without success:
  • Several cold pulls
  • adjusting the idler screws to barely grab the filament
  • switched to another role of filament
  • replaced the noctua fan with the sunon 40x40mm fan which has way more static pressure
  • Played around with the temperature (from 205 to 230°C)
  • Reduced Retraction to 0.2mm
  • Increased extruder motor current to 750mA
My last resort is now disassembling the hotend and give it a through cleaning as much as I can. If this fails as well I'm lost.

I appreciate any further ideas which may help us to get this solved.

Regards

Manu
So it seems I have found my source of frustration and failed prints: a not properly assembled hot end. During disassembly I registered that the heater block was quite easy to turn on the heat break. So somehow the heater block came loose. After disassembling everything, cleaning it as good as I could and reassembling it, making sure everything sits tight I seem to be back in business. I don't know how it came loose but maybe during the upgrade something wiggled around a bit and lead to this.
Design, Print, Repeat

alex.v3
Posts: 5
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Dec 08, 2018 9:48 am

Hi,
After upgrading to the MK2.5 recently I also ran into problems with a clogged nozzle. In my case the issue arises when unloading filament, it just cut's of filament at the top of the cooling rib, leaving a big part in the cooling. The only way to clean this is a full disassembly of the extruder, other attempts like heating up and try to push it through weren't very successful.
Any thoughts on this problem? I use the latest (updated) extruder parts.

Kind regards,
Alex

pekka.p
Posts: 13
Joined: Oct 26, 2016 7:53 pm
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Dec 21, 2018 12:38 pm

@alex.v3 I've had that happen to me once, the unloading left a trip of filament into the hotend that caused a jam when trying to feed new filament. Not sure what to do to make sure that doesn't happen. I usually do cold pull and not use the unload option.

Still having problems with jamming with prints that have lot's of retractions. Prints that don't have lot's of small details are fine. Haven't had time to disassemble the extruder and check the PTFE tube. I suspect that it's not the culprit, but I'm going to check it anyways and also properly bevel the tube end so there's now gap between it and the heatbreak.

Still, as I needed to print something that suffers from jamming, I hacked something together on the slicer that seems to help. I noticed that when the extruder is jamming, pausing the print from Octoprint, retracting 10mm, waiting few seconds, feeding 10mm and the resuming the print clears the jam and the print continues ok for some time. So I added following g-code to be executed during each layer change:

Code: Select all

G91 ; relative coordinates G1 E-10 F300 ; retract 10mm slowly G1 Z1 F2000 ; optional z lift G4 P1000 ; sleep 1 second G1 Z-1 F2000 ; optional z lower G1 E10 ; prime 10mm G90 ; absolute coordinates M83 ; relative extruder coordinates
So far the ~42h print has been progressing without gaps for 8+ hours. I had to hack this together mid print because I already have few partly missing layers that need to be fixed, if the print finishes.
This does add some extra time to the print, but for now it seems to help getting the print done. Also there seems to be a small blob after the layer change, for some reason the 10mm feed produces some extra? Maybe some jam related extra pressure or something...

vladimir.h3
Posts: 5
Joined: Mar 15, 2017 5:12 am
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Re: Extrusion failure / clogged nozzle since Upgrade to MK2.5

Jan 04, 2019 6:28 pm

Hey, Ive been having this problem for the last 6 months and havent had much luck. Some prints are good but the problem always comes back. Ive tried pretty much everything in this thread and even bought a brand new E3D V6. Re-printed the R3 parts 2x. If I remember correctly this started after switching to the new R3 parts.

@pekka.p One thing I havent tried using M907 E750 which Im doing as we speak and printing a Cali Cat. One thing I wanted to know is does the command auto save and anytime I use the printer it will have that setting? also incase I need to revert what is the stock current?

Other thing I noticed is the fan is pushing air OUT of the heatsink which from what Ive read is whats most agreed on instead of pushing air through the extruder. I feel its the Noctua fan causing all these issues. Before this upgrade included the Noctua fan ppl were upgrading there fan to the Noctua as did I wanting a quieter printer but found I started getting clogging issues so reverted back to the stock fan.

I have tried eeeeverything and it just seems there isnt enough airflow to cool down the heatsink and Noctua just isnt doing the job. I think I might have the stock fan so if M907 E750 doesnt work I will try the stock fan and report back.

Edit: Cali Cat printed! So prior to changing to M907 E750, I was having issues printing Cali Cat on first layer started clicking. While clicking I loosened the idler screws and pulled filament out a bit then let it flow. Printed Cali Cat the current changed and it printed perfect. The print is only 1hr long so the real test will be tonight when I can start a longer overnight print. Will update.

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