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Problem with filament feed  

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Bastian
(@bastian-2)
Trusted Member
Problem with filament feed

Hi there,

i've a Prusa MK2, printing PLA/PETG.
Sometimes, my prints fail, because the filament seems to stuck in the meltchamber (= no continous flowrate).
This little metal-gear on the filament-extruder seems to slip through, with an hearable sound. This happens sometimes, not on every print, but i like to find the cause.

Also, don't know how this is on other MK2's, i can't unload the filament using "Unload Filament" on the first try. I have do it 3-4 times, till the filament leaves the Extruder-Head.

I tought, that some old filament remains in the moltchamber of the Heater, and that they "block" new filament, so the Filamentextruder "slips through". Don't want to disassamble the half printer - is there any chance to check this? If not, i also would like to upgrade to MK2S - that would be the right time to fix my issue.

I upload a video / photo of the print. In the video, you can hear & see what i mean.

Thanks for your help!

Video: https://1drv.ms/v/s!AmHs-ik2VszOh5YAyfWG3DxvLsUWcA
Pic: https://1drv.ms/i/s!AmHs-ik2VszOh5V_kxKEdQ3cFkXKyQ

Napsal : 12/08/2017 7:13 pm
AJS
 AJS
(@ajs)
Noble Member
Re: Problem with filament feed

Both of these problems sound like incorrect tension on your extruded springs. Mine are set to 14mm from the body without filament installed.

Other possible solutions here:

http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/-before-you-ask-troubleshooting-video-updated--t472.html#p39190

Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…

Napsal : 13/08/2017 3:41 am
fnico
(@fnico)
New Member
Re: Problem with filament feed

In fact check :
Extruder stops extruding filament. (Works for a while then stops)
Common causes:
1. Tension on the extruder springs is set wrong (see above).
2. Filament spool is not free to turn creating intermittent friction or binding. (Or filament is not wound well on the roll). Fix filament holder. Consider alternate designs on Thingiverse.
3. The extruder “Hobb-Goblin” pulley is dirty and debris is following the filament into the extruder.
4. The extruder “Hobb-Goblin” pulley is warn and is no longer grabbing the filament.
5. The extruder cooling fan (that cools the heat-break) is not keeping the heat-break below the filament melting temperature so it is melting and causing a clog. If in an enclosure, open the door. Verify the fan is running.
6. Intermittent (or broken) connection in the cable bundle for the extruder stepper (not stepping), cooling fan (not cool enough) or thermistor (causing the printer to think the temperature is cooler than it is, causing it to increase temperature beyond the range of the filament). Intermittent comes and goes as the cable flexes at different Z values.
7. Bad temperature for the filament.
8. Set screw on the extruder “Hobb-Goblin” pulley has come loose allowing the pulley to spin independently of the extruder stepper motor.
9. Set screw on the extruder thermistor is loose, creating a poor temperature reading of the heat block (see 6).
10. Poor quality on the filament diameter. Measure it with a caliper over a short span. Try a different spool.

If not, your trouble seems similar to :

http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/extruder-feed-problem-t2892.html

It's like an erratic extruder motor working, not solved by now.

Napsal : 13/08/2017 9:13 am
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