Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing  

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Although filament seems to be flowing well, I'd suggest doing a cold pull to ensure the hotend and nozzle are clear. Material build-up in the nozzle or hotend could account for the extruder problems you're seeing.

It's possible you've got other settings issues, but it sounds like everything worked before. Can you try re-printing gcode that worked previously?

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

does the Z calibrate print?

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

I have a similar problem happening with one particular filament, in my case the Janbex White PLA.
It gave rise to a problem described here in the forum.
https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/filament-stuck-to-print-head-brand-dependent-jam--t24631.html

Suggest the following:

If you don't see extrusion, open the idler door and inspect the pulleys, look for signs of dust that may indicate filament degradation.
You may consider switching filaments to see if this is filament-dependent, or a more general problem.
Also, consider doing a "cold pull" - don't forget to open the Idler door if you do so!

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

You have a partial blockage somewhere. Do the usual cold pull, needle up the nozzle etc. Minor blockages can have a tendency to hang around, just after you think you've cleared them they re-emerge, so be persistent.

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

How do you do a cold pull? Always says I need to preheat nozzle.

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Cold pulls is easy even for idjits like me. Here's how I do it.

1) Open the door to the filament extruder gear. I usually turn off the filament sensor also.
2) Set yourself up with some filament that requires a higher heat than what you last used. I use nylon from samples sent by the different filament clubs I have joined.
3) Heat the nozzle up to the temp for the filament you have chosen to use.
4) Hand feed it down the normal path it would follow if printing until you have some start coming out of the nozzle.
5) Keep some slight downward pressure so it feeds slowly and turn off the heat to the nozzle.
6) Once the temp drops to about 110 to 130 degrees (depending on what you are using for the pull) pull the filament back out.
7) Look at the end you have pulled out and see how clean it is or is not. And note the shape of it also. Best to use a light colored filament.
8) Clip off the used end as if you were going to normally load the filament.
9) Repeat steps 3 to 8 until the filament comes out clean.

Checking the shape of the filament end when you pull it out can help you see if your pfte tube is seated correctly.

Hope that helps,

Neal

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Checking the shape of the filament end when you pull it out can help you see if your pfte tube is seated correctly.

Hope that helps,

Neal

What shape is good and what is bad?

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Ideally it would be kinda flattish with a tiny little nipple on the end. Think of what the inside of your nozzle would look like and that is should act like a mold when you pull out the filament. That is the perfect shape. You don't want a bulb that is bigger in diameter than the filament.

Understand that you pull the filament out melted in most cases so smooth and pointy is okay.

Hope that helps,

Neal

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Although filament seems to be flowing well, I'd suggest doing a cold pull to ensure the hotend and nozzle are clear. Material build-up in the nozzle or hotend could account for the extruder problems you're seeing.

It's possible you've got other settings issues, but it sounds like everything worked before. Can you try re-printing gcode that worked previously?

Thanks for the reply!

Yep everything worked previously for many long and short prints. I tried reprinting with the same gcode and I have the same fundamental issue (extruder seems to be weak... sporatic when extruding).

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

You have a partial blockage somewhere. Do the usual cold pull, needle up the nozzle etc. Minor blockages can have a tendency to hang around, just after you think you've cleared them they re-emerge, so be persistent.

Thanks for the advice!

I did a cold pull, acupuncture needle up the nozzle, and heating up the nozzle to ABS temperatures, same issues 🙁

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

does the Z calibrate print?

Thanks for the reply, first layer calibration prints but not correctly due to the extruder sporadically slowing down and/or stopping. Attached is what my first layer calibrations have been looking like.

Re: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

I have a similar problem happening with one particular filament, in my case the Janbex White PLA.
It gave rise to a problem described here in the forum.
https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/filament-stuck-to-print-head-brand-dependent-jam--t24631.html

Suggest the following:

If you don't see extrusion, open the idler door and inspect the pulleys, look for signs of dust that may indicate filament degradation.
You may consider switching filaments to see if this is filament-dependent, or a more general problem.
Also, consider doing a "cold pull" - don't forget to open the Idler door if you do so!

Thanks for all the suggestions!

I've increased the temperature of the nozzle to ABS temps (previously only printed PLA). I"ve used the acupuncture needle. I've moved the axis and also loaded filament in an attempt to get any clog out. Filament comes out in what appears to be a healthy dose. Extruder still sometimes stops/slows sporadically during loading though.

I've opened the idler door, pulleys are clean. I've only used Hatchbox white and the included Prusa silver. Switching to the Prusa silver yields the same problem 🙁

RE: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Just started having this problem. My print actually quit out on me 50% of the way through at the 9:30 hour mark. I say quit out, but it was still moving around, just not extruding anything. It just stopped spitting out filament and was making unusual clicking noises. I haven't been able to feed anything through it, nor does it leave any filament on the plate during the first layer calibration. This is extremely frustrating as I just got it back from the shop and only printed 1 piece until it started to act up again. Different problem this time, but still.

Some good suggestion here. I'll take a stab at using the acupuncture needle and heating the head up according to the notes above. I'll let everyone know how it works out.

RE: Extruder struggling to extrude.. gear sometimes doesn't move and/or skips when printing

Posted by: @anthony-r8

[...] Some good suggestion here. I'll take a stab at using the acupuncture needle and heating the head up according to the notes above. I'll let everyone know how it works out.

Having experienced this problem a few times:

• I'm hesitant to use the needle on a soft brass nozzle. After "rescuing" my original nozzle using the needle I realized I was having fine stringing problems. I tossed that nozzle and put on a new one and the problem went away. I suspect I damaged the all-important opening by twisting that needle around in there.
• I've since adopted cold-pulls and have largely eliminated any sort of jams with most filaments. I run cleaning filament through whenever swapping nozzles or when changing between filament types, being sure to use a higher temperature than I print with (265C). I store each nozzle after cleaning it this way to ensure I don't forget and try to print PLA with a bit of PETG left inside the nozzle.
• Be sure your extruder tension screw is not over- or under-tightened. Open the extruder cover and check the state of the filament, including shredding and filament dust (indicating over-tightened tension) or lack of Bondtech teeth marks on the filament (indicating under-tightened).
• When in doubt, slow down. The Prusa default speeds for infill are very aggressive (Note: They do seem to have reduced them recently). You can slow down speeds individually, but I find adjusting the Filament settings->Advanced->Maximum volumetric speed setting for jam-prone filaments is the easiest fix. Prusa uses a default of 15mm^3/s for PLA, but my own casual testing shows that 11.5mm^3/s is more realistic. Reduce this value until you get reliable prints. Use preview mode after slicing to view resulting speeds.