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I'm pretty new to 3D printing, got my printer about 5 days ago and spent most of my time with it.

First off, it is an Ender 3 Pro with everything stock, haven't made any upgrades except I run it with OctoPrint from a Raspberry Pi Zero but I have determined that's not the source of the problem as it's well within 80 % idle on its CPU.

The issue I'm experiencing is that the extruder starts slipping at some point along the print. It's not the clicky type of slipping that appears to be the common issue but rather it's just spinning and grinding on the filament which is remaining stationary. When this happens the printer continues on about its business as it's unaware that filament is not coming out. I move the Z-axis up, squeeze the extruder lever and try to push on the filament which is not budging, which made me think I had a clogged nozzle. I was surprised as it's a brand new printer but the internet says that nozzles clog up so I disassembled and cleaned it just to find that it happens again on my very next print. I noticed that when I pull or push on the filament by hand while squeezing the extruder lever - relieving pressure from the gear, it is quite hard to do so, even partly impossible as my fingers start to slip, I have to squeeze extremely hard or use pliers. I pulled the filament out using quite a bit of force, then snapped off the piece that was already in the tubing and inserted fresh filament which slid very easily through the white tubing to the hot end and when reaching it by pushing very gently I start to see filament coming out as opposed to pushing really hard and barely anything coming out previously. If I do that and return the Z-axis to its position then resume the print it continues until that happens again.

My bed is leveled as best as I can, I downloaded the bed leveling G-codes that help a lot to achieve good adhesion, my prints look pretty much perfect, smooth lines very pleasing to the look and touch, until what I mentioned above happens.

I don't understand what could be the reason that my filament would just bind up like that and snipping it off and inserting a new piece there's no sign of the issue whatsoever.

Notes for what it's worth:

  • I'm using cheap black PLA 1.75 mm
  • Hotend temperature 200 °C
  • Bed temperature 60 °C
  • Printing speed 50 mm/s
  • The extruder pulley (white wheel with the bearing) bolt is not tightened to the end as recommended on the internet
  • The spring bolt on the extruder is not tightened also, as I see there are marks on the filament that went past the extruder wheel, anyway I tried tightening it for the sake of it and it didn't help
  • My extruder arm is not cracked
  • The gear (brass wheel) doesn't seem to be damaged
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  • $\begingroup$ Have you unscrewed the nozzle and tried pushing filament manually through the Bowden to see if there is a lot of friction in the system itself? $\endgroup$
    – 0scar
    Jun 28, 2022 at 6:34
  • $\begingroup$ @0scar yes I tried, it didn't seem to have any issues going through, although there are some scratches on the outside of the tube where it meets the (i don't know what it's called) on the top but I assume that it's fine on the inside. $\endgroup$
    – php_nub_qq
    Jun 28, 2022 at 15:40

3 Answers 3

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This is probably the filament. I've had the exact same issue on my Ender 3 Pro and solved it by baking the filament.

I suggest you try with another filament just to make sure. Or bake a length of the filament for a couple of hours at 50 degrees and try again.

The other possibility is that the filament is not consistent in diameter.

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  • $\begingroup$ Well it's an Acccreate 1.75 PLA filament and reviews online seem to be only positive. I'll try getting anothrr brand but what would be a recommended one? Is sunhokey any better? $\endgroup$
    – php_nub_qq
    Jun 7, 2022 at 10:07
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    $\begingroup$ I've found it's not so much the brand as whether the filament has absorbed enough moisture to create the problem. Mine came seafreight which took months and were mostly rubbish by the time they arrived. The same filament brand that came airfreight printed fine. $\endgroup$
    – Kilisi
    Jun 7, 2022 at 11:37
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I experienced similar problems when I changed to other filament. The solution was to open my enclosure as the inside temperature was too hot and the filament got too soft for extraction.

Moreover have a look at the gear wheels position and maybe adjust the height a bit. At one time my wheel screws got loosened and the wheel was sitting too low resulting in irregular skipping.

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    $\begingroup$ Ender 3 Pro doesn't have an enclosure $\endgroup$
    – Kilisi
    Jun 11, 2022 at 4:49
  • $\begingroup$ also on my 3 pro the gear height can not be adjusted $\endgroup$
    – php_nub_qq
    Jun 11, 2022 at 17:14
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I had a similar issue with my Ender 3, and it was a combination of things. First, the hot end (inside) was clogged. I took the entire thing apart, heated it up, and cleaned it out. There is also a method called a cold pull, I did that a few times.

I then also replaced the Bowden tube because it had gunk in it and cause the filament to not flow as it needed.

After doing those two things, the printer began extruding.

One thing I noticed is that those little brass wheels get worn down by the filament really quickly if the stuff isn't moving through the Bowden tube. The PLA just grinds the gear down. You should probably replace that wheel/roller or just get the all-metal extruder like one from Amazon. I think this is worth the $10.

Also, you may suffer from under extrusion after doing this and you should probably calibrate your extruder.

It's not hard.

Doing these things got my Ender back up and running.

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  • $\begingroup$ I think I figured mine was also a combination of a few things but not necessarily the ones you have mentioned. I put a desk fan right next to the printer and after doing a few 8h+ prints I think it's safe to assume that the 40x10 fan is just not up to the task at 27+ C ambient. We'll see how it goes when it gets colder after a few months without the fan. $\endgroup$
    – php_nub_qq
    Jun 27, 2022 at 21:38

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