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gregwar

Filament slipping

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Hi all,

My filament is constantly slipping in the feeder of my UM2

I can't print faster than 0.1 layers @40mm/s extruding...

For instance: when I change my material and insert it again, I can hear it slips like every second (during the Material->Change last step), I guess that's not normal at all, right?

Any idea?

 

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Any number of reasons:

Partially blocked bowden tube ( particles from extruder process inside tube)

blocked nozzle/head (most likely, check Atomic Method, reco use PLA and 220/85)

partially destroyed teflon coupler

too low temperature (= blocked nozzle)

This is not for you since you say you CAN print slowly, but still:bowden tube not correctly inserted into teflon coupler, so filament is stopped before entering any metal part in hot end top end..

far possible: filament squared due to wrong storage (would have to be really wrong), malmanufacture, so not sufficiently round and oversized (least likely)

 

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This test is not really clear, the filament melt easier at 240 than 180 but the difference is not that simple

Another test would be how many time it takes to reach temperatures, seems we have the same power supply I guess it should be quite similar, isn't it?

My times (from "cold" to ...):

180: 52"

200: 1'

220: 1'10"

240: 1'19"

Edit: I set the target temperature to 260 and noted the time to reach the above temperatures

PS: My thermistor definitely doesn't seems good:

Broken thermistor cable

 

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Thanks, I'm trying Atomic and it seems that there is a lot of dirtiness in my nozzle. How frequently one should do that?

And what feeder do you advise?

 

ha, easy :-P

https://www.youmagine.com/designs/feeder-for-ultimaker-2-rail-system

most people use roberts feeder, ... if you use his make sure to also improve the entrance path of the fillament into the feeder, best put the fillament on a spoolholder a bit lower, anything that makes the fillament path a bit more straight.

 

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I think too. I'll change my Hot end and my Bowden, maybe this will make the difference, but I don't think so... I really don't understand what's going wrong.

Is it really a problem with the feeder?

Can you confirm me that if you put PLA in your printer and let it extrude (during the last step of Material->Change) it doesn't slip?

 

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I think too. I'll change my Hot end and my Bowden, maybe this will make the difference, but I don't think so... I really don't understand what's going wrong.

Is it really a problem with the feeder?

Can you confirm me that if you put PLA in your printer and let it extrude (during the last step of Material->Change) it doesn't slip?

 

(I mean with default feeder)

 

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Please try loosening the 4 long vertical knurled bolts keeping the whole hotend assembly together.

It has helped several by decreasing the pressure on the end of the teflon coupler.

If the teflon coupler had a hot life ( 240 +) then it has decomposed somewhat,

inducing the lower end of it to collapse and getting a "grip" on the filament.

Just have them finger tight, make sure the brass gliders are still in the correct postion, the ones

on the X and Y axis.

 

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Ok!

First assemble the complete head correctly by aligning the two black plastic pieces

and tightening those 4 screws more. I can see its wrong in the video.Make sure the brass tubes around the X Y axis are aligned and nothing sticks out, you will see what I mean.

Then in menu: Advanced, move material, wait for the head to heat up,

Then, loosen the bowden tube on the hot end side, by pulling out the small plastic ring, pushing and holding down the white insert, and pulling the bowden out, while holding DOWN the insert ( it has little knives to holde the tube, which are disabeled when you push it down.

turn the wheel in "move material" menu choice, and verify that the

pla is moving. if there is a larger "drop" on the end of the pla filament, cut it off or it

gets stuck in the bowden tube. If it IS stuck, heat the bowden on the outside with a lighter.

the filament will be unstuck immediately (3-5 secs).

Once you got the pla to move back and forth by turning the wheel, try to hold it and see

that it pulls STRONGLY.

IF it does, you have a blocked hot end. See atomic etc..

If it pulls weakly (like a small child can hold the filament end) before skipping you have an issue in the extruder assembly.

Beware it is a little fiddly to re-assemble but you will manage, should you decide to open it.

Re-inserting the bowden is fiddly too, make sure it ENTERS the top of the teflon coupler and sicks ca 5mm (until it stops) into it. Hold it down FIRMLY while pulling up the white insert locking the tube and inserting the horeseshoering (little bit fiddly).

good luck.

Lets hear tomorrow how it went.

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Actually, the block 4 screws were loosened before the video (to try), but it is normally correctly assembled

What do you call "strong"?

Here's what happen:

 

  • If the pressure is low on the filament (the screw of the feeder drive the white+spring+bearing system totally up), and if I place my thumb at the end of the tube, there is no slipping but the filament doesn't come out. I guess it actually slips against the driver
  • If the pressure is a little higher (the screw is a little more turned) and I place my thumb at the end of the tube, I can it make it slips easily (it doesn't even hurts)

I imagine this is too weak, isn't it?

What can be the problem so?

 

  1. Feeder?
  2. Nema17?
  3. Power supply?

(Note I'm not affraid disassembling the feeder or so, already done it several times)

 

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Can YOU block the filament with your thumb? (or does it hurts before it slips)

A small correction: the problem is not really "slipping", but is that the NEMA17 is unable to push the filament. Don't know the exact word for that

 

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Hey!

I know it is not exactly halal to say this: I have never touched the feeder except opening to look and remove some rubble, then close it again.

The knurled drive should make quite an impression on the filament (-bad for laybrick

and other fragile fils.. good for PLA etc).

It should be adjusted so that it pushes the filament STRONGLY out of the bowden tube on the hotend-end. I guess like hurting if you held your backhand in front if the tube.

My advice, make the push work. it COULD be still skipping (without the symptoms of the "chuffs", if the drive has rubbed ahlfway through the pla in the same place and there is no bite anymore... but maybe not your case).

It should push with several kilo pressure.

Then, make sure the tube is reinserted correctly into the teflon piece (more fiddly than you would imagine), also help the filament entry by cutting a pointed sharp end of the filament so to help it past the assembly in the hot end. (there is even more to this but tough to explain),

Use Advanced Move material, play with it and see it move the filament back and forth.

Then move it slowly (20-30ish clicks) into the hotend and see it come out.

When it does, back off 15 clicks.

Then make a print. Use 5-10 line BRIM ( more with very small pieces) to get

the filament "going" after the operation.

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My extruder is *not* blocked, everything works, but if I print too "fast" (layers of 0.2, 50mm/s) the extruder fails tu push the filament and the part is underextruded

I've already tried a lot of pressure, filaments, etc. And I think this is not a matter of tuning

If other UM2 users can print 0.2 layers @50mm/s without any underextrusion problem, there is an issue with my hardware. Else, maybe it is a more generalized problem in the design of the printer (maybe the NEMA17 that pushes the filament is simply undersized)

 

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