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holoped

Jam or filament stripping, not sure which causes which

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Hi,

I have an Ultimaker (with the extruder upgrade) that I got used from a friend.

I've only had it a week.

It worked well in the past but now I can't get it to finish a print.

It will always jams and strips the filament.

Sometimes it works great for a while, then starts to print 'fluff', very airy with no

structural strength.

My PLA is transparent from Protomachine. It might be bad, i'm not sure.

I've tried playing with the temperature settings, I've tried turning off retraction and I've tried to tighten or loosen the extruder spring screw, nothing seems to help.

I would welcome any ideas to troubleshoot this.

Thanks,

HP

 

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On the extruder, is the bolt on the locking lever all the way to the bottom of the slot when you are printing? It should be.

What speed, layer height, and temperature are you printing at?

How long is the sprint on the extruder when the filament is loaded?

If you heat up the head and then turn the large extruder gear my hand, does the plastic extrude nicely and fairly smoothly?

 

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Please answer illuminarti's questions.

To answer if it is nozzle/heat related versus extruder related, test how much the extruder can pull when the filament isn't reaching the nozzle (pull it back a bit). It should be able to pull about 22 pounds without slipping. There are other tests, but this one is a good one.

If it fails this test then send us pictures of your extruder when it is closed all the way.

If it passes then concentrate on temperature and clogged nozzle issues.

 

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Yes, that was a typo. I meant 'spring'. You might try tightening the screw a few turns, so the spring is more like 11mm from the back of the extruder to the underside of the washer.

Cut off any filament that's been damaged by getting stuck in the past, and then check that the filament passes through the Bowden tube ok, without significant friction - it shouldn't be hard to push all the way through until it reaches the hot end.

Finally, take some pictures of your hot-end assembly and your closed extruder drive, and we'll see if everything looks like it's assembled ok.

I'm beginning to think that you might have some dirt inside the nozzle that's interfering with extrusion, so you may need to clean out the hot end. You might start by heating the hotend to 250, and then manually turning the gear to pump a few tens of cm of filament through the system, and see if that flushes it through. Quicker and easier than taking it all apart, but it might come to that.

 

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First test print (about 3 hours) was good,

second failed at the first layer. It stopped extruding, then started again, then stopped - a few times like this -

and then jammed completely.

I did another flush at 250c and something popped and it started to flow again.

I only have two PLA reels, they both are not new and may have gone bad (?)

 

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I think its unlikely to be 'bad' filament as such, but you should make sure its clean, and isn't dragging dirt into the hot end with it.

Also, does your printer have the v2 hot-end? Thats the one with a broad lip on the brass tube where it goes into the PEEK insulator, and a gap of exposed tube before the aluminum block. The earlier v1 hot end was much more prone to plugging.

Btw, did you leave the hot end sat, hot for a while before the second print? That can cause heat to travel up the filament, and soften it higher up, leading to sticking. It can also cook the filament in the hot end, causing it to go bad and get stuck.

 

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I have been plagued with nozzle plugs on and off since I got my Ultimaker about 3 months ago or so. I believe I have traced the issue to some sort of foreign contaminant getting into the nozzle. I have my UM in a particularly dusty corner of my apartment, so I have a feeling this is part of the cause, though I have not observed much dust on the actual filament, which I try to keep clean. Here is a brief summary of the things I have found to help with a plugged nozzle:

- While printing at a higher temperature can help in the short term, it is rarely is a "fix". Flushing can help a bit, as you experienced, but it is rarely treating the cause and is only treating the symptoms of your clogging. I have found that ultimately, removing the nozzle is usually necsesary (if you are sure plugs are happening in the nozzle, and not in the peek or the white ePTFE tube).

- I remove the nozzle by first heating it to 240 C minimum, then using a needle nose pliers to grip the heater block and a wrench (not over-tightened) to twist the nozzle (just make sure you are twisting the correct way)

- When the nozzle is looser, I use work gloves to twist it off the rest of the way, but be careful of burns.

- Some people say to put it in the oven. I have not really found that to help. For me, gripping the nozzle with needle nose pliers (not on the tube portion, but on the hexagonal head), and holding the nozzle over a gas stove flame for about a minute. Usually excess PLA will bubble out as it expands, and that is fine.

- Now you need to run something through the nozzle to clear any sediment or blockage. I first try to ensure as much of the PLA is removed from the nozzle before attempting to run the wire through. Some people say to use a Q-tip, but I think that this just adds potential coagulants like cotton fibers, and so I will usually let the nozzle cool a little so the PLA gets sticky, and then pull out the plug that forms.

- As to what to run through the nozzle tip, II stripped a spare wire and twisted a few strands of copper wire. while the nozzle is heated, I hold the nozzle in one hand with the pliers, and push the wire in the back of the nozzle so I can see the tip of the wire peeking through. Then I grab the end of the wire peeking out of the tip from the other side, and pull it through. I do this a few times, and then carefully screw the nozzle back into the heater block (usually while hot). Then I do a bit of a flush at 250 C or so, and usually notice a difference pretty quickly.

- On someone else's recommendation, I bought and tried using some 0.4 mm drill bits to (by hand) clear blockages. I found these not to be so great, since they can break off quite easily, and cause their own (very hard to remove) blockage.

- Rather than having PLA that has gone "bad," I have found that certain types of PLA are more likely for me to run into a plugged nozzle. I don't know the science behind it, but certain colors just seem to have a particular color additive that is prone to forming sediment plugs. This is a little counter-intuitive, as it is more likely some foreign substance (wood dust from grinding in the extruder mechanism, or dust, or animal hair) is getting pulled into the hot end from your PLA reels. I heard at least one person recommending some sort of tissue paper rig that essentially wipes clean the PLA as it is fed into the extrusion mechanism. I never tried it, but will if my issues return.

- Good luck!

 

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Btw, I recommend not using the ulticontroller to advance the filament - e.g., when changing filaments, or reloading, as that can force the plastic through the head too quickly, spiking the pressure and leading to blockages due to molten plastic flowing back up into cooler parts of the head. Better to turn the gear by hand, as then you can feel the pressure involved.

 

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I don't think you ever said. Do you have the v2 hot-end upgrade? If not, get one. Also get the v2 extruder and v3 bolt if you don't have those. They make printing far more consistent.

If you already have those, then it sounds like the filament you're using may have problems - perhaps it has contaminants in it? Do you know what brand it is?

 

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Take a piece of kleenex or toilet tissue. Bunch / wrinkle it, then wrap it around the filament below the feeder. Put tape around it to hold it tightish against the filament. Make sure it slides up and down. Use another piece of tape to attach this "cleaner" to the side of the UM so that it doesn't slide up and get jammed in the feeder. After printing for 4 hours, take it off and examine how much dirt you removed from the filament.

Did you ever check the feeder carefully for chips of wood?

 

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I am only a relative newbie at this - but having had the UM for a month and running through the various pla that I have I suddenly found that the white UM filament would start stringy and then air print. manually pushing the filament through the extruder would suddenly push out the blockage and then I would get free flow.

I checked the filament and it was slightly wider than it had been at the beginning of the roll (2.9 in stead of 2.83) and it had been grinding.

I took off the extruder and used a brush to rush out the ground PLA. I then felt the bearing on the other side of the extruder and it did not turn at all - locked. A bit of light oil and some working the bearing loosened it.

I tightened the spring slightly.

Since I lubricated, brushed and tightened I have not had a failed print - so personally, in my instance, I think that the blockage was caused by the grinding (non feed of filament) rather than the grinding being caused by the blockage.

U was using 220 degrees for the PLA which seems to have worked well for the 'honey' fluidity of the filament.

This MIGHT have been newbie luck but I had de-bugged everything else and have printed non-stop since with a range of filaments, speeds and layer heights.

James

 

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A few thoughts....

1) The filament in your extruder looks to be pretty well chewed up where it's passing over the drive bolt. And as you close the extruder, I'm not seeing much movement in the spring. We don't really get a good view of the spring though, but you need to make sure that it's not so tight that there's no room for it to compress even more as the extruder is closed. The coils should not be touching one another.

2) WTF is going on with the red mess that's clamping the cold end of the Bowden Tube? :-) Are you sure that there's not some extra feeding resistance getting added in as a result of that? If it works, fine... but dang... ;-)

3) Your fan duct has a very crude opening, and set way back from your nozzle. I suspect that you are probably blowing cold air all over the nozzle and lowering its temperature a lot. That may be making it a lot harder to extrude the plastic. Are your prints more successful with the fan totally off?

 

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