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Ultimaker 2 stepper motor slipping preventing loading/unloading of filament

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Hi guys

Initially i could not get the UM2 to extrude or printer (just to note set up was no prob). as the machine would not extrude i went through the normal step to correct it;

re-leveled the bed that was OK

then went to unload the filament ( on screen menu, material-change) this would not work, was really stumped so tried googling to find info on how to change the filament but had not luck, so tried to figure it out myself. once you follow the on screen steps the machine trys to unload automatically but noticed the stepper motor slipping , which prevented the filament from retracting. so to fix it i simply gave it a helping hand by pulling it when it was trying to retract, work ok.

also noticed some deep chew marks on the filament when i took it out, not sure what caused it, possibly to much tension on the wheel which holds the filament against the stepper (this may also be the cause of the stepper slippage when it eats to far into the filament it is then unable to move it) . when i reloaded the filament the same problem occured stepper motor was slipping on the filament preventing it from going anywhere, so to solve this i gave it a pull up loaded no prob after this (noticed fresh chew mark after the filament started to load again).

i was then able to print 2 models successfully without any problem, but on the 3rd model the error reoccurred (so pulled up the filament, error resolved).

Could some one please explain why this is happening (or is it normal), i hope there is not a problem with the stepper motor. also the unloading of filament could be explained a bit better in the manual.

thanks

porter

 

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No it's not normal.

When you insert the filament, at first you have to push it quite hard to open the spring tensioner. Then you let the feeder wind the filament in slowly until it emerges into the bowden. You can then press the button on the front, and it will pull the filament in quickly. At the end of this, when the filament reaches the hot end, you may hear some clicking of the extruder slipping. That is normal - it's allowing the stepper to click back, rather than stripping the filament due to moving it faster than it can exit the head.

Finally it will slow down again to begin to push the filament through the head. You shouldn't really hear much clicking during that slow phase; if you do, it might be a sign that the filament hasn't entered the head properly (it's happened to me a few times, and I've had to cancel the load, back the filament out, and start again).

Where is the white indicator mark on your extruder head? I think it should most likely be in the highest position; it doesn't seem to be necessary to add more than the basic amount of tension. The other possibility is that maybe your extruder motor knurled bolt has slipped somehow so it is catching on something in the extruder assembly, and not turning properly. It could also be that the bolt has come loose on the shaft, but while that would prevent extrusion, it shouldn't cause visible signs of steps skipping or the filament getting chewed, since the motor should be able to turn freely without anything slowing it down.

 

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(it's happened to me a few times, and I've had to cancel the load, back the filament out, and start again).

 

Me too and instead I use the menu where you can move filament slowly in or out of the head - I back it out 10mm and then put it back in. It usually takes 2 or 3 tries. But of course this doesn't help the OP.

 

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Hi Guys, thanks for the info.

The problem occurred twice again today see pics of chewed filament.

chew mark 2

chew mark 1

 

illuminarti you my have hit the nail on the head, with the filament not loading into the extruder properly causing the knurl bolt to eat into the filament. To make sure their wasn't a problem with the stepper i dismantled it and put it back, have had no prob since did an 8 hour print without any problems. a few small mark on the print but other than that it turned out ok.

best

porter

 

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I've been having more slipping of the extruder motor lately. I cleared a nasty clog yesterday that may have been building up and perhaps explains some of it, but I think I got it pretty cleaned out. Now I'm still getting some slipping while printing the stock UM robot (using the G-code that shipped with the machine). I've printed it fine in PLA, ABS, and nylon in the past, and now my PLA one using all stock settings is very under-extruded. I can't figure out if it's still some type of blockage, or some problem with my extruder, or both.

I have noticed that it is easier than it used to be to manually push filament into the machine when the extruder stepper isn't energized. It used to be incredibly hard to push a fresh piece of filament into the extruder, and the last day or two I've been able to just push it in as far as I want by hand, backdriving the stepper with relative ease. Both of the little white indicators are in the uppermost position.

Looking through some posts I saw the picture showing the vertical screw nestled inside the top of the extruder assembly. I tried tightening it and found that it had become completely loose, it was several turns before I felt any kind of load at all. How tight should this be?

Does anyone have any ideas? My prints are all under-extruding now. I thought for sure the robot would print fine.

 

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Something is strange in your extruder. I would remove the cover. The motor may fall - don't panic about that. When screwing it together you can hold it up with your finger through the hole under it or you can take off the metal cover (only one screw holds the white metal cover - it goes into the white metal cover where a nut is welded to the white metal cover (look carefully along the 2 vertical edges).

Something may be jamming the white extruder L shaped lever into the wrong position. Or something. Take a picture of the inside please in case this happens to someone else so we can explain the issue.

That screw you played with isn't needed as the spring needs to be at it's loosest position. You can remove that screw and throw it away if you want.

 

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Nice work! I opened it up and blew it out and a chunk of semi-burnt blue filament fell out. My best guess is it came off at some point between filament changes or something, and jammed things up a bit in there. I was able to print out another UM robot using the same exact settings and it looks great, and I didn't hear any filament slips.

Thanks!

Following is a picture of the inside of my extruder, although I think it should look fairly ordinary now that the little ball of evil fell out. Taking it apart and putting it back together wasn't as bad as I had feared.

Extruder guts

 

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Hm, maybe I spoke too soon.. I printed up a couple of UM robots and things seemed fine, and then I started getting lots of under-extrusion again, and hearing the filament transport stepper skip steps.

On a whim I decided to try measuring this current filament diameter. It came from Makershed so presumably it's not junk, but the diameter came out at 2.97mm. I dialed that into my UM2 (the first time I've ever changed the diameter setting, as previous spools were very close to the default 2.85 mm) and am printing another robot now and have not yet heard another extruder stepper skip. Does that make sense to anyone? So previously it thought the filament cross sectional area was about 8% lower than it really was. I'd love for this to be the current culprit because it's an easy fix, but let me know if you think this seems reasonable or if you think I still have some kind of issue to track down.

 

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printbl.com is great in USA. Although their spools aren't compatible with the UM spool holder - but it's not a big deal - you will work something out.

For most printers out there 3mm filament works fine because the extruder is *on* the print head *after* the bowden. But for the UM it needs to be 2.85mm (+/- .15m)

 

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Has anyone bought from printbl.com in the last few months? I am wondering if they are still in business. They show items in stock, but I emailed them about a week ago and have heard nothing back, the most recent blog entry is from almost a year ago and the most recent Twitter and Facebook updates are from 2012. Everything I find online about them is people saying how much they love the Diamond Age filament, but it seems doubtful that they're still around. I'm giving ProtoParadigm a try but I am curious to hear if anyone knows anything. I'd order from Diamond Age directly but the shipping costs more than the filament!

-Dave

 

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Nice work! I opened it up and blew it out and a chunk of semi-burnt blue filament fell out. My best guess is it came off at some point between filament changes or something, and jammed things up a bit in there. I was able to print out another UM robot using the same exact settings and it looks great, and I didn't hear any filament slips.

Thanks!

Following is a picture of the inside of my extruder, although I think it should look fairly ordinary now that the little ball of evil fell out. Taking it apart and putting it back together wasn't as bad as I had feared.

Extruder guts

 

How did you reattach the extruder? I've just got an UM2 I had a similar issue whereby my filament wasn't feeding and the stepper motor was clicking as it missed steps.

I thought I'd have a look inside the extruder to see if I could see anything and that was a HUGE mistake. Taking out the four screws meant that the stepper motor is now loose and because it's inside the machine I can't get to it to be able to line it back up with the screws to hold it in place.

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Just fixed the same problem with my UM2.

A piece of filament was in the feed unit on the back and was causing me pretty much the same problem.

I dismantled the feed unit and out came a short piece of filament about 1/4 inch long, now it runs fine.

Note that you have to remove the inside cover to hold the stepper in place while you reassemble it.

And the wires want to get pinched under the stepper when when you put it back in, just hold them out of the way while reinstalling the stepper.

good luck hope this fixes yours as it did mine.

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