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Under extrusion after 1 Year?!

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My UM2 works well, except the last few weeks. I have a big problem with under extrusion, especially when I´m printing with 0.2mm layer.

With 0.1mm layer I must set up the temperature from the PLA to 230° and material flow to 110%, and even then I have this little steps in the print. Like the normal under extrusion I hear no clicking of the stepper or something, the filament comes out too slowly I think.

I´m using different filament from ColorFabb and InnoFill.


I have done some regular tipps, like cleaning the usual things. I´ve also using different versions of Cura, but nothing seems to work.

Would be every print so ugly like the example, I´ll have a big problem. But some 0.1mm prints are just working well and looks really perfect (but those are much bigger prints, as the example). 0.2mm prints are always looking bad and won´t work.

Thanks for your tipps!


Edited by Guest

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The nozzle is second in line of the parts which could see some changes over time, especially if you printed some abrasive filament.

If you don't have it yet, do yourself (or rather your UM2... ;) ) a favor and get an Olsson block with exchangeable nozzles with a new teflon and a new Bowden tube (which is the third part that could cause underextrusion due to scratches).

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Below is my standard post containing some of the more common issues. Most likely it's #6 since this is a recent problem and you checked #2 already. Second most likely would be changes in filament brand or when you put the head back together #5 or if you have hot weather then #10.


As far as underextrusion causes - there's just so damn many. none of the issues seem to cause more than 20% of problems so you need to know the top 5 issues to cover 75% of the possibilities and 1/4 people still won't have the right issue. Some of the top issues:

1) Print slower and hotter! Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers):

20mm/sec at 200C

30mm/sec at 210C

40mm/sec at 225C

50mm/sec at 240C

The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.

2) Isolator - this is most common if you've printed extra hot (>240C) for a few hours or regular temps (220C) for 100 hours. It warps. It's the white part touching the heater block. Test it by removing it and passing filament though it by hand.

3) Curved filament at end of spool - if you are past half way on spool, try a fresh spool as a test.

4) curved angle feeding into feeder - put the filament on the floor -makes a MASSIVE difference.

5) Head too tight? Bizarrely MANY people loosen the 4 screws on the head by just a bit maybe 1/2 mm and suddenly they can print just fine! Has to do with pressure on the white teflon isolator.

5b) Bowden pushing too hard - for the same reason you don't want the bowden pushing too hard on the isolator.

5c) Spring pushing too hard. Although you want a gap you want as small as possible a gap between teflon isolator and steel isolator nut such that the spring is compressed as little as possible.

6) clogged nozzle - the number one problem of course - even if it seems clear. There can be build up on the inside of the nozzle that only burning with a flame can turn to ash and remove. Sometimes a grain of sand gets in there but that's more obvious (it just won't print). Atomic method (cold pull) helps but occasionally you need to remove the entire heater block/nozzle assembly and use flame.

7) feeder spring issues - too tight, too loose

8) Other feeder issues, one of the nuts holding machine together often interferes with the feeder motor tilting it enough so that it still works but not very well. Other things that tilt the feeder motor, sleeve misaligned so it doesn't get a good grip. Gunk clogging the mechanism in there.

9) Filament diameter too big - 3mm is too much. 3mm filament is usually 2.85mm nominal or sometimes 2.9mm +/- .05. But some manufacturers (especially in china) make true 3.0mm filament with a tolerance of .1mm which is useless in an Ultimaker. It will print for a few meters and then clog so tight in the bowden you will have to remove the bowden from both ends to get the filament out. Throw that filament in the trash! It will save you weeks of pain

9b) Something wedged in with the filament. I was setting up 5 printers at once and ran filament change on all of them. One was slowly moving the filament through the tube and was almost to the head when I pushed the button and it sped up and ground the filament badly. I didn't think it was a problem and went ahead and printed something but there was a ground up spot followed by a flap of filament that got jammed in the bowden tube.

10) Hot weather. If air is above 30C or even possibly 25C, the air temperature combined with the extruder temperature can soften the filament inside the feeder such that it is getting squeezed flat as it passes through the feeder - this is obvious as you can see the problem in the bowden. The fix is to add a desk fan blowing on the back of the printer.

Edited by Guest
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You can print fine at .2mm, just at half the speed as .1mm. Are you exceeding the speeds of my point #1 above? If not and you are having underextrusion then I agree your printer has an issue. It's probably one of the 10 issues above but that is not a complete list. Still it's the most common issues and you should be able to eliminate some of those just by reading them. For example if your room as at a nice cool 20C and you still had the problem then #10 is eliminated.

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There are a ton of possible causes people have discovered for underextrusion. You have to give some feedback of how you eliminated numbers 1-10 or at least some of them above and why you eliminated them before you will get more help. The list above is not even half the causes. Just the more common ones.

When you say you changed isolator - you mean the white teflon part, right?

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