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Under Extrusion issue on UM2+E

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I have some under extrusion issues at the moment on my Ultimaker 2+ Extended. I'm getting the usual weak prints(they look externally fine, but break/bend easier than they should) and walls are not touching on my test 20mm cubes. If i increase the temp to 230-235 and flow to 125% the prints are fine(this is standard PLA with 0.2mm layers). I'm using S3D, but get the same results with Cura 3. My extrusion width is set to manual and 0.4mm to match my 0.4mm nozzle. If i change it to auto or manually increase to 0.48mm or reduce to 0.35mm as it is in Cura i get the same results more or less.

I plan to service the printer soon, so my question is what parts do i need to replace? I'm thinking I'll get a new bowden tube and TFN PTFE Coupler(I think this is the main issue i have right now) from 3DSolex.

The only other thing i can think of is the feeder is not pushing enough plastic in. The white plastic tension tab is all the way up the top and my understanding is it should be in the middle. But perhaps this is for the older UM2 feeder? Turning the top screw doesnt seem to change anything on it, it always stays on the top. The feeder is holding the plastic filament quite tightly, so its not slipping or anything when printing.

Any advice or direction is greatly appreciated.

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try this, take a small wire brush and go to the move function in the menu, poke one of the wires up into the nozzle and move the wheel to extrude. do that a couple of times and it might solve your problem.

I think you just have a build up burnt material inside the nozzle.

Thanks, But I've already replaced with a fresh 0.4mm nozzle. I can say after looking at that link tinkergnome shared that my feeder is not setup as it should. So I'll fix that up when home and see if it makes a difference.

It's probably a combination of the feeder and coupler, or at least i hope so as they are easy fixes.

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Try turning your screw anti clockwise - I seem to remember it was the reverse to what you would expect - the head of the socket screw rests on the top of the lid and turning anti clockwise will cause the spring to compress.

Both of my screws are in the area you indicated :)

Edited by Guest

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The screw head position in the picture shown above is wrong!

Here is another picture from 3DVerkstan's website:5a3340c0b9176_um2feeder.thumb.jpg.7583d2bc53c5c5a22f2673d15c825ea0.jpg

As you can see the screw head should be in the area RetromanIE marked red in his picture. A correct installed feeder should have tension on the spring, i.e. without opening the feeder housing you can see the spring head pressed against the inside of the housing (only 2 mm down).


1) The tension indicator should be about in the middle of the scale. When it is all the way up then the tension will be too low and you get under extrusion.

2) Perhaps your nozzle is clogged? Do a hot/cold pull.

3) Did you print abrasive materials like brass fill? Over a longer time this will wear the feeder wheel, bowden tube and perhaps other parts as well.

from what you described it seems issue 1) is your main problem.


Edited by Guest

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