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Infill not touching shell! Again!!

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Hey everyone -

Recently, I started a topic on what I thought was some X-Y inaccuracy (check it out here), and rigs directed me to 3DVerkstan's Ultimaker troubleshooting guide (which was really helpful). I tried out a few of the suggestions that seemed transferrable to my Original +. After moving the X and Y motors down (as the guide suggested), I reprinted - the walls stuck to the infill! Success!

But then, in the next print, it happened again (boo!). I checked the machine over and over, and did the following: re-leveled the bed, moved one of the timing pulleys (I had found it was off-centered), tightened the other timing pulleys, and did multiple atomic pulls and full nozzle cleanouts - took the hotend apart and everything. Everything seemed to make it worse - one of the prints I did didn't even have its shell; it was set to .4mm (my nozzle size) and it didn't even print. Aaah! Also -- sidenote -- a few of the test prints I did were print-in-places, and all of them had fused joints. Not even sure what to do.

If anyone could help me at all with this, I would love it. I'm kind of burned out on the printer; whenever I fix a problem, another comes up. Guess that's just the printing life, right?


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Is it the same issue like in your original thread where circles (or circle-like) shapes aren't coming out circular, or is the shape correct and the lines aren't touching each other? If the short belts are still tight (the motors haven't shifted back upwards since you tightened them), I'm thinking it could also be one or more of the pulleys not being held in place well enough on the axis and it's sliding ever so slightly during direction changes. A very easy way to check for this is to simply take a marker and mark a spot on the axis and a corresponding mark on the pulley and see if they shift after a print (don't forget the pulleys on the motors).

If you've modelled your shell to be 0.4mm in CAD it could be that the slight simplification that is performed when exporting the STL (circles are made up out of several straight lines) is making the walls slightly thinner than you expect in some places and cura is freaking out, thinking it can't print those lines. Try to make your walls a tiny bit thicker and see if the problem goes away. I never go under 0.8mm for walls.

For the fused joints. Could be a number of things. Printing too hot can cause the print to be slightly fat around the edges making it fuse. Could be slight stringing. Could simply be that you haven't left enough clearance between the parts. For this model I used this tolerance and that's just barely enough on an UM2.


Also, yes, it's part of the life :) And I'm glad you liked the guides, let me know if anything is unclear or missing.


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The shapes are correct, but there are places where an entire line of shell is seperate from the infill. I found a problem, though, and I've already contacted support about it -- the outer cap with EXTRUDE engraved into it is rubbing on both the black molded gear and a few screw heads. Just to be safe, I completely rebuilt the extruder, but nothing seemed to change. Hopefully Ultimaker support helps me out on that one. Prints still aren't doing well.

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Tried it with the tools, and the rods are all straight.  Also, since I started this topic, I tried printing a pair of sandals out of woodFill, and the shell was (I measured) 3mm away from the bottom shell.  I have no idea what's going on.


Photos please - people think words are clear but there is often something TOTALLY different going on than what we think and photos are helpful. Photos of the part and also show what you are talking regarding the feeder please showing where it is rubbing.

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If that's supposed to be 50% infill then I ahve one answer for you but assuming that's supposed to be 100% infill then clearly your problem is underextrusion:


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) Temp Sensor bad - even the good ones vary by +/- 5C and bad ones can be any amount off - they usually read high and a working sensor can fail high slowly over time. Meaning the sensor thinks you are at 220C but actually you are at 170C. At 170C the plastic is so viscous it can barely get out of the nozzle. You can verify your temp sensor using this simple video at youtube - on you tube search for this: mrZbX-SfftU

8) feeder spring issues - too tight, too loose

9) 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.

10) 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

10b) 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.

11) 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.

12) Crimped bowden. At least one person had an issue where the bowden was crimped a bit too much at the feeder and although the printer worked fine when new it eventually got worse and had underextrusion on random layers. it's easy to pull the bowden out of the feeder end and examine it.

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