Thanks for your answer, here some data:
Height: 0.15 mm
Thickness: 0.8 mm
Density: 20%
Speed: 50 mm/s
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This looks like a stream of cold air went by… try to close air sources like windows and doors, or use something to make a door to the open front of the printer 
Take all the time that you need, I’m not in a rush. It is just curiosity and willingness to learn 
And, if you find out any issue with the Gcode, can I ask to point me where is it? I’m trying to learn how Gcode it’s working and it’s always nice to have see the point of view of someone else
Hi @federico3,
Please check these 4 things:
1. Consistency of the filament diameter
2. Temperature variation; What is the off-set on your hot-end? 230 on your screen could be 215 or 245 etc. in real life with your machine
3. Are you certain that your PTFE is still in good condition (no brown parts when you open the hot-end assembly on the white PTFE part)?
4. How well is your machine performing at this point mechanically? Are all the belts tightened etc?
I’m suspicious of option 1. and 3. but let’s see what you can tell us
Hey Remcokatz,
Now I’m at home and tomorrow I’m not in the office, in any case, I’ll ask someone else to check it.
1&3. The material should be fine: the filament is completely new (I opened the plastic bag just one day ago) and I didn’t have any problems with other prints.
4. Mechanically speaking, the machine is perfect.
3. I’ll try to run again the code and I’ll let you know what was the temperature
Thanks for your help
Had a quick look at the gcode nothing glaringling obvious, the reason I was suggesting something mechanical rather than cooling or setting related is just because of the localisation of the problem, it doesn’t appear to be at the beginning or end of a tool path either. When you say this happened at two points, at different heights, were they in roughly the same location in x-y?
The hottend is moving freely… there’s nothing snagging, restricting the bowden tube at a certain point / extreme is there?
Curious to see the cause of this one!
Alright looking forward to the feedback!
Regarding point 1; Even cheap filament can look great but what you don’t see if it has diameter tolerance issues. Therefore you would have to measure it at several points on the spool with a caliper. So you can never say that filament is fine just by looking at it (even new spools). If you need help how to properly measure I can give some more info.
If you havent gotten any problems with the same spool and different prints then we can just move forward to solve your issue.
P.s. your retraction speed seems a bit aggressive but i’m not sure what the standard is for the 2+
Seems unlikely to be a filament issue doesn’t it? What’s the odds on the filament having an issue at exactly the same section of the print for what must be about 100 layers? If I’ve had an under extrusion issue because of inconsistent filament is usually just drops a layer.
Oh it’s just an extra check to make sure that there’s no issues at all with the filament but I agree that this is not going to solve the issues alone :). I work in the filament industry so I kinda have a standard list of like 30 points that I work through group-wise to pin down where the issues are.
I think it is a problem of temperature.
This is an error in your retraction or pausing when you change layers. That is why it is occuring at the same area on the print, because that is where the zaxis is moving up. This is also why the error is occuring elsewhere on the print, but NOT in the same layers.
One of two things.
1. Your layer height retraction number is screwy. You are retracting so far that the head moves up, the next layer starts, but it takes awhile for the plastic to get out of the extruder.
2. Or more likely, you have a mechanical issue. The extruder pauses, the z axis moves up to the next layer, and when the extruder unpauses, it is slipping, jamming, etc. As more and more plastic is pushed into the extruder, it finally builds up enough push to continue printing.
3. This could also be caused by a worn, difigured, burned PTFE extruder lining, that it needs much pressure to get going after a pause, zaxis move.
All the other temperature, speed, gust of wind, etc. posts are simply not realistic.
I will bet you a candy bar that if you watch the print as it is happening, it will be exactly where you printer is changing layer height.
Perry
Agree with everything here, but when I looked at the gcode for the area of the problem, the layer height appears to change at a different position for each layer???
Hi Perry_1,
Thanks for your answer. On Monday, I’ll check if there is any mechanical issue with the printer but I’d say that the printer is working smoothly. I’ll also try to run again the same gcode file, in order to understand if the problem is due to an external factor or to a problem in the code/printer/material.
Federico
@remcokatz I’ve measured the filament in three random spots, the results are quite regular: 2.90, 2.87, 2.92 mm
Good luck with figuring this one out, let us know any developments! I know how frustrating troubleshooting can be, particularly less obvious symptoms, and especially when it ruins long runs!
If the print was sitting inside the printer as per the second photo you printed, then that suggests that the failed part was at the back, so localised heating issues would seem to be unlikely. Also, only one leaf appears to suffer from this issue.
So, the only thing I can think of at the moment it to use the “cut off bottom object” feature of Cura (15.0x) and start printing from just below where the problem started, and then watch what’s going on. Ideally, video it as well, and make the video very steady. Then we might be able to diagnose the problem from that, or you might do so yourself just by observing what’s going on.
I’ve looked at the G code and there are no extruder retracts or Z hops near the locations where the defect is. The extrusion proceeds smoothly from the
sides right across the face where the defect is. The print looks like the extruder is starved of material in that zone of the print. Since it does not seem to
occur randomly but repeatedly in that one zone it might have something to do with the filament binding when the head moves into that particular location in
that particular direction at that particular height. Once the head is out of that zone the filament moves freely again and the starved extruder issue goes
away. My guess is the wire cable is stuck behind the filament spool and is causing drag on the spool and/or the filament path where it should not be. See the picture.
I drew a red circle on the picture but its hard to see.
Here’s a better picture.
Hi n23d,
Thanks for your feedback, I really appreciate your effort! I’m having more issues with the Ultimaker 2+, right now it’s almost not extruding material anymore. The cable isn’t stuck behind the filament spool: I suppose that there is some kind of deposit of PLA inside the hotend. I tried the “Atomic Test” and that’s the result: as you can see, the issue it’s not in the nozzle or in the filament but somewhere in the hotend. I’ll check it and I’ll update you about the situation
A lot of blind guessing in these replies…
This is a warping problem, caused by the plastic not having cooled down enough in that area when the next layer is deposited. It most likely happens in the sides facing away from the fans. So probably the temp was a bit too high, and slowing down will also help.
I also see that the infill is clearly visible in some parts of the shell. Better set shell to 0.8, that will help. And if you set fill to 100% that problem will definitely be gone. Print time will be longer, but it’s a long print anyway…
Shell was already set to 0.8. Print a lamp with a fill of 100% it’s super long and a waste of material honestly.
In that case, perhaps the infill overlap was set too high ? These lines from the infill shouldn’t be visible through a 0.8 mm shell…