Problems Getting a Clean Extrusion

[will_57 0]

I've been trying to print out a Screwless Gear Cube, but I've been having issues getting my Ultimaker to extrude properly. Namely, midway through a print, it has a tendency to have a very sparse extrusion on the outer walls, as seen below.

This problem is very unpredictable, though. It is usually just confined to a few layers of a print, as it is here. Also, sometimes it does not effect all of the outer walls of a print. (For example: if I try to print some square object, only one or two of the faces might be affected.) It tends to be localized, and it usually fixes itself by the time the print is completed.

There are some other issues with the extrusion as well, such as the blobs on the side of the print, but I think the sparse extrusion is more annoying, since it can't easily be cleaned from a completed print. Because of this, I was wondering, what might be causing these issues with the extrusion? Are there some settings in Cura that might be causing this, or is there something wrong with the printer?

[Daid 301]

It's a mechanical problem, maybe slowing down the printing speed helps a bit against it, but most likely your extrusion is slipping. Are you using UM filament? Or from a different supplier?

Do you have the spring extruder upgrade?

[will_57 0]

I haven't given the spring extruder upgrade a try, and I'm using Ultimaker silver PLA. I also haven't noticed any slipping, but I'll at least try turning down the speed a bit.

[joergen 2]

I haven't given the spring extruder upgrade a try, and I'm using Ultimaker silver PLA. I also haven't noticed any slipping, but I'll at least try turning down the speed a bit.

please install the spring extruder upgrade asap. then switch to another PLA, as I would label the UM silver an "unhappy filament" (I heard and seen too many problems): extrude some of the new filament by hand, to make sure none of the silver is left in the head... make sure you measure the correct diameter for the filament (2 sig digits), and enter it into the slicer.

since you have over hangs, print a bit slower and with fan on all the time.

at a later time, you can revisit the silver, but get confidence with a normal PLA first.

[Daid 301]

New silver is good, half year old silver is most likely the bad stuff with varying diameter. But I rather call it gray, as proper silver looks different :-)

But this looks like black PLA. Which is horrible for photos. But good for spotting problems in your prints.

First I would try increasing the temperature a bit, to see if that is causing the extruder problems.

[will_57 0]

All of the PLA I have came with my Ultimaker that I got 6 months ago. I just measured my two rolls, and the silver PLA I have varies from about 2.80mm to 3.15mm in diameter. I also have a roll of red PLA which is a little more consistent: about 2.95mm to 3.05mm in diameter. Should I give the red filament a try, or is the diameter still to varied to work well?

[Daid 301]

6 months ago, that could be the bad batch of gray (called silver on the sticker I think). 3.15mm can be too much for the bowden tube, depending on the tube, and makes it hard to push it into the hotend. 2.8mm should be no problem, IF you have the spring extruder upgrade. Without the spring extruder varying between 3.0 and 2.8 could cause some grinding and extrusion problems. For the 3.15mm, printing slower could help, as the extruder is stronger at slower speeds.

I recommend using the red PLA. Red is also a nicer color to print with. (I started out with black and red, hated the black, loved the red)

(I don't know if we have a return policy on the bad PLA. You could send a friendly email to support, they will know better then I do, they might also be able to find out if you have PLA from the bad batch.)

[will_57 0]

I just switched to the red PLA, and literally every problem I was having before has been resolved. I printed out one of the small gears as a test, and it turned out perfect.

Thanks!