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Filament Extrusion Issue/Incorrect Filament Diameter

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Hello All,

This is my first post here, let alone my first experience with a 3D printer, so bear with me if this has already been addressed.

About a month ago I started working on the Ultimaker 2 and so far my prints have turned out nicely. The sheer number of options and modifications of this printer is quite amazing(and intimidating), but for now I've concentrated on taking baby steps with my printer. So far, so good.

After getting tired of seeing the same blue filament, I decided to buy a couple rolls of PLA Red and Clear filament to change it up a bit. After receiving my new colors I removed the Blue I had and inserted the Red PLA. I properly fed my new line following the directions from the Ultimaker 2 manual and got the same results when I first had to load my Blue filament for the first time. Easy (well, not exactly easy, but I was able to figure it out with a little patience.)

Here's the problem: After loading the Red filament, it extrudes like it should with no issues. Great, I think to myself. I'm getting better at this. But when I go to print my Ultimaker robot as a test print, nothing comes out but a tiny little blob of Red. I've removed and reloaded the filament twice already and the results have been the same: After heating up and being fed through the Bowden Tube the material comes out nicely, but when it comes to printing my test print or any print for that matter, nothing comes out but that little blob I wrote about earlier. It's as if its clogged. BUT...if it were really clogged, no material would come out even during the "change filament process, correct?

Another consideration is that the filament from where it was purchased(Protoparadigm) really is 3mm instead of the required 2.85mm. I'm going to remove the Red filament here in a bit and put back the Blue filament to test that theory, but I wanted to get the input from more experienced 3Ders first, just in case I missed the obvious. Btw, I did double-check to make sure the Build Plate was properly leveled. It is.

Thanks to all in advance


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I would take measurements of the suspect filmanet with a caliper first to see if it really is under 3mm.

It could be that if the filament is near the bowden limits it's "flow" its restricted enough to ruin fine prints. Also have a look if it has been chewed up by the feeder motor (slipping) because the filament does not move smoothly inside the tube.

I got a cheapy reel once from somewhere which has never printed well because it was not extruded consistently.


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Hi Librarium,

What build date and firmware version is your printer running? (Maintenance|Advanced|Version) I ask because we've recently made some bug fixes that could help with this.

Is the tiny blob coming out while the nozzle is against the build plate, or is it not priming correctly while the nozzle is still far away?



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When you start printing, are you allowing some time for the filament to start flowing? Usually things are printed with a 'skirt' of several loops around the object that gives some time for the filament to properly pressurize the print head.

It's also quite possible that the firmware issues are causing problems for you, as Steve noted. We have tested some fixes lately that affect how the head is primed. These have not all made it into the released firmware yet, as far as I know.

You can find it here:




That fixes some problems with bed leveling, and also makes the initial priming extrusion less strong so that the extruder doesn't chew up the filament. Download the hex file listed on that post, and then install it using the 'Machine -> Install Custom Firmware' menu option in Cura.


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Thanks guys, still working on it but I wanted to respond to you all with what I got so far and what I THINK may be the problem:

Deepshots: Buying a caliper is one of my "To Do" lists. I changed my filament to the original Blue and getting the same results so I believe the filament is the correct size until I properly measure it. The Material Feeder slipping may be the cause. I am trying to correctly tighten/loosen the screw at the moment. Perhaps I pulled out the filament in an incorrect manner when changing material. Didn't think I did, but I can't rule out the possibility.

stevegt: My version is 14.01.2. The blob happens a few seconds before starting to print. The filament not being primed correctly seems to make sense, though I get the impression it is related to Deepshots assessment that the Material Feeder may being playing a part. I do have a "gouge" in the material that I think I may have inadvertently caused the problem myself. Gives me hope though that I have not seriously damaged the machine...I hope.

illuminarti: I THINK I know what you are referring to. When the printer operates normally, filament "strings" come out as it starts to get ready to print. After the warming process, from the front corner it does a couple "clicks" or "bumps" pushing melted filament out from the extruder as it makes its way toward its intended work area. Except now it doesn't. I will try to see what I can do from all of your suggestions first before I mess with the firmware.

Thanks guys. I will let you know how it goes, progress or not.


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I will be updating Cura soon.

As to the original issue, nothing serious as I had feared. The third time I feed my filament, my models began to print. I believe what happened is that I really just didn't properly load the filament. The other issue is that my material feeder needed a little adjusting so once I tightened the screw a couple quarter turns, my prints haven't had anymore difficultly coming out.

Thanks again everyone


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