Ultimaker 2 Under extrusion on one side

[Jay_Cee 2]

I recently got an Ultimaker 2 but haven't used it too much as have had quite a few issues which dampened my enthusiasm -- probably pretty silly not to past here earlier!

Basically my printer is under extruding on one side and I'm not sure why. In fact its kind of printing inconsistently throughout (flow seems different throughout). This is using PLA (which I have always used).

Here are the things I've done to try and fix it?

 

• I just bought a new bowden tube so its not that.
  
• I did the atomic method and it came out perfect cone shape[
  
• I have tried a range of different temperatures and speed combinations
  
• Have dismantled the feeder and messed around a bit with the tension - with the caveat being that I wasn't really sure what I was doing so I'm not sure how effective it was
  
• Have moved the filament roll onto the floor instead of stool
  

 

What else should I be checking? Any help greatly appreciated!

[IRobertI 521]

That looks more like a case of a bed levelling. Either you didn't level your bed well enough so that the front of the glass is higher than the back.

Or, the glass isn't perfectly flat.

Or the screws of the bed (in the corners of the bed) aren't countersunk properly causing the glass to bend slightly.

If your bedlevelling is good I would check the glass to see if it's straight. Sometimes flipping it over can help as well.

Oh, and make sure you're printing the first layer at 0.3mm as that helps compensate for slight flaws.

Edited October 29, 2015 by Guest

[Jay_Cee 2]

Thanks that is really helpful. It seems pretty simple fix so I hope it is right!

I'm wondering how extrusions differ depending on how close the nozzle is to the bed? How does the printer sense that?

I would expect the bed not being level to mean that the print was just quite messy - but it to be equally messy over the whole print. Can you explain how that relationship between bed level and volume of extrusion is working?

[IRobertI 521]

There is no feedback from the plate to the print head. The printer assumes that you have levelled the bed correctly and goes from there. It'll squirt out a constant volume of plastic and if the bed isn't where it's supposed to be you'll run into issues.

If the bed is too close, it will partially block the nozzle so that not enough filament is extruded. It will look almost transparent like in your pictures. This can cause a few things to happen. Ideally you'll hear a "tock tock" sound from the feeder which means that the stepper motor is skipping steps to avoid grinding the material.

Another thing that can happen is that when enough pressure has built up, the plastic will escape sideways rapidly and leave a blob of plastic which the head will then bump into on the next layer (this is usually fine, it'll recover after a couple of layers but it can look and sound pretty dramatic).

It can also lead to what is referred to as grinding where the feeder wheel eats into the filament, forming a divot. This usually leads to no more filament being extruded because the feeder can no longer grab it properly.

If the plate is too far away from the nozzle you'll see strings of plastic sitting on top of the bed and they wont stick properly. If it's a bit closer you'll see that there are gaps between the print lines (can easily be mistaken for underextrusion). The biggest problem here is bed adhesion. The print will simply pop off eventually which will ruin your print.

You can adjust the bed on the fly during a print if you want by simply turning the screws underneath the bed. If you want to get a feel for what's happening you can start a print of a square and then put your finger on the bed and push it down slightly, or lift it up slightly and see how the pattern changes. You want the lines to be uniform with a flat top and sticking together with its neighbour. I have an example picture on this page:

http://support.3dverkstan.se/article/47-getting-started

[Jay_Cee 2]

This was very helpful, thanks Robert.