Printhead moving through printed area

[SV-97 0]

Hey guys, first post here. I've been having problems with my printer(UM2+) for quite some time now, I even contacted ultimaker as well as their local retailer but they weren't able to help.

The problem is that the printhead moves through already printed layers after the first few layers, it seems like the Z-steps it takes aren't big enough. This happens with different nozzles, different layer-heights as well as materials. I already tried to reset it to factory conditions and updated the firmware to the newest version again (multiple times) and made sure the bed is leveled.

 

Fig. 1: Here you can see that the printed moved through the infill and destroyed it

 

Fig. 2: Same thing after continued printing

 

Fig. 3: Tracks in the TPU show where the printhead "tore" through the material.

 

You can also hear the printed moving through. With really small prints this leads to the printed mushing through liquid filament and not being able to produce anything.

 

In this video I made you  can see the first few layers printing absolutely fine and then it starts to mush the top into one blob.

https://www.youtube.com/watch?v=nImulhZ931k&feature=youtu.be

I know it's printed (too) fast but the same problem occurs at 10% speed.

My slicer is cura in the current version. The problems occur with files I created myself as well as ones from other people.

 

I hope someone here can help me figure out what's wrong and fix it.

Edited May 5, 2018 by SV-97

[gr5 2,230]

If the Z axis was messed up then the part wouldn't be the proper height when you printed it.  It would look all squished flat.  That's not the problem.

 

The problem is you are underextruding.  How fast are you printing that infill?  Cut the speed in half.  You may have a defective printer.  Have you ever replaced the teflon part?  That is a consumable that needs replacing often.

 

I know exactly what you mean about the nozzle hitting the layer below.  I've experienced that mostly on the edges of overhangs but also if I print infill too fast (just like in your photo).  You can slow it down from the TUNE menu while printing but expecit it to take at least 3 layers to recover and stop scraping the layer below so much.

[SV-97 0]

33 minutes ago, gr5 said:

If the Z axis was messed up then the part wouldn't be the proper height when you printed it.  It would look all squished flat.  That's not the problem.

 

The problem is you are underextruding.  How fast are you printing that infill?  Cut the speed in half.  You may have a defective printer.  Have you ever replaced the teflon part?  That is a consumable that needs replacing often.

 

I know exactly what you mean about the nozzle hitting the layer below.  I've experienced that mostly on the edges of overhangs but also if I print infill too fast (just like in your photo).  You can slow it down from the TUNE menu while printing but expecit it to take at least 3 layers to recover and stop scraping the layer below so much.

Hey, thanks for the reply.

Yeah you're right, a wrong Z-step would fuck everything up and I already thought that the infill looked under extruded but threw that out the window as I had no idea what could  cause it. I already tried 10% speed (relative to the standart value) and it still moved through layers. The TFM Coupler? I've never replaced it, thanks for the heads-up. While I haven't printed that much I'll disassemble the printhead as soon as I find time for it and put a new one in.