Good first few layers followed by under extrusion

[huub8 0]

Hi all,

 

I have a Ultimaker 2 extended, upgraded to the + model. I have been very happy with it up to recently, as it printed without problems. 

However, it now starts to show a weird problem: The fist few layers are fine, but after a few layers it starts to under extrude consistently.

 

I tried all kinds of things in the settings, like slowing it down and increasing the temperature. This does help a bit, but it shouldn't be needed right?

I'm printing with new regular PLA, and tried resetting everything including all Cura settings. I also levelled the bed multiple times.

 

Since I thought it might be a feeder problem I replaced the feeder by a Bondtech QR, which made no difference. I also made sure to clean the nozzle using the atomic method multiple times, and I can see right trough the nozzle (a 0.4mm), so it seems clean. Replacing the bowden tube also didnt' help, and I can feel no play at all in the bowden connectors.

 

I can't think of anything else to try, could it somehow be related to the hot end? (looking into the head the PTFE coupler seems perfect still, the whole printer has only printed 700 hours)

 

You would make me very happy if you have any tips!

[huub8 0]

I have just now also replaced the TFM isolator coupler, and put on a brand new 0.4 mm 3D Solex nozzle, but the problem still persists. I'm now testing with a simple 20*20*20mm cube, 20 percent infill and new PLA.

 

It the first layer looks good, but then the second layer is already under extruded. I've attached a picture of the problem, showing the second and just a bit of the third layer.

 

 

 

Edited October 10, 2020 by huub8