Porosity in center of print on UMS3

[conductive_printing 1]

Hi everyone,

 

I've had some issues with some underextrusion in the center of my parts (on a UMS3).  This appears to happen after the first layer, and it is almost always at the same spot on the print bed.  I checked if the print core was jammed, but it seems to be extruding fine otherwise.  The rods that support the print head don't appear to be bent.  Any suggestions?

[geert_2 558]

Since it seems to be running diagonally (as far as I can see on the photo), my first guess is that it is something with the glass plate? For example if the bed is dirty, greasy, or soapy in that area, so the print does not bond well? Or if you did use some bonding, maybe an uneven bonding layer (too thick/too thin)? So I would first do a thorough cleaning of the bed, and degreasing.

 

I don't know if autoleveling could cause such issues, if for example the probe would have encountered a piece of dust during measuring, resulting in an incorrect height measurement?

 

[conductive_printing 1]

It was actually horizontal when it was still on the build plate.  The first layer comes out fine, but the layers afterward have this issue, so I didn't think it was the surface cleanliness issue. 

 

I disabled the autoleveling and manually leveled it, but the issue persists.