Prusament PETG and powder coated sheet first layer issue  

Prusament PETG and powder coated sheet first layer issue

Hi all

I'm looking for some help/guidance with the first layer on the powder coated sheet using PETG (Prusament).

My issue: having on the build plate only objects that do not require supports works perfectly, but having on the build plate objects that require supports and objects with a solid first layer does not work for me.

If a set the z-value to a lower negative value (say -1.1200 mm) the first layer of the support structure adheres perfectly and does not lift, but then I have problems with the objects with a solid first layer: the nozzle seems to be scraping the material and then deposits it randomly in a glob somewhere in the print. If a set the z-value to a higher value (say -1.1000 mm) then I no longer have issues with the solid layers, but then first layer of the support structure does not stick anymore and lifts off the bed in places.

So far, the only solution I was able to come up with was to supervise the first layer and manually adjust the z-value for supports and solid object layers. But this does not always work since I need to anticipate what the printer will do.

Running the z-value adjustment using various patterns shows that the correct value is -1.2000 mm. But at this value I cannot make the first layer of the supports adhering to the bed. I've cleaned the bed with IPA 99+ several times. I've even tried to wash it with dishsoap and water. No improvement...

To me it looks like the printer uses different line hights for the supports and objects layers.

I am using the PrusaSlicer 2.1.0 and the default settings for PETG Prusament. I print with a 0.20 layer hight.

One last note: printing on the PEI smooth sheet works perfectly. For me, contrary to what I've read, the smooth sheet has a much stronger bed adhesion than the textured one.

Thanks a million for all possible suggestions!