First layer issue  

Re: First layer issue

Funny thing is that i didn't change it from date when i assembled my printer just before Christmas. When i've got my printer i set Z offset and there it was until now. It seems that whole printer must "settled" itself ... i can't explain otherwise.

This will happen. When you're talking about a machine that needs to operate mechanically with sub-millimeter precision, it doesn't take much before it requires readjusting. You should expect to readjust the Z offset from time to time for no obvious reason.

Re: First layer issue

I didn't even think of possibility that Z is too low... i've had two delta printers in the past and there calibration was almost daily routine 🙄 and it was pretty hard if not impossible to get perfctly even first layer, but i never experienced such strange behaviour - on delta if nozzle was too close then extruder started to slip, that was all.
Well, another thing learned...

Re: First layer issue

I didn't even think of possibility that Z is too low... i've had two delta printers in the past and there calibration was almost daily routine 🙄 and it was pretty hard if not impossible to get perfctly even first layer, but i never experienced such strange behaviour - on delta if nozzle was too close then extruder started to slip, that was all.
Well, another thing learned...

I would keep lifting it until you see tiny pin holes, most likely near the perimeters, then take it back down until those go away. In my attempts to get PETG working, I discovered that a pretty looking finish on the bottom (which you have now) might still be too squished. After doing this, on a 1 layer test print, the top feels nearly as smooth as the bottom and I have zero goop on my PETG prints. 🙂

Re: First layer issue

I had also very bad first layer issue, but not anymore. Every time before printing I used isopropylalcohol to clean bed. Everything worked fine about 3 weeks. But suddenly not sticking anymore. Not PLA and not PETG. Finally I cleaned bed by using acetone. Problem solved. My guess is that isopropylalcohol is polishing PEI surface.

Re: First layer issue

I had also very bad first layer issue, but not anymore. Every time before printing I used isopropylalcohol to clean bed. Everything worked fine about 3 weeks. But suddenly not sticking anymore. Not PLA and not PETG. Finally I cleaned bed by using acetone. Problem solved. My guess is that isopropylalcohol is polishing PEI surface.

Isopropyl alcohol is used to clean the oils from your hands off of the PEI sheet.