First layer issues - getting to it, temp, sheet cleaning, z axis calibration  

First layer issues - getting to it, temp, sheet cleaning, z axis calibration

Hi *,

my Prusa MK3 is my first 3d printer. I got it for 4 days now. Assembly was pretty quick and easy.

I had some troubles getting the first layer right. As the Manual for "First layer calibration" did not really mention what the amount is between to low and to high (I didnt think far enough) it took a while to find my settings. (Like in a car - your oil gauge is a liter between min and max)

An issue which i had whas that my coated print bed uses different z axis offsets for the different sheet sides. So whenever i turn the print bed i needed to recalibrate. I couldnt explain this but with settings which work on Side A i dont get any adhesion on Side B.

Took a while to find this. It might make sense to mark sides A and B somewhere.

Another issue was PLA adhesion. (PETG worked pretty good most of the times). I found the tip to use soap and water to be pretty good. I tried alcohol all the time to no success. Once i made the print sheet wet both sided felt completely different. One of them got slippery like it was full of oil, the other one was sticky (to my fingers) even when wet. So i guess the 2 sides of the print bed are different - at least for me, or the coating on my print sheet.

Also i increased bed temperatures to help adhesion. PLA Prusament to 65°, PETG to 95° first layer.

With the 60° PLA i had a lot of warp which disappeared with 65° bed temperature. As i was off in all temperatures to the recommended settings in prusaslicer i tried the PINDA probe temperature calibration which always fails. My suspicion is that the bed temp sensor is off by 5-10° - I need to get a thermometer to validate. Has anyone heard of temp sensor misreadings on the heatbed?

So - A long way but now i mostly getting what i try to print in the first run - Still some mysteries.

Flo