Print problems after 3.1.0 upgrade  

Re: Print problems after 3.1.0 upgrade

sorry if this is teaching granny to suck eggs..

are you using your normal start procedure? the Pinda is temperature sensitive, and you might simply be starting with the pinda closer than normal, or further than normal, from the build plate... I make a habit of starting about 60mm above the build plate, so the pinda doesn't get significantly heated by the build plate.

check to see if there is evidence of filament leaking above the heat block, or below the heatblock around the nozzle threads... unlikely but tiny possibility this would suggest loose or poorly installed nozzle.probably not going to be the issue, but, you never know, and it only takes seconds.

check the first layer on your failed frog.
is it smooth without dividing lines between filament traces? ... good
is it made of well defined individual strands of filament, round or nearly round in cross section?? not good... not enough Live Z, (too small a negative number)
is it made of misformed strands of squished filament with random minor sepparation lines... not good, probably too much live Z (too big a negative number). deposited filament being pushed out of the way by new filament...

make sure the bed is impeccably clean, if the frog first layer was not good, re do live Z calibration, using something like Jeff Jordan's 'Life adjust Z my way,' version 6.1 gcode or later ( this includes profiles for PLA, PETG and ABS, where as prusa's first layer calibration is only set for PLA and is difficult to verify the first layer quality...

when the first layer calibration of live Z is good,

start a new print in PLA, batman logo might be good, because it's thin with a smooth top surface.

watch the print carefully and try to see where the blobs are forming from.... if filament is picking up from the previous layer, you might be over extruding... if so, reduce the extrusion multiplier in Slic3r and re slice... try again.

as the second, third (any full layer ) prints, look for 'ruts' and surface indentations along the filament trace directions, usually with a rough surface, this suggests that the nozzle is ploughing through the surface filament, which is likely to promote build up on the nozzle and blobs.

as your recent models have started off well, you may have to watch until the later top layers to see this phenomenon... as successive layers may slowly cause..

If you identify the cause, and correct it... apply your chosen adhesion reduction preparation to the heatbed pei surface.
options include
Talcum powder, cheap, available in most houses, possible silicosis risk. don't inhale dust...
Gluestick, supplied with every new Original prusa printer... Some people love it, others, me included, hate it
Windex, or similar window cleaner, less messy than gluestick, some folk swear by it, Personally never used it.
Blue painters tape, I find it often sticks too well to the printed filament,
traditional painters masking tape, as above with the risk of baking onto the build plate...
finger grease, or forehead grease, found in every household, rarely in short supply. easily accessible at short notice. can even be applied during 9 point bed levelling, if you dodge the extruder...

once ready try a PETG sample print... you will almost certainly have to readjust your live Z for PETG...

when successful, go for your first upgrade print!

NOTE PETG doesn't like to be squished as much as PLA, and is MUCH more prone to picking up plastic, on the nozzle, so be observant during print...
mild under extrusion is better than over extrusion!

good luck,

regards Joan