Bed levelling & PETG boogers
When trying to print with PETG, the nozzle tends to ooze during warmup. I'll patiently sit there with my little brass wire brush and clean the strings off as they form. This works up until mesh bed leveling starts, then the 9 point check stomps the string that continues to ooze into a booger on the nozzle. Often, the nozzle purge before the print starts does not remove this booger, and a string gets dragged from the purge line to the print that ruins the first layer, or the nozzle booger catches the first few layers at some point.
If I get lucky and the nozzle purge removes the booger, then the prints are coming out fine, I don't think it is a layer height, temp, or other settings causing any issues. Stock Slic3rPE settings for PETG are working well for me, very little stringing and very nice prints except for some minor overhang issues. My PETG test benchy, with both Prusa & eSun PETG filaments, looks better than the PLA one. (Which looks pretty good, too.)
My nozzle height Z calibration was done using the 75mm square process posted elsewhere in the forum, they look great, and prints aren't failing other than the warmup & bed level booger/stringing.
What can I do to stop the designed startup process (bed level & nozzle purge) from killing the start of my prints?
Thanks,
Mark
Re: Bed levelling & PETG boogers
💡 Have you actually tried experimenting with different first layer temps? If not, try dropping 5 deg etc and see what happens.
Re: Bed levelling & PETG boogers
I have the same experience as you, even if it’s not been very serious in my case.
Some things that have helped:
Dry filament: some of the oozing seems to be related to humidity in the filament. Drying improved oozing and also stringing.
I also wait for a little while with heated up nozzle, that releases the pressure and after a few minutes the oozing is just minimal.
During be leveling I gently swipe off any small blobs and strings that remain on the heat bed and keep watching during printing of the first layer.
With those measures I have basiaclly all good prints, with minimal stringing and very few if any burned blobs which can usually be removed easily.
Cheeers!
Re: Bed levelling & PETG boogers
Thanks for the suggestions. I have a food dehydrator to dry my filament, and store it with desiccant in a ziplock bag, so that shouldn't be a concern.
I did have a partially clogged nozzle a couple weeks ago that made it worse, but that's cleared now and I've added foam filament wipers to help prevent that from happening again.
Waiting a bit and dropping temp a few just may work, thanks!