Ned some help on printing PETG with fillets
Hi, I have mostly printed with PLA, but this time it has to be PETG. Using MK3S with Prusa slicer. It's been a while since I updated it, but everything works great with PLA.
These caps have fillets, and they look nasty. I have tried several adjustments, temps from 230 to 250. Bed temp from 70 to 90. Messed around with retraction etc. Last try was the Generic PET profile in Prusa Slicer. The result is more or less the same. First layer seems ok.
Are there any tricks? Can anyone point out what this problem is? Or do I have to go for chamfers? (Not desired!)
RE: Ned some help on printing PETG with fillets
Fillets on the bottom of a print will always be tricky. The layers on the bottom have little to nothing to print on top of, so they're essentially printing in air with a severe overhang. The resulting extrusions will have a circular profile and lack the "squish" that helps with vertical surface quality. They'll tend to be stringy.
With PLA, you've probably got cooling turned on which, while still not perfect for overhangs, at least cools the filament quickly before it sags. Most PETG profiles don't use part cooling, so the hot extrusions have more time to sag. You might try enabling a small amount (30%) of cooling at the bottom and see if that helps. You may find the parts are very weak though.
RE: Ned some help on printing PETG with fillets
@bobstro
Thanks, that confirms my suspicions. Printing with a steep chamfer now, hoping it will look better!
RE: Ned some help on printing PETG with fillets
Your first layer is showing signs of being to low, your over hangs (the angle of your print) looks totally printable. If your printing at 0.2 layer heights try using 0.15< this will reduce the amount that each layer has to overhang before cooling, and for this print reduce the elephants foot comp to 0.1 or 0.15 turn on cooling after the first layer as Bob suggested about 30%, try starting with a base temp of about 235C nozzle and 85C bed. looks like a small print so to much hot filament in to short a time = sagging for PETG, you can either add more copies of the object to increase the cooling time in between layers or slow down the print, If you need more copies anyway I would opt for that strategy and spread them out for more travel time (Hence more cooling time).
good luck
The Filament Whisperer
RE: Ned some help on printing PETG with fillets
@dan-p12
Thanks for your effort, much appreciated! Tried to print with 0.15 and 4 pcs in one go. The result is the 2 caps to the right.
You said that the first layer looked too low, how can you see that? If i increase the distance I don't get a smooth surface, it seems that I have found a good sport for the first layer. But could be wrong since I'm new to PETG.
I'm guessing that the filmant itself can cause some of these problems? (Relatively cheap)
I need to print about 180pc of these by thursday! Still tweaking, and hoping!
