Am struggling with this PETG-HF material (Forest Green) - I do find prints much weaker than standard PETG, but that’s not the issue. It prints at high speed really well in most aspects, except for overhangs. Calibrated at 255Deg, 0.96 flow and PA of 0.05. Max flow set at 22mm3/s, but calibrated the actual limit at about 26.
All-in-one Torture Test prints pretty well, with bridges under 50mm being ok, and overhangs up to 70deg acceptable. After many trials, had to drop fan down to 40% and Aux fan up to 90% to get this result.
My actual part has a 40Deg overhang, about 50mm wide - which is nothing and should present no problem. It’s a double wall feature 2,4mm thk, each with 3 perimeters, so very little infill/no gap fill. Prints perfectly in normal PETG & PLA+. Enclosed chamber.
However, I just cannot stop this PETG-HF sagging; waviness on bottom surface, progressively gets worse as feature gets wider. Not even sure it’s sagging, more like tearing/waviness. Have Orca set up with usual overhang settings for extra perimeter, reverse on even layers etc. Have tried high/low temps, high/low fans, slow speed, lower accel on inner/outer walls, variable layer height, turning part into wind from Aux fan, modifiers for walls and the overhang settings. Subjectively, the material does not take too well at slower speeds, prefers to be driven so don’t get expected improvements when slowing the print.
Material is bone dry, feed from a heated dryer.
Have burnt through half a spool on mostly great parts, but this one part with overhangs consumed my time on trials and the other half. I’ve ordered another 4 rolls as it’s great value, & UV resistant, so just need to overcome this overhang issue.
Anybody any experience with this new Bambu HF filament / any ideas what other settings I can try?
Underside of 40deg overhang with 0,16mm layer height - for scale, torture test in background is 100mm long.
Torture test overhang - very good up to 65Deg, and acceptable up to 80Deg. Calibrated temp & flow, 30% fan with 90% Aux fan