Printing with #Hatchbox PETG, bit rough on the bridge and pillars, thoughts?
232C, 40mm/s, 1.75mm retraction PB Simple Metal.
Photos from homemade Lightbox, might make a small run of them.
If you have a cooling fan, run it on low. Keep the bed as cool as you can get away with, and possibly drop your temps a small bit (I haven’t printed hatchbox PETG specifically, but I’ve printed a ton of atomic PETG).
Overall it just looks like it was probably too hot overall. Needs to cool before you go back to the same spot, or the current layer disturbs the previous layer that hasn’t cooled yet.
PETG doesn’t particularly love super high acceleration/travel speeds either simply because it wants to string if you do quick travels (from lack of viscosity).
If you’re having issues with it balling up on the tip of your hotend and depositing chunks of it elsewhere, pick up some krytox and rub it on the hotend and it’ll keep you blob free for a few prints.
Unfortunately PETG always does show your imperfections quite well. It’s a great material but definitely doesn’t always make beautiful prints.
https://drive.google.com/file/d/0B7PJsUGqhvaJQUJ1UTFNa19LeUU/view?usp=sharing <-- a petg print I did @ 225c
@Mike_C Fan was on 100%, bed was @70C. Will try your tips there.
It did seem too hot, though the roll said 240-260 and I assumed 230 was already too cool, though I’m not having extrusion issues. I will try cooler and slower on my travel moves; I think I was about 70mm/s.
Thanks for all these tips, exactly what I was looking for!
@Michael_Johnson thanks, will be trying lower temps, seems like the key here.
Funny that, I print PETG at 0.2mm layer heights at 250C, 35mm/sec with 250mm/sec on my UM2. It’s my go to material for precision parts.
@Dani_Epstein When you’re runnin at 250mm/s you need really high temps to melt the plastic fast enough. Probably not getting the filament itself nearly that hot.
If i’m printing PETG very quickly i’ll go high with my temps, but I try to stay as low as possible without affecting the strength of the part.
Ultimately the glass trans temp of PETG is ~77c and 230+ is quite a ways above that, so it needs to drop from 230 to a point where it is no longer soft to be disturbed by the subsequent layer
@Mike_C Sorry, I should have made clear that the 250mm/sec was for travel moves. I have yet to see an FDM printing anything useful at 250mm/sec!
In fact right now I’m printing a small model with a 0.15mm nozzle at 260C. The aperture is so small that the PETG fails to extrude properly unless it’s viscosity is reduced by raising the temperature higher.
It’s also possible that the PETG is damp, and therefore needs more heat to overcome that. I have noticed that before, and got far better results after drying the filament.
@Dani_Epstein Interesting. I’ve found that (on my jhead) that the PETG i use prints best ~225c, but I’ll bump it up high (240+) if I’m doing a big part on a 0.5 nozzle at .3/100mm/s-ish. PETG has a ‘happy point’ where it bonds well and the polymer chains are strong. Seems like if you dip even 1-2c below that point, the parts are probably weaker than PLA.
I agree, 250mm/s surprised me but eh you never know… some people are crazy! I never really print anything over 100mm/s and that is pushing it. Even if your machine can handle those speeds, overhangs get horrible, and plastic just doesn’t lay down pretty.
0.15 nozzle would kill me waiting for prints to finish lol
I use the 0.15mm nozzle for really small precision parts, and everything apart from temps has to be scaled down, which means print times go up! But for really small parts it’s really neccessary.