If only there was some way I could have known to try this sooner! /s
Story: I wanted to try printing with petg, since I’ve read how much easier it is. But with a new roll I just had a really hard time. Lots of stringing, poor adhesion, and it just seemed like no amount of my usual fiddling would really make it better.
Somewhere I read that even new filament can benefit from drying, because maybe it wasn’t stored in the best way, or maybe it’s older than you think. I also read about putting the roll on the print bed, heating it up and covering it for a long time, since I don’t have a filament dryer. I did that for about half a day, and then sealed the roll in a ziptop bag with a silica packet because I needed a break from it. A week later and, it seems much better!?
Either the drying, the break, or something else seems to have helped a lot! Happy printing everyone.
PETG is truly a pain!! You’d think with a plastic used in water bottles, it would do better with moisture. I recommend the brand CC3D if you want something reliable (and ultra cheap!) Also remember that PETG needs more room between the nozzle and the build plate (higher z offset) so that the filament doesn’t stick to the nozzle and make a mess :)
@galaxi
@zipsglacier
Drying is part of the process when raw plastic pellets are used in injection molding. The only reason it’s not more common in 3DP is that common materials like PLA and ABS arent particularly hygroscopic. PETG is slightly more hygroscopic, but materials like TPU, PET, nylons, etc are highly hygroscopic and definitely need drying to print well.
This is one of those pieces of 3DP lore that isn’t correct. If Z offset is set accurately, it doesn’t need to be changed for any material, but extrusion multiplier/flow does.
The reason why bumping z offset bandaids the problem is because PETs are highly incompressible, i.e., they don’t respond well to being squeezed and will displace under pressure. Raising the z offset means you’re putting the same amount of material into a larger physical volume. This effectively lowers EM for the first layer, but introduces accuracy issues in the rest of the print.
Instead, it’s better to make sure z offset is dead on accurate and then adjust EM down so that flow is correct throughout the print.
Think about what happens to water if it’s heated above 100C… it turns into steam! The more water there is in the plastic the more steam there will be, causing the various issues like bubbling. The release of steam also means some of the heat is not being absorbed by the filament, leading to temperature issues as it exits the nozzle