Pronounced bowing of prints using PETG on MINI+
I'm still learning the basics for FFF printing but I have been printing quite a lot since I got my MINI+ last December and I've gotten a lot of really excellent PETG prints (using Prusament) in that time. Recently an odd problem emerged when printing PETG – but not PC. As shown in the photos, the sides of my prints are bowing inwards between the top and bottom layers of the print. I've searched the internet for a description of why this would happen and how to correct it but I haven't seen anything that is specifically about this type of print problem. I'm printing in an enclosure so the ambient temperature is under my control. It may be too hot or cold - I don't know – but it's always consistent. Has anyone else seen this type of defect and do you know what causes it? Any pointers would be helpful. Thanks!
RE: Pronounced bowing of prints using PETG on MINI+
Is the bottom of this print designed to lift off the plate? Because this looks like good old warping to me, which then can lead to the bend you're seeing. Plenty of ways to address warping: print a brim around the model, use layerneer or magigoo, etc etc.
Also, I'd be weary of printing PLA and PETG inside a closed enclosure. I close the front panel for ABS, PC, etc but leave it open for PLA and PETG after experiencing several examples of printing artifacts.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Pronounced bowing of prints using PETG on MINI+
Thanks fuchsr, but the photo is a bit deceiving in this regard. The print did not lift and adhered perfectly in this case an in others where I've seen this bowing in of the sides. The bowing is also symmetrical. In this print, which is mostly a cylinder, the bowing is consistent around the entire circumference.
RE: Pronounced bowing of prints using PETG on MINI+
How many perimeters and percentage infill did you use? You said it started recently — any changes you made to printer or filament?
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Pronounced bowing of prints using PETG on MINI+
I used the default settings for Prusament PETG (2 perimeters) and this example has no infill as it is a thin wall. I've see this, however, when printing solids which would be 15% gyroid infill.
Unfortunately a lot changed before I noticed this and I haven't been able to isolate the change that started it. I started printing poly carbonate with a hardened .4 nozzle with excellent results in a new enclosure and with a new extruder so the delta is:
- E3D v6 hardened steel 0.4 nozzle
- Hemera bowden-kit extruder (the adapter I designed for the Hemera) 393 steps per milli
- Heated enclosure
Here are three more examples with PETG, PLA, and PC+cf:
RE: Pronounced bowing of prints using PETG on MINI+ (solved)
After experimenting with the problem I found it was the enclosure my printer was in. Even with one door open it was too insulating and heat was building up causing the bowing when using PETG. By printing with both doors open and with a ventilation fan running my printer returned to its previous, excellent, performance.
So, lessons learned; when designing an enclosure you need to accommodate both heating for materials like PC, and cooling, for materials like PETG and PLA.
RE: Pronounced bowing of prints using PETG on MINI+
Yay, I was right! 🙂 Glad you found the culprit.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Pronounced bowing of prints using PETG on MINI+
After experimenting with the problem I found it was the enclosure my printer was in. Even with one door open it was too insulating and heat was building up causing the bowing when using PETG. By printing with both doors open and with a ventilation fan running my printer returned to its previous, excellent, performance.
So, lessons learned; when designing an enclosure you need to accommodate both heating for materials like PC, and cooling, for materials like PETG and PLA.
This is a common issue. I never use the enclosure unless the filament requires it. TPU, PETG, and PLA do not need it.
--------------------
Chuck H
3D Printer Review Blog